Part throttle hesitation cruising highway in 4th and 5th gear.

Chenn2389

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Hey all. Having an issue with the car stumbling and hesitating on the highway while cruising. It feels weird, will be cruising then I can feel the power and rpms start to drop and then it jerks back and does it intermittently. I changed out the fuel pump with a spare I had and took my bbk fuel pressure regulator off and put on a new motorcraft unit as well. This solved about 85% of my running issues with surging idle and lean condition codes. The only things I can think of is I am still using the alternator that came on the car when I bought it. Its of unknown brand and amperage and has significant whine under acceleration in 1st and 2nd gears. The new motorcraft 02 sensors may be shit and need warranty I might call summit to get them swapped out anyways just to rule it out. My BBK maf calibrated for 24# injectors may have a bad calibration. TPS might not be giving good reading, but I did voltage test it through the whole range and there was no issues. Or I need to get my tune looked at again. The engine is new and im so close to finally having it running well.

I have smog pump, egr, thermactor, thermistor all removed and tuned out of the code.
 
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RAU03MACH

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No code codes for the mass air flow
I'd check it make sure it's clean
Make sure that the cold air sencor is clean
Just a start
 

ttocs

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I am not sure how the alt makes noise in 1rst and 2nd but no other gears. Is this noise your hearing from the speakers or just from the alt itself? If its from the speakers you probably need to replace the ac noise condenser on the coil.
 

Chenn2389

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I am not sure how the alt makes noise in 1rst and 2nd but no other gears. Is this noise your hearing from the speakers or just from the alt itself? If its from the speakers you probably need to replace the ac noise condenser on the coil.
Not from the speakers. Nothing but the drivers seat and gauges are in the car right now. I think I just don’t notice as much in higher gears because I’m not accelerating as hard and the drone of having OR x-pipe and dronemaster 40s.
 

Chenn2389

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I'm not 100% sure, it could be gear wine in my trans since I have all the interior out but its just a T5 shouldn't be getting tons of gear noise. Upon further reading I am thinking it could be the distributor is going bad or the ignition control module is bad. The hesitations happen after I been driving for 20-30 mins or when its excessively hot and alot of stuff I have read on this forum points to the dizzy or ignition control module. My batter isn't dead nor am I seeing any noticeable voltage drop on the gauge. I tried to test the ignition controller a few months ago at autozone and it failed, but I had them test two new ones and they also failed so I didn't trust their machine and didn't buy a new unit.
 

Chenn2389

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Another thing, last year before I pulled the 302 the engine would have trouble starting or stalling just after it was started when it was hot and warmed up after driving for extended period. This also is making me suspect the ignition control module as the symptoms of it starting to fail usually occur when it gets really hot.
 

ttocs

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I had an interesting problem that I discovered while remote tuning my car. After the motor was hot the TPS was showing 4-7% throttle at idle and it was screwing everything up. I replaced the tps and we got back into it and discovered the same problem. This time I replaced the harness to the tps and that fixed it. The tps(and many other sensors) reads a variable resistance as the throttle blade moves to know how much gas your giving it. When the motor was hot, the harness was loose and that caused resistance to go up slightly with out it being held tightly together.

Next time it gets hot and its acting strange pop the hood while its running and see if any of the harnesses are loose. They should be able to take a fairly strong tug/pull with out really moving but certainly not being able to be pulled off. Give them all a jiggle first and see if the motor changes how its running and then like I said give a solid pull on any harness you can see and see if it studders or changes.
 

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