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Either way, they are kinda of old and a reman set is so cheap, I'd do it just to get the crud out. See image below.
I'd do a couple of things. Send the Cold Start Injector out for service since they do have build up. Next, check the coolant temperature sensor. Scan it so you know what the ECM sees and hit the sensor with an infrared thermometer so you know that it is somewhat consistent. What you describe could be the injectors not doing the job right or the temp sensors are not quite right or the IAC isn't as good as it should be. If it is the IAC, the cure is to clean it and if that works, life is good. Take the TB off. Remove the top plate, the IAC solenoid and the IAC housing. Clean passages. Clean the IAC pintle with a gentle spray of brake cleaner and GENTLY wipe the pintle off. Reassemble with fresh gaskets. Also, check the IAC counts with the scanner once it has reached stable operating temps and everything but the motor is off. Should be around 20 to 30 counts.
So I already did replace the coolant temp sensor when I flushed the system. I pulled the IAC valve and cleaned it as well. I cleaned the throttle blades, but not any other passages. There was really not much to clean....
So I already did replace the coolant temp sensor when I flushed the system. I pulled the IAC valve and cleaned it as well. I cleaned the throttle blades, but not any other passages. There was really not much to clean....
Dont have a thermometer nor a scanner...
It does sound like it is high and the ECM is compensating. Either way, a scanner will tell us what the command idle speed is and what the RPM really is. It does sound like there is extra air coming in and the ECM is slowly trying to get it to whatever the program wants.
It does sound like it is high and the ECM is compensating. Either way, a scanner will tell us what the command idle speed is and what the RPM really is. It does sound like there is extra air coming in and the ECM is slowly trying to get it to whatever the program wants.
Yea, I'm not certain... Its only when I first start the car and its dead cold.... If I never touch the throttle, it operates perfectly..... you would never detect a problem.... it runs, idles and slowly decreases rpm(about 1000/900 down to 650/700) as it warms up as it should. Jump in and take off,,,, everything is normal.
Im going to check the timing tomorrow and see where its at. This whole thing started the other day when I noticed some pretty bad ping under heavy load. Not from a dead stop, but after Im cruising pretty well, I hammed down and it pings.... never noticed before.
My guesses are timing, injectors, FPR, or now that everyone is saying dont use 91 octane, maybe the gasoline.... this is exactly contrary to how I understand higher octane gas works.... but its worth a fill up of 87 I guess....
Yea, I'm not certain... Its only when I first start the car and its dead cold.... If I never touch the throttle, it operates perfectly..... you would never detect a problem.... it runs, idles and slowly decreases rpm(about 1000/900 down to 650/700) as it warms up as it should. Jump in and take off,,,, everything is normal.
Im going to check the timing tomorrow and see where its at. This whole thing started the other day when I noticed some pretty bad ping under heavy load. Not from a dead stop, but after Im cruising pretty well, I hammed down and it pings.... never noticed before.
My guesses are timing, injectors, FPR, or now that everyone is saying dont use 91 octane, maybe the gasoline.... this is exactly contrary to how I understand higher octane gas works.... but its worth a fill up of 87 I guess....
Car has 31 years on it, but only 35k miles...
If I understand you correctly, you are saying YOU didn't detect anything amiss. It doesn't tell me if the ECM compensated for it or not.
Could be bad gas or dirty injectors or FUBARed injectors. Hard to say at this point. My understanding is that the Multec injectors don't tolerate ethanol well. Coils are fuel cooled and ethanol eats away at the insulation. Run the gas down to the end and fill up with fuel from a good source or another place. See what the scanner finds.
Higher octane resists auto ignition better. Not totally sure about the increase in starting efforts.
Base timing was off at about 8*.... now at 6* BTDC... Havent had a chance to test drive.
What spark plugs are you guys using in an iron head L98?
FWIW, in my 85, i'm running NGK G-Power Platinum Spark Plugs, number UR5GP/3547. no issues.
BTW, my base timing at 7°, and I flip back and forth between plus and premium. no reason, just something I do, and to be honest, I can't tell any difference -
Base timing was off at about 8*.... now at 6* BTDC... Havent had a chance to test drive.
What spark plugs are you guys using in an iron head L98?
8* is perfect. Mine runs better all the way around at 8 vs 6.
NGK is what I run in almost everything.
Run spark plug: Part no. UR4, stock no. 6630 for an iron head.
8* is perfect. Mine runs better all the way around at 8 vs 6.
NGK is what I run in almost everything.
Run spark plug: Part no. UR4, stock no. 6630 for an iron head.
Maybe later after he gets this sorted out but till then, I'd run stock values so we have less variables.
Well I hope the 6* helps.... Its pinging bad under load at 8* Like I said, not from a dead stop or under normal driving conditions... that's whats funny, car runs excellent and has great throttle response.... starts well cold, but the 2 things I am having an issue with are the ping under load when I hammer it while already moving.... then the harder than normal restart after it sits and gets heat soaked. I'm leaning harder towards injector related. The other thing I thought was maybe ICM..... for the harder restart issue.
Also, I am at 5300' altitude if that helps determine anything for where the timing should/could be.
Well I hope the 6* helps.... Its pinging bad under load at 8* Like I said, not from a dead stop or under normal driving conditions... that's whats funny, car runs excellent and has great throttle response.... starts well cold, but the 2 things I am having an issue with are the ping under load when I hammer it while already moving.... then the harder than normal restart after it sits and gets heat soaked. I'm leaning harder towards injector related. The other thing I thought was maybe ICM..... for the harder restart issue.
Also, I am at 5300' altitude if that helps determine anything for where the timing should/could be.
I'm not a fan of turning up the timing on the distributor. I'd rather have it done in the ECM. Either way, I doubt 2 degrees will do that much so as to have it ping. Sounds like a fuel issue but check everything out with the scanner. See if the O2 is lazy and the ECT is right.
I'm not a fan of turning up the timing on the distributor. I'd rather have it done in the ECM. Either way, I doubt 2 degrees will do that much so as to have it ping. Sounds like a fuel issue but check everything out with the scanner. See if the O2 is lazy and the ECT is right.
I dont have a scanner or access to one.... wish I did.
Update: So I took it out for a spin tonight and no pinging at all... I cant imagine how 2* made that much difference..... but I TRIED to load it to and it wouldn't ping.
I honestly expected the power to feel less than it was, but I could tell no difference.
I also pumped $25 of 87 octane in the tank, but after my test drive and on my way back up to the house.
The only real difference between tonight and a couple days ago was the ambient temps. Tonight is about 42* The other day it was 77* The coolant was the same though around 160-165*
Before setting the timing today at lunch, I did not check or clear codes. After I was done setting the timing I did disconnect the battery for a minute or two as described in the FSM. Is it possible I had a code stored that was affecting timing and now its not?
Damn it, I hate an intermittent issue.... or one that fixes itself... Im still planning on changing plugs to a solid copper core I think, and I still want to do the injectors.... if nothing else to have better technology.
I was looking at Ecklers and the FPR diaphragm kit is $200. Can that be true? Seriously???
The DA (air) change affected you car WAY more than 2* timing. If you go back and do the math, what time you were driving, and figure out what the DA was both times i bet it was a 2-3000’ difference. I’ll bet you dollars to doughnuts thats your ‘intermittent fix’.
Also instead of pumping 87 into the tank find some pure gas (ranges 89-91) run a couple of tanks through it and report back.
Run the plugs I posted and gap them down to about .040
The DA (air) change affected you car WAY more than 2* timing. If you go back and do the math, what time you were driving, and figure out what the DA was both times i bet it was a 2-3000’ difference. I’ll bet you dollars to doughnuts thats your ‘intermittent fix’.
Also instead of pumping 87 into the tank find some pure gas (ranges 89-91) run a couple of tanks through it and report back.
Run the plugs I posted and gap them down to about .040
Ok, what is DA? I dont think I can find any gas without ethanol in it.... if thats what you mean by pure gas Its winter blend time here in Colorado.... right now Im using NGK 3547 plugs...
Ok, what is DA? I dont think I can find any gas without ethanol in it.... if thats what you mean by pure gas Its winter blend time here in Colorado.... right now Im using NGK 3547 plugs...
1) DA= density altitude
2) I have no clue what those plugs fit but they are no where on NGK’s catalog for your car.
3) Acorn Gas and South Shore Marina in Pueblo.......don’t know if thats close to you.
1) DA= density altitude
2) I have no clue what those plugs fit but they are no where on NGK’s catalog for your car.
3) Acorn Gas and South Shore Marina in Pueblo.......don’t know if thats close to you.
So as far as the DA.... I assume nothing I can do there....
So as far as the DA.... I assume nothing I can do there....
That station is about 45 miles from me....
ugh facepalm.....corvette owners on forums! no you cant do anything about the weather but you can figure out the DA for both days and get a better understanding on why your car ran differently on the the two days you spoke about.
ugh facepalm.....corvette owners on forums! no you cant do anything about the weather but you can figure out the DA for both days and get a better understanding on why your car ran differently on the the two days you spoke about.
I dont think I can find any gas without ethanol in it.... if thats what you mean by pure gas Its winter blend time here in Colorado.... right now Im using NGK 3547 plugs...
I think your bigger concern should be to find a gas station that has fresh gas. IOW, avoid the Mom & Pop stores. Get something with heavy traffic instead of a car every 2 hours. Ethanol has been talked like it is asking someone to take a dump in your tank. If you were having your boat sit at the marina in the water all day long, it might be an issue. Otherwise, IMO, just get fresh gas and forget it. I used to live where they had no ethanol in 93 octane. Didn't seem to help mileage much, if any at all.
As to plugs, get whatever NGK recommends. Install them. Run the car and night and spray a fine mist of water around the wires to see if they are leaking.
