Rough Idle!!
Thread Starter
Burning Brakes
Joined: May 2006
Posts: 857
Likes: 1
From: Morrisonville Illinios
Thanks alot just what I needed will check it out when I get home this afternoon. I can't say that I have seen it since we have moved a bunch of stuff around with the engine swap but I am sure it there somewhere. It's just a PIA that my FM isn't clear on this and then to see that it is something else. THANKS wro
Le Mans Master
Joined: Feb 2006
Posts: 8,753
Likes: 9
From: Louisiana
Make sure to disconnect the EST wire when setting timing. Other wise the ECM will retard it. Disconnect the EST and loosen the distrubitor hold down bolt and set the timing to 6*BTDC. Once your set, tighten the bolt down and recheck timing. Shut the engine off and connect the EST wire. Start the engine and observe the timing mark. It will be around 18-22* or about 12 o'clock. The check engine soon light will probably be on as Rick stated and you just disconnect the neg battery cable or pull the ECM fuse to reset.
Thread Starter
Burning Brakes
Joined: May 2006
Posts: 857
Likes: 1
From: Morrisonville Illinios
Thanks Again WILL DO!! I am surprise that we have yet to get any wanrning lights or codes yet! This might be because when PCMforLESS didi the chip that they took some of this in consideration but the total run time so far hasn't been about 3-5min a couple of time it is load with the open headers and like I said sounded like it was trying to back fire thru the intake and my daughter was wide eyed
when she saw smoe flames out the headers on the bottom side, but boy did it sound 
just have to figure it out a little more. Thanks gang
when she saw smoe flames out the headers on the bottom side, but boy did it sound just have to figure it out a little more. Thanks gang
Le Mans Master
Joined: Feb 2006
Posts: 8,753
Likes: 9
From: Louisiana
One thought about you being suprised of no SES light. Have you made sure the bulb is good? If the bulb is blown, you might have multiple codes waiting on you. If the light comes on when the key is in the "on" position then you o.k. Let us know how it goes.
Thread Starter
Burning Brakes
Joined: May 2006
Posts: 857
Likes: 1
From: Morrisonville Illinios
The SES does light when ign. is turned on but so far no indication when we are running. Did replace all the lt1 injectors last night they all check good but something is a miss found the 2 that were leaking by. Put 8 from my other L98 that I know are good and maintaing 42psi when key is off. Way better that earlier they are only 22psi (off 87' ) but should get me buy to run just not reaching full potental. Pushing hard to get this running and make it to FUNFEST
my 17yr old is frothing at the bit to take it out and over for me so is the daughter(12) allready gear head. WRO
my 17yr old is frothing at the bit to take it out and over for me so is the daughter(12) allready gear head. WRO
Thread Starter
Burning Brakes
Joined: May 2006
Posts: 857
Likes: 1
From: Morrisonville Illinios
Gang Thanks for all the help
!! SORRY ABOUT THE DELAY ON GETTING BACK FOR SOME REASON CAN'T LOG IN FROM HOME.I found the EST by the power brake booster (no help from FM) the pics where a BIG TIME saver. OK Heres what I got NOW. IT runs ROUGH we HAVE to keep the pedal down and maintain about 1400rpm we can not get the timming to set after diconnecting the EST having to keep the idLE up I? Have replaced all the injectors with good ones from a 87'L98 and the pressure is set around 44PSI (is this too high for these injectors)it does fluctuate some when it is firing. We where able to get it up to TEMP 180 on water 170 on oil still would not run well REAL ROUGH and would die if it got to below 900rpm. Heres my thought VAC leak or the IAC maybeT THE SES IS UP AND HAVE A CODE #12 WHAT IS THIS CNA'T FIND IT IN FM. I am open to suggestion still. As my son says we gota be there (FUNFEST) Saturday. WRO
!! SORRY ABOUT THE DELAY ON GETTING BACK FOR SOME REASON CAN'T LOG IN FROM HOME.I found the EST by the power brake booster (no help from FM) the pics where a BIG TIME saver. OK Heres what I got NOW. IT runs ROUGH we HAVE to keep the pedal down and maintain about 1400rpm we can not get the timming to set after diconnecting the EST having to keep the idLE up I? Have replaced all the injectors with good ones from a 87'L98 and the pressure is set around 44PSI (is this too high for these injectors)it does fluctuate some when it is firing. We where able to get it up to TEMP 180 on water 170 on oil still would not run well REAL ROUGH and would die if it got to below 900rpm. Heres my thought VAC leak or the IAC maybeT THE SES IS UP AND HAVE A CODE #12 WHAT IS THIS CNA'T FIND IT IN FM. I am open to suggestion still. As my son says we gota be there (FUNFEST) Saturday. WRO
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Melting Slicks
Joined: Jun 2004
Posts: 3,032
Likes: 4
Code 12 is just an ECM check. If that is the only one you got, it means you have no stored trouble codes.
What does your fuel pressure do after shutting the car off?
My car idled even at 8 degrees retarded with the EST wire disconnected.
What does your fuel pressure do after shutting the car off?
My car idled even at 8 degrees retarded with the EST wire disconnected.
Thread Starter
Burning Brakes
Joined: May 2006
Posts: 857
Likes: 1
From: Morrisonville Illinios
SO far the only code we got was #12 nothing else pops up. The fuel pressure stays about 38-40 psi when we shut down. IT IS REALLY ROUGH IDlE can not get it to idle by it's self we have to keep either giving it throttle or try to maintain about 1400rpm. IF we try to set the timming down to the 6 BDC it runns even worse have it around 12-15 BDC. wro
Le Mans Master
Joined: Oct 2003
Posts: 6,130
Likes: 2
From: seattle WA
If you're absolutely sure you have no vacum leaks and the lifters are adjusted properly I'm gonna bet you're 180* out.You need to get #1 up on the compression stroke and see where the rotor is pointing.
Your fuel pressure is great!
BTW...what kinda FM do you have???
Your fuel pressure is great!
BTW...what kinda FM do you have???
Thread Starter
Burning Brakes
Joined: May 2006
Posts: 857
Likes: 1
From: Morrisonville Illinios
I have a gm 1987 FM (the big white GM bible) also 85/89. I will look at my IAC I had to make a gasket for it and ?. WE swapped the dist thinking that was it around last night and it would not run(even pulled one of the contacts of the new cap@#@%$^#). So we put it back and it would fire but had to keep it around 1400rpm still. I don't know if I can put a vaccum gauge on since we have to rise the rpm to keep it running? WRO
Le Mans Master
Joined: Feb 2006
Posts: 8,753
Likes: 9
From: Louisiana
Yeah, sounds like the fuel pressure good and it holds good. At this point I don't think fuel is the problem. I believe you either way off on timing or your valve may be too tight. Hard to tell since we are not able to see/hear for ourself.
Read through this and see if it helps.
http://forums.corvetteforum.com/show....php?t=1485069
EDIT: forgot to add...make sure your spark plug wires are connected good and are going to the correct cylinder.
Read through this and see if it helps.
http://forums.corvetteforum.com/show....php?t=1485069
EDIT: forgot to add...make sure your spark plug wires are connected good and are going to the correct cylinder.
Last edited by RRT vette; Sep 13, 2006 at 10:02 AM.
Thread Starter
Burning Brakes
Joined: May 2006
Posts: 857
Likes: 1
From: Morrisonville Illinios
OK lets see if I can comunicate what we did last night better. We pulled the dist out and droped it back in at 180 thinking it might be 180 out. Wouldn't run at all. SO we pulled it again and put it back in where we started at and it would run but ROUGH stumble stall until we got it to about 1400rpm did get oil/water temps to op. conditions unpluged theEST and could not get it to idle down or try to set timming when we went to 6BDC it was worse. After reading the last thead connection you sent I will check the wires out well we still have tape on them and the cap marked but who knows? I will look at the IAC since I had to make a gasket and after all the post it has me wondering. WRO
Le Mans Master
Joined: Feb 2006
Posts: 8,753
Likes: 9
From: Louisiana
Whenever setting the minimal idle on my 86E, you have to ground the ALDL and wait for the IAC to become fully extended in the air passage. This cuts off any air flow through the IAC passage and lets the TB butterflys control idle. Even with the IAC fully exteded my car will still idle well, just a little harder to start. How does the exhaust smell when the car is running? Any smoke? I know you mentioned installing a different intake.
Thread Starter
Burning Brakes
Joined: May 2006
Posts: 857
Likes: 1
From: Morrisonville Illinios
The exhaust isn't too bad a little smoke still burning off neverseize on all the exhaust. I coated everything all slip joints and the widebody clamps. Don't seem to smell gas when had injectors screwed up I have thought about the runners since they have benn custom manufactured to large siemeis tubes. Going to try some propane around to see if I get a increase in idle. Do have another set to try but now with the wiring rig and the bigger vlv covrs PIA to get to the lower bolts. Going for the IAC and wires here shortly leaving my office early to get back on the vet. WRO
Thread Starter
Burning Brakes
Joined: May 2006
Posts: 857
Likes: 1
From: Morrisonville Illinios
OK for those that want to know heres what we have found out. The LT 1 injectors like I said were leaking(sent for repair). My buddy brought over his SNAP-ON reader we had to keep the throttle moving so we could get some readings(the only code I had was 12) found it running lean and the number bouncing all over we unplugged the mas and then it would run better and tried to adjust the tps to get some idle up. Finally unplugged the custom chip and tried a 89'ecm no better, 89 ecm with ADS chip no better, this thing would idle real rough all the time had to keep giving throttle. Finally went back to the 87' ecm stock could start to get it to idle and readings on the machine. No matter what we do it is running lean (getting a new o2 sensor tommorow). The engine is a L98 from an 89 with comp cam, 1.5 roller rockers, cut air cleaner, 58mm TB, ported plenum, custom siemeis runners, bigmouth intake, ported and polished heads, long tube headers no cats no air/egr and 3" exhaust put in a 87' roadster with auto. So far it sound pretty good. had to use the 87 injectors withthe fuel pressure at 45PSI trying to get more fuel in so not as lean. We are open for suggestions. WRO
Team Owner
Joined: Jan 2003
Posts: 20,293
Likes: 240
From: Summerland B.C. Canada
Originally Posted by wro87
OK for those that want to know heres what we have found out. The LT 1 injectors like I said were leaking(sent for repair). My buddy brought over his SNAP-ON reader we had to keep the throttle moving so we could get some readings(the only code I had was 12) found it running lean and the number bouncing all over we unplugged the mas and then it would run better and tried to adjust the tps to get some idle up. Finally unplugged the custom chip and tried a 89'ecm no better, 89 ecm with ADS chip no better, this thing would idle real rough all the time had to keep giving throttle. Finally went back to the 87' ecm stock could start to get it to idle and readings on the machine. No matter what we do it is running lean (getting a new o2 sensor tommorow). The engine is a L98 from an 89 with comp cam, 1.5 roller rockers, cut air cleaner, 58mm TB, ported plenum, custom siemeis runners, bigmouth intake, ported and polished heads, long tube headers no cats no air/egr and 3" exhaust put in a 87' roadster with auto. So far it sound pretty good. had to use the 87 injectors withthe fuel pressure at 45PSI trying to get more fuel in so not as lean. We are open for suggestions. WRO