View Full Version : Idle problems
sjpuccini
02-14-2005, 12:08 AM
updates.....as follows: set the tps and iac ...tps to .46 and iac to 24 at idle in park.....replaced the 02 sensor with a four wire heated version.....reset the computer of course.....still have idle issues.....its not the fuel, because it is strong, the maf is 4-6 at idle and good while driving.....replaced the coil pack, both parts....not sure where to look....what i get is sometimes, on and off, when i start it- it runs a bit fast then sometimes stalls, also may do this while driving as well at low rpm.....not sure what to do......recently replaced the drivers side header, so its not that and also the turbo puck vacuum hoses, those are good......thinking it could be the EGR, but not sure how to check...also bought a vacuum tester, and not sure where to start....thinking about testing each of the 5 hard lines coming from the throttle body, and not sure where else to test or how strong the vacuum should be...please help
:cheers:
Keller
02-14-2005, 12:49 AM
For those not reading along from the previous discussion, see http://www.gnttype.org/forums/showthread.php?t=980&page=1 for details...
My opinions / ideas:
- 0.46 is too high for idle. The car will not stay in the idle block on the BLM table.
- 150 is too high a block learn (BLM). It is trying to correct for something. It thinks the car is running LEAN. Very lean.
This all could be due to an air leak. One that is somewhere beyond the MAF. It could also be due to a chip not programmed for the injecors you have.
What MAF are you using?
Some light reading related to the subject:
http://www.gnttype.org/techarea/faq/BLMINT.html
http://www.thrashercharged.com/chips_htm/cal_hints.shtm
(I've renamed the subject to something more meaningful so that others might be helped if they are reading along.)
vipers t type
02-14-2005, 10:35 AM
I beleive your prob will be in your iac.Your TPS you said is .46 well GM says .5 or half a volt is perfect.Any lower on TPS your car will a worse stalling problem.Also look at your GPS or grams per second on your mas air flow this should read around 4 to 8 GS.Your throttel plate will not move at Idle so this is wear you iac comes in.If iac is skewed or stuck in closed position car will stall no matter what BLM or block learn says or does.So if you remove your IAC valve look at pinnel take some fine emery cloth clean tip and manualy reset IAC by pushing back on tip and reinstall.Now in order to reset ECM has to see TPS at certain percent so drive the car between 45 to 55 MPH. for 10 min or so.If this does not work take some brake clean(WHY) because has no residue and spray your intake and hoses and check for a vacume leak.IF your EGR is stuck open or has carbon behind pinnel you will have a definate rough idle or even stall. To check remove EGR and look inside.If it is the diaphram type manualy cycle diaphram with both index fingers.EGRs are not to expencive I would just replace.
kenmosher
02-14-2005, 01:01 PM
To clarify some of these things ... I think vipers t type gave some great tips ... just that some might be more for later model cars than ours, so I wanted to add to his tips.
I beleive your prob will be in your iac.Your TPS you said is .46 well GM says .5 or half a volt is perfect.Any lower on TPS your car will a worse stalling problem.Actually, Not for the turbo regals ... 0.5 volts is usually the threshold that indicates part throttle (not idle) for this particular calibration. Recommended TPS settings are 0.40-0.45 volts. If it reads that high, it will not be in the idle cells in the BLM tables. Lower readings are better in this case.
Also look at your GPS or grams per second on your mas air flow this should read around 4 to 8 GS.Most healthy MAFs read right around 4-6 gps at idle (depends on the car and placement of the MAF in some cases). I think it sounds OK.
So if you remove your IAC valve look at pinnel take some fine emery cloth clean tip and manualy reset IAC by pushing back on tip and reinstall.:eek:
Be VERY VERY careful if you do this ... our IACs can easily strip the little stepper motor gear inside that moves the plunger. (Ask me how I know! :D)
It's better to reset the IAC with it installed in the car using the jumper in the ALDL port (as outlined in the IAC reset procedure on the links above).
Now in order to reset ECM has to see TPS at certain percent so drive the car between 45 to 55 MPH. for 10 min or so.The specific "relearn" procedure is on the web site ... the basic idea is to hit most of the BLM cells for a bit at different throttle positions. Our ECM isn't quite as sophisticated as the later versions, so it doesn't zero the TPS dynamically like the later ones do (to figure a percentage).
[* Snip *] Great advice on checking for vacuum leaks and cleaning things ... you can also CAREFULLY use a propane torch (unlit of course) with a piece of rubber tubing to run it around all intake joints and openings. If the idle changes, you found the leak.
sjpuccini
02-14-2005, 01:33 PM
i will lower the tps to around .43, and reset the iac using the aldl procedure. i think the maf is ok though. it may be a vacuum hose issue, other then looking what is the best way to check for a vacuum leak, i bought a tester, but not sure what the vacuum lines should read- and do i test in park, neutral or what! i just want to make sure i get it right....i did notice some frayed hoses near the egr/behind the drivers side header (high heat area), if i swap those vacuum hoses where can i get replacements with the same bend!
i appreciate all the help you guys give me, so thank you!
sam :banghead:
sjpuccini
02-15-2005, 11:28 PM
back again............
lowered the tps to around .43 and iac is great in idle and drive...i also increased the fuel pressure to a tad over 40lbs...i think this helped quite a bit, thinking thay may have helped the air/fuel- LEAN problem solved i think....still having issues with the vacuum hoses, please help or maybe something else to look for?
sam :cheers:
sjpuccini
03-06-2005, 09:03 PM
hi there,
still having problems with the idle...even after replacing two of the vacuum lines and heated 02 sensor...still having this issues.....read any of the posts from this before...please need help for this....!
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