1990 Toyota 4Runner Cold Stall

1990 TOYOTA 4RUNNER
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MIKE9721
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  • 2 POSTS
I have a 1990 4runner with the v6 engine and 230,000 miles. For quite some time now i have had an issue when the engine is cold. When accelerating form a stop, the engine will hesitate and sometimes stall out. When it stalls it also is quite difficult to get restarted. The problem appears to occur every time the engine is started cold. But once the engine has been running for about 15 min or so and warmed up, it runs beutifully. I have pulled out the cold start injector and it apears to be fine. And I have also done some minor troubleshooting on the EGR system and have not found anything obvious. Can anyone point me in the right drection?
May 30, 2006 at 9:32 AM
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LOSONE
  • ✓Experienced Mechanic
  • 1,616 POSTS
Read my toyota moderators comments. It's the 1st on the list. I think you have a head gasket problem like the recall mentions. It's a free repair. I had it done on my 92 and my 94. Good luck
May 30, 2006 at 10:38 AM
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MIKE9721
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Funny you should mention that, this last weekend I just finished replacing the head gasket along with rebuilding the heads. Having the dealer do it was not an option because the previous owner of the vehicle had already had the 1 time deal done. Thus this was the 2nd head gasket job.

The cold engine issue seams to be unrelated to the head gasket because the problem was present before i did the last head gasket change.

Any other suggestions?
May 30, 2006 at 10:49 AM
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LOSONE
  • ✓Experienced Mechanic
  • 1,616 POSTS
It is refreshing to see an articulate post. So many I receive are very difficult to read.

From 87 up to 94 there have been issues with the coolant temperature sensor. I have replaced many and I did learn to use a Toyota part.

I have also seen a lazy O2 sensor cause a cold issue but I am sure it has been replaced .

Was the knock sensor replaced when the head gaskets were replaced? It is under the intake. If it fails in at a set position it will retard the timing 4 degrees.

If you aren't belching black smoke in the morning most all cold issues are caused by a lean condition.

Let me know

losone
May 31, 2006 at 12:39 AM
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Suggested Repair

Replace the coolant temperature sensor with a genuine Toyota part. Also check for a lazy oxygen sensor and confirm the knock sensor under the intake was replaced during the head-gasket job, since a failed sensor can retard timing. Cold hesitation without black smoke often indicates a lean condition.

Conversation Summary

The owner of a 1990 Toyota 4Runner V6 reports hesitation, stalling, and hard restarting when accelerating from a stop with a cold engine; it runs normally after about 15 minutes of warmup. Cold-start injector and EGR checks found nothing obvious, and a recent head-gasket and head rebuild did not fix the cold issue. The expert recommends a Toyota coolant temperature sensor, checking a possibly lazy oxygen sensor and the knock sensor, and notes that cold problems without black smoke are usually caused by a lean condition.

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