A month ago I purchased an 07 G35x. After a few weeks the engine seems to rev up/stutter when slowing down or braking. I purchased it from a small dealer without warranty. I did purchase an additional warranty 5yrs / 100k, but doesn’t kick in for another 2 months. Anyway, the engine revs/stutters a little when slowing down or braking. After I purchased it, I automatically did an oil change w/ filter, changed air filters and cabin filter… still no change. So then I cleaned the throttle body for good measure… and again the rev/stutter is still there. I just reset the ECU and rev/stutter is still there. Has this happened to anyone else? Can someone please help? I’m out of ideas on what I can do to fix it.

I appreciate any and all feedback.

 

Maybe try cleaning your MAFs and double check your tranny fluid.

.02

 

What is this additional warranty 5 yrs/100k miles you have? Why doesn't it kick in or another 2 months? Is this a third party warranty, because it seems like it. How many miles are on the car?

Anyways, when you do slow down and brake, engine does rev up and uses the "engine braking" feature to slow the car down. I'm not sure how bad yours is, but it does that sometimes with my G.

 

I might have the same problem that you are talking about OP. Lets say i am stopped at a red light wanting to make a right turn, as the light turns green, i step on the gas to make the turn and a pedestrian wants to cross and i need to brake, i then immediately feel the car shudder/hesitates and the car Rpm's rev up and down and then back to normal. Sometimes however, the car would shut down and i would then need to park, and start the car again and all is fine. I have done all the recommendations noted above to no help. Only thing i haven't done is changing the transmission fluid which i will be doing at 120k miles, im currently at 112k. Everything else with the car is perfectly fine and still runs like new (knocks on wood). Hope someone can chime in on this.

 

When was the last time you changed transmission oil?

 

I'll try it. Is there a "safe way" in cleaning the MAFs?

 

It is a 3rd party warranty that covers bumper to bumper, engine, electrical and all that good stuff. The downside is waiting the 3 months... I get the waiting period, but don't like it. Either way, these cars are expensive to pay for repairs out of pocket so I figured why not.

I'm about to hit the 73k miles mark.

 

I just changed the PCV valve today... it runs better, but the issue is still there. I'm going to do what VGSMILE suggested and clean the MAFs and check the tranny oil. You'd figure that they would check the tranny fluid level when doing an oil change, but you never know. For those of you who care, I will post my results within a day or two.

 

Do you mind letting me know which company you are with for extended warranty? I have 80.5k miles on my car but no problems as of yet. I opted out of extended warranty 6 years/100k miles when I bought the car used at 21.5k miles. I made the right choice because *knock on wood* my car had no costly repairs out of pocket so far.

I looked at extended warranty bumper to bumper coverage and they seem to be over $2k. The problem is I believe most of them need you to provide proof that you were maintaining your car through receipts from mechanics detailing the maintenance, or otherwise they deny your claim. Be sure to check your policy, because it is much harder with a used car when the seller has no maintenance records. Third party extended warranty insurance is known to easily deny claims or hold out on payment or try to find loopholes. Your problem actually may sound like a transmission issue, which would cost thousands to fix. They may require you to provide them with service records proving that the transmission was serviced at regular intervals.

Also, it sets off a red flag if you make a claim right when your policy starts. The reason for this "waiting" period is to make sure your car was actually in good condition with no problems to deter insurance fraud.

 

Update: I cleaned the MAFs and checked the transmission oil, the oil was at the right level with a nice color and no smell.

Can anyone else come up with any other ideas? Many thanks in advance for your forthcoming response.

 

Do you have any check engine light?

Otherwise, the transmission should be replaced.

 

No check engine light. I mean the thing drives like a dream, except for this issue that's driving me nuts!!!

 

I bought my car at 87k miles and will be doing a full service to the car at 120k. I already serviced the majority of the basics when i first got it, but didnt change the transmission oil yet. Will do a drain and fill soon.

 

I can't tell if your car's engine is just stumbling, or if it's just responding in sync with a tranny that's shifting poorly.

 

Does it only occur in sport mode, or all the time? When in sport mode, the g does the engine braking pretty aggressively. It definitely seems odd if you're not used to it.