1994 940 Turbo - Poor performance, stutters

inchcombec · Post by **inchcombec** » 01 Nov 2012, 07:17

Okay, so I've been having some issues for a few weeks with a 1994 940 Turbo I got awhile back that I'm having a hard time tracking down.

The car idles fine, but gets extremely little power when actually driving, runs noticably rich, will put out dark smoke if trying to force it to accelerate, seems to just lose power with more gas if anything, sputter and seems to miss a bit when driving with any speed and barely has the power to up hills. It'll go up, but at around 30kph. Also, no CEL.

I've tried a few things so far but with no luck. First off was I suspecting it was the Mass Air Flow sensor. Found one for a decent price so just got a new one. That didn't fix things. Air filter also looks fine. I've also looked for loose or broken air lines past the MAF but so far haven't spotted any.

Had a couple people suggest the catalytic and some the symptoms fit, but took that off (what a pain) and it wasn't clogged so that one is out. Also put in new plugs in it since they're fairly cheap and was planning to do that anyway but that didn't fix things up either. I also took a look at the oil to see if it was flooded with gas or anything like that as that might have led me towards an issue. It smells a bit of gasoline, but that isn't surprising considering it is running rich, it still is at the normal level and looks proper.

I've taken it out on short little drives around the block to test it a couple times and have noticed that when I hit the gas I get power for about a half second to a second but then it just drops off. The best way to get it to move is to pump the gas pedal on and off a bit. Not sure exactly what would cause it to act like that.

At this point I'm getting suspicious about the fuel pressure regulator or fuel pump but haven't time to get a gauge and do a full test yet. I did take the vacuum like of the fuel pressure regulator to look for gas coming out but after 10 minutes didn't get a drop out and the hose looked really dry. I've never owned a car with a Turbo before so not sure if I'm missing obvious symptoms of an issue with that.

If anyone has seen a car acting like this and has a suggestion it would be much appreciated. I'm starting to get a bit frustrated now as everytime I think I might have found an issue that matches the symptoms it ends up leading nowhere.

Post by **jimmy57** » 01 Nov 2012, 07:36

CHeck fuel pressure driving. The fuel press regulator on B230Ft has a history with age of getting bound up diaphragm and going to very high fuel pressure.
3 bar with key on before start. 2.4-2.6 Bar idling and goes up to 3.4-3.6 under load with high throttle.

I suspect from your description that you have a leak in hoses to/from intercooler or at the idle air control valve. The intercooler itself could be leaking. If air passes through MAF sensor the engine control unit will deliver fuel to match that air. If the air is lost through a leak then the engine runs rich with low power as the fuel is delivered into cylinders but not the air. Poor perfromance and black smoke results. There is rarely a fault code as the engine control unit does not detect a number of faults at high engine load. High MAF signal is taken as high engine load.

inchcombec · Post by **inchcombec** » 01 Nov 2012, 21:03

Alright, I'll start checking all the hoses. Do you know if there is a picture/diagram of all the vacuum hoses? I've taken a quick look before and didn't find an issue and just want to make sure I'm not missing any.