Trouble Starting and High Idle

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Bailey8756

New member
I have been having 2 issues with my 2000 4Runner 2.7L. I am not sure if they are related or not and have no idea what is causing either of them.

Issue 1 is that it is having trouble staring when the engine is warm. When it is cold it will fire right up no issue but once I run it and it gets hot when I shut the car off it will either crank a few extra times before starting or just crank no start. It started a few weeks ago and was pretty intermittent but it has become a persistent issue. I had a buddy spray starter fluid in the throttle body and it helped it start but unfortunately I cant do that every time. Spark plugs were replaced 3 months ago.

Issue 2 is that I have a high idle once the engine warms up. When its cold it will idle normally between 800-1000 rpm but when it gets hot it will jump to around 1800 rpm and stay there, sometimes dropping down to 1600 rpm. I have cleaned my Mass Airflow Sensor, bought a new Idle Air Control Valve, cleaned the Throttle Body and none of that worked. I have no DTCs (current or pending). I checked for a vacuum leak by spraying starter fluid around the engine and hoses to see if any would get sucked in but didn't find one.


I need some help. I love this car and its my daily driver. Has anybody else had this issue?
 
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What difference did the new iAc valve make? What brand did you get?

Is there anything causing the throttle to hang open a crack?
 
Kanoe said:
What difference did the new iAc valve make? What brand did you get?

Is there anything causing the throttle to hang open a crack?
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Made no difference at all. Car started fine when i put it on but once the engine warmed up and I turned it off and on again the idle returned and the starting issue showed back up.

I looked at the throttle body when I was cleaning it and it looked like it was shutting all the way. I have tried lightly 'forcing' it closed while its running at the high idle but its shut all the way an wont move anymore.

The brand of IAC was Intermotor. Got it from OReillys
 
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If the throttle body is fully shutting and the iAc is ok, I can’t think how it could be reving high.

I wonder if the truck is telling the iAc to raise the idle.

You need someone smarter than me.
 
I understand you checked for leaks already but off the top of my head it sounds like a leak somewhere. Intake manifold gasket??

This could explain both issues. More oxygen exists in cold air so the leak is not large enough to lean the mixture out until thermal expansion creates a bigger area for air to come in.


Then when you shut off the motor the warm air inside has less oxygen and now a larger leak due to thermal expansion so it leans out the mixture and won't start.

You mentioned your buddy sprayed into the throttle bodies which then started the motor: you are making the mixture richer allowing ignition.

Or, this could be completely off...
 
Whakeen said:
I understand you checked for leaks already but off the top of my head it sounds like a leak somewhere. Intake manifold gasket??

This could explain both issues. More oxygen exists in cold air so the leak is not large enough to lean the mixture out until thermal expansion creates a bigger area for air to come in.


Then when you shut off the motor the warm air inside has less oxygen and now a larger leak due to thermal expansion so it leans out the mixture and won't start.

You mentioned your buddy sprayed into the throttle bodies which then started the motor: you are making the mixture richer allowing ignition.

Or, this could be completely off...
Click to expand...

Makes sense. Ill take a closer look around the intake manifold for a leak.
 
FIXED!?!?!!!!!!!

So i was reading on another thread on the site where someone had a similar issue and the common theme seemed to be clean the MAF and reset the computer by disconnecting the battery. Damn near sprayed a whole can of MAF cleaner on that sun' gun and disconnected the battery and left it overnight and fired right up this today and no high idle even when engine is hot. Restarted the car a few times and no issues at all. Took it for a little drive on the highway and all systems are normal. As I'm writing this I'm probably jinxing myself and its probably back but as of now that did the trick.

Thanks for all the help. Ill be back if the Toyota gods don't deem my fix worthy...
 
I'm back, hopefully not for long. Issue came back yesterday briefly. Driving into work I got a high idle and my car battery died twice while at work (It was old and I was due for a new one). Got a new battery on my way home and when I threw it in i started having the trouble starting and high idle issue again. Got it started and drove it home at around 2100 rpm which is the highest its been. Let it sit outside for about an hour and went back out to mess around with it and it was working fine again. Ran great all weekend so this seems to be an intermittent problem. I think it may be an electronic glitch or something with the computer.

Also, I think it is worth noting that when the issue is present and the engine is idling in neutral at about 1800 rpm (moving OR stopped) my MAF is reading about 10 g/sec of airflow. When the car is in gear and moving at a speed that would have the engine running at 1800 rpm my MAF is reading about 25 g/sec of airflow. That's 2 different readings but the same rpm, just different situations. My takeaway from this is that its not a throttle or IAC issue because if it were wouldn't there be more airflow when it is idling? (Normal for my car in idle is 4-7 g/sec)
 
When it exhibits the high idle condition, disconnect the Throttle Position Sensor from the back of the throttle body. If the idle drops that might be the culprit.
 
Bailey8756 said:
Disconnected it. Didn’t drop the idle. I’m going to take it off when I get off work and test it with my multimeter.
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TPS isn't the cause of the high idle then. This one's a head scratcher, that's for sure. I'm not super familiar with the 4 banger, I have not worked on one but for the 5VZ-FE there's a cheapo MAF on Amazon for about $15. Would at the very least rule out as the offending sensor since you did get some odd MAF data, if not fix the problem.
 
i'd say the fuel pump is failing. i had the same symptoms a couple years ago and that fixed it for me. There is a weird check valve in the pump that fails and messes the flow up completely. Hard hot starts, high idle once started, etc.
 
May have fixed it. I noticed while the car was running with the high idle that my ECT was reading 6C. I replaced the ECT and on the old one the wires that went into the harness on the engine side came right out of the plug so I put them back in and glued them so they stay (Were more than likely loose and throwing off the readings to the computer). New one is in and car is running fine for now...
 
AntleredRuin said:
i'd say the fuel pump is failing. i had the same symptoms a couple years ago and that fixed it for me. There is a weird check valve in the pump that fails and messes the flow up completely. Hard hot starts, high idle once started, etc.
Click to expand...

That will be my next check if my latest fix doesn't work. I appreciate it!
 
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