high rpm a symptom?? (1 Viewer)

[bwr9300]

Being all I know about mechanics I've learned off this forum over the last 4 months since I got my first LC, when I notice things that don't seem normal I worry about the chance it could be a symptom of something going wrong with my prize...


High RPM to roughly 1500 at start up, goes down not too long after (less than 1 minute) but I've noticed it does a high RPM in Park and sometimes Neutral.... sometimes after a few hours off-roading, today when I re-inserted the egr resistors (to cancel out the P0401 code) RPM was up to about 2000 in P.

QUESTION: Are the high RPMs normal like this, randomly when in P or N and at startup, or is this a symptom of something major that will soon need to be done???

 

[informationjunky]

also know as the oring trick

http://www.lcool.org/technical/80_series/fast_idle/fast_idle.html

 

[bwr9300]

Thanks informationjunky. By the lack of replies, the link you posted, and from any threads I found from searching it appears the high idle is not a symptom of worse-to-come problems, huh?

I was just concerned that maybe this was something worse getting ready to happen

 

[retrofive]

Sounds pretty normal to me.

 

[lowbanks]

High rpm on a hot engine could also indicate a worn accelerator cable.
Many in the forum have chased this problem down to this cable.
Replace with a new one and you wouldn't believe the difference.

 

[Ebag333]

Sounds pretty normal to me.

x2, as long as we're talking about cold starts.

Warm starts may go up to a high idle, but should drop almost instantly.

Hot starts shouldn't have the high idle.

 

[AGGRESSIVEMACHINIST]

My cruiser also has high idle at cold start up. I've not had the problem with the heated engine start up and stay in a high idle. I've noticed that after adding a pioneer avic gps system and other electronics that this will increase the engine start up rpm due to the draw of higher amps needed to run these items.

 

[bwr9300]

What is my Rig trying to tell me?

So I spray off the engine with a simple water hose with a gun attached to it (not a pressure washer). I spray out the alternator some to get mud out. I take the rig for a quick drive to let it dry out a bit (and to get it over the light rumble that usually happens after an engine clean/spray down). A CEL comes on. I've washed my engine a lot and never seen a CEL from it. I check the code and it reads P0306.

I pull out the fuse #10 like I remember reading on here someone said was the CEL resetter. Didn't reset CEL. So, when I get home I disconnect the battery. Rig is off, keys are out of it. I hold the battery disconnected for about 15 seconds and put the negative terminal back on. THE LIGHTS ARE NOW ON. I've never seen that before when disconnecting and reconnecting the battery... and the keys were out of it!

Then, and this is the most concerning part, I get back in and start her up. RPMs go immediately to 2200, then back down, then back up over 2k, then back down, and it fluctuates like this at least 5 times while in P. I go for a short drive. Everytime I turn her off and back on it revs over 2k RPM.


What is my Rig trying to tell me?

Oh, but after disconnecting the battery, the CEL has not come back on (as of yet).

 

[bwr9300]

Nobody's had that up and down high rev multiple times at startup before?

 

[retrofive]

Got nothing sorry. Except the CEL (TMK) will go through a test in cycles. So if it fails x amount of times within x amount attempts it will throw the CEL. Resetting will clear it. After x amount cycles it could easily return if the problem still exists.

 

[ERG80]

If you disconnect the battery the ECU has to relearn some settings causing the fluctuations in RPM's.

Its a good idea to cover the distributor when spraying off the engine. I use a plastic bag and it keeps mine from getting the 'stumbling' in idle after the wash.

Search and you'll find a lot more info on both.

Nobody's had that up and down high rev multiple times at startup before?

 

[bwr9300]

so that rough idle after spraying off the engine is probably from water in distributor cap?


I've disconnected the battery a lot (mostly when I was battling the p0401/2 code) and never experienced the fluctuating high low rev before

 

[arndog123]

I thought it was only 93-94 ECU models that had to relearn when the battery is disconnected?

 

[Ebag333]

I've washed my engine a lot and never seen a CEL from it. I check the code and it reads P0306.

Misfire Detected - Cylinder 5.

You have water in your spark plug cylinders. Pull the boots and use compressed air to blow out your spark plug cylinders. When the water stops coming out, hook everything back up.

You may also need new wires, if they're slightly cracked when they get wet they can arc and cause a short to the block, which causes a misfire.

Then, and this is the most concerning part, I get back in and start her up. RPMs go immediately to 2200, then back down, then back up over 2k, then back down, and it fluctuates like this at least 5 times while in P. I go for a short drive. Everytime I turn her off and back on it revs over 2k RPM.

If you disconnect the battery the ECU has to relearn some settings causing the fluctuations in RPM's.

What ERG (and Retrofive) said.

I thought it was only 93-94 ECU models that had to relearn when the battery is disconnected?

Nope. They all have to relearn.

 

[bwr9300]

It's driving fine now. is the water in there going to evaporate or is it something that can cause more major problems?

 

[Ebag333]

It's driving fine now. is the water in there going to evaporate or is it something that can cause more major problems?

Mine caused problems, drove fine, caused problems, drove fine, caused problems.

Just because it's driving fine doesn't mean it won't cause problems. It's maybe 15 minutes to pop off the boots and blow it out with some compressed air.

If there's no water in there, then I'd bet that your spark plug wires are arcing when they get wet. How old are they? Are they OEM?

 

[bwr9300]

They are OEM and 2 or 3 months old. Yours really caused problems and fine like that? what'd you do to fix them?

 

[Ebag333]

They are OEM and 2 or 3 months old. Yours really caused problems and fine like that? what'd you do to fix them?

pop off the boots and blow it out with some compressed air.

I had multiple cylinders with water in them, despite only getting one misfire code.

 

[bwr9300]

Thanks Ebag, I'm always glad to see your posts because I know you won't hold back from telling me any ugly truth about a situation.

Speaking of water in stuff (I've done searches and haven't found anything) how bad is water in differentials?

 

[Ebag333]

Speaking of water in stuff (I've done searches and haven't found anything) how bad is water in differentials?

Bad, but not the end of the world as long as you have grease in it. I wouldn't want to let it sit though. If you have water in there, just drain the diff and refill.