Bucking/Hesitation Problem...Cause?

[monk36]

Lately, I've been experiencing a bucking or extreme hesitation problem. When this occurs, the gas pedal goes limp for an instant, the engine almost sounds like it stops turning, and there is an abrupt stop to exhaust noise. This all lasts for roughly a quarter of a second, then drives like normal again.

There is no belt issue that I can see. It always does this at normal speeds, while the car is in motion. There are no codes thrown whatsoever. The engine never bucks or acts oddly when the car is idling and this occurs no more or less frequently based on air temp, engine temp, and driving tendencies(aggressive vs not).

My question is two-fold. What could be the culprit?

And secondly, could my estimation of what it is, be causing it:
When I installed my 4.10 gears, the backlash, I believe was on the high side of the factory specs, but still within those specs. However, since the install, 2-3 years ago, I have had a gear whine on deceleration. Could the gears be wearing out prematurely, and binding at certain points, causing intermittent jerking like I'm experiencing?

I have not drained the fluid to check to shavings or quite possibly in my case, if this is it, chunks of metal, but wanted to see if something like that could cause my problems before I did. I do have the original 3.55s that I can (reluctantly) put back in, but don't want to without being sure what's wrong.

BTW, the engine is built with eagle internals at stock bore/stroke, running a techco blower at 10#.

 

[BruceH]

I'd start with the usual suspects. Maf, tb, plugs.

 

[monk36]

I have yet to check the maf, but the tb is good, and the plugs were just put on back in January, so they should be good, but will be checked to be sure.

I really doubt its those things because the problem is very intermittent. Driving it every day, it happens maybe every 5th or 6th day, and has no problems otherwise with response.

 

[Gallagher]

possible boost leak?

 

[NjsGT]

Have you changed or re-loaded the tune lately?
Also how many miles on it? Bad fuel filter?

 

[nate80]

Check with your tuner. I had a bucking problem when I installed my Whipple. Fuel pressure was not stable. The shop blamed on a bad pumps and grounds. They had the car for 2 weeks and no fix. Took the car to a better tuner now all smooth.

 

[monk36]

Shouldn't be a boost leak. If so, it would have to come from the intake to block connection, correct?

The tune was reloaded back in january with the engine building. I can try reloading it to see if it helps. The car has about 65000 miles on it, and the engine has about 2500 since the rebuild. Not sure on the fuel filter, how could I check that?

If I datalogged using the sct livelink with my tuner would I be able to see if the fuel pressure was fluctuating too much?

I got it tuned out of town, but I trust the tune. It worked beautifully for many miles before the engine was built, which is why I suspect something else.