Help Needed: High-Idling (tried everything, hopefully not)

[tsk]

Hi everyone,

Please help me with a strange high-idling issue on my 1997 4Runner Limited. (I've checked many threads, but haven't found a solution yet to my problem).

Here's some info:

Issue: Consistently idles high at 1800RPM in Park and around 1000RPM in Drive (but at standstill). Am using up a lot of gas (used to get about 300mi to one tank, now I get 230 mi). Once the engine is on, it runs with no issues.

Background: At one point, before the consistent high idling, the engine would occasionally and randomly idle high (400-600 RPM more than regular) momentarily when just sitting at a light or in park. Sometimes the engine wouldn't even start (would have to pump the gas pedal a lot and would have to wait and retry until it finally turned over [definitely not a starter or battery issue). Based on various forum threads, I thought it would be the TPS, IAC Valve, or dirty Throttle Body (TB).

Sometimes after unsuccessful starts, I'd clean the TB and IAC Valve with carb cleaner and the car would finally start. After a while, I even replaced the TPS, but no change. After the start problem got worse, I one day completely removed the TB (cleaned it well), replaced the TB gasket, cleaned the MAF sensor, and replaced the IAC Valve. Just after having done this, I started the car and immediately noticed consistent high-idling (as I've described above), which wasn't the case up until the cleaning/replacement. Thought maybe I had replaced the old IAC Valve with a faulty one... but I put back the old one and the engine was still consistently idling high (so I put on the new one again). This made no sense since everything should have been the way it was before did the changes. I took the car to two mechanics and they can't seem to find the issue either. One thought the TPS had gone bad... replaced it again, but to no avail. Both said I seemed to have put everything back correctly (they even removed and put everything back also) and that there were no signs of cracked hoses, vacuum leaks, loose throttle cables, etc.

I don't know what else to check. Does anyone have any other ideas?

Thanks in advance for your help.
-Tony

 

[NOT ME OR SOMEBODY]

Maybe leaking injectors?

 

[BrianSD_42]

are your throttle body cables set to factory specs?

 

[J-money$$$]

bad butterfly valve in the throttle body? I had a very similar issue. And thats what it ended up being. I found that in my case i could get it to idle right if i manually revved the motor from the TB and slammed it shut and held it shut with quite a bit of force.

Good luck. Idle issues are a PITA

 

[tsk]

Thanks for the posts thus far...

Leaking Injectors as in fuel injectors? (sorry for my ignorance)

Throttle cables: Not sure what the factory specs are, but I did adjust them to minimize too much slack from when I had then disconnected while I cleaned the TB. They're not tight/snug either, but very close to, if not the same, as I remembered before disconnecting them. Where can I find the factory specs for this?

Butterfly valve: I thought about this when I read other threads on here. The mechanics and I had checked this also. While the car idled, we would rev and close the valve as tight as we could (via the throttle cable arms). But didn't notice any difference. Other than doing this, is there another way to check that it could be a worn butterfly valve?

I'm also wondering if could've perhaps installed a faulty IAC Valve and not realize it.

Any other thoughts/ideas? (I'll take anything at this point).

Thanks again,
-Tony

 

[tsk]

Also, today the car had some trouble starting again.... hadn't done this in a while. finally, after letting the car rest for about 5 minutes, it started up no problem.

Another observation of the high-idling is that, sometimes, the car would idle around 1000RPMs upon startup, then rise up to the typical 1800RPMs after a few minutes. But typically it would just idle at 1800RPM upon startup. It's strange, but any thoughts on this?

 

[VTR9961]

I have seen this happen a few times after the throttle body was cleaned. The carbon that was cleaned around the throttle plate left a gap between housing and plate, basically throttle body is no good. If you haven't diconnected your battery to reset the ecm memory after cleaning the throttle body, do that first.

 

[tsk]

Interesting... I've replaced the gasket in between the Throttle body and Intake manifold. Shouldn't this new gasket have created a better seal? Or are you talking about a different plate?

And so that I can understand better... why is the throttle body no longer any good? i.e., what happened to the throttle body?

 

[BrianSD_42]

this =>

throttle cables: Not sure what the factory specs are, but i did adjust them to minimize too much slack

Basically my money is that you adjusted them incorrectly with the idle cable set to high. I have actually done this myself as well.

 

[VTR9961]

The carbon build up acted like sand paper and shaved away a small amount of aluminum, so when you cleaned the throttle body there is now to much clearance. This is very rare, but possible. I thought you said it got worse after you cleaned it. Have you disconnected your battery for a few minutes after you cleaned it?

 

[jonwilly2]

Mine use to do that for a while. I would leave it in drive and it would coast at 30. It only did that with the AC on, when it was off it was still bad. Toyota said the 5vz set idle speed is 700 + or - 50 rpm. Mine only does that after its been running for at least 15 minutes. I don't know what caused it but that was right before my MAF sensor took a poop.

 

[Baja Runner]

Does this happen when warm or cold?

What it sounds like is that your truck is getting stuck in open loop mode, which means that it is going off a pre-programmed mixture/configuration from the engine control module (computer). If any feedback sensors are sending bad information, your computer will automatically go into this loop.

You can try also connecting a ODBII program to it, and it will tell you if its running in closed loop (using sensors, good), or open loop. Open loop is normal when running under operating temperature.

The main 4 sensors are: TPS, O2 sensor, ECT, and MAF. Most of the time, they will throw a code with the 3.4L, but its good to check.

First though, check your coolant level. A low coolant level *might* cause the ECT (engine control temperature sensor) to not read the temperature correctly. Also the IAC will not get a sufficent flow of coolant, thus also causing it to run in open loop since it feels its still warming up.

 

[Baja Runner]

Lastly, I find it really odd that people are quick to judge that you have leaking fuel injectors. In 99% of the cases, that is not the problem. I have a few mechanic buddies who work for Toyota and they have told me that in their entire career, they have maybe seen 3-4 bad injectors in 20 years.

 

[tsk]

Thanks again for the replies. So,...

The issue did get worse after I took it apart, cleaned it, and put it back. To clarify, about the carbon build-up shaving away some of the aluminum and creating too much clearance... are you referring to the part on the throttle body that connects to the manifold or the valve plate inside the throttle body? If it's the part that connects to the manifold, wouldn't a new gasket help to seal it? otherwise if about the valve plate, is there any way to replace just the plate and not the whole throttle body? I do notice that the plate is connected via two screws (would hate to replace the entire throttle body if not necessary).

Also, this high-idling issue has been going on since June to present, and I live in the Washington, DC metro area. (Needless to say, it's been quite warm here)

And about the throttle cables... After I had put everything back together, the cables were fairly loose (from not being connected for 1-2 hrs?), but I left it that way when turning on the engine and that's when I noticed the high-idling issue. I adjusted the nuts to take out some of the slack, and though I most likely didn't put it back to factory specs, it made no difference it seem. But I would like to adjust them to factory spec if someone could shed some light on that or point me to the correct/previous thread?

I did disconnect (-) terminal on the battery, but maybe not for long enough (the radio didn't even reset). I will do that again but longer this time.

The coolant levels seem plenty.

And the mechanics (or folks at the Advance Auto) said the computer wasn't providing any codes (where as previously it would for a faulty/broken TPS).

 

[tsk]

Anyone have any other thoughts or ideas of my issue?

I'd really like to find the root cause ASAP before this becomes a money pit (also am burning a lot of gas).

Your help is greatly appreciated.

Thanks
-Tony

 

[theizzardking]

Lastly, I find it really odd that people are quick to judge that you have leaking fuel injectors. In 99% of the cases, that is not the problem. I have a few mechanic buddies who work for Toyota and they have told me that in their entire career, they have maybe seen 3-4 bad injectors in 20 years.

i've had to replace 2 injectors personally and had the same problems as described....just saying....

 

[gotsboost]

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