problems

[johndeerel]

I have a 1998 chevy tahoe 6.5td and when i accelerate kinda hard it seems like there is no power and alot of black smoke comes out. Does anybody know what would cause this

[6point5]

It probably has something to do with the wastegate systems. Do you have a boost gauge? 3 probabilities, vacuum pump, wastegate actuator, wastegate solonoid. Also check for vacuum line pulled off, fell off or broken. You can check the system with a vacuum gauge. Check the vacuum at the pump (should be about 20) and at least 15 at the actuator. If you have that, its probably the solonoid. (about $40)

[johndeerel]

no, i dont have a boost pressure guage but i am going to get one now.
i checked my wastegate actuator and my doesnt snap back it goes back slowly is that the problem.

[sixnickel]

JD How did you check the waste gate movement? With the engine running it should be very hard to move be hand! If you can move it at all. If it moves easily and returns very slowly check all the things that 6point5 mentioned about the vacuum system. One other thing I always forget to talk about is the air filter unless it's new replace it. Also if you still have the snorkel in the fender for the air filter yank it out and get rid of it (you just made your first up grade!)

[johndeerel]

i checked the wastegate actuator when it was not running

[sixnickel]

With the engine running the rod should be pulled into the chamber. In that position the valve is closed for maximum boost.As power and boost come up the vacuum backs off and the rod moves out to control max boost. There is not enough load in neutral to get it to move it has to be under a load to make boost.

[_Fox_]

JD How did you check the waste gate movement? With the engine running it should be very hard to move be hand! If you can move it at all. If it moves easily and returns very slowly check all the things that 6point5 mentioned about the vacuum system. One other thing I always forget to talk about is the air filter unless it's new replace it. Also if you still have the snorkel in the fender for the air filter yank it out and get rid of it (you just made your first up grade!)

Is the snorkel your talking about the one that's mounted by the battery and runs down to the back side of the right side turn signal? The reason I asked is I've seen pictures of the snorkel on the net and mine doesn't look like the one I've seen on the net. The truck is a 96.

[sixnickel]

I'M sorry my mistake. I forgot what year we were talking about.The newer ones don't have that snorkel just the older ones with the panel type air filter. Good catch FOX!!