Major Missing Issue!
Thread Starter
Drifting
Joined: Feb 2013
Posts: 1,465
Likes: 12
Major Missing Issue!
Ok so I have delt with alot of missing problems with mt 92 LT1 car but this is new to me. The Car runs great for the first 10 minutes and right as soon as the temp hits 150-160 degrees the thing starts to stumble and run like crap. Its like flipping a switch, She gets warm and bang missing and popping out the exhaust like crazy! I can shut it off, let her cool down a bit and she runs perfect until 150-160 degrees again! What in the world is going on? I have no check engine light either. Any ideas would be greatly appreciated! 
Drifting
Joined: Dec 2007
Posts: 1,647
Likes: 4
From: Argillite KY
It appears that when your engine warms up and is entering closed loop is when the trouble starts. It is possible and I have seen a bad O2 sensor NOT throw a code and cause similar problems to what you're experiencing. The O2 sensors aren't used when the car is cold but once it warms up they will do the controlling. If they are giving improper readings then your car will run like crap.
Le Mans Master
Joined: Feb 2005
Posts: 6,485
Likes: 566
From: Clearwater Florida
It appears that when your engine warms up and is entering closed loop is when the trouble starts. It is possible and I have seen a bad O2 sensor NOT throw a code and cause similar problems to what you're experiencing. The O2 sensors aren't used when the car is cold but once it warms up they will do the controlling. If they are giving improper readings then your car will run like crap.
... Closed loop @ approx. 150* ... Does the exhaust stink ? bad gas ? headers ? exhaust leaks ? A.I.R. Diverter valves ? MAP Sensor ? As I recall , the '92 had oxy sensors on both sides ... check them and take a look at your spark plug coloration , correct plugs ? .......
Thread Starter
Drifting
Joined: Feb 2013
Posts: 1,465
Likes: 12
This is on a modified 383. All the air and smog stuff is gone. Could be a plug issue. I will pull them today. They are new. Not sure If the 02s would cause it to run like that! How can I check them? What about the coolant temp sensor? It was brought up to me. I guess they can do some weird things?
Last edited by smooth1990; Jun 9, 2014 at 10:48 PM.
Le Mans Master
Joined: Dec 2006
Posts: 5,139
Likes: 482
From: H-Town Texas
From reading the clutch post, you are using the LTCC ignition with LS7 coils?
I agree that you have a closed loop issue. With a blown LT1 383, I would imagine it might take some more refined tuning to get things working together. Perhaps another trip to your tuner might be in order, if for anything, they might be able to get a clear picture of what the PCM is seeing and go from there.
I agree that you have a closed loop issue. With a blown LT1 383, I would imagine it might take some more refined tuning to get things working together. Perhaps another trip to your tuner might be in order, if for anything, they might be able to get a clear picture of what the PCM is seeing and go from there.
Drifting
Joined: Dec 2007
Posts: 1,647
Likes: 4
From: Argillite KY
Try this. start with a cold engine. Keep your RPM's around 2000 for the entire warm up time and see if you get the same symptoms. Since you have a modified engine you probably have headers. Headers are a big heat sink and cool exhaust gasses a lot before they reach the collector. If there's a problem with the O2 heater circuit then the sensors won't get hot enough to function properly. Keeping the engine at 2000 should allow them to get to their operating temp of 600 degrees and see if anything changes. If your car doesn't have O2 heaters then this will still tell us something.
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Thread Starter
Drifting
Joined: Feb 2013
Posts: 1,465
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I ran the car today but before I did I changed a couple things. The coolant sensor and I unplugged both 02 sensors and I hooked up the wide band so I could watch it. As soon as the car hit about 160* it was like flipping a switch! Instantly it started missing and the air fuel jumped to 15-17. I'm thinking the opti is crapping out. This is the same tune as last year with the same ignition! The car ran decent last year so i dont think anything changed. Are there any other ideas before i rip the opti out?
Thread Starter
Drifting
Joined: Feb 2013
Posts: 1,465
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I Checked a few more things tonight! I pulled the plugs and they looked terrible but I wasnt suprised due to the way she spits and sputters after it reaches 150 degrees! I also swapped them out with new NGK TR6s. And ran the car at 2500 rpm in 2nd gear and when it reached 150 bang, it did it again!
When the car is at temp and in neutral at idle with no load on it, she idles great and even revs up awesome. It doesnt miss a beat. So its only doing it under load At 150+ degrees. It seems like the warmer it gets, the worse it gets.
I I believe it is either a Tune related problem or the opti spark! does anyone have any other ideas? Would the O2s make it miss that bad? Should I pull them out? They are 1 wire. Is there a way to check them? I have no codes!!!
Thanks guys
When the car is at temp and in neutral at idle with no load on it, she idles great and even revs up awesome. It doesnt miss a beat. So its only doing it under load At 150+ degrees. It seems like the warmer it gets, the worse it gets.
I I believe it is either a Tune related problem or the opti spark! does anyone have any other ideas? Would the O2s make it miss that bad? Should I pull them out? They are 1 wire. Is there a way to check them? I have no codes!!!
Thanks guys
Race Director
Joined: Apr 2002
Posts: 10,036
Likes: 346
From: Anaheim CA
I had a similar issue. The car ran great when cold and started missing like crazy when it got hot. It turned out to be a bad plug wire. It was arcing to nearby metal. I found it by looking at the plug wires in a dark garage.
Le Mans Master
Joined: Dec 2006
Posts: 5,139
Likes: 482
From: H-Town Texas
I really don't think it's the opti. If it were, I would think that it would have more problems regardless of the temp.
From your description, this seems to be 'closed loop' issue, which would involve the pcm and however it was tuned around the emission modifications. But then again, if it's only under load conditions, I wonder about that too.
The one thing on these cars that can cause a major misfire that is temp related is the ignition control module. Perhaps there wasn't enough heat sink grease applied, or it has worn off.
My other thought is fuel related. You said this is a 383 build, did you replace with a higher flowing pump and injectors to meet the added fuel demand? Of course I would have to assume you did, but feel a need to ask.
I think it's strange that your not getting any codes. If your having a misfire condition, the pcm should at least report that via the knock sensor.
From your description, this seems to be 'closed loop' issue, which would involve the pcm and however it was tuned around the emission modifications. But then again, if it's only under load conditions, I wonder about that too.
The one thing on these cars that can cause a major misfire that is temp related is the ignition control module. Perhaps there wasn't enough heat sink grease applied, or it has worn off.
My other thought is fuel related. You said this is a 383 build, did you replace with a higher flowing pump and injectors to meet the added fuel demand? Of course I would have to assume you did, but feel a need to ask.
I think it's strange that your not getting any codes. If your having a misfire condition, the pcm should at least report that via the knock sensor.
Thread Starter
Drifting
Joined: Feb 2013
Posts: 1,465
Likes: 12
I really don't think it's the opti. If it were, I would think that it would have more problems regardless of the temp.
From your description, this seems to be 'closed loop' issue, which would involve the pcm and however it was tuned around the emission modifications. But then again, if it's only under load conditions, I wonder about that too.
The one thing on these cars that can cause a major misfire that is temp related is the ignition control module. Perhaps there wasn't enough heat sink grease applied, or it has worn off.
My other thought is fuel related. You said this is a 383 build, did you replace with a higher flowing pump and injectors to meet the added fuel demand? Of course I would have to assume you did, but feel a need to ask.
I think it's strange that your not getting any codes. If your having a misfire condition, the pcm should at least report that via the knock sensor.
From your description, this seems to be 'closed loop' issue, which would involve the pcm and however it was tuned around the emission modifications. But then again, if it's only under load conditions, I wonder about that too.
The one thing on these cars that can cause a major misfire that is temp related is the ignition control module. Perhaps there wasn't enough heat sink grease applied, or it has worn off.
My other thought is fuel related. You said this is a 383 build, did you replace with a higher flowing pump and injectors to meet the added fuel demand? Of course I would have to assume you did, but feel a need to ask.
I think it's strange that your not getting any codes. If your having a misfire condition, the pcm should at least report that via the knock sensor.
When I pulled the plugs last night number 3&7 on driver side was black as heck and number 4&8 on passenger side where black!!!
Burning Brakes
Joined: Mar 2005
Posts: 800
Likes: 2
How old are the plug wires? Maybe run it in dark and see if there is any arching. I had a truck at one point that would run like crap under load, but idle fine and reg fine in neutral. Turn out the coil wire was arching off intake.
Drifting
Joined: Dec 2007
Posts: 1,647
Likes: 4
From: Argillite KY
Have you checked all the switch and dial settings in the Bailey LTCC box. Have you looked at the diagnostic LED's in the box? Bob's LTCC takes control of the ICM and the pulses from the Opti. I'm not sure why the temp would be a factor though. Is it possible that the tuner just missed the tune?
Thread Starter
Drifting
Joined: Feb 2013
Posts: 1,465
Likes: 12
Ahhhhh!
Have you checked all the switch and dial settings in the Bailey LTCC box. Have you looked at the diagnostic LED's in the box? Bob's LTCC takes control of the ICM and the pulses from the Opti. I'm not sure why the temp would be a factor though. Is it possible that the tuner just missed the tune?
Ok so I have officially ruled out the 02 sensors! I sent my chip that was from the tune for this car last year into a very knowledgeable tuner to have him check the tune out for issues! It turns out that the closed loop in the tune was locked out which essentially locks out the 02 sensors!
So even tho this seams to be a "TEMP" issue, it does not have to do with going into closed loop!!!! I really thought it did considering it starts missing as soon as the car hit 150-160 degrees!
I drove the car again tonight and The same exact thing happend! Its so repeatable its crazy! the thing runs beautiful until it hit operating temp!
I have only a couple of options left to check and they are both expensive! Either the ECu is warming up and causing issues or the OPTI is warming up and causing issues! I am thinking anout changing out the TPS sensor since when I checked it I couldnt get a normal reading but I dont think that would cause a Issue like this! Would it?
I know 3&7 and 4&6 are misfiring when this happens do to the color of the plugs when I pulled them last week. What would cause an Intermittent Miss on 4 cylinders ONLY when the car is warm?
At this point its Change the Opti OR change the ECU!!! What do you guys think? Am I missing something?
Thread Starter
Drifting
Joined: Feb 2013
Posts: 1,465
Likes: 12
I went outside and started the car in the dark to look for arching wires. I did see a couple that were arching and I fixed them But the problem is still there!
I think I want to put the stock wires and coil back on the car and see what it does! maybe the issue is with the LTCC or coils? I guess going back to stock would tell me for sure!
In order to go back to stock I need a diagram of the wiring to the coil! Mine was cut and modified to put the ltcc system in the car. I also need the to find the two plugs that go side by side in the coil. They were cut off and who knows where they ended up!
So if someone could help me out with a wiring diagram or a few pictures of the wiring for the coil in their car, I would greatly appreciate it!
I think I want to put the stock wires and coil back on the car and see what it does! maybe the issue is with the LTCC or coils? I guess going back to stock would tell me for sure!
In order to go back to stock I need a diagram of the wiring to the coil! Mine was cut and modified to put the ltcc system in the car. I also need the to find the two plugs that go side by side in the coil. They were cut off and who knows where they ended up!
So if someone could help me out with a wiring diagram or a few pictures of the wiring for the coil in their car, I would greatly appreciate it!
Last edited by smooth1990; Jun 9, 2014 at 11:43 PM.
Safety Car
Joined: Apr 2011
Posts: 3,660
Likes: 22
is this engine on a charger ??
'cause the mention of 60 lb/hr injectors is a bit MUCH for that displacement.....just a lil.
Part of your problem is that you're FOULING the plugs. Sure, its gonna run ok cold, the cold engine WANTS that extra fuel. BUT once its warm the extra fuel becomes a liability and quickly fouls the spark plugs...hence serious misfiring and burping.
60 lb inj is a LOT even for a blown 383 IMO.
'cause the mention of 60 lb/hr injectors is a bit MUCH for that displacement.....just a lil.
Part of your problem is that you're FOULING the plugs. Sure, its gonna run ok cold, the cold engine WANTS that extra fuel. BUT once its warm the extra fuel becomes a liability and quickly fouls the spark plugs...hence serious misfiring and burping.
60 lb inj is a LOT even for a blown 383 IMO.
Thread Starter
Drifting
Joined: Feb 2013
Posts: 1,465
Likes: 12
is this engine on a charger ??
'cause the mention of 60 lb/hr injectors is a bit MUCH for that displacement.....just a lil.
Part of your problem is that you're FOULING the plugs. Sure, its gonna run ok cold, the cold engine WANTS that extra fuel. BUT once its warm the extra fuel becomes a liability and quickly fouls the spark plugs...hence serious misfiring and burping.
60 lb inj is a LOT even for a blown 383 IMO.
'cause the mention of 60 lb/hr injectors is a bit MUCH for that displacement.....just a lil.
Part of your problem is that you're FOULING the plugs. Sure, its gonna run ok cold, the cold engine WANTS that extra fuel. BUT once its warm the extra fuel becomes a liability and quickly fouls the spark plugs...hence serious misfiring and burping.
60 lb inj is a LOT even for a blown 383 IMO.
Race Director
Joined: Apr 2002
Posts: 10,036
Likes: 346
From: Anaheim CA
Since you mentioned the injectors are at 80% duty cycle, I assume you can data log. Do you see anything weird happening when it starts to miss?
I like to import my data logs into Excel and then graph the various parameters. That will show things that go wacko.
I like to import my data logs into Excel and then graph the various parameters. That will show things that go wacko.
