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Discussion Starter #1
So for the past month or so, my car has been shaking and popping(sounds like a backfire) at 4000rpms in 2nd-4th gear. I recently fully redid the exhaust with shorty headers, off-road h pipe and American thunder catback. The car ran great for a couple of days after I redid the exhaust, however now the issues previously encountered have returned tenfold. The car shakes and makes the pop/backfire noise in all gears at around 2-4000 Rpms. It's as if I have to shift as soon as I get it in to gear. This problem starts about 5 minutes into the drive. I'm getting a fuel gauge tomorrow to check the psi but I'm thinking maybe a blown fuel pump? I'm not really sure here. Help me out gear heads ! This is my daily. I need a fix fast!

EDIT: the car has also died out on me twice. The RPMs start slowly dropping and at wot the car won't go past 4k Rpms. When the car is about to die I can push the pedal all the way down and I get no throttle response whatsoever. It's as if the gas pedal doesn't even work. I have no CEL on or any other lights for that matter. Thanks again!

'88 GT
 

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Still need to run your codes.

Eliminate the obvious.

Sent from the Bathroom
 

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Not even a 11.

Sent from the Bathroom
 

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Discussion Starter #5
Literally couldn't pull any codes at all. Got no feedback from the 12v test light or cel


'88 GT
 

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Discussion Starter #6
I'm thinking map sensor, vacuum leak, and stuck in closed loop cause O2 sensors are bad.


'88 GT
 

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Like you said check your fuel pressure also it might be timing/dizzy related/pip.

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If you cant get the koeo test to start by inserting a jumper wire between the VIP terminal & STI terminal, insert the wire between the STI terminal & the neg battery terminal. Make sure the engine is at operating temp when doing the test & make sure the transmission is in park(auto)neutral (5 speed)If the test still doesn't begin,press & hold the clutch pedal to the floor while running the scan.You should always run a koeo koer test first before doing anything else because the cel doesn't have to be on in order for codes to be present.Any current trouble codes(if they exist)will help you trouble shoot more thoroughly.
Make sure the engine is at operating temp before doing a koeo koer test.Check & adjust(if needed)the timing to 10° before test.A bad ground can also cause your issues so check all of them for tight,corrosion free contact.
#1)Neg battery cable to engine ground
#2)Rear side of RH or LH cylinder head to firewall ground
#3)EEC ground-small gauge wire screwed to driver side fender apron,to the right of the starter relay.The small gauge wire that runs alongside the neg battery cable also mounts at this same location.It sounds more like a defective TFI module, pip sensor,tps or distributer but don't start buying parts in an attempt to guess at the problem.I had a TFI module go out and it would do the same exact thing as your car except it would cut out completely between 2500-4500rpm,but would do fine outside of those rpm levels.The fact that the symptoms don't occur until you've driven it for 5-10 minutes indicates a possible sensor heat soak issue or a sensor/EEC problem that only occurs when the ecm is in closed loop mode.AUTOZONE can test the ignition module if you remove it and carry it in.They're notorious for going out once heat soak is affecting them.The links below will help test the TFI module,pip sensor & tps since it can also cause your symptoms.
http://351winsor.com/joel/Ignition_Systems/tfi2.html
http://sbftech.com/index.php/topic,29736.0.html
 
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