The turbo build has been done for a while and I'm just driving my car easy to break the motor in before I do the fuel system and tuning. My car has a bucking/surging problem after it warms up that is obviously related to a sensor. The car is okay at moderate throttle, but at light load steady-state cruising it bucks and surges and has a hard time holding a steady load. After a little research I've learned that the MAF may not like a lot of tubing in front of it for some reason. I've got mine mounted after the front-mount and about 2.5 feet from the throttle body.

The tune and injectors are stock for now, so I'm fairly certain it isn't a tune or fueling problem, and the ignition seems fine. Any ideas? Who has dealt with this problem or a similar one? Does anybody else have the MAF behind a lot of piping?

-Chris

 

It's probably too close to the intercooler. The air coming out of the intercooler is probably swirling and moving all over the place, this will make the MAF not get an accurate reading. Move it to the stock location (right before the bend before the TB) and see if it continues..

--Sean

 

I have several feet before the maf but after the intercooler. Maf is in about the same location as stock. I have no problems like you describe.

 

The comment about the turbulent air got me thinking. I have a descreened MAF, and maybe a screen would help. So I threw a stock MAF back on the car and it almost seemed like it ran worse, although I can't be sure. Oddly, though, later I disconnected the battery to reset the PCM and the car was great for about 10 miles before it slowly started freaking out again. Maybe the PCM doesn't like the turbo for some reason?

-Chris

 

I have a stock de-screen MAF in the stock location (after the front mount intercooler) with no problems.

 

How about if you unplug the MAF all together? How does it run?

--Sean

 

My MAF is mounted about 2.5-3 feet before the TB after a front mount. Has always been like that and ive never had a problem with it.

Sounds like O2s or a couple of crossed plug wires to me.

 

Sean, I'll try your suggestion tomorrow.

CJ, your suggestion got me thinking. I put the O2s in the downpipe, about two feet away form the turbo. I figured that the distance wouldn't be an issue since they're heated. Maybe the O2s need to be closer to the exhaust port?

-Chris