88 V-6 :: Hunting Idle while on brakes
11-23-2004, 10:56 PM
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88 V-6 :: Hunting Idle while on brakes
Hey guys:
I just picked up my very first 4Runner and I'm loving every minute. I come from a Mazda rotary background so this whole piston thing is so foreign. Well, not really foreign, it's just way different than what I've been lookng at for the past ten years. I have one question for the group.....
When I start the truck cold, it starts right up and idles a little low then rises slowly to about 1200-1400 rpm. It keeps rising and stops at 1600 rpm and the truck's temp guage is reading normal operating temperatures. So the truck idles really high. The second part of the equation is when you apply the brakes while the engine is warm, the idle hunts rapidly from 900-1500 rpm. When you step off the brake, idle resumes at 1600 rpm.
This really needs to be fixed asap. Is there a fast idle cam that is controlled by a thermo wax pellet or something? I'm thinking that it's sticking somehow. Is there a way to disable the cold idle enrichment? If there is someone local (southern california) that could lend me a hand, I would be eternally greatful and would definately supply beer and pizza.
Thanks for the ears.
Joe Breese
88 Runner
SR5 V6
I just picked up my very first 4Runner and I'm loving every minute. I come from a Mazda rotary background so this whole piston thing is so foreign. Well, not really foreign, it's just way different than what I've been lookng at for the past ten years. I have one question for the group.....
When I start the truck cold, it starts right up and idles a little low then rises slowly to about 1200-1400 rpm. It keeps rising and stops at 1600 rpm and the truck's temp guage is reading normal operating temperatures. So the truck idles really high. The second part of the equation is when you apply the brakes while the engine is warm, the idle hunts rapidly from 900-1500 rpm. When you step off the brake, idle resumes at 1600 rpm.
This really needs to be fixed asap. Is there a fast idle cam that is controlled by a thermo wax pellet or something? I'm thinking that it's sticking somehow. Is there a way to disable the cold idle enrichment? If there is someone local (southern california) that could lend me a hand, I would be eternally greatful and would definately supply beer and pizza.
Thanks for the ears.
Joe Breese
88 Runner
SR5 V6
11-24-2004, 11:02 AM
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First - welcome to the world of 4Runners!
Second - you most likely have an air/vacuum leak, probably in the air intake running between the air filter and the throttle body. Cracks on the end that attaches to the throttle body are very common. Once you find and fix the leak, reset the engine computer by pulling the EFI fuse for a few seconds, then check your idle speed and timing.
Good luck.
Second - you most likely have an air/vacuum leak, probably in the air intake running between the air filter and the throttle body. Cracks on the end that attaches to the throttle body are very common. Once you find and fix the leak, reset the engine computer by pulling the EFI fuse for a few seconds, then check your idle speed and timing.
Good luck.
11-25-2004, 12:29 AM
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Woodland Hills is like 10min me,I'm off the 210 and Polk. I have a '91 w/the v6 and I've got the FSM for my truck, but I'm thinking the 'nner isn't very technology different, I can let you check 'em out if you'd like.And If ya buy the beer, I might even "loan" them to you.....lol
In other words, anytime you need the books, let me know
Welcome to 1 of the few honest toyota forums around!!!!!
T
In other words, anytime you need the books, let me know
Welcome to 1 of the few honest toyota forums around!!!!!
T
11-25-2004, 03:58 AM
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Get the truck up to operating temp and adjust the idle speed down to around 900 rpms. This should take care of the idle prob when using the brakes.
Might want to check out the inside of the throttlebody too and see if it needs cleaning.
Might want to check out the inside of the throttlebody too and see if it needs cleaning.
11-28-2004, 08:32 PM
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Arnold,
That's what the problem was. I adjusted the idle down to 900 rpm and the hunting was eliminated. But now the truck doesn't want to cold idle. I'm thinking that the previous owner adjusted the idle up as a bandaid...
Thanks guys.
That's what the problem was. I adjusted the idle down to 900 rpm and the hunting was eliminated. But now the truck doesn't want to cold idle. I'm thinking that the previous owner adjusted the idle up as a bandaid...
Thanks guys.
11-29-2004, 04:29 AM
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There is probably oil in the iac valve on the side of the throttle body. Check the PCV valve and try cleaning the IAC out. The Dashpot is also probably off as well as mentioned above.
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11-29-2004, 09:15 AM
#8
Your idle speed is too high. See this Q@A from a rcent TLCA Toyota Trails Truck Tech column:
Hi Roger;
I have a 94 4wd p/u w/ 22re. My engine runs great, except for when it is idling and I depress the brake pedal. The engine then idles really weird, kind of a strong then weak then strong then weak, so on and so forth. It never cuts out, though, and continues to idle normally when I take my foot off of the brake. I've only noticed this after driving, like at a stoplight. Thanks; Jason McDannold
Hi Jason;
Assuming there are no vacuum leaks, such as in the brake booster, it's likely because your idle speed is set too high. I can exactly duplicate this "problem" in my '85 by bumping up the idle speed to a bit over 1000 RPM and it'll act as described. Turn the idle speed back to normal, and it works fine. It's really not a problem, its supposed to work this way and if everything is set properly, and you won't have the "problem".
Why is this the case? Because the ECU has logic built in that says if you hit the brakes and the engine is turning over 1000-1100 RPM, it'll cut the fuel to the injectors in an attempt to help you stop faster. After all, no sense pumping gas into the engine when you are braking to a stop. So idle rises, fuel is cut, idle falls, fuel restored, idle rises, etc. Turn the idle back to 850-900 RPM where it's supposed to be and it'll get back to normal. Idle speed is adjusted with the large slotted screw atop the throttle body. Turn it in to lower the amount of air passing through the throttle body at idle (and thus lower the idle speed).
If you don't want to do that or it doesn't fix the problem, here's a more drastic fix:
http://www.geocities.com/toyotashawn/bizzareidle.html
Which basically involves cutting the wire that feeds the brake light signal to the ECU. Without that input, the ECU will never know you are braking, so it'll not be able to cut off the fuel injectors.
- Roger
I have a 94 4wd p/u w/ 22re. My engine runs great, except for when it is idling and I depress the brake pedal. The engine then idles really weird, kind of a strong then weak then strong then weak, so on and so forth. It never cuts out, though, and continues to idle normally when I take my foot off of the brake. I've only noticed this after driving, like at a stoplight. Thanks; Jason McDannold
Hi Jason;
Assuming there are no vacuum leaks, such as in the brake booster, it's likely because your idle speed is set too high. I can exactly duplicate this "problem" in my '85 by bumping up the idle speed to a bit over 1000 RPM and it'll act as described. Turn the idle speed back to normal, and it works fine. It's really not a problem, its supposed to work this way and if everything is set properly, and you won't have the "problem".
Why is this the case? Because the ECU has logic built in that says if you hit the brakes and the engine is turning over 1000-1100 RPM, it'll cut the fuel to the injectors in an attempt to help you stop faster. After all, no sense pumping gas into the engine when you are braking to a stop. So idle rises, fuel is cut, idle falls, fuel restored, idle rises, etc. Turn the idle back to 850-900 RPM where it's supposed to be and it'll get back to normal. Idle speed is adjusted with the large slotted screw atop the throttle body. Turn it in to lower the amount of air passing through the throttle body at idle (and thus lower the idle speed).
If you don't want to do that or it doesn't fix the problem, here's a more drastic fix:
http://www.geocities.com/toyotashawn/bizzareidle.html
Which basically involves cutting the wire that feeds the brake light signal to the ECU. Without that input, the ECU will never know you are braking, so it'll not be able to cut off the fuel injectors.
- Roger
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