When I am driving the engine just speeds itself. It does not happen to often only a few times. last time it happen was 2 days ago. It speed it self a little bit for couple of seconds then goes back to normal..

 

Fair chance it's an air leak, maybe a hose flexes.

 

I checked the hoses and hear no noises of a vacuum. Once the car got warm i can hear the engine noise changing up and down.

 

Typical leak is small and you can't hear it.

OBD will show it.

 

It may be the throttle position sensor.

 

Have you checked and/or cleaned your throttle body? Along with the other responses, I'm curious if the TPS may be trying to adjust if the butterfly won't close properly?

 

I did a "tune up" in December, that's is also when I cleaned the TB. How would I go about going the TPS. And what do I look for in the scan tool for an air leak?

 

Look for the Long Term Fuel Trim (LTFT) for each bank.

They should operate in a range of some +/-3 for an healthy engine.

You will read higher positive values if you have an air leak (indicating that the ECU is adding more fuel, as the extra sucked air from the leak needs to be compensated).

 

But readings of under 10 are not serious.

 

I dare to disagree for the LTFT's.
On the longer run (>25mls), and with the engine hot, the trims should be close to zero at idle, or constant speed without much load.

 

If you suspect an airleak, there is an good old trick you can try; with the engine runing on idle, use starting gas and carefully give a little blast next to any place where an airleak can be suspected, if the engine momentarily increases its rpm and then falls back and if its repeateble.. you just found an problemarea to give an closer investigation.


-If the engine are doing something the ECU haven't "ordered" or if the ECU gets erratic feedbacks, you would atelast get "LIMP HOME MODE" and a bunch of faultcodes..


The thottlebody problems where more related to sudden engine cutouts, if i remember it correctly..
/E

 

what do i spray, I don't wanna spray carb cleaner because of a possible fire.

 

Hmm.. i am not sure what you call it where you live.. here in sweden we just call it Startgas (starter gas) with is just a mix of usually ether and a few other very volatile chemichals.. Its used to force that old beaten lawnmover or shitty car to start by spraying some in the airintake.. it will huff and puff and eventually start.. :-)

It leaves the bottle like fluid but turns to gas instantly and do not leave anything behind

Use with care and NOT near any open flame etc.. ie. do not smoke and play with starting gas.. you may sh*t yourself.. well.. if the gas go POFF for wahtever reason.. same result.. (i sprayed it down a carburator while looking down in it... when it backfired back up in my face.. guess if i got surpriced..)

The whole idea is that if you spray it near a place on the engine where it suck air where it should not.. some startergas gets sucked in and increases engine rpm..

/E

 

Maybe a better description of when, how much, how you noticed etc. The issue could easily be transmission related.

 

only 2-3 times for a couple seconds, 10mph.

 

Again, pretty vague.

Do you meant the car speed varies by 10 mph or it happens when the car is going 10 mph? How much does the engine RPM vary?

 

rpm doesn't increase by much. I could be going 30 and it goes up at 5-10mph not just 10 mph.

 

Any other MAF related issues? Does it hesitate on hard acceleration?

Reason I ask, and possibly what Mikey is getting at, is that the MAF is used as a load sensor for the transmission and ECU, so if it's faulty, it could be tricking the ECU into thinking you're trying to accelerate.

TBH if it was mine, I'd just go straight to a local garage and get them to do a smoke test. It shouldn't take them very long at all, and they're got all the right gear, rather than starting to spray lighter fluid all over your engine!

 

Ok, I haven't done a hard acceleration yet. I will do that. I will be taking the car to a shop. Should I do a hard reset or not?

 

The cruice control on these cars are operated with the help of vacuum taken from the intake manifolder. Two valves are working togeather in order to balance a controlled leak that allows a vacuum to build up and act, more or less, on membrane in that "can" that protuds up at next to the thottle housing. On a LHD they are located under the black panel on the aft left side in the engine bay.


It is quite likely that a leak there somewhere or if the valves are not woking properly, migth cause the rpm to become nervous..
Make sure the black, plastic spagetti sized pipes are fitted properly everywhere, but be careful not to crack them.. they have after 20 years of a life next to a hot Engine become brittle.

Does this problem occur with the cruisecontrol engaged?


/E