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Ted Ritter
Ted Ritter, Toyota Master Tech
Category: Toyota
Satisfied Customers: 4182
Experience:  Toyota Master Tech, ASE Certified
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I have a 1990 Toyota 4runner 4cyl. 22RE engine. Rough idle,

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I have a 1990 Toyota 4runner 4cyl. 22RE engine. Rough idle, shuts off on low idle. Already set the throttle adjust sensor & checked/replaced vac lines. Timing will read consistent. Airflow meter checks OK according to service manual procedure using ohm meter. Suspect the Ingnition Control Module. How can I confirm this before spending the money on a new one ?
Please advise.
A rough idle is normally not caused by the igniter, I have looked at the things already done and I have a couple of suggestions. Have you checked the large air intake hoses that connect to the throttle body from the air filter? The can have cracks in them causing an intake leak which will cause a rough idle and stalling but may run normal above idle, the other thing to check is the engine compression on each cylinder, a leaking valve can also be the cause for this condition and finally, the EGR valve, if the EGR valve hangs up and doesn't close all the way it will cause a rough idle and stalling as well. The EGR valve can be tested using a vacuum pump and applying vacuum to the operating port. With vacuum applied the engine should run rough and die, when vacuum to the valve is released the engine should idle normally, one other thing that used to be a common problem is the intake manifold gasket between the head and the manifold, they had a habit of coming apart and leaking near the port for the EGR valve, I hope some of these recommendation will lead you to solve the problem. Pleas let me know if you have any further questions regarding this.
Customer: replied 7 years ago.
I made a typo in my initial submital. I meant to say "Timing will read inconsistent".
In that case you may have a problem with the distributor or possibly a worn timing chain, is there any timing chain noise? Even if not I would recommend removing the valve cover to inspect the chain and the guides. By inconsistent did you mean the timing flutuates rapidly when checking with a timing light?
Customer: replied 7 years ago.
Yes, the timing fluctuates rapidly when checking with a timing light. The mark jitters between TDC 0 , 5,8, 12. What kind of noise or signs of damage should I check for on the chain or guides ? What check would you recommend for the distributor ?
If the timing chain is worn or a chain guide is broken there would be some rattle type of noise from the front of the engine. The timing is controlled internally by the distributor from computer input signals. This han't been brought up yet but I have to ask: Is the check engine light on or does it turn on sometimes and go off? The chain can be checked by removing the valve cover, there are two plastic chain guides that can break, it will be obvious if that's the case when inspecting. One more thing, have you tried adjusting the idle speed screw on the throttle body and if so did it change anything?
Customer: replied 7 years ago.

Yes, the check engine light went on and gave me three codes.

Yes, I tried adjusting the idle speed screw and nothing changed. I removed it completely and noticed the "O" ring had become hard plastic and allowed some play when installed. I replaced the rubber "O" ring and re-inserted the screw, it now has a snug fit. I have not restarted the engine yet.

Thanks, XXXXX XXXXX let me know what those three codes were?
Customer: replied 7 years ago.

I worked on the EGR valve, re-started the engine and it ran alot smoother. The idle adjust screw now responds when it is turned in either direction. Timing is now steady at 5 deg. and RPM is set at 750. Took it for a test drive and it runs better.

It still has a slight studder when idling at a stop signal, & lacks power.

 

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Customer: replied 7 years ago.

Ted,

Yes, your reply was helpful.

I appreciate your advice.

Thank you.

 

 

Thank youfor accepting.