Engine revving by itself --2002 V70 75k PART C....What now?

Post by **ssforcey** » 24 Apr 2008, 07:40

Been noticing here and there in the past 2 weeks when I start the car for the first time of the day the engine will rev and the tach will go up to about 2 to 2.5, stay there and then come back down to normal. Car is in park. Doesn't do it while sitting at a light. Just in the morning the one time in park. Doesn't happen every morning but here and there about 5 different times now. Any ideas? Read something about a leak or something. Wanted to know what you experts think. Mileage at around 75k.

Thanks in advance,
Sharon

Post by **MadeInJapan** » 24 Apr 2008, 15:23

Pretty normal that it soars then comes back down. Tap on the gas and it should come down earlier. If not, you could have something up but still, I'm doubtful something is horribly wrong. Do you get any trouble codes? Check engine light?

Post by **ssforcey** » 24 Apr 2008, 15:27

No, not the normal go up and come down. More like someone is actually pressing the gas to get it up there. First time it did it I wasn't sure how high it was going to go. And this all just started.

I do have a check engine light on but it a thermostat/coolant temp thing. Something about coolant temp being higher than thermostat temp.

Any other ideas?

T/Y
Sharon

Post by **MadeInJapan** » 24 Apr 2008, 15:44

I'm thinking that the coolant temp. is all related to the engine surge. The engine is trying to heat up to compensate for the faulty signal. Get your thermostat or coolant temp. sensor (really, if you're getting into it this far, I'd replace both) replaced, reset the trouble code and I'll bet your engine will stop doing this.

Post by **ssforcey** » 24 Apr 2008, 17:26

Okay, sounds like a plan. Duh, I forgot to mention that when at a light it revs up and down ( no air conditioning on).

Thank you SO much for your info.
Sharon

Post by **MadeInJapan** » 24 Apr 2008, 22:31

I may be off, but I'd say it's worth a try. I do hear of surging engines from bad coolant sensors and/or thermostats, so that's what I'm going on. Let us know the follow-up

Post by **ssforcey** » 25 Apr 2008, 13:54

Okay, I think I'm going to change the thermostat and sensor. Which degree thermostat should I be looking for?

Thanks again,
Sharon

Post by **MadeInJapan** » 25 Apr 2008, 15:14

Factory OEM temp is 87C (190F) for turbo'ed engines and 90C (195F) for non-turboed engines at least on the 850's...I assume it's the same with your car.

sony2000 · Post by **sony2000** » 26 Apr 2008, 06:17

I noticed that after I had cleaned the throttle body with carb cleaner, the engine surging on a cold start was considerably less. Now It goes to 1700 rpm and doesn't bother me. With the return of the good weather, I'll do it again.

Post by **ssforcey** » 04 May 2008, 18:39

Okay, changed out the thermostat yesterday. And it's still revving by itself. Didn't change the sensor yet. Wanted to see if the thermostat changed anything before investing $75. Went to AAP and reset the check engine light (coolant temp is lower than thermostat temp). While we were resetting, was talking to the guy there and he noticed that the fan hadn't come on and I had been driving the car a bit. I left AAP and drove home, fan still not on.

So at this point I"m waiting to see if the check engine light comes back on with the same message. Then I guess I'll do the sensor.

Any thoughts on the revving up and down and the fan not working?

Thank you, thank you, thank you.