Engine Turbo 5.0 Mustang bad misfire at WOT

Noobz347

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Start looking through all of your ignition components. You have a [lot] of ignition add-ons.

I don't get a warm fuzzy about after-market distributors. I forget if you're running one.

Look at the MSD stuff and start bypass those components one at a time.

Also: Did you check your base timing? --And-- Don't forget the chip and ECU connectors.


It's weird that worked and then just didn't. So... Something took a dump. Your fuel system is still suspect too.
 
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AwxyMoron

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Start looking through all of your ignition components. You have a [lot] of ignition add-ons.

I don't get a warm fuzzy about after-market distributors. I forget if you're running one.

Look at the MSD stuff and start bypass those components one at a time.

Also: Did you check your base timing? --And-- Don't forget the chip and ECU connectors.


It's weird that worked and then just didn't. So... Something took a dump. Your fuel system is still suspect too.
It had an MSD distributor(PN 8456) although it seemed the pip sensor in it went out(car wouldn't start, pip signal didnt flash with led test), I replaced it with a used Motorcraft distributor(with motorcraft TFI module) and the car ran again although the other problems have remained. I did swap back to the stock ignition for now although I would like to run the MSD box for the 2step in the future if possible, I have an accel coil laying around that I will try instead of the MSD coil, and that would eliminate all the MSD components besides the rotor and cap.

My base timing is right at 10 degrees with the spout out, and with the spout in at idle it seems to sit around 14 or so. Also about to clean those computer components

Fuel system is also my suspicion, the problems first start appearing after the fuse for the fuel pump blew (which now that I think about it, I never checked the wiring for that)
l am getting the fuel pressure gauge to go inside the car tomorrow and then I'm going to pickup a new fuel filter... The car has 6an lines and aluminum fuel rails which I sprayed out with an air compressor and then ran Techron through it the other day.
 
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AwxyMoron

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Okay, just finished checking the wiring for the fuel pump, it was all good, I also used some electrical contact cleaner on the chip and the ecu connectors.
 

Noobz347

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Okay, just finished checking the wiring for the fuel pump, it was all good, I also used some electrical contact cleaner on the chip and the ecu connectors.

Ok. Don't leave the contacts soaking in the cleaner though. Spray the cleaner on, agitate, and wipe clean. Displace with something that's not petroleum-based like silicone spray or something. Not WD-40.
 

AwxyMoron

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Ok. Don't leave the contacts soaking in the cleaner though. Spray the cleaner on, agitate, and wipe clean. Displace with something that's not petroleum-based like silicone spray or something. Not WD-40.
Yup I used the kind that doesn't foam up and then dabbed it dry and let it set for a bit before reconnecting everything
 
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AwxyMoron

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You still get a code for driver side O2?
No, during KOER this time i got a code 13(idle too high) and a code 26(MAF voltage out of range). Heres the thing, I went ahead and ran another test and checked the voltage with a voltmeter while it was running the test, The voltage was right at .5 volts during idle and when it was at like 1500rpm for the test it was at .6 volts. I am pretty confused but this would have to do with the computer correct?

also this is the first time i have gotten either of those codes
 

Noobz347

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No, during KOER this time i got a code 13(idle too high) and a code 26(MAF voltage out of range). Heres the thing, I went ahead and ran another test and checked the voltage with a voltmeter while it was running the test, The voltage was right at .5 volts during idle and when it was at like 1500rpm for the test it was at .6 volts. I am pretty confused but this would have to do with the computer correct?

also this is the first time i have gotten either of those codes
I do not know what the scaling is for your meter or what has been input for scaling on your tune. I couldn't answer either of those questions.

Even if you had the 30 point reference for the meter, you still don't have the means to check the tune to see whether or not it is correct.

However, since it [did] run but doesn't now, you can kind of eliminate the tune itself being the culprit. At least, for now.

I'd be looking harder at the connections and the meter itself. Even changing how a meter housing is clocked (causing or eliminating turbulent air directly over the MAF sensor) can have a huge effect.
 
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AwxyMoron

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I do not know what the scaling is for your meter or what has been input for scaling on your tune. I couldn't answer either of those questions.

Even if you had the 30 point reference for the meter, you still don't have the means to check the tune to see whether or not it is correct.

However, since it [did] run but doesn't now, you can kind of eliminate the tune itself being the culprit. At least, for now.

I'd be looking harder at the connections and the meter itself. Even changing how a meter housing is clocked (causing or eliminating turbulent air directly over the MAF sensor) can have a huge effect.
I guess I might have worded my last post badly, the voltages are within the range for the test, I think the range is .2V to 1.5V. I also went and checked the other wires to the MAF sensor connector and the red wire is getting 12V, and the grounds are good

I have a laptop, would I just need the cable to connect to the chip and then some software to see the tune? I do agree with you that the tune shouldn't be the issue since the car did run good before
 
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Noobz347

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You're not exactly a perfect fit for the checklist (for obvious reasons) but the sensors that are present are still applicable:

 

AwxyMoron

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Okay, I clocked the MAF, and I am getting code 26 only now. The engine actually backfired during the engine code test as well. The voltages for all 4 wires at the MAF connector are good so I am not sure what why the car keeps throwing code 26?
 

AwxyMoron

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Okay, I clocked the MAF, and I am getting code 26 only now. The engine actually backfired during the engine code test as well. The voltages for all 4 wires at the MAF connector are good so I am not sure what why the car keeps throwing code 26?
Okay I think i found out why its throwing the code 26, the connector is failing the first test, it is reading out about 12.1V between VPWR and GND. MAF_test.gif
 

AwxyMoron

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It says 10.5 Volts or greater. It's only a fault if it's less than that.
Okay, on the middle test the connector is showing no continuity when the connector is disconnected(is there supposed to be?) and only about 8.5ohms when its connected to the MAF. Am i supposed to be testing the MAF connector or the MAF Sensor itself?
 
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