What's happening???

[elipsekid]

Ok heres my problem, my car runs fine as a daily driver...but when I get on it and hit around 4500 rpm in any gear the car bucks and dumps a big dark smoke cloud out of the back ....cant seem to figure out what the problem is ?? anybody know of anything to look for or what might be my problem?
TIA

 

[krazywhitboy]

any mods?

checked basic stuff like plugs, wires, etc?

 

[IHeartTurbo]

fuel cut

 

[elipsekid]

it has a 6 bolt, arp head studs, nology wires, ngk plugs...other than that its all stock

 

[krazywhitboy]

your not going to hit fuel cut on a stock car

 

[IHeartTurbo]

If you have a boost leak you can.

 

[krazywhitboy]

ok well i was assuming there wasn't a boost leak....

 

[Thomas91169]

i really didnt think fuel cut could be associated with a boost leak, as fuel cut is reached when the map sensor reads 2000karmen or higher, it sees too much air coming into the engine and it doesnt like it, so it cuts fuel to slow the engine. and its kinda hard to have a boost leak before the turbo.

though i think fuel cut could be hit if you turn up the boost a little and its really cold outside. i hit fuel cut the other day, cause it was about 50* outside and i was hitting 18lbs and my ecu no likey.

 

[elipsekid]

so I should check for boost leaks and go from there?

 

[IHeartTurbo]

its kinda hard to have a boost leak before the turbo.

That would be a vacuum leak. Same thing, only negative pressure instead of positive.


But anyways, yeah, check for boost leaks. Even if that's not the cause of your problem, you still don't want any anyway. Also, does it just stop dead like you hit a brick wall for a half second then come back on? If so, that's fuel cut. If not and it's more gradual, then it's most likely a maintenance problem (i.e. plugs, wires, fuel filter, etc)

 

[elipsekid]

But anyways, yeah, check for boost leaks. Even if that's not the cause of your problem, you still don't want any anyway. Also, does it just stop dead like you hit a brick wall for a half second then come back on? If so, that's fuel cut. If not and it's more gradual, then it's most likely a maintenance problem (i.e. plugs, wires, fuel filter, etc)

its more like whiplash, seems to loose power but not for very long about a half second

 

[IHeartTurbo]

It sounds like fuel cut to me. Make a boost leak tester. Directions are at www.vfaq.com Try that first, and we'll go from there if it's not that.

 

[elipsekid]

thanks for all the help, ill see what happens and post back

 

[crankbender]

i really didnt think fuel cut could be associated with a boost leak, as fuel cut is reached when the map sensor reads 2000karmen or higher, it sees too much air coming into the engine and it doesnt like it, so it cuts fuel to slow the engine. and its kinda hard to have a boost leak before the turbo.

though i think fuel cut could be hit if you turn up the boost a little and its really cold outside. i hit fuel cut the other day, cause it was about 50* outside and i was hitting 18lbs and my ecu no likey.

Think about what you wrote there for a second. Lets just say we have an engine using enough air to give you 1500hz or so. Then you have a boost leak that is letting out more air on top of that. As our MAFs are located before the turbo they count all the air entering the turbo and not the engine. So the 1500hz of the engine is a baseline and any air lost through the boost leak will add to that. A very small hole will loose a lot of air at 15+ psi.

 

[v8s_are_slow]

running really rich maybe. what KIND of plugs and what's the gap? also, check your fuel pressure regulator incase it went bad. i've had that problem and my car would kick and buck, and backfire, and smoke out the exhaust. just some extra ideas to look at.

 

[krazywhitboy]

yea my car was doing almost the same kinda thing after i installed my 3" exhaust. it would buck and backfire, then smooth out at higher rpms. changed out the plugs to some NGK's and it fixed the problem. start checking out the little things first, then let us know what happens.

 

[elipsekid]

just pulled the plugs non of them are fouled but #s 1 and 4 have oil on them 1 was really bad and 4 wasnt that bad. bad rings maybe? #s 2 & 3 were perfect. i have NGK BPR6ES plugs gapped at .032...
any ideas about what could be the problem??
TIA

 

[krazywhitboy]

just pulled the plugs non of them are fouled but #s 1 and 4 have oil on them 1 was really bad and 4 wasnt that bad. bad rings maybe? #s 2 & 3 were perfect. i have NGK BPR6ES plugs gapped at .032...
any ideas about what could be the problem??
TIA

well yea that could be a problem. fouled plugs wouldn't give a proper spark. and yes, oil on the plugs would suggest bad rings....

 

[elipsekid]

The car only smokes when i get on it. Could the head gasket be in need of a change?
...so would getting the rings, seals, and head gasket replaced probably solve all this?
thanks again