Re: rough Idle
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Joined: May 2008
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From: Milwaukee Wisconsin
Re: rough Idle
Hi Guys, I did some work over the winter. I put a bigger cam and roller rockers,headers,borla muffs,removed egr and pollution pump. I sent my chip to TPIS for reprograming. I can't find any vacum leaks, but when I first started the thing would not idle. I had to turn the idle screw up alot. Now it idles rough and it just seams like it is loading up. Sometimes it justs kills. Does anybody have some ideas that I can try to fix this idle. I don't know alot about TPI so be gentle.
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From: Albuquerque New Mexico
Hi Guys, I did some work over the winter. I put a bigger cam and roller rockers,headers,borla muffs,removed egr and pollution pump. I sent my chip to TPIS for reprograming. I can't find any vacum leaks, but when I first started the thing would not idle. I had to turn the idle screw up alot. Now it idles rough and it just seams like it is loading up. Sometimes it justs kills. Does anybody have some ideas that I can try to fix this idle. I don't know alot about TPI so be gentle.
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Joined: May 2008
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From: Milwaukee Wisconsin
I double checked the lifters and I know about the timming plug. I also replaced the injectors with gen. 3 bosch. They all ohm at 16 to 16.2. I did a compreion and they were all about 140 to 150. Temp gage reads 180 to 200. I don't know what a ica is.
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From: sw Ohio
You said you werent familiar with the TPI. Check the small black vacuum lines that run underneath the plenum to the passenger side to make sure they're not leaking. There is a rubber piece of vacuum line coming out of the driver side of the intake base that connects to a metal line for the PCV valve. That rubber part may be leaking, try squeezing it while its running.
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From: Summerland B.C. Canada
Adjust your TPS to .54 volts at idle and then try and set the min idle and TPS again.
http://www.lbfun.com/warehouse/tech_...ch%20Paper.pdf
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From: Acworth Georgia
IAC (Idle Air Control) and TPS probably both need to be re-calibrated. The IAC has to be done before setting the TPS at .54 volts. It can be tricky setting the TPS. Took me awhile to get it right on .54 and then to stay there while I tightened the screws.
Or it may be a vacuum leak. Some use carb cleaner and some use starting fluid to spray around the lines and intake to see if you get a change in RPM. Find a spot where the spray changes the RPM and there's your leak.
Or it may be a vacuum leak. Some use carb cleaner and some use starting fluid to spray around the lines and intake to see if you get a change in RPM. Find a spot where the spray changes the RPM and there's your leak.
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From: Summerland B.C. Canada
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From: Acworth Georgia
:o It was late and I didn't word it right. You are correct, the ECM does control the pintle. However, the ECM needs a baseline to adjust from.
For the IAC/idle setting:
Ground the A and B ports on the diagnostic connector under the drivers side dash. (This grounds out the ECM diagnostics)
Turn on ignition without starting for 30 sec
With ignition still on unplug IAC
Remove grounding of A and B connectors
Start engin and allow to reach operating temp (You may need to play with the gas to keep it running until heated up)
If automatic -- set parking brake and chock front wheels---now put in drive
Adjust idle screw to obtain 400 rpm or 450 in neutral
Shut off engine and re-connect IAC
Hope this helps.
Sorry for the mix-up.
For the IAC/idle setting:
Ground the A and B ports on the diagnostic connector under the drivers side dash. (This grounds out the ECM diagnostics)
Turn on ignition without starting for 30 sec
With ignition still on unplug IAC
Remove grounding of A and B connectors
Start engin and allow to reach operating temp (You may need to play with the gas to keep it running until heated up)
If automatic -- set parking brake and chock front wheels---now put in drive
Adjust idle screw to obtain 400 rpm or 450 in neutral
Shut off engine and re-connect IAC
Hope this helps.
Sorry for the mix-up.
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From: Milwaukee Wisconsin
I read how to set the ica from the manual and I did all that and once it warms up it it sounds like it loads up. The idle gets to lopping and then it will kill. But the engine starts write up. I can keep it running if I use two feet and gas brake.
Pro
Joined: Oct 2004
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From: Melbourne Victoria
If the idle goes bad once it warms up then sounds like you have a problem once you go closed loop, has it ever idled right with the new chip ? If not maybe the new chip does not like your cam, getting a mail order chip is a bit hit or miss especially if you have not supplied any data logs to them.
Le Mans Master
Joined: Dec 2006
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From: H-Town Texas
Just asking, but when you sent your chip out to be reprogrammed, did you include your cam specs and inform them that you deleted the egr and smog pump? This could be the problem.
Bigger cams tend to idle differently, depending on the overlap. If your cam is really big, there you go. I just put a Hot Cam in the lt4 and it idles fairly rough, sends random misfire codes and such. This is on a stock tune with all emissions still in tact. I look at as I paid good money for that rough idle. But the Hot Cam is a milder cam. I'm throwing this out there because the symptoms you describe are those of a big cam engine.
Bigger cams tend to idle differently, depending on the overlap. If your cam is really big, there you go. I just put a Hot Cam in the lt4 and it idles fairly rough, sends random misfire codes and such. This is on a stock tune with all emissions still in tact. I look at as I paid good money for that rough idle. But the Hot Cam is a milder cam. I'm throwing this out there because the symptoms you describe are those of a big cam engine.
Le Mans Master
Joined: Jan 2006
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From: Orlando FL
Just a few suggestions. You say it runs good cold but runs bad when it gets hot and goes into closed loop. I would take a look at the O2 numbers and the BLM numbers. Might give you a clue and additional information for the problem.