HELP!! 86/87 ECM swap problems

[camaro75racer]

Ok, finally got everything to swap the ecm over to the 86/87 and changed everything over.(MAT install kit and sensor,87 ecm,87 MAF, and both chips one of which is a Thrasher 92 chip) Once everything was changed over the car idled rough and gave no codes. My scanner (one of the ACTRON's) read that it was constantly lean instead of cycling between LEAN/RICH like it's supposed to. After a coupld minutes the O2's drop to zero and stay there. After this the car begins to cut out at 2000rpm to the point of the motor dying. Whats up with this? Swapped the computers back out and car runs great with 85 ecm and 87 MAF installed and O2's are normal. Please help.
Thanks
Dale

 

[camaro75racer]

Anyone????

 

[GNeric]

I replied in the general tech area. I'm too lazy to type it all here now.

 

[HOTSIX]

What injectors u have ?

Could be your chip is not burnt for them ?

Possibly also a bad cal pak or Thrasher ? What about the MAF - tap it w a screwdriver head while the car runs....does it stumble ? Might be bad if so

 

[camaro75racer]

I have stock injectors and the thrasher is for stockers. The 87 MAF works perfect with the 85 computer. Im using the same small chip in both computers(swapping) so thats not it.(i checked the #'s its the same for 85 and 87) Only thing i can think is the thrasher is bad or the new ECM is bad. I dont have another chip for stock injectors though so i dont know how to check.

 

[6SENSE]

Thrasher is open loop chip at idle so hence the reason for o2s not moving. Same would be for other readings, i.e. int, blm...
"Small chip" is the calpak which you are correct, its the same for 84-87 Turbo cars. # on it should end with 503 or 504 [either is fine].
Swapping in another known good ecm would be the easiest thing to try, Would be nice to know what other readings are (although not sure how much help all would be with open loop chip).
Hey, what do you have your fp at? With a Thrasher chip the fp is supposed to be set at 45psi static. However, (I know, I know, some use them with no issues ) the Thrasher chip was never recommended for a non-intercooled car (so recommended fp setting may have to differ).
Again, more info could help. Fp, int, blm, tps, af .... iac, etc.
Also, car cuts out at 2000rpm? Thats a bit high for idle, so that is when driving the car?
ECM or MAF could be suspect. Not likely, but possibly the chip. You could try your 84MAF just for grins and see if idle smooths out at all.

 

[camaro75racer]

Ok, here's some more info. I tried with the 85 MAF and no change. The fuel pressure is at stock.(dont hav adjustable fpr on yet) The car idles from 800-1250 jumping around. What i meant about "cutting out" is when i give it gas at between 2000-2500 the motor quits running...if i get off the gas it starts going again but if i dont it die's. There is a little diffrence in reading im getting between the 2 ecm's so i'll list both. Thanks

85 87
TPS .41 .41
IAC 35 52-54
BLM 128-130 150
O2's cycles 0

This thing dont tell me much more than that. I did notice at idles it says the spark advance is at like 56 deg.

 

[6SENSE]

Hey, do you have a fp gauge? Sounds like your fuel pump is having problems. Attach a fuel pressure gauge and see if the pressure drops when you rev it up or doesnt go up after a certain point, etc. With vac line off regulator should be about 34-38psi (w/ stock 233 regulator) and with line on should drop pressure roughly 6psi? Upon acceleration as you begin to make boost the fuel pressure will climb to the static setting (the fp amt w/ line off) and must match boost pressure pound for pound. If this does not happen youve got a problem.

tps #s are fine. iac is a tad high with 87ecm, but not alarming. blms are right on with 85 ecm, but too high with 87, showing a lean condition. o2 cycles, is that cross counts or o2 mvs? probably cross counts Im guessing. Regardless its with the thrasher which is in open loop so thats probably why. Thrasher + 87ecm is looking for more fuel also. I would check that fuel pressure issue. Has the fuel pump and sock been changed before? [Even if so, still check the fuel pressure].