Hello all, my Evo IX is having some serious tachometer jumps and sputtering problems. Problem first started when I was driving to Dallas, TX from Shreveport, LA. Car was rising in temps when just barely getting into boost (it was also super hot outside) so I backed off the car for the remainder of the trip.

Went to drive home the same night and ended up being too tired to finish the drive so I stopped for a nap in a parking lot. When I went to turn the car back on and drive away, it was sputtering and jumping all over the place like it was fuel cutting and misfiring constantly. Completely undriveable.

It threw a code for the map sensor, so we rigged up a pressure regulator out of a bicycle pump and ran it to the sensor and it wasn't reading anything above atmospheric pressure at like 1.18v or something. So I figured that was a huge red flag. Ordered a new omni 4bar map sensor hoping that would be the fix. Turns out it didn't so i'm at a loss right now as far as what else it could be.

The car starts up just fine, but even in neutral, not driving the car, with little throttle, the tach still jumps all over the place. I've read that it could be the camshaft / crank position sensor. But at the same time, they are saying that the car wouldn't even start if those were to go back. I'm a bit new to the platform so I don't have enough knowledge with the car to troubleshoot electronics.

Any help or leads to the cause would be greatly appreciated!

Thanks all for any suggestions and info on potential solutions!

- Zack

 

Have you started investigating the small stuff first....like vacuum piping? my tach jumped all over the place in neutral or in park tach was steady but any light application of throttle it the car would break up. (I'm not sure if your problem is vacuum related) but start inspection intercooler pipes start from the J-pipe to nipple hose on the j-pipe to intercooler to intake. what fuel were you using on your trip. I'm sure other knowledgeable evo brothers will chime in.

 

Haven't tried a boost leak check yet just because of the fact that I feel like it's an electrical issue due to the spike in tach jumping.

Edit : fuel I ran has always been 93.

 

bump?

 

do a boost leak test

car temps rising, even in hot heat, should be a red flag. do a compression test as well

 

Yeah, that caught my eye too. A working stock cooling system never exhibits a rise in temperature no matter what the conditions.

 

wasn't my actual car temp needle. was water temp. but we will be doing a boost leak test later this evening.