94 Mits Mighty Max stumbles under acceleration

[89Mirageman]

Just picked up a 94 Mighty Max 2.4L, auto trans a few days ago. 194k on the odometer but the compression still reads 180 on all four cylinders. It has started missing under acceleration. If you gradually give it gas it will rev up nicely, however if you hit the gas very quickly it will bog and cut out. The ECU looks mint but I just replaced the caps anyway. Plug wires are new along with NGK plugs gapped to the correct specs. I also swapped in another TPS and coil, same problem. Any other ideas guys? I know its not GVR4 but the basics are the same. Give me some more options to try. Thanks in advance!

 

[dammitjim]

Wild guess - your fuel filter is clogged.

 

[89Mirageman]

Just removed it and I could blow through it easily but I will grab a new one while its off. Any other ideas in the meantime?

 

I'd be looking at the fuel injector wiring/connections. Worked on a talon that did that. Took me way too long to find a loose connector.

 

[TRBODSM]

What about the coolant temp sensor. Does it start up fine or have a rough start? If a wire was broken or something I'm pretty sure it would cause it to run in limp mode since the ecu doesn't know what coolant temp it's at. This is just a guess

 

[89Mirageman]

Thanks guys! Also something I thought about earlier but forgot to mention. Seems it didn't start this until after I filled it up with gas. We called the store today and they said nobody else had complained of bad gas or anything (not that they would actually admit it if they did). When I took the fuel filter off the gas had a strong smell and I didn't see any bubbles or anything so I'm guessing its fine.

The truck starts right up although I do have to feather the throttle for a few seconds before it can idle on its on. After it warms up it will start right up and idle fine. I thought the temp sensor made it hard to start? At least it did on my old summit wagon when it went out.

 

[89Mirageman]

Changed the fuel filter but no change. Next on the list is the maf I guess. It uses a 2g style maf but its a 182 instead of 609. I swapped in a 609 since I have a few spares but no dice. Wouldn't even idle so I guess its off to the junkyard to try to find a 91-94 MM/D50 maf.

 

[89Mirageman]

Grabbed another 182 maf from a 91 mighty max today at the yard and it fired right up and takes the gas perfectly. Thank God my little max is back on the road. /ubbthreads/images/graemlins/worthy.gif