|
|
Register To Post |
| Weavsvet | Idle rpm vs in gear idle rpm | ||
|
Senior Guru
 
|
On a '96 LT1 A4 what controls this?
IOW, when I put the put the car in gear the idle does not seem to compensate for it being in gear. Is this something that is controlled in the PCM or is it handled by the IAC or what exactly? Thanks |
||
Posted on: 2010/7/1 11:22
|
|||
|
_________________
1996 Corvette Coupe,AFR 195 street Eliminators,Edelbrock LT4 Air Gap intake manifold,9.5" 2800 stall,TPIS LT headers,Bullet 226/230.565.565/111 lsa cam,1.7 Scorpion rr's,EWP, X Pipe, Stock Exhaust,Elec.Cutouts,Dana 44/3.45, Tune by Wester's Garage |
|||
 Transfer
|
 
|
||
| flyboy | Re: Idle rpm vs in gear idle rpm | ||
|
Elite Guru
 
|
The IAC motor is controlled by the ECM according to engine load and temp. My '91 would die when cold when put into gear and almost die when warm with my mail order chip. Now that the car has been tuned on site by an expert (not me) the transition is seamless.
|
||
Posted on: 2010/7/1 12:51
|
|||
|
_________________
'91coupe, LT4Hotcam, some other stuff. If it's too loud, you're too old. "He works on old cars, then junks 'em" |
|||
|
Transfer
|
|
||
| Steve40th | Re: Idle rpm vs in gear idle rpm | ||
|
Elite Guru
 
|
The ECM does tell the engine what rpm to idle at in gear, with and without AC too, as you can add rpm for ac.
What is it doing exactly? |
||
Posted on: 2010/7/1 13:33
|
|||
|
_________________
Ko'u ohana aia ku'a ikaika |
|||
|
Transfer
|
|
||
| vetteoz | Re: Idle rpm vs in gear idle rpm | ||
|
Senior Guru
 |
Quote:
There is a switch on the auto shifter that tells the PCM if car is in N/P. |
||
Posted on: 2010/7/1 14:19
|
|||
|
Transfer
|
|
||
| Steve40th | Re: Idle rpm vs in gear idle rpm | ||
|
Elite Guru
|
I know within the transmission there is a switch that tells the ecm what gear it is in so the ecm will compensate. At least on my 93. Ask me how I know
 |
||
Posted on: 2010/7/1 14:46
|
|||
|
_________________
Ko'u ohana aia ku'a ikaika |
|||
|
Transfer
|
|
||
| Woodstock | Re: Idle rpm vs in gear idle rpm | ||
|
Senior Guru
|
96 is always a tough case, but the earlier OBD1 softwares were giving you a desired idle speed and an actual engine speed, according to set ECM parameters.
Throttle body opening and IAC play the main role in control. Quote: My '91 would die when cold when put into gear and almost die when warm with my mail order chip. Now that the car has been tuned on site by an expert (not me) the transition is seamless. @flyboy Do you got a copy of the bin prior to the correction and now? I am fighting with this problem on a friends 87 with stock torque converter, though. He's got an LT4 hotcam in his 383 stroked L98. We are to a point where idle quality suffers by trying to correct this issue. A copy of the bin would be a big help. I might find similar values in the $6E hack. |
||
Posted on: 2010/7/1 15:51
|
|||
|
_________________
91 convertible |
|||
|
Transfer
|
|
||
| flyboy | Re: Idle rpm vs in gear idle rpm | ||
|
Elite Guru
|
Quote:
Sorry, no. The guy I paid to tune the computer did all that data stuff. It's greek to me. |
||
Posted on: 2010/7/1 17:25
|
|||
|
Transfer
|
|
||
| Weavsvet | Re: Idle rpm vs in gear idle rpm | ||
|
Senior Guru
|
Quote:
Ok, this sounds like my problem because when I turn the AC on it wants to die or search for it's idle also. It never seems to recover from the AC until the compressor cuts out. When I put it in gear with my foot on the brake it's the same thing, it never recovers it's idle. I was hoping there was a switch bad or something but I guess that's not the case. It sounds like a tuning issue. |
||
Posted on: 2010/7/1 17:48
|
|||
|
_________________
1996 Corvette Coupe,AFR 195 street Eliminators,Edelbrock LT4 Air Gap intake manifold,9.5" 2800 stall,TPIS LT headers,Bullet 226/230.565.565/111 lsa cam,1.7 Scorpion rr's,EWP, X Pipe, Stock Exhaust,Elec.Cutouts,Dana 44/3.45, Tune by Wester's Garage |
|||
|
Transfer
|
|
||
| Weavsvet | Re: Idle rpm vs in gear idle rpm | ||
|
Senior Guru
|
I did mention this to my tuner and he said he added 50 rpm to the in gear setting in the PCM but it ain't getting it. Just a pain to throw it in neutral at every stoplight.
|
||
Posted on: 2010/7/1 18:20
|
|||
|
_________________
1996 Corvette Coupe,AFR 195 street Eliminators,Edelbrock LT4 Air Gap intake manifold,9.5" 2800 stall,TPIS LT headers,Bullet 226/230.565.565/111 lsa cam,1.7 Scorpion rr's,EWP, X Pipe, Stock Exhaust,Elec.Cutouts,Dana 44/3.45, Tune by Wester's Garage |
|||
|
Transfer
|
|
||
| Weavsvet | Re: Idle rpm vs in gear idle rpm | ||
|
Senior Guru
|
Went to town a little while ago and paid attention this this idle issue. Seems it gets a lot better when the water temp gets to 170 or above. Still not the greatest idle but much improved over a cold start. By the time the temp gets to 190 it's even better but still not as good as it should be. You guys with a 111 lsa or in the range anyway,what is your normal idle at? He has mine at 850 I believe.
|
||
Posted on: 2010/7/1 20:33
|
|||
|
_________________
1996 Corvette Coupe,AFR 195 street Eliminators,Edelbrock LT4 Air Gap intake manifold,9.5" 2800 stall,TPIS LT headers,Bullet 226/230.565.565/111 lsa cam,1.7 Scorpion rr's,EWP, X Pipe, Stock Exhaust,Elec.Cutouts,Dana 44/3.45, Tune by Wester's Garage |
|||
|
Transfer
|
|
||
| Steve40th | Re: Idle rpm vs in gear idle rpm | ||
|
Elite Guru
|
Quote:
I hate to say it, but your idle problems are identical to ou mine when the IAC went out. You have a new one correct from early in your troubleshooting. The ECM only tells you what it wants the IAC to do, you will never know what it is doing. only what is being commanded. Take IAC out, measure to ensure it is at the right setting as if it was a new install, then put it in, but dont connect it. Start car and see what happens. I bet the IAC is dead. |
||
Posted on: 2010/7/1 21:19
|
|||
|
_________________
Ko'u ohana aia ku'a ikaika |
|||
|
Transfer
|
|
||
| Weavsvet | Re: Idle rpm vs in gear idle rpm | ||
|
Senior Guru
|
Quote:
Ok, I'll see what happens. Thanks! |
||
Posted on: 2010/7/1 21:37
|
|||
|
_________________
1996 Corvette Coupe,AFR 195 street Eliminators,Edelbrock LT4 Air Gap intake manifold,9.5" 2800 stall,TPIS LT headers,Bullet 226/230.565.565/111 lsa cam,1.7 Scorpion rr's,EWP, X Pipe, Stock Exhaust,Elec.Cutouts,Dana 44/3.45, Tune by Wester's Garage |
|||
|
Transfer
|
|
||
| Steve40th | Re: Idle rpm vs in gear idle rpm | ||
|
Elite Guru
|
I have had a IAC that OHM'd good, and it was bad as the pintle was moved around by me. Not good so I must have broken the plastic gears. I am not sure how the 96 style IAC pintle is in there if it screws in or what, but, I think they are common across the board through GM. IE, if you have a 96 Camaro, Pontiac etc that has an IAC, I believe they are interchangeable to test them if yours OHMs good, but you may think it is bad.
|
||
Posted on: 2010/7/1 21:39
|
|||
|
_________________
Ko'u ohana aia ku'a ikaika |
|||
|
Transfer
|
|
||
| Aboatguy | Re: Idle rpm vs in gear idle rpm | ||
|
Senior Guru
|
Mike
You may have to mechanically set your TB blade IOT get the IAC count low enough that it can compensate for the AC.. If you pull the IAC out of your TB and leave it plugged in and it moves when you turn the key on its probably good.... (don't start it just turning the ignition on should make the IAC move "test") ....and setting the throttle blades correctly will probably fix your problem... (It the throttle blades are too closed the IAC will not have enough range of motion left to keep the IDLE smooth in gear with the AC kicking... I know this from experience....) Mike |
||
Posted on: 2010/7/2 17:03
|
|||
|
Transfer
|
|
||
| Weavsvet | Re: Idle rpm vs in gear idle rpm | ||
|
Senior Guru
|
Quote:
I'm pretty sure the IAC is good. I can test it on the Tech1 I have. I've been playing with the blades readjusting the TPS voltage and then repeat that again. It's getting better every time. |
||
Posted on: 2010/7/2 17:12
|
|||
|
_________________
1996 Corvette Coupe,AFR 195 street Eliminators,Edelbrock LT4 Air Gap intake manifold,9.5" 2800 stall,TPIS LT headers,Bullet 226/230.565.565/111 lsa cam,1.7 Scorpion rr's,EWP, X Pipe, Stock Exhaust,Elec.Cutouts,Dana 44/3.45, Tune by Wester's Garage |
|||
|
Transfer
|
|
||
| Steve40th | Re: Idle rpm vs in gear idle rpm | ||
|
Elite Guru
|
On your car tps voltage resets every time you start.
The blades should be opened a little. I drilled the center out, as I posted on the other thread, and I put the throttle blade a 1/4 turn past touching. http://www.ls1tech.com/forums/lt1-lt4 ... arizona-speed-marine.html |
||
Posted on: 2010/7/2 17:41
|
|||
|
_________________
Ko'u ohana aia ku'a ikaika |
|||
|
Transfer
|
|
||
| Stl94LT1 | Re: Idle rpm vs in gear idle rpm | ||
|
Guru Newb
 
|
Quote:
There is a seperate tuning table for the IAC counts with the A/C on. The counts will be much higher. |
||
Posted on: 2010/7/2 17:55
|
|||
|
_________________
|
|||
|
Transfer
|
|
||
| Aboatguy | Re: Idle rpm vs in gear idle rpm | ||
|
Senior Guru
|
Quote:
I agree....however , if the TB is closed too much the IAC will have to open more IOT idle and then it may be maxed out with out enough headroom to IDLE with the AC on... Mike |
||
Posted on: 2010/7/2 18:22
|
|||
|
Transfer
|
|
||
| Aboatguy | Re: Idle rpm vs in gear idle rpm | ||
|
Senior Guru
|
Quote:
Depress accelerator slightly Start engine, then release accelerator pedal, run engine for 5 seconds Turn ignition "OFF" for ten seconds Restart engine and check for proper idle operation (I try to get my counts between 30 and 40 at idle) |
||
Posted on: 2010/7/2 18:26
|
|||
|
Transfer
|
|
||
You can view topic.
You cannot start a new topic.
You cannot reply to posts.
You cannot edit your posts.
You cannot delete your posts.
You cannot add new polls.
You cannot vote in polls.
You cannot attach files to posts.
You cannot post without approval.
|
|