Ever heard of this??

L

lsmit605

New member
1999 T4R 3.4L w/ 145k mi

Problem: Rough/inconsistent idle (rpm drops and comes back up over and over) and sometimes a crank no start
-audible clicking (sounds like a relay) under passenger side of dash while idle is inconsistent
-not always symptomatic, seems to be intermittent without noticable pattern
-if i rev it up it will usually go away for a bit and then come back if it was already symptomatic
-if it is idling up and down, I can put it in the wind and it runs fine under power

recent repairs in attempt to fix problem:
-fuel pump
-fuel filter
-MAF sensor clean
-spark plugs (OE)
-inspected pcv valve - no problem
-and yes, I have checked the air in the tires :^)

Please help
Thanks!
 
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Sounds like a couple of issues. But possibly the crankshaft position sensor. That's what I would think is causeing the crank no start, bad idle, Ect.
 
Thanks for the replies.

Anyway to test the crank position sensor?

I was hoping the audible clicking under the dash would be indicative of something causing the issue...does this not sound familiar to any one?
 
I had something like this recently, check your coil packs and make sure they are seated, check your plugs (don't use Bosch), I had a broken plug that separated in the middle and allowed the engine to suck air after each detonation of that particular cylinder.
 
sort sounds like a vacuum leak.
Check the basics spark, vacuum, etc.
Put a vacuum gauge and see if its boucing around or low, if so spray some throttle body cleaner around intake and vacuum ports see if your idle changes.

did you use dual electrode spark plugs, its common to get the wrong plug in these. Also 4runners seem sensitive to plug wires, make sure you have a good set on.

Good luck
 
mj440 said:
sort sounds like a vacuum leak.
Check the basics spark, vacuum, etc.
Put a vacuum gauge and see if its boucing around or low, if so spray some throttle body cleaner around intake and vacuum ports see if your idle changes.

Did you use dual electrode spark plugs, its common to get the wrong plug in these. Also 4runners seem sensitive to plug wires, make sure you have a good set on.

Good luck
Click to expand...

x2.......
 
Yeah I used oe plugs when i replaced them. Original wires ars in there so I will go ahead an replace them. As well as check for vacuum leak. Will update soon. Thanks
 
Replaced plug wires with the NGK that came recommended on here. Runs much better when it is running well, but at least still the same problem with idle. Did it this morning when i first started it up. Much lower than normal idle (~510rpm), and then it will surge sometimes-up (~1000rpm) and down up down- with the audible click from under the passenger side dash.

If I rev the engine or put in gear and dirve it runs excellent with plenty of power and smooth as ever. Only, and intermittenly, does it seem to have the issue with the idle and/or crank no start.

I am going to keep digging
 
Sounds like a dirty IAC(Idle Air Control) valve. The IAC takes the place of a choke in fuel injected engines. IT's usually part of the throttle body. I don't have any pics, but someone else on here might...

The way it works is there's a piston-like solenoid that moves back and forth to either restrict or increase the amount of air needed to maintain the right air/fuel mixture while at idle. If/when this gets dirty, it can't move freely and it's movements become jerky causing dramatic rpm instability at idle.

Take it out and give it a good cleaning with some throttle body cleaner and you should be good to go.
 
Fixed it

It was the IAC - runs better than ever now

My wife went out of town before I could fix it and sure enough it cuts off and wont cut back on while she is gone. Was able to talk her through cleaning/oiling the IAC through the air port in the throttle and that worked great

Thanks to all
 
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