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Need Toyota Man's Help


dirty dan's Avatar
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01-16-04, 11:02 AM   #1  
Need Toyota Man's Help

'87 Toyota MR2 N/A MK1

I'm getting an engine idle surge when my engine warms up (nice idle till warm). Idles up to around 1500-1700 and then back down repeatedly. The coolant is full and bled per Toyota's instructions. I can't find any vacuum leak. The car has 187,000 on it and I'm taking it out of mothballs for my son. Any suggestions on where to look for this problem?

 
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01-16-04, 01:02 PM   #2  
car_boy_16
It could be a bunch of things. Did you try cleaning the throttle plate with carb cleaner or anything along the lines of that? It sounds to me like your Cold Start Valve could be jammed open. A symptom of that would be a good idle before it warms up, but when the ECU changes from "cold start" mode (supplies more gas, ect...) and when it switches to normal closed-loop mode for normal temps the idle will become more unstable if the CIV is stuck open by debris.
It could also be your PCV valve, to check that, leave the pvc valve on the valve cover but take the hose off the PCV that leads to the intake tract. If you do that and your PCV is in working condition the idle will surge more than normal, if it doesn't surge more, replace the PCV valve with one from Toyota (Not a cleapo universal Autozone one).

That's all I can think of right now, I know there are more things to look at but...Davo or someone else will help ya out hopefully.


Good Luck!

 
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01-16-04, 01:27 PM   #3  
Very common to have an air pocket in air bypass valve. Ok when cold but once warm with tps showing idle rpm is too high and goes into fuel cut.

Have to bleed it out well.

Possible to have valve stuck but not very common.

Also thermostat must be good and must go to almost half on temp gage. Will cause same problem.

This engine not equipped with PCV if memory is correct.

 
dirty dan's Avatar
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01-17-04, 08:03 AM   #4  
I haven't seen a PVC valve on the TVIS engine, but then again there are a lot of things on this engine I've never seen before.
Where is the air bypass valve and what does it look like?
I've got the electrical green book for this car, but I haven't been able to find the mechanical book. @ 187k all I've ever had to do is routine maint and change the parking brake cable and speedo cables. It's been a great little car.

 
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01-17-04, 01:23 PM   #5  
car_boy_16
I believe you are right, there is no PCV on those 4age T-vis engines....I was just assuming there was.
But you'll have to "burp" your system. in the morning when your engine is cold remove your radiator cap then start your vehicle. let your vehicle warm up a tad then replace your radiator cap and make sure your coolant resivour is filled up. do this every morning or so until the problem has dissapeared. usually takes a few times to get rid of the problem.
I believe on your engine, the air bypass valve is underneath the throttle body....Maybe toyota can confirm for sure...If burping your engine isn't working, take your throttle body off and give it a good clean, inspect everything that connects to the throttle body and see if any of those components need cleaning also. Either way, it should run better after a cleaning.

 
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