89 C4 Base Coupe Idle Issue past 200F
09-24-2017, 09:43 AM
#21
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I will check it with a standard air filter and see what she does.
Right now I am guessing that I should check or replace:
MAT sensor
Timing
Coolant
Coolant Temp Sensor
O2 Sensor
EGR System
IAC (possibly)
and just go hog wild on vacuum lines since most are original from the factory
The biggest symptoms are O2 reading lean. Rough idle, but only after 200F+ of which the car runs fine if I remove one vacuum hose on the plenum that runs to the back cylinder near the dizzy, but under the plenum. (Definitely not a repair. A band - aid masking a massive issue somewhere at best). Smoke behind passenger side block when car is pushed when cold, but shows no sign of oil/fluid or stains...
Ran some tests last night. The BLM is reading about 7 after 30 minutes of rough idle. The Fuel Trim reading starts at 128 (Research shows this is the equivalent to 0 with modern ODBII), but will drop to 106. Which would be -22 if it were an OBDII system.
MAF remained pretty consistent, which it should have since the car wasn't moving.
MAT remained all over the place, which it shouldn't have since the car wasn't moving. It's coldest reading was nearly -50F in a controlled 80F environ. I am assuming it is gone.
The O2 only bounced around .45 the entire time. Highest was .6 lowest was .1.
Like clock work 200F hits and the car sounds like it "relaxes" then starts hunting with an occasional jitter when she nearly drops off. Like Rocky mid match. Then snaps back and starts hunting. She never revs past 700. Just hangs around 600 then falls to 400, then jumps to 700, then bounces between 500 to 600, drops to 400 after about 10 seconds, then bounces back up again.
I do appreciate all the information and help guys. I didn't even think the K&N could mess with the MAF, but it would make sense with oil content in the air with such a small surface area in the sensor to get contaminated. It was in the car when I bought it so never thought about it.
Occasionally her and I do "snow driving". I do love leaving little donuts for the snow angels. lol
I will report back after I have had a good garage day here soon. Thank you for the info. I was pretty dead set on the EGR being the culprit, but now I am seeing a lot of smaller stuff could actually cause the same symptoms.
This thread will be helpful to someone else restoring an 89.
Right now I am guessing that I should check or replace:
MAT sensor
Timing
Coolant
Coolant Temp Sensor
O2 Sensor
EGR System
IAC (possibly)
and just go hog wild on vacuum lines since most are original from the factory
The biggest symptoms are O2 reading lean. Rough idle, but only after 200F+ of which the car runs fine if I remove one vacuum hose on the plenum that runs to the back cylinder near the dizzy, but under the plenum. (Definitely not a repair. A band - aid masking a massive issue somewhere at best). Smoke behind passenger side block when car is pushed when cold, but shows no sign of oil/fluid or stains...
Ran some tests last night. The BLM is reading about 7 after 30 minutes of rough idle. The Fuel Trim reading starts at 128 (Research shows this is the equivalent to 0 with modern ODBII), but will drop to 106. Which would be -22 if it were an OBDII system.
MAF remained pretty consistent, which it should have since the car wasn't moving.
MAT remained all over the place, which it shouldn't have since the car wasn't moving. It's coldest reading was nearly -50F in a controlled 80F environ. I am assuming it is gone.
The O2 only bounced around .45 the entire time. Highest was .6 lowest was .1.
Like clock work 200F hits and the car sounds like it "relaxes" then starts hunting with an occasional jitter when she nearly drops off. Like Rocky mid match. Then snaps back and starts hunting. She never revs past 700. Just hangs around 600 then falls to 400, then jumps to 700, then bounces between 500 to 600, drops to 400 after about 10 seconds, then bounces back up again.
I do appreciate all the information and help guys. I didn't even think the K&N could mess with the MAF, but it would make sense with oil content in the air with such a small surface area in the sensor to get contaminated. It was in the car when I bought it so never thought about it.
Occasionally her and I do "snow driving". I do love leaving little donuts for the snow angels. lol
I will report back after I have had a good garage day here soon. Thank you for the info. I was pretty dead set on the EGR being the culprit, but now I am seeing a lot of smaller stuff could actually cause the same symptoms.
This thread will be helpful to someone else restoring an 89.
09-24-2017, 10:16 AM
#22
Zen Vet Master Level VII
The biggest symptoms are O2 reading lean. Rough idle, but only after 200F+ of which the car runs fine if I remove one vacuum hose on the plenum that runs to the back cylinder near the dizzy, but under the plenum.
MAT remained all over the place, which it shouldn't have since the car wasn't moving. It's coldest reading was nearly -50F in a controlled 80F environ. I am assuming it is gone.
The O2 only bounced around .45 the entire time. Highest was .6 lowest was .1.
Like clock work 200F hits and the car sounds like it "relaxes" then starts hunting with an occasional jitter when she nearly drops off. Like Rocky mid match. Then snaps back and starts hunting. She never revs past 700. Just hangs around 600 then falls to 400, then jumps to 700, then bounces between 500 to 600, drops to 400 after about 10 seconds, then bounces back up again.
.
MAT remained all over the place, which it shouldn't have since the car wasn't moving. It's coldest reading was nearly -50F in a controlled 80F environ. I am assuming it is gone.
The O2 only bounced around .45 the entire time. Highest was .6 lowest was .1.
Like clock work 200F hits and the car sounds like it "relaxes" then starts hunting with an occasional jitter when she nearly drops off. Like Rocky mid match. Then snaps back and starts hunting. She never revs past 700. Just hangs around 600 then falls to 400, then jumps to 700, then bounces between 500 to 600, drops to 400 after about 10 seconds, then bounces back up again.
.
Your symptoms seem consistent (to me) with your Coolant empetature sensor being off. You car seems to run fine when cold, hit 200 and everything goes to hell. The hunting idle, vacuum leak smoothing all tell me that your engine thinks it is cold when it is not.
It is Sunday. Run to Auto Zone and swap a $15 Coolant Sensor and I bet your follow on tests will all be different and more in spec. Do not throw any more parts until you swapped one of the most basic/important sensors on your engine.
Last edited by billschroeder5842; 09-24-2017 at 10:17 AM.
09-24-2017, 04:02 PM
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Well, I opened back up the engine to get to the EGR just to check its condition. Ya... so out of the two bolts the one at passenger front came up with out much issue. Driver side back... well... I custom bent a 3/8 box wrench to try to get it off. I cannot exert enough force, which is impressive for me since I did hardwood floors for 6 years as a edger/hand sander and am a bass player with monster strings, so playing mercy is normal for me. Nope, the bolt wouldn't budge. I did hand check the EGR by pressing the valve in from the inside and it took a bit of squeezing, but it finally moved making a "whoosh" sound. Did it a couple of more times and it was really easy compared to the first time where it felt solid. I am going to guess it was stuck. Will have to go to a shop to get it cleaned or changed. I lack the cool tools to make complete it. Two hours of attempts and only a homemade 3/8 offset box wrench to show for it.
Also, update. The hose that was leaking was probably my fault. I realized the clamp wasn't all the way tightened. That being said, when I took back apart the throttle body and removed the hoses from it, the ones carrying coolant felt like they had sand in them where they contacted the metal and up to the flange pieces on the metal side only, nothing in the hose...
I have been halted in progress though. Will need to pick up a CCV(?) hose. (Hose on the passenger side valve cover that connects to the throttle body) The one there was torn and was held together with electrical tape... (Might not be helping with the idle?) When I went to remove it, it ripped again, just fell apart like sponge. Also, it had oil in it... it that normal?
Strangely enough the coolant valley in the throttle body was actually cleaner than the throttle body by a long shot. No discoloration, no nothing, not even moisture build up. Made the rest of it look like a mess.
Thinking about replacing the IAC. The entire thing is covered in soot and feels pretty stiff to the hands. Also, it seems to rattle when gently shaken. I am thinking that is not normal.
The rest of the small hoses seem stable and solid, but are the original (to my knowledge) hard plastic ones. Could be leaking, but am not sure. Like Alkim said, propane may not show up small leaks.
Anyway, figured I would give you guys an update on progress today.
I am also noticing the coolant is green. Like really really green. Doesn't look 50/50. Looks like 100% anti-freeze. I know water is a better coolant. I might get in and correct that here in the very near future.
This will be a very clean L98 since I am detailing everything as I go and wearing gloves when I do reassemble it.
Thank you guys for the suggestions and help. It really is appreciated. I was running out of books and threads to read about potential suspects. My favorite thing about the Corvette Family is how helpful and knowledgeable everyone is. Thank you guys for all the help. Really, it means a lot to me.
I will definitely keep you guys updated on how progress goes during reassembly. I am using the opportunity now to recheck everything as it goes back together, almost with a fine tooth comb.
Also noticed a missing torques bolt off of one of the fuel rails at the passenger side engine underneath the throttle body. It seems to be one of 2 holding the bracket there. Not sure if both are important, but a good rule of thumb is that if the company put it there, it has a purpose.
Also, update. The hose that was leaking was probably my fault. I realized the clamp wasn't all the way tightened. That being said, when I took back apart the throttle body and removed the hoses from it, the ones carrying coolant felt like they had sand in them where they contacted the metal and up to the flange pieces on the metal side only, nothing in the hose...
I have been halted in progress though. Will need to pick up a CCV(?) hose. (Hose on the passenger side valve cover that connects to the throttle body) The one there was torn and was held together with electrical tape... (Might not be helping with the idle?) When I went to remove it, it ripped again, just fell apart like sponge. Also, it had oil in it... it that normal?
Strangely enough the coolant valley in the throttle body was actually cleaner than the throttle body by a long shot. No discoloration, no nothing, not even moisture build up. Made the rest of it look like a mess.
Thinking about replacing the IAC. The entire thing is covered in soot and feels pretty stiff to the hands. Also, it seems to rattle when gently shaken. I am thinking that is not normal.
The rest of the small hoses seem stable and solid, but are the original (to my knowledge) hard plastic ones. Could be leaking, but am not sure. Like Alkim said, propane may not show up small leaks.
Anyway, figured I would give you guys an update on progress today.
I am also noticing the coolant is green. Like really really green. Doesn't look 50/50. Looks like 100% anti-freeze. I know water is a better coolant. I might get in and correct that here in the very near future.
This will be a very clean L98 since I am detailing everything as I go and wearing gloves when I do reassemble it.
Thank you guys for the suggestions and help. It really is appreciated. I was running out of books and threads to read about potential suspects. My favorite thing about the Corvette Family is how helpful and knowledgeable everyone is. Thank you guys for all the help. Really, it means a lot to me.
I will definitely keep you guys updated on how progress goes during reassembly. I am using the opportunity now to recheck everything as it goes back together, almost with a fine tooth comb.
Also noticed a missing torques bolt off of one of the fuel rails at the passenger side engine underneath the throttle body. It seems to be one of 2 holding the bracket there. Not sure if both are important, but a good rule of thumb is that if the company put it there, it has a purpose.
Last edited by Wooddavid88; 09-24-2017 at 04:09 PM.
09-24-2017, 04:05 PM
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You are getting a lot of "arm chair quarter backing" so here is my latest play calling...
Your symptoms seem consistent (to me) with your Coolant empetature sensor being off. You car seems to run fine when cold, hit 200 and everything goes to hell. The hunting idle, vacuum leak smoothing all tell me that your engine thinks it is cold when it is not.
It is Sunday. Run to Auto Zone and swap a $15 Coolant Sensor and I bet your follow on tests will all be different and more in spec. Do not throw any more parts until you swapped one of the most basic/important sensors on your engine.
Your symptoms seem consistent (to me) with your Coolant empetature sensor being off. You car seems to run fine when cold, hit 200 and everything goes to hell. The hunting idle, vacuum leak smoothing all tell me that your engine thinks it is cold when it is not.
It is Sunday. Run to Auto Zone and swap a $15 Coolant Sensor and I bet your follow on tests will all be different and more in spec. Do not throw any more parts until you swapped one of the most basic/important sensors on your engine.
09-24-2017, 05:34 PM
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09-24-2017, 06:57 PM
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Very true. It is the 3rd car I have owned and the newest "old car" I have messed with. It's also the first V8 I have gotten to mess with. Its a very different beast from both my old 02 Saturn SC1 and my (gasp) 68 Ford F100 Long Bed.
Its like the dawn of the computerized cars. Me being a computer techy hobbyist, a lot of this is kinda ancient by todays' standards. Just the way I like it to tinker with.
Its like the dawn of the computerized cars. Me being a computer techy hobbyist, a lot of this is kinda ancient by todays' standards. Just the way I like it to tinker with.
09-24-2017, 09:49 PM
#27
Team Owner
Thinking about replacing the IAC. The entire thing is covered in soot and feels pretty stiff to the hands. Also, it seems to rattle when gently shaken. I am thinking that is not normal.
The rest of the small hoses seem stable and solid, but are the original (to my knowledge) hard plastic ones. Could be leaking, but am not sure. Like Alkim said, propane may not show up small leaks.
I am also noticing the coolant is green. Like really really green. Doesn't look 50/50. Looks like 100% anti-freeze. I know water is a better coolant. I might get in and correct that here in the very near future.
Also noticed a missing torques bolt off of one of the fuel rails at the passenger side engine underneath the throttle body. It seems to be one of 2 holding the bracket there. Not sure if both are important, but a good rule of thumb is that if the company put it there, it has a purpose.
The rest of the small hoses seem stable and solid, but are the original (to my knowledge) hard plastic ones. Could be leaking, but am not sure. Like Alkim said, propane may not show up small leaks.
I am also noticing the coolant is green. Like really really green. Doesn't look 50/50. Looks like 100% anti-freeze. I know water is a better coolant. I might get in and correct that here in the very near future.
Also noticed a missing torques bolt off of one of the fuel rails at the passenger side engine underneath the throttle body. It seems to be one of 2 holding the bracket there. Not sure if both are important, but a good rule of thumb is that if the company put it there, it has a purpose.
I would check it with a scanner since it is more precise than propane.
Before you speculate with color, why not use the coolant gauge and see what it is?
I would say it is important as it holds the rails down which keeps the injectors in place despite the 40 psi of fuel that is trying to separate them.
09-24-2017, 09:50 PM
#28
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That is why I always say you need to figure out what the budget is before you buy the car. Have a PDI and always add something else for this sort of thing. If the EGR bolt breaks off and you can't get it out, figure on a new manifold or a machine shop to drill it out unless you think you can do that.
09-24-2017, 10:27 PM
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That is why I always say you need to figure out what the budget is before you buy the car. Have a PDI and always add something else for this sort of thing. If the EGR bolt breaks off and you can't get it out, figure on a new manifold or a machine shop to drill it out unless you think you can do that.
Already ordered parts. Will get back into it when they arrive. Grabbed an O2 sensor, coolant sensor, and grabbed a new MAT sensor. Strangely enough the MAT sensor I pulled is nearly identical to the Coolant Sensor I purchased. Not sure if that was suppose to be in the Plenum or not... I suspect tampering unless that is just what the old MAT sensor were, the same as the coolant sensors.
Well, this project got a lot bigger this week. Just was checking the EGR and MAT wires under the plenum and wham, lots and lots to do now.
I do love me some projects.
Last edited by Wooddavid88; 09-24-2017 at 10:39 PM.
09-24-2017, 10:37 PM
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And just on the clear side. I didn't strip the head of the bolt for the EGR. When it didn't budge I just let it be. Figured I would just hire a dealership to come in and mess with it with some crazy voodoo tool they have that I have probably never heard of and just loosen the bolt in a couple of seconds. Figured better safe than sorry.
09-25-2017, 09:04 AM
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09-28-2017, 11:54 AM
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Update: Later today I should be getting the CCV hose, MAT sensor, and EGR heat shield. I already grabbed new gaskets for the plenum and the throttle body. Cleaned the IAC to a nice shine. Released the stuck EGR by hand where now it moves and makes a vacuum whooshing sound like new ones do. replaced the coolant temp sensor which the old one was very dirty and covered in like a tan slime?
Anyway... I will be updating either tonight or tomorrow to let you guys know how it goes.
Also, the MAT sensor I guess is also known as the Intake Air Temperature sensor in some shops. The one that I removed from the plenum looked to be the same model as the coolant temp sensor, but the one that Eckler's sold me looks different. It has more of an open tip than the solid tip of the coolant sensor. I am going to assume that someone put the wrong temp sensor in the plenum.
Also, swapped the O2 sensor. The one that was replaced was green. Like corroded green. I think it was time for it to be retired to the parts drawer.
Anyway... I will be updating either tonight or tomorrow to let you guys know how it goes.
Also, the MAT sensor I guess is also known as the Intake Air Temperature sensor in some shops. The one that I removed from the plenum looked to be the same model as the coolant temp sensor, but the one that Eckler's sold me looks different. It has more of an open tip than the solid tip of the coolant sensor. I am going to assume that someone put the wrong temp sensor in the plenum.
Also, swapped the O2 sensor. The one that was replaced was green. Like corroded green. I think it was time for it to be retired to the parts drawer.
09-28-2017, 02:00 PM
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Right to left. New MAT sensor, sensor out of plenum (MAT?), old coolant temp sensor. <br/><br/>the new one has small holes in the tip. hard to tell in the picture.
09-29-2017, 07:02 PM
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Alright. Update:
Last night I took her for a cruise on the highway for about 20 minutes, did some city driving.
So far she is doing really well now. The rough idle has gone away for the most part.
I have found, what I think might be the final issue and will be a new thread for sure. I noticed a bit more smoke that normal and was able to track it down to the Distributor. While the car was off I had noticed that the dizzy was different then where it had been before. Note, I have never removed or loosened this part. It is loose enough that I can move it by hand. Like it is finger tight...
Pretty sure I will be taking her in for a timing issue.
But, info read outs showed no faults.
O2 is reading right around .45v and is much more responsive to fuel/air mixtures now. It jumps around almost immediately when gas pedal is pressed.
IAC is hanging right between 25 and 40 at nearly every light and when in park/neutral. (Before it was 160 nearly all the time)
MAT sensor is reading roughly within 5F to 10F of the Coolant Temp Sensor. (Before it would waver between -40F and 300F regardless of coolant sensor info)
RPMs are hanging right at 600 to 700. They waver a bit, but nothing like before and this remains the same regardless of temperature. Let her warm all the way up 235F and it didn't change. She still stumbles when slowing down. I am wondering if it is timing related.
Also, repaired the rubber gasket that connects to the vacuum hose to the brake booster. Noticed it was leaking, but only at certain angles.
No check engine lights. Smooth (ish) running. Will get the car's timing checked now and make sure the distributor is re-locked. Found online that a loose distributor can cause a vacuum leak and a bunch of timing issues. The engine can't move it on it's own. (Tested with a silver sharpie and a quick hard highway ride and it didn't move at all), but I do need to get it checked out by a pro.
I wanted to thank you all for the help and suggestions. I am pretty sure a good chunk of the problems were compounded to cause a massive issue because of the cars age and most of these I would have never thought about.
And this is why the Corvette Community is awesome.
Last night I took her for a cruise on the highway for about 20 minutes, did some city driving.
So far she is doing really well now. The rough idle has gone away for the most part.
I have found, what I think might be the final issue and will be a new thread for sure. I noticed a bit more smoke that normal and was able to track it down to the Distributor. While the car was off I had noticed that the dizzy was different then where it had been before. Note, I have never removed or loosened this part. It is loose enough that I can move it by hand. Like it is finger tight...
Pretty sure I will be taking her in for a timing issue.
But, info read outs showed no faults.
O2 is reading right around .45v and is much more responsive to fuel/air mixtures now. It jumps around almost immediately when gas pedal is pressed.
IAC is hanging right between 25 and 40 at nearly every light and when in park/neutral. (Before it was 160 nearly all the time)
MAT sensor is reading roughly within 5F to 10F of the Coolant Temp Sensor. (Before it would waver between -40F and 300F regardless of coolant sensor info)
RPMs are hanging right at 600 to 700. They waver a bit, but nothing like before and this remains the same regardless of temperature. Let her warm all the way up 235F and it didn't change. She still stumbles when slowing down. I am wondering if it is timing related.
Also, repaired the rubber gasket that connects to the vacuum hose to the brake booster. Noticed it was leaking, but only at certain angles.
No check engine lights. Smooth (ish) running. Will get the car's timing checked now and make sure the distributor is re-locked. Found online that a loose distributor can cause a vacuum leak and a bunch of timing issues. The engine can't move it on it's own. (Tested with a silver sharpie and a quick hard highway ride and it didn't move at all), but I do need to get it checked out by a pro.
I wanted to thank you all for the help and suggestions. I am pretty sure a good chunk of the problems were compounded to cause a massive issue because of the cars age and most of these I would have never thought about.
And this is why the Corvette Community is awesome.
06-01-2022, 04:03 AM
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I have read many forums here and the impressive "Google" and "YouTube". None have been my exact issue. Also talked with a Corvette Club that has helped a lot too, but...
I have an 89 Corvette. Rough Idle, surging when gas pedal is barely pressed when going down street @ 25 to 35 mph and at stop lights. Car seems to stabilize around 600 - 700 when cold up to 200F, which seems to be around 40F above the 160F required for Closed Loop. At that magical number the engine starts pumping, stumbling, and acting funny driving or in park/neutral. Also, when engine is warm, seems to try to drop off when slowing down to a light. RPM will go below 500 then "catch" itself and pop back up.
I have replaced:
Injectors
Sparkplugs, wires, rotor, and, cap
Cats (very clogged),Y pipe and mufflers (rusted out completely)
Oil, oil filter, transmission oil and filter
Gaskets on Plenum and throttle body and manifold.
Changed PCV Valve and Gaskets.
Oil Pressure sensor.
Throttle Position Sensor (And set to exactly .54v)
Cleaned Throttle Body
The car used to completely stall before all these parts were checked, tested, and found faulty before finally retiring them.
Checked for vacuum leaks and finding nothing. No changes in the RPM or stumble.
Strange observations. When engine is warming up around 150F, if I push the car up to 1500rpm, neutral or drive, smoke, almost like burned oil, appears, then leaves quickly from behind the L98. Investigation revealed nothing. Not even oil.
Car has 78k miles total.
After 200F the car sounds like it starts sucking in a bunch of air through the air filter. As if some one has turned on compressed air and blasting it through the MAF.
Also, after resetting the ECM (battery disconnected for around an hour, then plugged back in) did a test drive and WinALDL reports O2 error, but soon went away.
Driving on the highway seems to go smoothly, but with get a service light that comes on for a second after around 20 minutes of driving at 55mph. It then turns off very quickly, but the only saved code is the O2 claiming a Lean condition.
I have checked for vacuum leaks, but am finding none. Nothing seems to stumble it before 200F.
Past the O2 reading I am getting no other errors.
Last strange observation is that removing the hose off of the plenum that goes to the EVP container seems to let the engine stabilize at 600rpm over 200F.
No smoke coming out of exhaust. No smoke coming out around cats or manifolds. No oil on ground.
If anyone has any ideas I am all years. Been after this one for a while.
After cat replace, injector replace, and plugs, the car is driving worlds better than when I got her. Also, 5k miles on the old plugs and they were just brown, nothing strange. Not black, not white, not blue, nothing out of what manuals claim are normal operation.
This is my first OD1 car. I am used to OBDII and cars from the 60/70s, this is kinda a new beast for me.
Sorry for all the text. Just wanted to make it clear what I have observed and the work done to hopefully narrow down a suspect. Any information would be awesome. I have a manual, but, though useful, hasn't completely solved the issue.
I have an 89 Corvette. Rough Idle, surging when gas pedal is barely pressed when going down street @ 25 to 35 mph and at stop lights. Car seems to stabilize around 600 - 700 when cold up to 200F, which seems to be around 40F above the 160F required for Closed Loop. At that magical number the engine starts pumping, stumbling, and acting funny driving or in park/neutral. Also, when engine is warm, seems to try to drop off when slowing down to a light. RPM will go below 500 then "catch" itself and pop back up.
I have replaced:
Injectors
Sparkplugs, wires, rotor, and, cap
Cats (very clogged),Y pipe and mufflers (rusted out completely)
Oil, oil filter, transmission oil and filter
Gaskets on Plenum and throttle body and manifold.
Changed PCV Valve and Gaskets.
Oil Pressure sensor.
Throttle Position Sensor (And set to exactly .54v)
Cleaned Throttle Body
The car used to completely stall before all these parts were checked, tested, and found faulty before finally retiring them.
Checked for vacuum leaks and finding nothing. No changes in the RPM or stumble.
Strange observations. When engine is warming up around 150F, if I push the car up to 1500rpm, neutral or drive, smoke, almost like burned oil, appears, then leaves quickly from behind the L98. Investigation revealed nothing. Not even oil.
Car has 78k miles total.
After 200F the car sounds like it starts sucking in a bunch of air through the air filter. As if some one has turned on compressed air and blasting it through the MAF.
Also, after resetting the ECM (battery disconnected for around an hour, then plugged back in) did a test drive and WinALDL reports O2 error, but soon went away.
Driving on the highway seems to go smoothly, but with get a service light that comes on for a second after around 20 minutes of driving at 55mph. It then turns off very quickly, but the only saved code is the O2 claiming a Lean condition.
I have checked for vacuum leaks, but am finding none. Nothing seems to stumble it before 200F.
Past the O2 reading I am getting no other errors.
Last strange observation is that removing the hose off of the plenum that goes to the EVP container seems to let the engine stabilize at 600rpm over 200F.
No smoke coming out of exhaust. No smoke coming out around cats or manifolds. No oil on ground.
If anyone has any ideas I am all years. Been after this one for a while.
After cat replace, injector replace, and plugs, the car is driving worlds better than when I got her. Also, 5k miles on the old plugs and they were just brown, nothing strange. Not black, not white, not blue, nothing out of what manuals claim are normal operation.
This is my first OD1 car. I am used to OBDII and cars from the 60/70s, this is kinda a new beast for me.
Sorry for all the text. Just wanted to make it clear what I have observed and the work done to hopefully narrow down a suspect. Any information would be awesome. I have a manual, but, though useful, hasn't completely solved the issue.
