Intermittent Idle Issue with 3VZE
10-10-2016, 11:19 AM
#1
Intermittent Idle Issue with 3VZE
I have spent quite some time doing research on this issue. I cannot seem to find a straight answer (or idea).
363,000 miles 3VZE in an 89 4Runner. For the last year it has had an idle problem as follows:
Idles perfectly @ 850rpm when started (once warmed up of course).
50% of the time (flip of a coin) the truck either idles at 850 perfectly when pulling it out of gear (standard trans) and coming to a stop (think red light, stop sign). Or, it will bounce from 350-500 and obviously act like it is about to stall every time it bobs back and forth from 350 to 500. If I wait 15 seconds (at the light of stop sign) the idle goes right back up to 850. The bobbing idle from 350 to 500 is almost like a major vacuum leak, as how the engine would act if I tried to idle it with the oil cap off the valve cover.
Those 15 seconds risk stalling, and I am sure the problem won't get better as time goes on.
Things I have done:
Plugs, Denso (FSM PN) gapped at 31. Truck is good and responsive.
A good throttle body cleaning.
Checked for vacuum leaks with starting fluid and cannot find any.
Valve cover gaskets and rear cam plugs (had a leak on driver's side valve cover, it is now fixed)
I am stumped, especially because the issue is intermittent. Anyone have a hunch about something? It is probably vacuum related, but what would cause the delayed vacuum issue when coming out of gear and stopping?
363,000 miles 3VZE in an 89 4Runner. For the last year it has had an idle problem as follows:
Idles perfectly @ 850rpm when started (once warmed up of course).
50% of the time (flip of a coin) the truck either idles at 850 perfectly when pulling it out of gear (standard trans) and coming to a stop (think red light, stop sign). Or, it will bounce from 350-500 and obviously act like it is about to stall every time it bobs back and forth from 350 to 500. If I wait 15 seconds (at the light of stop sign) the idle goes right back up to 850. The bobbing idle from 350 to 500 is almost like a major vacuum leak, as how the engine would act if I tried to idle it with the oil cap off the valve cover.
Those 15 seconds risk stalling, and I am sure the problem won't get better as time goes on.
Things I have done:
Plugs, Denso (FSM PN) gapped at 31. Truck is good and responsive.
A good throttle body cleaning.
Checked for vacuum leaks with starting fluid and cannot find any.
Valve cover gaskets and rear cam plugs (had a leak on driver's side valve cover, it is now fixed)
I am stumped, especially because the issue is intermittent. Anyone have a hunch about something? It is probably vacuum related, but what would cause the delayed vacuum issue when coming out of gear and stopping?
Last edited by 89fourrunner; 10-10-2016 at 11:21 AM.
10-12-2016, 04:30 AM
#2
Thought about deleting this thread because I worked within another thread to solve the problem. I will keep it alive for search function purposes.
Idle issue has been resolved.
I replaced all the vacuum hoses related to the EGR vacuum modulator (even though they seemed okay, a bit rotted on the surface)
I used carb cleaner to clean the EGR VM's filter, and inside the housing.
I used carb cleaner through all the vacuum line hard lines.
I used carb cleaner to clean the EGR valve through its vacuum ports without removing the EGR valve.
Finally I found that the vacuum line from the BVSV to the throttle body was disconnected. I inspected and reconnected the line (knock myself on the head with that one).
Idles smooth and steady at 850rpm.
For me, it was old age maintenance, so I suggest those who have this problem start with some cleaning before throwing parts at it. Engine has 363,000 miles on it.
Idle issue has been resolved.
I replaced all the vacuum hoses related to the EGR vacuum modulator (even though they seemed okay, a bit rotted on the surface)
I used carb cleaner to clean the EGR VM's filter, and inside the housing.
I used carb cleaner through all the vacuum line hard lines.
I used carb cleaner to clean the EGR valve through its vacuum ports without removing the EGR valve.
Finally I found that the vacuum line from the BVSV to the throttle body was disconnected. I inspected and reconnected the line (knock myself on the head with that one).
Idles smooth and steady at 850rpm.
For me, it was old age maintenance, so I suggest those who have this problem start with some cleaning before throwing parts at it. Engine has 363,000 miles on it.
Last edited by 89fourrunner; 10-12-2016 at 04:31 AM.
10-12-2016, 04:19 PM
#4
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Good to hear. I suspect a lot of "vacuum leaks" are actually carbon in EGR system problems. That mileage is encouraging. Any oil leaks at main seal? As an aside, I assume I'll be posting a few comments in near future on Flamethrower injectors. 3 days in and I highly recommend them. Like a tune up on steroids IMO.
10-13-2016, 03:58 AM
#5
Good to hear. I suspect a lot of "vacuum leaks" are actually carbon in EGR system problems. That mileage is encouraging. Any oil leaks at main seal? As an aside, I assume I'll be posting a few comments in near future on Flamethrower injectors. 3 days in and I highly recommend them. Like a tune up on steroids IMO.
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