rough idle

[markdifferent]

hello all. i will try to explain this as clearly as possible. i have a 1990 t4r. it has 145k on it. and the v6. when i got it there was a slight miss. it has never stalled but it can be rough when at a stoplight. after doing a tune up, to include new plugs, wires, dist cap, therm stat, rad flush, ac flush, oil change, trans flush and filter, as well as plenty of fuel injector cleaner. well i still have a rough idle. oh and by the way had the mechanic look it over and he said the motor was clean, i was worried it was a burnt valve. so now i have a good ride, until i get to a stop light. then i am shaken . on another post i saw sea foam, so i tried it today. i cleaned the throttle body, and put half a can in the brake booster line. then i put the other half in the crankcase. i also put another can in the fuel tank. this helped the rough idle a bit, but i decided to change the idle speed, is that bad to do? what else can i do or should i have done, and 1 more question.,anyone had the recall for the steering done and it seemed to make things worse? i have so much play it seems now and its starting to worry me. thanks

 

[Elton]

what does it idle now at

 

[markdifferent]

before i messed with the idle speed it was at 500 maybe a touch below. that was in gear, now i attempted to raise it by turning the nut and using the allen wrench on the bolt on the throttle body. then i used the idle screw to tune it in more. i am now running at 750-800 in gear and 1200 in neutral

 

[Elton]

maybe your tps needs adjustment

 

[markdifferent]

ok what is that and how do i correct it. thanks, not to sound stupid but i dont know much about this at all.

 

[Elton]

http://www.4crawler.com/4x4/CheapTricks/TPS/index.shtml

 

[markdifferent]

thanks. i took alot of time to read and re read the info on the page you posted. alot of good info there. but i am not sure my problem would fit in this solution.
Symptoms of a bad or mis-adjusted TPS include:

* Varying idle speed
* Hesitation while accelerating
* Poor fuel economy
* Inability to correctly set base ignition timing

i have a steady idle speed. acceleration is decent for the v6, and i usually get 280 to 300 miles to a tank highway. is that normal or should i expect more? i adjusted the allen bolt that provides more or less tension to the throttle cable, then tuned it further with the idle screw.

 

[hardhat]

Do you smell fuel under the hood after you turn the motor off? I had the same symtoms you do. I figured out it is the fuel damner/pulsater after it started to finally leak fuel. from Toyota they're @ $120. A junkyard should give you one for @ $25.

 

[Elton]

o2 sensor ? check engine light on ?

 

[markdifferent]

no i dont smell fuel, at all, and there are no lights on check engine etc. i have been tryin to find someone that has the computer reader so i can hook it up and see whats really going on. as far as parts my good friend owns a salvage yard and sets back all the 4runners for me to go thru so any part i need i get for free. i am thinking of just getting a newer motor to put in it. will the 3rd gen motors fit? thanks i appreciate all the help i can get. by the way i honestly dont have a clue where the fuel damner/pulsater is. would it cause the rough idle? and if so would setting up the idle speed cure it or would i still need to look into a replacement

 

[Elton]

yep a 3.4L will drop in you will need a wireing harnessand some other stuff .... search for 3.4L swap at YotaTech

 

[T4R4ME]

When mine was doing that a few years ago with just over 100k, it ended up being a burned valve. I still have that valve sitting on my workbench in my garage as a reminder.
Good luck!!!

 

[Elton]

yep the 3.0 loves to burn vavles and headgaskets

 

[kingvandal]

Gonna throw my 2 cents in here to. Vacumm leak? Intake gasket leak? If it is in intake then you may see a very small fluid leak on the edge of the intake, so small to the point that it looks discolored or small drips of green rad fluid. I had this happen to me once on a truck we had and I spent months on the bad idle to find out that the intake as leaking. Could cause the odd idle problems. I would check those before throwing away a good motor. Listen for any very slight sucking noise. if you can hear one then likley it would be the cause of a small carb hose or smog hose line that is cracked or leaking.

just my 2 cents

:: Edit ::
Forgot to add that if that is the problem you will need to re-adjust your idle back down as you have tryed to raise idle for a problem that was not nessarly related to the idle which will cause your motor to idle very high and burn fuel like, heating issues etc..