Why must you die?

[ShiftTheDrift]

Here we have a 1994 Cobra with a basic engine rundown as follows:

-Stock 302ci
-E303 Cam
-TF Heads
-MAS calibrated for 24# injectors
-JMS Custom Chip
-70mm TB

My question is this. The car idles good, doesn't hang, operates, as it should once going. However, I've noticed often that just simply turning on the A/C will kill the motor or drop significant RPMs including backing out of the driveway or especially coming to an abrupt stop.

Can anybody explain what's causing this?

I've thought that it might be an injector, fuel pump, alternator, or the AFPR. I haven't done anything about testing anything. Just looking for direction right now.

Thanks!

 

[Mavrick]

This happens only when the AC is on?

 

[krahkin]

I would check the idle air bypass set-screw and also the fuel pressure. I would almost put money on the first, though (based on my experiences).

 

[Gt1995]

easy with the thread titles man

 

[86T-Top]

If it is only stalling on you when your a/c is on and especially when you come to a quick stop, you I would increase your base idle speed. When I installed my E-cam I had to jack my base idle to 850 - 900 RPMs to use my A/C, other wise the car would stall when I came to a stop fast.

 

[Michael Yount]

If it's truly a Cobra with a Cobra computer, and you've got an maf calibrated for 24's - that's a problem. The Cobra stock maf is calibrated for 19's and the adjustment for 24# injectors that came stock on the Cobra's is made in the Cobra computer. If you put an maf in that's ALSO calibrated for 24's it should really mess things up. With the Cobra computer making the adjustment for 24's, the maf should be calibrated for 19's.

 

[Daggar]

If it's truly a Cobra with a Cobra computer, and you've got an maf calibrated for 24's - that's a problem. The Cobra stock maf is calibrated for 19's and the adjustment for 24# injectors that came stock on the Cobra's is made in the Cobra computer. If you put an maf in that's ALSO calibrated for 24's it should really mess things up. With the Cobra computer making the adjustment for 24's, the maf should be calibrated for 19's.

Great catch Mike... did not know that about the Cobra computers.

 

[4dStang]

If it's truly a Cobra with a Cobra computer, and you've got an maf calibrated for 24's - that's a problem. The Cobra stock maf is calibrated for 19's and the adjustment for 24# injectors that came stock on the Cobra's is made in the Cobra computer. If you put an maf in that's ALSO calibrated for 24's it should really mess things up. With the Cobra computer making the adjustment for 24's, the maf should be calibrated for 19's.

I learned that my Cobra ran like crap with the 24 LB maf tube on my C&L. I changed it to the 19LB and it runs GREAT. But I had popping problems with the incorrect tube, not stalling issues. I too would also first look at the base idle speed with that different cam in there. But you do need to calibrate that MAF to a 19 lb injector. If you look at the C&L calibration chart, it clearly shows it. Should be the same with a pro-m but you have to send that in to recalibrate it.

 

[Michael Yount]

Oh -- and the first thing I'd do is pull the diagnostic codes to see if anything obvious shows up. Perhaps the IAB solenoid is shot and the ecu can't control idle speed the way it should.

 

[HISSIN50]

Oh -- and the first thing I'd do is pull the diagnostic codes to see if anything obvious shows up. Perhaps the IAB solenoid is shot and the ecu can't control idle speed the way it should.

right on - my first thought was the IAC. the a/c is one of the bigger loads one can put on the motor. nice catch on the cobra puter calibrating/correcting for the 24#ers too.

 

[TrickStang37]

easy with the thread titles man

LOL yeah i agree with that as well. I thought it would be a thread about the meaning of life