Big hesitation, black smoke.

[b00stedtalon2]

Posting this for a friend who has no internet access. Car is a 91 AUTO TSI AWD, bone stock. We replaced the MAF with 2 different ones and problem was not fixed.

It's almost impossible to get the car over 3k RPMS. car hesitates and cuts out. builds boost way too quick, lots of black smoke. It idles fine until you start driving it then it starts to cut out and hesitate.

Here's a quick video of what it does when he pushed the throttle in.

Video - TinyPic - Free Image Hosting, Photo Sharing & Video Hosting

Any Idea's will be appreciated, thanks!

 

[vr4_3000]

Black smoke = too much fuel. pull the plugs and look first off. they are probably all fouled. You could have more than one thing wrong. Have you checked that the wastegate works? Need a little more info on what you have tried.

 

[twicks69]

Did you touch the cam angle sensor before this stuff happened? If you put it back on and had the sensor 180-degrees off, it will cause this.

Otherwise, it could be timing belt stuff -- have you checked your timing marks? Have you checked its compression?

ECU?

Any check engine lights? O2 sensor? Knock sensor?

 

[MrGriff750]

I would suggest checking the ECU capacitors. I had the same problem with my car until I replaced the leaky buggers. When you inspect them be sure to look them over well because it was difficult to notice that they had leaked at all. To be honest it would be best to solder new ones in just to be safe. The capacitors cost me less than 5 dollars.

Here is a link for information on purchasing the capacitors and how to replace them:
89-94 Capacitor Replacement

 

[98gst14b]

MY car did the same thing, but from being horribly rich before my dsmlink came in. Are you running bigger than stock injectors? Any tuning devices?

 

[eclipse_16g]

fuel pressure regulator, boost leaks. does it buck really hard when your driving on full throttle? might wanna check the coil pack.

 

[b00stedtalon2]

It's been a while but its nice out again and the car is still having the same problem, its been tucked away in his garage.

We replaced the ECU, Spark Plugs, Wires. CAS is not 180* off, and compression is 160 across the board, and timing marks are perfect. No check engine lights. When we pulled the old plugs they are coated heavily in black.

We test drove the car earlier today, and it was perfectly fine until it warmed up. Then it would do its thing again which was not being able to rev past 3k, bucking, blowing all kinds of black smoke and having like no throttle response.

This weekend will replace:
fuel press regulator
coil pack
coolant temp sensor

But since it only does it when its at full operating temp, seems like our new to-do list would not matter minus the temp sensor, possibly.

 

[Justinawd]

I would imagine its running way to rich thats usually what black smoke means...

 

[b00stedtalon2]

Yes, its running very rich. Trying to figure out why.

 

[GsXdSmKingGsX]

What are your plugs gapped at?

 

[Justinawd]

Is it running stock injectors? I know my buddy is running 650cc injectors and a walbro 255 without a FPR, stock 14b at 15psi and its a turd because its just pouring the fuel and it also blows as much black smoke as my diesel ram with a 180hp tune on a big laggy turbo...

 

[ArticNemesis]

boost leak test.

You've described a very large boost leak.