truck idling extremely low/dying after driving
10-02-2013, 07:40 PM
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truck idling extremely low/dying after driving
Hello All,
I'm new to this forum and signed up to pick the brains of all you Yota-junkies out there! Just to get things straight, the name TurdRunner was just being funny, I absolutely love my Runner.
Onto the business. I have a 1990 4Runner that I bought a little over a year ago. It has a 3VZE with 140,000 miles. The cat was cut out before I bought it and I had to put new exhaust from just behind the O2 sensor all the way back.
On my first trip with the truck, I was pulling a trailer on the highway out of OD running around 60-65. It still had a pretty good load for the motor. I stopped to get gas and upon starting the motor back up, the RPMs fell low, bounced some and then died. I tried again, same thing. After a few tries of letting it idle alone, I gave it some gas and got it going enough to shift into drive and take off, keeping the idle up with my foot at the few lights before getting back onto the interstate. I noticed that after a few minutes of keeping it going by giving it gas it would idle on its own again.
After owning it for over a year now I've noticed that this happens any time the motor has a good load on it, such as pulling a trailer, or gassing hard uphill for a long time. Sometimes now it even happens just after normal driving. Just to be clear, it's ALMOST always on start-up after sitting for just a few minutes (again I say Almost). I've also noticed that if I just kick the AC on it won't do it, but I'm guessing that is just because it idles it up some when the AC compressor kicks on.
I looked on some forums, including this one, and found quite a few tests for MAF, engine coolant sensor, and TPS. So I checked resistance on those and everything seemed to be in order. Saying that, I checked them at operating temperature and NOT when the problem was happening. I did not check the O2 sensor, but I have been meaning to change that out anyways, so I will replace it soon.
Is there anything I am doing wrong? Anything else I can test? Others that have had the same problem? Thanks for any help you can give me. I used to turn wrenches a lot and always stayed in tune with these things, but after many years of working other jobs I feel like I've forgotten everything but the basics. Hopefully all of you true Yota gearheads can help me out!
Mitch
I'm new to this forum and signed up to pick the brains of all you Yota-junkies out there! Just to get things straight, the name TurdRunner was just being funny, I absolutely love my Runner.
Onto the business. I have a 1990 4Runner that I bought a little over a year ago. It has a 3VZE with 140,000 miles. The cat was cut out before I bought it and I had to put new exhaust from just behind the O2 sensor all the way back.
On my first trip with the truck, I was pulling a trailer on the highway out of OD running around 60-65. It still had a pretty good load for the motor. I stopped to get gas and upon starting the motor back up, the RPMs fell low, bounced some and then died. I tried again, same thing. After a few tries of letting it idle alone, I gave it some gas and got it going enough to shift into drive and take off, keeping the idle up with my foot at the few lights before getting back onto the interstate. I noticed that after a few minutes of keeping it going by giving it gas it would idle on its own again.
After owning it for over a year now I've noticed that this happens any time the motor has a good load on it, such as pulling a trailer, or gassing hard uphill for a long time. Sometimes now it even happens just after normal driving. Just to be clear, it's ALMOST always on start-up after sitting for just a few minutes (again I say Almost). I've also noticed that if I just kick the AC on it won't do it, but I'm guessing that is just because it idles it up some when the AC compressor kicks on.
I looked on some forums, including this one, and found quite a few tests for MAF, engine coolant sensor, and TPS. So I checked resistance on those and everything seemed to be in order. Saying that, I checked them at operating temperature and NOT when the problem was happening. I did not check the O2 sensor, but I have been meaning to change that out anyways, so I will replace it soon.
Is there anything I am doing wrong? Anything else I can test? Others that have had the same problem? Thanks for any help you can give me. I used to turn wrenches a lot and always stayed in tune with these things, but after many years of working other jobs I feel like I've forgotten everything but the basics. Hopefully all of you true Yota gearheads can help me out!
Mitch
10-03-2013, 04:01 PM
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Have you checked all the vacuum hoses and flexible intake tube for cracks and are they tight? A tiny vacuum leak can cause crazy problems. All electrical grounds clean and connected?
10-03-2013, 04:46 PM
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I would definitely check the coolant temp sensor while the problem is occurring. Also check that the coolant hoses to the throttle body are not plugged. They should both warm up at about the same rate. EGR sticking open can cause low idle/stalling, but that should be noticeable when you come to a stop after freeway driving. Even before a restart
10-04-2013, 08:12 AM
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Awesome! Thanks for getting me started guys!
J2the-e, how would I check EGR function? Also, if it was the coolant temp sensor, wouldn't that also affect my shift points? Transmission seems fine when this is happening and will shift in and out of overdrive no problem.
J2the-e, how would I check EGR function? Also, if it was the coolant temp sensor, wouldn't that also affect my shift points? Transmission seems fine when this is happening and will shift in and out of overdrive no problem.
10-04-2013, 10:06 AM
#6
To check if the egr valve is sticking open you would apply vacuum to the valve while idling. The engine should stumble or stall. It should return to normal when you release the vacuum. If it continues to run rough after releasing vacuum, its stuck open. Although rare, I have seen this happen before.
Also check that the vacuum lines and tubes are not plugged. If a tube is partially plugged it may prevent the vacuum from being released by the egr valve, also causing it to stick open. The 2nd scenario is just a theory. I have never seen this actually happen.
EGR doesn't really sound like your issue, but a quick and easy test to rule it out
Also check that the vacuum lines and tubes are not plugged. If a tube is partially plugged it may prevent the vacuum from being released by the egr valve, also causing it to stick open. The 2nd scenario is just a theory. I have never seen this actually happen.
EGR doesn't really sound like your issue, but a quick and easy test to rule it out
10-04-2013, 04:21 PM
#7
I would suspect EGR sticking as well based on original posting.
The EGR functions on acceleration, and after opening and closing multiple times during excessive high load and high speed driving its possible its leaking/stuck when the engine is hot.
Removing the Vacuum line from the EGR valve may remedy your problem.
The EGR functions on acceleration, and after opening and closing multiple times during excessive high load and high speed driving its possible its leaking/stuck when the engine is hot.
Removing the Vacuum line from the EGR valve may remedy your problem.
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10-05-2013, 10:50 AM
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Kiroshi - thanks so much and thanks for the diagram. I'll start with looking for obvious vaccuum leaks and then maybe just try unhooking the line like you said. Seems like cracked lines with vaccuum leaks would be more consistent, though, so the sticking might be more likely.
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