Hi,

I have a problem with car recently that whenever the car rolling down hill (eg. highway) at around 40mph ~ 50mph, the RPM will start bouncing from 1500 to 2000 the moment I let go the gas pedal. The RPM will stop bouncing when the speed drop below 40mph. I replaced all gaskets and vaccum hoses with no luck. And also recently the exhaust smell from the muffler is so strong that it almost smells like a diesel truck instead of a gasoline car. Any suggestion?

Thanks

 

Sorry to jump on the wagon, but my problem is the same:

When going at around 80mph and letting go the gas pedal, the rpm jumps from 1500 to 1800 (aprox) a few times, stabilized to 1500 and then the car slows down normally. However, it does it also on a plane surface.
I have not tried to fix this problem and I have been driving my car like this for 4-5 months with no problems.

Any ideas what could this be

Once again sorry for going along with your thread

 

both you guys running on Automatics?

 

When I'm running 120MPH And I let go of the Gas my RPM'S are at like 4300RPM'S.....
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Yz100
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LovelyWendie99

 

I feel some VG jokes/jabs coming...

 

Haha, I assumed they'd be coming in shortly
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MORTGAGE LIFE INSURANCE FORUMS
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Kitchen Measures

 

mine is automatic

 

That's ok, but do you remember did you do anything to your car prior to that happened.

 

Mine is 93 GXE so yeah automatic,
Did this a little while after I told a mechanic to clean the throttle body/EGR Valve

 

i have a 94 gxe, and mine does this. as soon as u put the car on it would or sometimes i dont even move. while driving it would jump. sometimes it would work..but just once every few weeks. and if it does work only for 5-10mins. then it jumps up and and its dead again.

someone mensioned to me about a cable that is burst or slack...dunno what kind of cable.

 

Honestly guys

My guess would be a nasty TB or Idle control unit, or dirty MAF.

Neither of my cars are auto, so maybe you could roll down hill and then as you let off the gas, slip it into neutral and see if it does the same thing.

If it seems to work normal when you do that, my guess would be something tranny related.

 

Another thing I remember now,
Before the summer I disconnected the MAF and cleaned the chamber with electronic cleaner.

Maybe it is related

I will try the neutral trick though

Thanks alot

 

Mine too. It started right after I cleaned the TB. I thought I messed up the gasket that's why I bought a new one from dealer and replaced it, but it doesn't fix it. I think it's something related to the TB.

 

Good day to all,

I tried 89blackse's transmission test which was to put the car in neutral to see if the symptoms will occur. However, when doing so, the rpm drops completely so I don't think this will tell me if it's tranny related or not.

I don't know if you understand what I mean.

 

It probably wasn’t the best test, but if you RMS drop and stay at idle when in the big N then (assuming my logic is good) that means its not some idle issue with the MAF or Idle control thing and either the transmission is hunting for the right gear to put you into or something else is going on.

My girl friends car will jump RMPs as it comes to a stop, almost like its putting her into 1st gear, and blipping the throttle to give it a smooth transition.

Other members opinions would be a help cough*mygreen*cough

 

The problem we have is that the RMP will go up and down until the speed drop below 40mph not just a RPM spike. There should be some kind of sensor or valve that control the airflow when the gas petal is let off, otherwise how can an engine maintain it RPM if the TB is fully shut.

 

Ide Control thing


I forget what its called exactly, and I dont have the FSM handy, but it draws air in from the tube the arrow is pointing to and then sends it to the intake.

They (Idle control and TB) do tend to get dirty with age, but the TB will be the first to get dirty and cause problems.
After I cleaned mine it idled MUCH better.

 

I've had the same thing happen. When you're coasting the engine will surge, like whatever is the fuel cutoff for coasting goes on and off.

 

I've cleaned the IAC and it didn't make a difference. Perhaps the rubber air tubes in and out are cracked.

 

I just bought the gasket for the round thing in the red circle (I think it's called Air Cut valve). I will put it in this weekend hopefully that fix it. Will let you guys know what's the result

 

make sure you post results !

 

Yur brake fliud is dirty...

 

^^^ I like riding durty

 

I prefer white and nerdy myself :roll:

 

ok, changing the AAC gasket didn't fix the problem. I guess we all have to look at something else now.

 

thanks for posting, I seriously don't know what can be wrong with our cars, how long have you had the problem for ? aspirin240?
I have driven like this for the whole summer with no problems except the annoyance of having an invisible foot pressing and letting go off the gas !

My mpg is very good, the engine is not overheating except the fact that my temp gauge is not working (see my other thread started a few weeks ago) I don't think my problems are related however.
It is not burning oil, my transmission is very good, heck I only got 95k miles on my car. Air filter changed at the begining of the summer, regular oil change etc.......

I will try to post a video of what it's doing to see if we have the same problems.

If anyone has an idea please help !

Thanks in advance

 

Same here, I've been having this problem for the whole summer. It started happen after I cleaned the Throttle Body.

"MAXIMUS G EKSUS"
Did you car idle high after drive? My car will idle at 700~800 rpm after warm-up, but it will rises to 1200 after maybe 5 minutes drive. Don't know if that is related to the problem we are having.

 

its kinda simmilar to all of ur guys problems.... I get more of a popin/backfire sound in the muffler(it has exhaust) but for most part I think its my transmission just not working good...

 

No, idling normal after all uses

 

I have 94 Maxima Gxe Auto tranny. I have had this problem for about a year now and finally I got it figured. My car RPM bounced whenever I put it in neutral or drive between 35-50 mph (when I let go gas). At first I thought it was air leakage. So i replaced all hose and valve, but I had no luck. Then I changed spark plugs and wires, still no luck. Finally, I took out each fuel injector one by one, and found out that my injector 1 and 2 were bad, so it was running on 4 pistons. After replacing fuel injectors it run pretty smooth. And I can feel the huge difference in power/torque.
Some people might want to try changing injector wires as they can be bad, not injectors.