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Discussion Starter #1 (Edited)
like the title states I cant figure this out! I have fuel and spark and checked all vacuum lines no leaks. what should I look for?
the car idles fine, and runs fine up to 2800 and then loss of power popping and sounds like back firing. then clears up after 3900 rpm
86 mustang gt
tko 500
331
screamin demon coil
live wire plug wires
hot forged dui distributer
brand new champion plugs rc12yc
bosch ev1 style 30lbs injectors
trickflow 170 heads
trickflow r intake manifold 75mm throttle body
prom m80 mass air got at the same time as prom efi
 

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c/p from pro m

"OBD II compatible. Codes read and cleared and sensor data read using a generic OBD II scan tool. The new Pro-M EFI processor uses the same code strategy and the same codes, that all of the OEM's use!

Fully laptop programmable. Your laptop also acts as a powerful scan tool. See data in real time. There is more information available to the user than you ever imagined possible. Much more than with any conventional scan tool, or any of the hand held programmers offered by the other guys"


what does your powerful scan tool show, when looking in real time data?
 

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OP, have you data logged anything?
Spark, MAF voltage, rpm, bank1/2 lambda, etc...?
Any DTC codes displayed?
What fuel pump do you have?
Is this a new problem?
Is this a fresh install? Not sure if you are having a distributor/coil issue. I fought a distributor issue when installing the system and I ended up putting in a stock distributor shutter wheel.
 

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I went with the DUI distributor too and the shutter wheel measurements were very inconsistent. I would take it out and measure them. I was skeptical but I bought the Pro-M wheel and they were all within .001 of each other.


Large teeth — .398 to .400

Small tooth — .258 to .262
 

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I agree with the above.

Also, was the base spark advance table manipulated in any way?

Does this only happen during partial throttle (low load) at this RPM range? If you go wide open throttle at 2000 and stay in it, do you go right by 3000 no problem?

I ask because I have seen a case where overly advanced timing in the 2500-3000 rpm / low load range resulted in breakup and the inability to rev past 3000 outside of WOT. Putting commanded spark advance back to Pro M's values cured the issue.
 

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I went with the DUI distributor too and the shutter wheel measurements were very inconsistent. I would take it out and measure them. I was skeptical but I bought the Pro-M wheel and they were all within .001 of each other.


Large teeth — .398 to .400

Small tooth — .258 to .262
Thanks for posting that. I have been looking for this info. Im most likely going to have to call them once my new distributor comes in. Ill need to measure the windows in the holley to see how far they are off. Being that MSD is owned by Holley, they may use the wheel and if that is the case, it will need to be replaced.
 

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Discussion Starter #11
c/p from pro m

"OBD II compatible. Codes read and cleared and sensor data read using a generic OBD II scan tool. The new Pro-M EFI processor uses the same code strategy and the same codes, that all of the OEM's use!

Fully laptop programmable. Your laptop also acts as a powerful scan tool.
See data in real time. There is more information available to the user than you ever imagined possible. Much more than with any conventional scan tool, or any of the hand held programmers offered by the other guys
"


what does your powerful scan tool show, when looking in real time data?
Only codes I was getting were 02 sensor codes I replace both sensor and those codes went away.
I havent data logged anything yet still learning
 

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Discussion Starter #13
OP, have you data logged anything?
Spark, MAF voltage, rpm, bank1/2 lambda, etc...?
Any DTC codes displayed?
What fuel pump do you have?
Is this a new problem?
Is this a fresh install? Not sure if you are having a distributor/coil issue. I fought a distributor issue when installing the system and I ended up
putting in a stock distributor shutter wheel.
I agree with the above.

Also, was the base spark advance table manipulated in any way?

Does this only happen during partial throttle (low load) at this RPM range? If you go wide open throttle at 2000 and stay in it, do you go right by 3000 no problem?

I ask because I have seen a case where overly advanced timing in the 2500-3000 rpm / low load range resulted in breakup and the inability to rev past 3000 outside of WOT. Putting commanded spark advance back to Pro M's values cured the issue.
Havent logged anything didnt know what to log.

No codes now was getting o2 codes replace both sensors and the codes went away.

Its New install and it's been doing this since.

I havent adjust anything else except what the install video says to adjust. Dont know enough to change anything else

It does this no matter what the throttle input it is partial or wide open
 

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Discussion Starter #14
I went with the DUI distributor too and the shutter wheel measurements were very inconsistent. I would take it out and measure them. I was skeptical but I bought the Pro-M wheel and they were all within .001 of each other.


Large teeth — .398 to .400



Small tooth — .258 to .262

I was reading prom website about the shutter wheel after posting this I'll try that first
 

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I'd get rid of the champion plugs.

Sent from my SM-G950U using Tapatalk
 

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Log commanded AFR, actual AFR, timing, and MAF voltage.
 

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like the title states I cant figure this out! I have fuel and spark and checked all vacuum lines no leaks. what should I look for?
the car idles fine, and runs fine up to 2800 and then loss of power popping and sounds like back firing. then clears up after 3900 rpm
86 mustang gt
tko 500
331
screamin demon coil
live wire plug wires
hot forged dui distributer
brand new champion plugs rc12yc
bosch ev1 style 30lbs injectors
trickflow 170 heads
trickflow r intake manifold 75mm throttle body
prom m80 mass air got at the same time as prom efi
Troubleshooting a vehicle over the internet is tough because the person helping you has to assume a lot. The best troubleshooter, I've ever seen is Chris Richards from Pro-M Racing, so you may want to call him.

The first thing Chris will say is you need four things for the car to run and those four things are Air, Fuel, Spark, and Compression. You're missing one of those variables. Find out which one you're missing and it will put you on the path to finding the culprit.

Answer the following, whats your Tach doing when this stuttering and popping happens? If your Tach is jumping up and down or doing something funky then your problem is ignition related.

What's your fuel pressure doing when this happens? Is your fuel pressure dropping? If yes, then you may have a fuel delivery issue. Do you have the correct fuel parts? Were they installed correctly? No fuel pressure gauge, then what is your widebands showing when this happens. Troubleshooting in a systematic way will help you identify your problem.

I hope this helps and good luck
Michael Plummer
 

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Does it happen all the time, regardless of driving conditions.

I've also had loose clips on my fuel injector connectors cause a very similar problem.
 

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Discussion Starter #20
Does it happen all the time, regardless of driving conditions.

I've also had loose clips on my fuel injector connectors cause a very similar problem.
It does happen all the time no matter the driving conditions


I ordered the shutter wheel from prom and their injectors
 
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