cold idle hunting (goes crazy lean) & iat rwads 102º on scan tool all the time.

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Originally Posted by Steelpanther

Ive confirmed the ect sensor is reading correctly. The only thing ive noticed that soon as it fires it runs good for about 10-15 seconds after that is goes off chart lean & surges like mad and sometimes dies.

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My sons 87 CSX has been doing exactly this. Car will fire up, fast idle and when it comes down do the mad surging idle and or stalling till warmed up. With the old TB we adjusted the base idle up quite a bit, made little difference.

I have not picked at it as he is suppose to be a mechanic in training and just graduated tech school and it is his car. I can tell you we checked the fuel pressure (fine) swapped out the TB for a stocker with sealed base idle screw (no difference) swapped out a MAP sensor (no difference)

I did suggest unplugging the AIS connector, effectively locking the AIS in one spot for testing. It still surged about but not as much. Clearly something is causing the idle to surge and the computer is driving the AIS in and out trying to compensate making the situation worse. Since it is still surging, I'd extrapolate that the AIS and related wiring and circuitry is not the problem at least in his case.

Gary Donovan

Is he using mptune aswell? I just need to inow where to try and adjust this out of it possibly in mptune. I know for sure the doner l.m. I socketed ( a stock t1 86) ran just fine in stock form. Im really thinking its somethin in the calibration but don't know where to look for it at.

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Originally Posted by Steelpanther

Is he using mptune aswell? I just need to inow where to try and adjust this out of it possibly in mptune. I know for sure the doner l.m. I socketed ( a stock t1 86) ran just fine in stock form. Im really thinking its somethin in the calibration but don't know where to look for it at.

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My sons car has a bone stock 1987 Turbo II calibration.

Injector or distributor shutter wheel issue maybe? Possibly weak ground for computer or injectors? Sticky baro solenoid? PCV issue?

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Originally Posted by Force Fed Mopar

Injector or distributor shutter wheel issue maybe? Possibly weak ground for computer or injectors? Sticky baro solenoid? PCV issue?

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Idle is fine when warmed up, ground I'm doubtful as that would cause other issues, baro was bypassed for testing.

Injectors, shutter wheel, possible. But unless my son shows more interest in fixing it I'm not exploring further as I have my own projects to attend to

My car had this issue for awhile now too,Cold starts read fine at 14.7 or so then rpms start surging until warmed up to where it idles perfect at 900rpms, and 14.7.

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Originally Posted by Steelpanther

My car is an 86 glh omni. I converted to t2 blow through recently. Alk parts were off a 89 Shelby z daytona. Im using mptune & GLHS 2 calibration from boostbutton. Getting it ironed out except for 1st start of the day. Pops rite off goes into normal fast idle. After about 10sec wideband goes off chart lean it about dies. Then catches up wideband goes rich. It does this crazy lean/rich dance for about 30 seconds or so then all is well. How do I go about curing this one? Also I noticed using my solous pro snap-on scanner iat sensor reads 2.50v & 102º all the time. I unplug it stays the same but engine idle is effected & then drops a code. Any help id appreciate!

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Fix your IAT issue first.

Then make sure your tune is running great after the car is warmed up.

Then you have to experiment with fullcoldenrichmentcurveA, fullcoldenrichmentcurveB, and fullcoldenrichmentcurveC

Ideally, you'd want 13.3 -13.7 at cold idle. Steady air fuel ratio AND steady ignition timing makes idle steady. If the air fuel ratio/ignition jumps all over, so will your RPM.


http://www.turbo-mopar.com/forums/sh...l=1#post324318

I don't know if the scanner is reading iat correct. If I back probe the iat with my dvom voltage changes as it should. On my scanner it also says timing is about 83º my timing lite says otherwis & correct. I have adjusted coldenrinrichment A hold time form 90 down to 75. It was a little better cold in the a.m. and was fine when i went to leave work 8 hrs later. So I adjusted it down to 55 & waiting to see if that helped even more on stone cold start. Once warmed up it runs GREAT! also I can drop it into gear rite away & you'd never know there ever was a problem. Cold drop rite in gear its just fine. But not doing that in the winter.

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Originally Posted by Steelpanther

I don't know if the scanner is reading iat correct. If I back probe the iat with my dvom voltage changes as it should. On my scanner it also says timing is about 83º my timing lite says otherwis & correct.

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Find another scanner.

Its a snap-on solous pro... it has worked correctly on EVERY stock vehicle ive ever plugged it into. The T1 log calibration (from fwd) read just fine with it before I T2 swapped it. Maybe other cheaper scan-tools read different but never had a problem with any of my snap-on diag tools. Im sure thats got to be in the calibration itself im guessing.

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Originally Posted by Steelpanther

Its a snap-on solous pro... it has worked correctly on EVERY stock vehicle ive ever plugged it into. The T1 log calibration (from fwd) read just fine with it before I T2 swapped it. Maybe other cheaper scan-tools read different but never had a problem with any of my snap-on diag tools. Im sure thats got to be in the calibration itself im guessing.

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Once you start messing with a calibration some scan tools have trouble displaying the correct readings.

They are after all designed for stock vehicles.

Can anyone tell me what area coldenrichment A & coldenrichment c have control of? Like waht one comes into play 1st and such. Less time un coldenrichment A did not do anything to cure cold start surges. Im completely throwing darts blindfolded at this point! Ill gladly pay for the correct info on what I need to do if thats whatbit takes.

dont try to tune around this.

especially if you are using stock T2 parts and stock injectors and stock 2-bar map sensor.

figure out what the real issue is.

your car should run like stock from what im seeing.

check every and all grounds. add some more grounds just in case.

clean the LM connections and the PM connections.

try another LM.

etc.

if the cal is stock MP GLHS stage 2 it shouldnt be doing this.

try swapping in a new 220uF, 10v electrolytic capacitor into the logic module itself. cant hurt, might help.

Brian

220uh should be 220uF. Minor typo

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Originally Posted by chromguy

220uh should be 220uF. Minor typo

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lol thats what i meant. :) thanks

fixed it..... :)

also, dont get cheap crappy caps. order good quality caps like nichicon, nippon, rubycon, panasonic etc.....

Brian

Ok where on the board does it go?

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Originally Posted by Steelpanther

Ok where on the board does it go?

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You can't miss them. Just remember that they have a polarity. You have to put them in a certain way. Look at the stripe on them when you remove them, and match it up when you replace it.

for the 87 LM it is right in the middle of the board. OEM on the LM's that i took a look at the other day were a nichicon cap, 220uF, 10v, 85c.

now im not totally sure this is the issue but it is cheap to try and makes sense given the age of some of this stuff and how no LM is seeming to perform the same as one that looks identical to it lately.

Brian

Brian

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Originally Posted by Aries_Turbo

dont try to tune around this.

especially if you are using stock T2 parts and stock injectors and stock 2-bar map sensor.

figure out what the real issue is.

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Agreed.

ok figured out its the ONLY big one on the board. de-solderd it & put in another known good one from another known parts l.m. no difference.
What I do know is with a friends mopar GLHS stage II (670) it run fine & HARD! all values on my scan tool read correct no issues. other than it is a loaner & I had to give it back.