Hey guys can anyone tell me what would cause my engine to just start acting up for no reason?
As soon as I start the truck it revs up past 3000 rpms and doesnt want to idle down, even when its warm. I'll get to a stop light and go into neutral or clutch in and again it revs up to 3000, sometimes it comes down to like 1200, sometimes not, but never to normal idle rpms, very annoying and a waste of fuel. My guess is obviously TPS but I havent got a check engine light or anything. WTF??

Can someone please help as I dont know what to do short of take it to a mechanic which Id like to avoid, strapped for cash in this economy.

Thank you for any advice...

 

Vacuum leak.

Mine was doing literally the exact same thing. Turned out the hose clamp on the vacuum booster was broken. I replaced it and it has worked fine since.

Good luck tracking it down. Took me a while (multiple afternoons) poking around the engine bay with a stethoscope then I heard a leak as I was going up the vacuum hose to the booster and DOH! there it was. lol

So check all your hose clamps first and then go from there. If you find a hunk of hose that has a leak replace it. :)

 

IAC
Idle Air Control valve is dirty.It's mounted on the throttle body .

 

On my 4.0 OHV I had the same problem and the issue was the IAC but i'm not sure about a 3.0.

 

Mine does the same thing... its just it seems to only do it randomly?!
One day its fine, then the next it does it once, other days it does it all the time...

Whats the easiest/cheapest way to find a vacuum leak... after checking the clamps?

 

Get a mechanic's stethoscope. The poor man's version is some vinyl tubing and a T fitting. Poke around each and every vacuum hose with your stethoscope listening for a sucking noise while the engine is running.

 

Start by cleaning or replacing the IAC, much easier to get to and find.

 

Thank you guys. I will have a look at things tomorrow and see what I find. Got caught in some terrible backed up traffic on the way to work today, stop and go for 30 minutes, let me tell you what nightmare it was!! Every time I stopped engine roared up over 3000, i must have burned an extra quarter tank

 

Try tapping the gas when it does that while in neutral and see if it doesn't idle down. That worked about half the time on my truck.

Did people look at you crazy? lol

 

LOL funny you say that. Being summer and lots of windows rolled down I did get a few strange looks haha!! Im sure they were thinking WTF is this guys problem lol???

Yes I did try to tap the gas pedal but it didnt work, only made it rev higher lol. The only thing that worked was disengaging the clutch into first gear and somewhat riding the clutch (ugh i know). But it was the only thing I could do to avoid looking like a freak!!

Anyway just gonna finish my coffee and get out there and have a look see...

 

Once again you guys have come through for me!! I took the IAC valve off and cleaned it and VOILA she's back purring like a kitten again!!!

You guys are awesome, so glad to be a member here. I dont even need a mechanic half the time now!

Thanks so much you guys for taking the time to help me out, i really do appreciate it. Enjoy the rest of your weekend guys! Cheers!

 

What do you clean the IAC with? Mine is doing the same thing and I need to clean mine today.

 

Bump.

 

Just buy a new one

 

Now thats just stupid.

I figured it out.

 

I just used electrical parts cleaner and blew it out with compressed air.

 

How is it stupid? Mine used to do the same thing sometimes and then one night I couldn't drive my truck because it would only idle at 2k. Its doing that because its going bad, I cleaned mine like 10 times total and it didn't stop it from going bad. Just replace it before it goes bad and stops you from being able to drive your truck.

 

Make sure the IAC isn't backwards. Mine was backwards and caused that exact issue.

 

I cleaned my MAF and IAC and now she runs alot smoother and quiter.

 

mine idles too low, could it be a similar issue?

 

Does it sputter or does it just idle to low? What RPM does it idle at?