I have posted serveral times on different forums and can't find an answer.

I have a 99' white trans am M6. When I'm driving and I go from 4->5 at 40, as soon as I get to 46MPH the car has a slight hesitation. It is almost as if it bogs down and then everything is normal again.

It isn't everytime I hit 46 MPH and i tried to slow down from 5th with no brake to see if it would cause anything at 46 but I felt nothing. I can feel it even when I'm in 4th gear (not as noticeable). When I'm at a full WOT I can't notice anything. What would be causing this? I am getting very annoyed at feeling it bog down at this speed. Also, If I slow down but don't stop, I won't get the hesitation. It is usually when I stop and then go. I don't really feel any problems with the clutch, and I don't get any slippage especially when I slam gears.

 

same here. Its happens to me in 4th at around 45 mph or so. I can feel it hesitate, then after 50 mph it goes away

 

it doesn't last that long. it's just a slight hesitation. it lasts about 1-2 MPH

stuck injector? problem with ecu programming? its driving me nuts

 

Sounds like an EGR problem.

 

woohoo, I'm not crazy. I have been trying to track down a similar problem on my '98 Z for years. I have isolated the failing condition to two points ~1800 and ~2300RPM in any gear(M6) while accelerating. The higher the gear the more noticible the hesitation. Also, using a very light throttle and going uphill while accelerating causes it to be more noticible. Very rarely(once per year), I will get hesitation so bad that it feels like the engine shut off. Here are my possible culprits:
1) false knock causing ignition retard
I suspect that the false knock might be caused by my rattling idler pully.
Rev you engine slowly in neutral from 1000 to 2500RPM and see if your idler goes beserk.
2) Throttle Position Sensor flaking out causing poor A/F ratio
3) Crank position or Cam position sensor flaking out.
4) Some weird EMC problem that only occurs when the moons are in alignment(I hope not).

I have not yet been able to track down the problem with ATAP yet.

 

hmmm... anyone know what the specific conditions are before EGR kicks in. I know it is during light throttle. Maybe I'll just throw in a blockoff plate and see if the problem goes away.

 

I get no ses lights or cel lights at all. wouldn't some of those problems throw a code?

 

i hope it's as simple as the egr valve. i'm going to change that sucker tomorrow. hopefully it solves the problem.

 

Let us know if that works, I have been thinking of pulling mine as well.

 

Not all the time will they set the light. I work for Honda and the 3.5L V6 models (Pilot and Odyssey) have this problem with hesitation ~40-50 mph and the EGR is the cause of the problem. If you know someone else with one that doesn't have this hesitation problem you might want to swap it out and see if that stops the problem. Thats just my suggestion.

It might not be the problem but I would give it a shot.

 

or you could just get rid of the crap. EGR just dirties up your intake

 

Any updates on this? Im havig the same issue.

 

going to clean my MAF. if that does not work i'm going to clean the EGR. ill keep you guys posted

 

Think it could be the PCV system?

 

Clean your MAF with contact cleaner. I worked for me.

 

I just cleaned the MAF. It had black carbon looking dirt along the small tiny filament wires connected to the metal bars that go across. I very very carefully cleaned the filaments with a dry q-tip. The bars also had some of the dirt build up. I cleaned these very carefully (avoiding hitting the filaments).

I test drove my car for about 5 miles. Have not had the problem at all. I'll keep everyone posted if I happen to get the hestitation.

I am also going to go clean my EGR. I'm going to buy a bottle of carb cleaner.

 

I have a 2001 corvette and it does the same thing. It doesn't have a EGR system!

 

What is contact cleaner?

 

As I became confident the problem was 100% gone, I found only disappointment when the damn thing hesitated at that exact speed again. I am going to clean the EGR valve with carb cleaner either saturday or sunday. Hopefully that solves the problem, otherwise I'm left clueless once again.

 

You're car does have an EGR system (if you're not the original owner the previous owner must've taken it off). I know they were moved to a different location though. Not sure where.