c4c5 specialist - cold start problem

[DAWSC5]

On cold start, engine revs to 1500 rpm for 2-3 secs, then drops to 900 rpm over next 5 secs. Then idle pulsing occurs between 900 and 1100 rpm. Drops to normal idle 600 rpm as it warms up. This started after a custom PCM tune but tuner says he didn't change anything that might cause this. Suggested a dirty MAF sensor. Any ideas? Thanks.

 

[c4c5specialist]

HI there,
It doesnt matter if the tuner does NOT say he did anything to affect this. Everything is affected when the GM calibration is changed. This is why I NEVER recommend that the tuning be changed from factory, unless you do a minimum of heads and camshaft. Was this done to the car??????
Dirty MAF????? What was done other than the programming???/ Was a oiled filter, like K and N installed at this same time???? IF not, no, I dont believe that this is a problem. Besides, if this was true, there would be even more fluctuations after the engine was warm.
If not, the original calibration should be installed back to factory, and see if the condition presents itself again.
My theory is that it will NOT.
Allthebest, c4c5

 

[DAWSC5]

Filter was cleaned

c4c5. Thanks for the reply. Heads and cam are stock. I did clean my Haltech TRIC filter the day before the custom tune where this problem started. Actual this install was to tweak and earlier one (which didn't have the cold start problem). The TRIC is a Donaldson oiled filter. Could I have over-oiled it which resulted in soiling the MAF sensor? There are no idling or pulsing problems when the engine is warm. Your further comments are appreciated.

Dawson

 

[c4c5specialist]

HI there,
It is possible that the MAF has an issue. I would simply remove the sensor, and check for oil residue on the elements in the center of the MAF.
As for the rest, also make sure that the air bridge in between the sensor and the engine is on, and correctly tightened.
Allthebest, c4c5

 

[DAWSC5]

Thanks, I'll check it out.

Dawson

 

[DAWSC5]

c4c5. One more question. If I find oil on the MAF sensor, how should I clean it? I was thinking of an electrical contact cleaner as it should leave no residue. Do you have a recommendation? Thanks for your help.

Dawson

 

[c4c5specialist]

HI there,
Honestly, I do not have an answer for you on this one.
I know in the GM service arena, you are told NOT to clean MAF sensors, with anything.
So I do NOT know of what to clean them with under guidelines that will NOT harm the MAF.
I will do some research and repost later.
Allthebest, c4c5

 

[DAWSC5]

Thanks, c4c5. Let me know if you find out anything. I have talked with others who have used the electrical contact cleaner without problems. I will be changing the TRIC to a Blackwing soon and plan to clean the MAF at the same time. Appreciate your help.

Dawson

 

[c4c5specialist]

Hi there,
I would only recommend compressed air, due to the fact as there is nothing else that I would trust.
Electrical contact cleaner may work, however, per GM guidelines, NO chemical should be used.
I would just used compressed air, from the opposite side of the sensor, so the particles blow outward.
Allthebest, c4c5

 

[DAWSC5]

Thanks, I appreciate your suggestions.

Dawson