2008 Toyota 4Runner V8 unknown issue

Lucas606

Lucas606

New member
Hey all

I’m hope you guys can help me figure this out. It has been plaguing my 4Runner for a while now and it’s driving me nuts. It has just over 154k miles and it bogs under heavy acceleration as well as while when it’s in neutral and you press hard on the gas. Not only this but it’s even searching for idle. I’ve only had this happen once and it stopped searching when Put my foot on the throttle. I’ve also had to stall on me once while accelerating from a stop, and once while coming to a stop. The strange thing is that it starts right back up like nothing ever happened. Other than this it drives completely fine. I would like to mention is that it has Doug throuley headers but this issue began well after they were installed.

I’ve tried some troublshooting myself and this is what I’ve noticed. I don’t believe this is related but it’s low on coolant after being filled up not too long ago. Maybe coolants getting into a place that it shouldn’t be? I also went to remote start it a few days back and it refused to start. The engine would turn but not start for some reason. The second time I used the key and same thing. It would just turn and not start. It eventually started on the third try with the key. Also no check engine lights. I have no idea what’s causing this and my local mechanic can’t seem to figure this out either and it’s driving me insane. I’ve been told to check for spark, air, and fuel but becides that I don’t know what else to check for I’m hoping that you guys can shed some light on the situation and provide some input.

I tried uploading the files but it would let me. Here are the Imgur links.
Searching for idle while parked - Album on Imgur
Imgur: The magic of the Internet

Edit:throttle body was replaced today. Truck still bogs and idle fluctuates constantly while the AC is on
 
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My truck didn't do the bogging under accel, but it did, on occasion, search for idle while stopped. It would also quit on me... one time, it quit atleast a dozen times leaving the parking lot of a mall. Not its best moment.

Replaced the throttle body with a low-milage unit from a Tundra, no problems since.

There were no diagnostics that could isolate the issue. I read a thread somewhere about a guy who had his truck quit on him when he hit a bump, and his mechanic suggested replacing the TB, solved the issue. Having no other recourse, I did the same. Miraculously, it was my issue.

Simply that it seems you've got nothing else to go on, it might be worth a try (mostly 'cuz it's cheap and easy if you can find a TB). I got my new TB for about $100 from a wrecker.
 
Has it been scanned for codes, specifically looking for "pending" codes that won't set a CEL? Has the MAF ever been cleaned or replaced? Same for the throttle body.
 
gm350reratliff said:
Has it been scanned for codes, specifically looking for "pending" codes that won't set a CEL? Has the MAF ever been cleaned or replaced? Same for the throttle body.
Click to expand...

It has not been scanned for codes recently, but the last time it was scanned there was nothing pending. The MAF has been replaced with a new one but the throttle body is original from the factory. It has not been cleaned
 
Lucas606 said:
It has not been scanned for codes recently, but the last time it was scanned there was nothing pending. The MAF has been replaced with a new one but the throttle body is original from the factory. It has not been cleaned
Click to expand...

Is the new MAF sensor OEM or aftermarket?
 
Lucas606 said:
It has not been scanned for codes recently, but the last time it was scanned there was nothing pending. The MAF has been replaced with a new one but the throttle body is original from the factory. It has not been cleaned
Click to expand...

New or aftermarket MAF?

Has the timing belt ever been replaced? The crank sensor wiring runs close to the pulleys and after a timing belt, sometimes the clips don't hold right causing the wiring to rub through. I've read about another member on here with similar issues and that was the cause.

I would also recommend to check all the vehicle electrical grounds and connectors for signs of corrosion, specifically the wiring at the front of the engine and underneath the fuse box. Might as well make sure all the relays and fuses are seated correctly.
 
gm350reratliff said:
New or aftermarket MAF?

Has the timing belt ever been replaced? The crank sensor wiring runs close to the pulleys and after a timing belt, sometimes the clips don't hold right causing the wiring to rub through. I've read about another member on here with similar issues and that was the cause.
Click to expand...

It’s an aftermarket MAF. Old one was throwing codes so I replaced it about a year ago. No codes since then. The timing belt was replaced at 100k miles and then again because it was wearing quickly. The current belt that’s on it is beginning to squeak when it rains so that’s a pain. Plugged in my scanner to check for codes but there’s nothing pending. The short term fuel trims seem to be everywhere though for both banks. Short term for B1 fluctuates anywhere from -7.8 to 3.9 at idle, and short term for B2 -2.3 to 3.1
 
Lucas606 said:
The timing belt was replaced at 100k miles and then again because it was wearing quickly. The current belt that’s on it is beginning to squeak when it rains so that’s a pain.
Click to expand...

This sounds like you mean the auxiliary drive belt for PAS, AC, alternator etc?
 
Sounds very similar to my issue except I’ve got a P0430 code to go along with it. Just replaced both downstream O2 sensors and the issue persists. Seems like it all started after a pretty hard bump on some rocks, so kinda thinking it may be electrical. Symptoms below:

If i go heavy on the throttle (in park, neutral, or in gear) it feels like it’s choking. Like a stutter, but its not always around the shifting so not confident it’s trans/torque converter related. Always happens right around 2800-3000 rpm.

If I jump in and turn the key right away it’ll crank, start up, and die almost immediately. But if I flip the key to on and wait like 10 seconds before cranking, it starts up and stays running. It also randomly stalls while I’m driving, but I just toss it in neutral and it starts right back up.

Cleaned the MAF, TB, and checked all the fuses to make sure they are in there nice and tight. Checked connections on fuel pump and battery terminals. Thinking maybe a crankshaft position sensor or fuel pump but I’m kinda lost at this point. Don’t want to keep throwing money at non-issues
 
Did some poking around in the engine bay and it turns out the throttle body is making some very loud buzzing. I took off the intake tube and the plate looks visually dirty, but what’s odd is that the throttle plate isn’t sitting fully closed and had some play in it possibly? This can totally be nothing But it’s the only thing that I can notice. Everything else seems fine. I purchased some cleaner earlier today so I’m hoping that helps.

Links to videos:

Imgur: Throttle body buzzing
Imgur: Play in throttle plate

Edit: dirty throttle body wasn’t the issue
 
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Lucas606 said:
Did some poking around in the engine bay and it turns out the throttle body is making some very loud buzzing. I took off the intake tube and the plate looks visually dirty, but what’s odd is that the throttle plate isn’t sitting fully closed and had some play in it possibly? This can totally be nothing But it’s the only thing that I can notice. Everything else seems fine. I purchased some cleaner earlier today so I’m hoping that helps.

Links to videos:

Imgur: Throttle body buzzing
Imgur: Play in throttle plate
Click to expand...

It's a balance of spending more money on diagnosis of both the whole vehicle and the throttle body, or just start with replacing the throttle body. It doesn't sound happy...as Keros said he just replaced it and it sorted his problem.
 
SurferUK said:
It's a balance of spending more money on diagnosis of both the whole vehicle and the throttle body, or just start with replacing the throttle body. It doesn't sound happy...as Keros said he just replaced it and it sorted his problem.
Click to expand...

This is what I’m going to do next. I want to attempt to replace it myself but I believe I’d still have to do a throttle relearn. The OBD2 scanner that I currently have doesn’t have the option to do the relearn. I’ve read that disconnecting the batter could work so I guess I’ll give that a go
 
Lucas606 said:
This is what I’m going to do next. I want to attempt to replace it myself but I believe I’d still have to do a throttle relearn. The OBD2 scanner that I currently have doesn’t have the option to do the relearn. I’ve read that disconnecting the batter could work so I guess I’ll give that a go
Click to expand...

Let us know how you get on :)
 
Schnalan said:
Sounds very similar to my issue except I’ve got a P0430 code to go along with it. Just replaced both downstream O2 sensors and the issue persists. Seems like it all started after a pretty hard bump on some rocks, so kinda thinking it may be electrical. Symptoms below:

If i go heavy on the throttle (in park, neutral, or in gear) it feels like it’s choking. Like a stutter, but its not always around the shifting so not confident it’s trans/torque converter related. Always happens right around 2800-3000 rpm.

If I jump in and turn the key right away it’ll crank, start up, and die almost immediately. But if I flip the key to on and wait like 10 seconds before cranking, it starts up and stays running. It also randomly stalls while I’m driving, but I just toss it in neutral and it starts right back up.

Cleaned the MAF, TB, and checked all the fuses to make sure they are in there nice and tight. Checked connections on fuel pump and battery terminals. Thinking maybe a crankshaft position sensor or fuel pump but I’m kinda lost at this point. Don’t want to keep throwing money at non-issues
Click to expand...

Yep, my truck did all of these things, with the exception of the code. It was also totally random, never related to weather or road condition (uphill, downhill, turning left or right, etc).

It just kinda did batsh*t crazy things randomly, and other times it'd be fine.

Replacing the TB solved all of it. I used a Tundra TB, I'm unaware if there's a particular difference between that and the 4Runner TB. I was about to go down the route of replacing the O2 sensors but came across that other dude who had the TB replaced, solving his issues.

Re-reading my previous post, I don't know why I said it didn't bog under accel, I recall one day in Surrey, I had no ability to apply power; like, the engine would produce just enough power to move the truck forward at constant speed and nothing more. Thankfully it started that shit after I got off the highway, but it was pretty scary because it could have happened 5 minutes before and I'd have been in REAL trouble.

I arrived, shut it off, said a prayer to the God Boost, and his disciples, Intake, Compression, Combustion, and Exhaust, so that when I return to the truck I can make it all the way home. And the gods blessed the 2UZ, she fired up and got me back home.

I swear I was a few microns from using a Molotov Cocktail to fix the damn thing.

The first sign of problems was it stalling on me during a snow storm turning left in a neighbourhood in winter of 2014. 2 years later, it did it again in the dead heat of summer. Then around ~2018 or so, it did the above mentioned shit every other week.
 
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Lucas606 said:
It’s an aftermarket MAF. Old one was throwing codes so I replaced it about a year ago. No codes since then. The timing belt was replaced at 100k miles and then again because it was wearing quickly. The current belt that’s on it is beginning to squeak when it rains so that’s a pain. Plugged in my scanner to check for codes but there’s nothing pending. The short term fuel trims seem to be everywhere though for both banks. Short term for B1 fluctuates anywhere from -7.8 to 3.9 at idle, and short term for B2 -2.3 to 3.1
Click to expand...

I don’t care for aftermarket MAFs and TBs (and numerous other parts) due to issues I’ve had on various vehicles with them. It does sound more like the TB in your case.
 
Sounds like I need to try replacing the TB, I hit a bump and that seemed to cause the issue which sounds similar to the story referenced.

appreciate the insight
 
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