HELP! Intermittent Stalling, tried everything.

[cbr900boy]

There is the one behind the ABS Diagnostic box on the upper manifold.

If it isn't fuel related and the IAC is new (so is the MAF) then I would say MAF but I know it is new.

I take it you don't have a scanner or app that shows live data still.

The MAF is not new, it's the original. When I got the rig, it was filthy so I cleaned it with MAF cleaner. The IAC valve is new. I have the Torque app (full version) and OBD II bluetooth reader. I use it all the time to check live data on my fuel trim, O2 sensors, vacuum, coolant temp, as well as intake temp which BTW is much cooler since I got the snorkel.

Do you think the MAF can go bad without throwing a code? Would the MAF also cause a stall?

 

[kball]

I've been keeping up with this thread but never commented since you've tried everything I thought of. If the maf was bad it should run for a minute or two and then die. Lately I've been thinking bad ground or maybe a flaky crank position sensor or cam sensor. The cam sensor is behind the top timing belt cover. I wouldn't mess with it yet. If you can get to the crank sensor and pull it and clean it, maybe it's dirty and not getting a good read..?

 

[cbr900boy]

I've been keeping up with this thread but never commented since you've tried everything I thought of. If the maf was bad it should run for a minute or two and then die. Lately I've been thinking bad ground or maybe a flaky crank position sensor or cam sensor. The cam sensor is behind the top timing belt cover. I wouldn't mess with it yet. If you can get to the crank sensor and pull it and clean it, maybe it's dirty and not getting a good read..?

I hope it's not the MAF because for the 98 the OEM costs $750!!!! I'm going to check both cam and crank sensors this weekend. Thanks.

 

[cbr900boy]

I've been keeping up with this thread but never commented since you've tried everything I thought of. If the maf was bad it should run for a minute or two and then die. Lately I've been thinking bad ground or maybe a flaky crank position sensor or cam sensor. The cam sensor is behind the top timing belt cover. I wouldn't mess with it yet. If you can get to the crank sensor and pull it and clean it, maybe it's dirty and not getting a good read..?

So still no resolution as of yet. I cleaned my MAF again and even put my intake all back to stock, just because I've read a couple of guys mention that they had stall issues after doing the ISR mod. Couldn't hurt to try. Based on my scan tool, my MAF sensor is reading 3.4 g/s at idle and around 120 g/s at WOT. So based on those readings, my MAF seems good. Double checked all my grounds as well as all my vacuum hoses with no issues.

I've come across quite a few posts and articles on other forums that mention similar issues as mine, most of them mentioned the crank and cam position sensors. The symptoms sounds spot on as mine ie warm weather, intermittent, no code, etc. Those sensors will be my next project. It makes sense because issues associated with fuel delivery and MAF usually has some other characteristic associated with it right before it stalls ie lurching, bogging down, hesitation, etc. In my case the "cut off" is abrupt and with warning.

I feel like I'm getting close so wish me well.

 

[LittleCaesar]

Start with looking at the connectors of both, at worst give them a good cleaning.

I hate throwing parts at a problem without solid evidence or numbers but good luck to you.

That MAF new is no joke. I would think you could find a cheap one in a CA junkyard for under $30.

 

[zoombyu86]

Start with looking at the connectors of both, at worst give them a good cleaning.

I hate throwing parts at a problem without solid evidence or numbers but good luck to you.

That MAF new is no joke. I would think you could find a cheap one in a CA junkyard for under $30.

I was able to score a junkyard MAF in Ohio for $35. They come in other vehicles other than 4runners too.

 

[ajonesnv]

I apologize for not reading the thread thoroughly, however has the Evap Canister been looked at? Typically it throws a code, but it will cause a vehicle to stall typically when its warm out if its leaking or has a bad VSV.

 

[cbr900boy]

I apologize for not reading the thread thoroughly, however has the Evap Canister been looked at? Typically it throws a code, but it will cause a vehicle to stall typically when its warm out if its leaking or has a bad VSV.

Can you explain how the evap canister or vsv might cause a stall?

 

[ajonesnv]

Can you explain how the evap canister or vsv might cause a stall?

Unfortunately no, not in detail. I know that was the reason mine was stalling, however I got a code so I knew where to be looking for the problem.

Best I really know is it affects the vacuum.

 

[cbr900boy]

Evap Canister Question

Hey guys, while checking my vacuum hoses the other day I noticed something peculiar. While my rig was idling I pinched the vacuum hose that goes front the evap canister to the intake (after throttle body) which caused a stall (#1 on picture). I started the engine and pinched it again, this time I can hear the RPMs fluctuate but could not cause it to stall again. So my question is, why would this cause my engine to stall or fluctuate? Is this the only source of air while the throttle plate is closed at idle? I though the IAC provided air while idling.

Based on ajonesnv's suggestion, I'm looking into the evap canister as well.

 

[Bumper2Bumper Auto]

Hey guys, while checking my vacuum hoses the other day I noticed something peculiar. While my rig was idling I pinched the vacuum hose that goes front the evap canister to the intake (after throttle body) which caused a stall (#1 on picture). I started the engine and pinched it again, this time I can hear the RPMs fluctuate but could not cause it to stall again. So my question is, why would this cause my engine to stall or fluctuate? Is this the only source of air while the throttle plate is closed at idle? I though the IAC provided air while idling.

Based on ajonesnv's suggestion, I'm looking into the evap canister as well.

Two possible things could cause a stall when pinching off that hose.
1. The system is in purge mode, and the computer EXPECTS this extra air in the system, and when it doesn't have it, it can stall
2. There is a failure in the purge system or canister, and the IAC has adapted to the additional air coming through, but when you pinch it off, the engine will stall because it doesn't have enough air. I haven't read the entire thread, but am simply answering that one specific question.

 

[cbr900boy]

Two possible things could cause a stall when pinching off that hose.
1. The system is in purge mode, and the computer EXPECTS this extra air in the system, and when it doesn't have it, it can stall
2. There is a failure in the purge system or canister, and the IAC has adapted to the additional air coming through, but when you pinch it off, the engine will stall because it doesn't have enough air. I haven't read the entire thread, but am simply answering that one specific question.

Hmmm interesting. I have a question about the VSV (#1 in picture). I know it's a simple open/close switch that feeds air to the intake but is the valve itself variable? The reason why I ask is I've noticed that the ticking intensity on the VSV is sometimes quite and sometimes loud. Shouldn't it be consistent?

Thanks Bill

 

[ajonesnv]

Pretty sure it's an on/off solenoid.

I would also suggest that you pull the canister and inspect the seam where it is pressed together. This area has a consistent rate of failure in these trucks and can be a source of a vacuum leak. The factory glue gets brittle and starts falling out. Many have been able to reseal the edge with a heavy RTV or Silicon successfully.

 

[cbr900boy]

Pretty sure it's an on/off solenoid.

I would also suggest that you pull the canister and inspect the seam where it is pressed together. This area has a consistent rate of failure in these trucks and can be a source of a vacuum leak. The factory glue gets brittle and starts falling out. Many have been able to reseal the edge with a heavy RTV or Silicon successfully.

Seems like we are getting somewhere, I've noticed that when I shut off my engine I hear a very very faint high pitched noise like air either being sucked in or escaping from the canister. I've never though much of it because it was so faint, I'm now assuming it supposed to be a sealed system right?. Until now, I would have never suspected the evap canister to affect the vehicles driveabilty characteristics because I though it was only an emissions device.

Some of this is starting to make sense because the stalling only occurs during warmer weather and after longer drives. It has to be somehow connected right? The reason why I never suspected the evap canister is because every Goggle search I've done has only produced posts where people had to replace there canister because of a CEL, not because it caused a stall. You are the only person who mentioned that the canister had a direct relation to stalling.

 

[ajonesnv]

Seems like we are getting somewhere, I've noticed that when I shut off my engine I hear a very very faint high pitched noise like air either being sucked in or escaping from the canister. I've never though much of it because it was so faint, I'm now assuming it supposed to be a sealed system right?. Until now, I would have never suspected the evap canister to affect the vehicles driveabilty characteristics because I though it was only an emissions device.

Some of this is starting to make sense because the stalling only occurs during warmer weather and after longer drives. It has to be somehow connected right? The reason why I never suspected the evap canister is because every Goggle search I've done has only produced posts where people had to replace there canister because of a CEL, not because it caused a stall. You are the only person who mentioned that the canister had a direct relation to stalling.

Yes it is a sealed system and is connected, as I was originally cleaning the TB and the valve below the TB (briefly forgot it's name). For what it's worth, I got a code, but it would still stall after the code was cleared.

Have you ever had a CEL before? Are you the only owner. I have heard of some folks removing the CEL bulbs prior to selling the truck, idk, just a thought.

 

[cbr900boy]

Yes it is a sealed system and is connected, as I was originally cleaning the TB and the valve below the TB (briefly forgot it's name). For what it's worth, I got a code, but it would still stall after the code was cleared.

Have you ever had a CEL before? Are you the only owner. I have heard of some folks removing the CEL bulbs prior to selling the truck, idk, just a thought.

I know the CEL works. It came on when i had the MAF unplugged.

 

[kball]

The evap canister making noise on early 4runners after shutting it off is pretty common. I know it is for 96's and think it goes through the 98 model year. They even had a fix for it years ago from the dealer that's not offered anymore. Do a Google search for evap canister making noise or bumblebee noises and you'll find threads about it.

 

[Kotrin]

I just posted something that may help also as your problem was almost exactly like mine from what I was reading. Mine only does it at a crawl when I would apply the gas. If i 'Drove it like I stole it' it wouldn't ever happen..

I replaced my Throttle Position Switch which fixed my problem. I went more into detail in my post of Kotrins 3rd Gen Adventure...

 

[cbr900boy]

The evap canister making noise on early 4runners after shutting it off is pretty common. I know it is for 96's and think it goes through the 98 model year. They even had a fix for it years ago from the dealer that's not offered anymore. Do a Google search for evap canister making noise or bumblebee noises and you'll find threads about it.

The noise I hear is a faint high pitched noise, almost like letting air out of a balloon.

 

[cbr900boy]

I just posted something that may help also as your problem was almost exactly like mine from what I was reading. Mine only does it at a crawl when I would apply the gas. If i 'Drove it like I stole it' it wouldn't ever happen..

I replaced my Throttle Position Switch which fixed my problem. I went more into detail in my post of Kotrins 3rd Gen Adventure...

Thanks for the info, the first thing I did was replace my TPS.