surging idle, am i on the right path?

[Cobra_Dusten]

Ok, the car is an 89 vert. 5 liter with a 5 speed.
Motor is fresh with approx 2500 miles. GT40 heads, e cam, 24lb injectors, explorer intake, bbk 65mm tb, c&l maf for the 24's, short tubes, no cats, no ac, no smog pump, no egr, no can purge. All the emission stuff was off when i bought the car. I built and installed the engine. Problems have shown up in the last month.
I started following the check list.
Pulled codes, got 41 and 91(along with the egr codes) showing lean.
Car stumbles when started(warm or cold)(some times) but seems to idle ok when cold, once it warms up the problems arise. i can run down the freeway all day, without a cel, it only shows up in traffic.
from reading the checklist, its possible i need an iac, but i could clean it first. but, without getting my AFR's read, is it possible that at 105K on the car it needs both 02 sensors?

Anyways, i have stopped at this point, looking for a little advice before i go buy parts.
when the rough idle starts it will bounce from like 400-1200 a few times and die, i can stab the throttle and keeping it running, and sometimes after a quick stab it will settle down and run fine for a while.

 

[GTOreturns]

Loosen up but sides of the MAF and twist both ways while it is running, and bring it to the position that idles best then lock it. If that doesn't work go through this thread for idea's.
http://forums.stangnet.com/698148-help-me-create-surging-idle-checklist.html

 

[Cobra_Dusten]

i've gone through the thread, and got to the point of pulling codes, but the only thing i got was lean. but my idle symptoms fit the that. i'll play with the maf and then go from there.

 

[GTOreturns]

When I put in a 75mm bullet the same thing was happening. So I twisted the maf and the idle smoothed out very nicely. Give it a shot.

 

[Cobra_Dusten]

the idle issues seems to have cleared up quite a bit, however my father thinks lean on both banks is a vacuum issue... oh the joy

 

[Cobra_Dusten]

does it sound normal that with my MAF at certain "clocked position" i lose a ton of power, but regain it with a slight turn of the maf?

 

[93 LX]

the idle issues seems to have cleared up quite a bit, however my father thinks lean on both banks is a vacuum issue... oh the joy

+1

If you still get lean codes and its running rich then you do have a vacuum leak! Start looking at hoses under the intake and around the brake booster...

 

[Cobra_Dusten]

well, i got to thinking, its throwing EGR codes due to not having one, won't that cause it to go lean(the car leaning itself out to accommodate the EGR, when its not there?)

 

[jrichker]

well, i got to thinking, its throwing EGR codes due to not having one, won't that cause it to go lean(the car leaning itself out to accommodate the EGR, when its not there?)

No. Evidently when the computer sets an EGR code, it disables all EGR functions and runs the non EGR normal parameters.

 

[SMOKEDYA]

If you have zero vacume leaks then yes the MAF is what i'm thinking. I had a C&L also on my 95 and like everyone else said just by turning it it smoothed out and ran good.I doubt it's the 02's my car has 146,xxx miles on it and as far as i know still the stock 02's? BUT you could also might need a tune to get stuff in line. You might not gain any power out of it AND you could loose power but it would be a good A/F ratio and you would have driveability. Do you know what your fuel pressure is at? jrichker is correct about the EGR it wont run any diffrent if it's not hooked up,mine isnt hooked up and i just had mine tuned with the chip and everything was flying colors, just sucks cause i didnt even think of the tuner to program my chip to turn off the CEL light because of it peace





john