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My car idles high and accelerates by itself! HELP!

(Forgive the Honda cross-post, but you guys seem to know a lot... I own a Honda too!)

My mechanic completely screwed up my car (95 Nissan 200SX SE-R with the SR20DE engine), and I was hoping someone out there might know how, since he doesn't. I took it in for an oil change and he recommended doing a throttle body cleaning and a fuel injector cleaning. I said what the hell, okay. The result? First, I noticed my car now has a high idle -- about 950 RPM at rest in Drive and 1100-1200 RPM at rest in Neutral -- so it always feels like the engine's cold. It also goes faster when I just let the idle take me along in the parking lot. I took it back to him, he fooled around with it some more but couldn't figure out what's wrong. So it still has those problems, but now (and possibly before) it ACCELERATES ON ITS OWN. If I leave it in Drive without pressing any pedal, it will slowly accelerate all the way up through THIRD gear and at least 22 MPH, possibly higher if I hadn't run out of residential driveway. Scary stuff.

WHAT'S GOING ON??? Thanks for any reply.

In the meantime, don't visit All Tune & Lube in Mountain View (Middlefield Road). Please.

Reply to
Crunchy Cookie
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sounds like a helluva vacuum leak somewhere.

Reply to
SoCalMike

He probably didn't get all the sensor wires & hoses connected back correctly when he reinstalled the air box to the intake. It sounds like the car thinks it's cold and the cold start mechanism (or whatever they call the choke/fast idle cam these days) is on. Hopefully he didn't destroy any of the sensors taking it apart or cramming it back together.

Reply to
E. Meyer

I agree with the previous post. It could be sensor problem specifically Throttle Position Sensor but usually you will get the check engine light come on if the sensors are messed up.

Reply to
MikerX

what's not so funny is I just got this problem yesterday on my '99 V6 Accord. I just did a total detail of the car (wash, wax) and of course degreased the engine. It then sat in the garage for 3 days before I started it. Not sure if the degreaser did something or not. Just thought I'd fill in all possible data.

Luckily for me, I have a huge maintenance visit coming up next week and I can let it sit until I get there. But the (very reputable) garage told me to check the coolant in the radiator, not just in the reservoir tank. (all good there... make sure the engine is COLD) Then next suggested looking at all of the vacuum hoses. He said that they don't clamp down, so they can become loose or the case of old hoses, can lose their "grip" and hence the vacuum leak. I couldn't see anything, but not a lot of room around the engine to get a good look.

Was told while driving (mine is an automatic) to the garage, and sitting in traffic, drop it into neutral and save on the brake system. Sure you'll be rev-happy at the light but saving the strain on the brakes and tranny. I don't care so much about the brakes, but a transmission is like gold.

Keith

(Middlefield

Reply to
Keith J

Reply to
E. Meyer

Go somewhere else and have them adjust the idle. It's a screw, if I recall (I owned a 200sx SE) that adjusts the amount of air getting into the throttle body at idle. When all the gunk is cleaned out of the TB, it needs to be put back to factory idle because it's no longer being restricted by all that carbon.

Nick

(Middlefield

Reply to
Nick

Nick, thou art wiser than my mechanic. He took my car to a mechanic friend of his and that's exactly what he did: adjust that stupid little screw. Tah-dah: idle's back at 800. What a relief. Still, what the hell was up with that random revving up to 1,700 that took me for a ride through 3rd gear and 25 MPH (and probably beyond)? And how often is a TB cleaning recommended?

His theory was that the previous owner of my car messed with the screw in the first place to compensate for a low idle. Does that mean if you just let your throttle body get dirtier and dirtier, your idle speed will gradually drop?

On another note, can I reduce the idle further to save gas? I noticed that all Hondas are engineered to have really weak idle, though I don't know if that's the same thing.

Reply to
Crunchy Cookie

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