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Discussion Starter · #1 ·
Hi Guys, I have been away working on a Jeep project. I built a 331 stroker motor to go into my Jeep. I used parts from 89-93 EFI off a Mustang. Completely new EFI wiring harness from RJM. Ford Racing aluminum heads and Cobra intake. 24 lbs injectors, 85 mm MAF and TB. Sent the MAF off and had it calibrated. Went to start the motor on Monday and took about 30 seconds after fuel got flowing.. Motor sounds strong but have some issues on the lower RPM's off idle (almost like vacuum leak). Idle little rough but figured the B303 cam is most of it. It will idle after warming but real low RPM's. I ran the codes before starting and only code that came up (other than the 80 codes) was 23. It said it was a hard code. Seems like I have a stumble or misfire off idle, then goes away or gets better as RPM's go up. The 23 code is the TPS. Since I bought the TB and MAF off Craigslists, was cautious. Suppose to work fine but you know how people lie... That was why I sent the MAF back and had it checked and calibrated. I went yesterday and bought a new TPS and installed. It cranks with no problem and a little better but still not running like it should (slight backfire every once in awhile sounds like). I am using the A9L computer which I also got off of CL.. I hate to start replacing everything I have not already but I am a carburator guy, not EFI. Here is a list of stuff I have bought new...
VSS
Fuel Pump
TFI
BP
TPS
ECT
ACT

Could the TB or A9L be an issue??? Timing about 10 degrees...
I appreciate any help... I hate to take to a dealer or shop and get bent over....
thanks...
Calvin
 

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Sounds like your TPS is out of range needs to be set @ .98v or as close as possible (+ or - .3v) Make sure the 10 pin (AKA salt and pepper shakers) are getting good conn also. Sometimes the male ends need flared due to ford making them round and the female pins oval. Could also replace the TFI module but I would say TPS is out.
 

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Discussion Starter · #3 ·
How I test the voltage? It is a new TPS I bought yesterday but I also noticed the throttle body has a adjustment ring that can set as well (rotate the TPS). The guy I bought the MAF and TB from was racing with this setup. I read where if the idle speed adjustment screw is changed (raise/lower rpm), it also changes the TPS circuit and would need to be adjusted accordingly. I was thinking maybe it is off from somone messing with it.... So I need to check voltage at closed 0.98 volts to wide open at 5.0 volts with a smooth climb...

I have a new distributor/TFI module so probably ok. The RJM does not have any connectors since it is one wire from the computer to the point it terminates... So I would assume there would not be a connection issue.. Atleast hope not....

thanks..
 

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Discussion Starter · #5 ·
Excellent write up... It was about 1.26... So dialed it back to .99. It definitely help with some of the issues... It still is hard to get off idle without rpms going up to about 3k... There is only about 3 idling cycles (heat and cool) on the motor. Probably about 45 minutes... I am waiting on insurance before getting it out on the road..... Hope get some time on the motor and things will level out... Any other theories???
thanks guys...
 

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What brand MAF are you using i know that C&L really picky to how they are placed. I know some other MAFs are to but can not remember the kind.
 

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Discussion Starter · #7 ·
It is a 75 MM Pro-M. I sent it to them to calibrate and test. Also 75 MM Accufab throttle body....
 

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Discussion Starter · #8 ·
Well, I am really baffled on what I have wrong. Since the above, I have replaced the TPS and IAB. I have really replaced all of the electrical stuff in the engine compartment. The motor will run good above 3000 rpm. It idles a little rough but really not bad. It just does not come off idle and up to about 2000 rpm's before it levels out. I thought it might be a vacuum leak and pulled the upper section of the intake and replaced the gasket even though it looks like it was seating okay. There is nothing that stands out mechancial that would be causing this. I am thinking it is still electrical or computer related. I guess I will go rent the code reader and check codes again.. Originally the TPS was only thing out of range. The motor feels really strong with no unusal noises. It just does not idle and come off idle right.... Anybody got any suggestions??? I hate to take to a shop but I am about ready to give up.
thanks....
 
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