Q45 hesitant to acclerate when warm

[CoastyAV8R]

My 94 Q45 seems to stumble pretty noticeably when trying to accelerate once the car is warm. When it's cold it runs fine. Once it does warm up, if I shift it myself and keep the rpms' over 2500, it doesn't do it very badly but still slightly noticeable. Once you get to 4000 rpms, it accelerates fine. If you give very light throttle applications, the car will acclerate but anything more than 1/8th throttle and the stumbling starts and will continue until the RPM's build over 2000-2500 rpms. The idle on the car is fine and it starts right up, hot or cold. From what I have read, it sounds like a MAF. I have cleaned the throttle body, MAF and the MAF connector 2 times and even though the throttle body was dirty it didn't solve the problem. I hate to throw parts at something unless I have either a troubleshooting flow chart or somebody has had a similar experience and can atleast let me know if I'm on the right track. I ain't got no flow chart so I'm hoping somebody will chime in...

Thanks,Pat

[elwesso]

Pat, id try and find someone who has a MAF they could send you

Either way, its probably worth a shot getting a used one for under $100....

[maxnix]

Well, it could be your intake path from the throttle body in. How clean is that part of your induction path?

[DAEDALUS]

Take measurements on the sensed voltage, at the ECU is easiest, and on an analog meter if you can. See if you can get someone to take readings vs. RPM when cold vs. hot, or at least watch the needle.

[CoastyAV8R]

Thanks Daedalus. I only have digital meters but I can get my hands on an old analog one from work. The sensed voltage I'm looking at, is that developed in the MAF and sent over to the ECU directly? I assume that voltage should change with a change in engine RPM, correct? This check will rule out the MAF as the cause if the sensed voltage is linear throughout the RPM range both cold and hot, right? I appreciate your input, Thanks again.

Pat

[DAEDALUS]

You got it. Reading your symptoms again, I wonder if you have an arcing coil. If the MAF checks out I would suspect arcing. Unfortunately there's no easy way to check for that. The plugs have to come out and only if they show signs can you confirm it. Is the stumble getting worse over time?

[CoastyAV8R]

I just put new plugs in it 5 days ago and it made a huge difference but it still hesitates some once it warms up. I'm not sure how long the plugs had been in the car, but they were definitely ready to get swapped out. I hadn't thought of the coil arcing but I thought with these plugs, it had the coil built in to the end of the spark plug lead. We've been swamped at work from the hurricane so I haven't had time to check the voltages yet so I can't say whether those are good or not yet. I have a used MAF coming from Utah that is suppose to be here tomorrow. I'll know something soon...