1991 Land Cruiser throttle body leak.

[Curtis Briggs]

Hey fellow 3fe 80 series owners, I have a 1991 Land Cruiser with an interesting issue. It had always run a bit weird with a low rough idle. I have been slowly eliminating vacuum leaks and bad sensors.

After countless hours of diagnosing and failing to fix the issue I hooked up a smoke machine. I found that I have a vacuum leak coming from the throttle body shaft. The shaft also has some play in it. I am wondering if anyone else has run into this issue and if there is any way to fix it. I haven’t been able to find any place to buy seals and throttle bodies are like $500 so I don’t really want to go that route unless I have to.

Thanks!
Curtis

 

[MissahPapaJ]

Hey fellow 3fe 80 series owners, I have a 1991 Land Cruiser with an interesting issue. It had always run a bit weird with a low rough idle. I have been slowly eliminating vacuum leaks and bad sensors.

After countless hours of diagnosing and failing to fix the issue I hooked up a smoke machine. I found that I have a vacuum leak coming from the throttle body shaft. The shaft also has some play in it. I am wondering if anyone else has run into this issue and if there is any way to fix it. I haven’t been able to find any place to buy seals and throttle bodies are like $500 so I don’t really want to go that route unless I have to.

Thanks!
Curtis

I’ve for sure seen this on other Toyotas and the fix is typically finding a better one if that is the actual underlying issue. It honestly would be the least of concerns to fix until it’s the only option. Have you done a vacuum gage test yet? Go off of the brake booster line for best results. Also if the vehicle smooths out after the booster has been disconnected you may want to look into a intermittently leaking booster… seen that too.

 

[Curtis Briggs]

I’ve for sure seen this on other Toyotas and the fix is typically finding a better one if that is the actual underlying issue. It honestly would be the least of concerns to fix until it’s the only option. Have you done a vacuum gage test yet? Go off of the brake booster line for best results. Also if the vehicle smooths out after the booster has been disconnected you may want to look into an intermittently leaking booster… seen that too.

Thanks for the reply! I have not done a vacuum gage test yet but I will try that and see what I find. Do you know the reading should be at idle? I also thought it was possibly the vacuum booster because I also had a squishy brake pedal. I replaced the booster and the squishy pedal went away but not the idle issues.

 

[MissahPapaJ]

Thanks for the reply! I have not done a vacuum gage test yet but I will try that and see what I find. Do you know the reading should be at idle? I also thought it was possibly the vacuum booster because I also had a squishy brake pedal. I replaced the booster and the squishy pedal went away but not the idle issues.

Should be higher than 15-16” and not fluttering during idle should be steady run it to 1600 RPM and hold, check cold and up to temp for scientific purposes 20-22” is tits.

 

[Curtis Briggs]

Should be higher than 15-16” and not fluttering during idle should be steady run it to 1600 RPM and hold, check cold and up to temp for scientific purposes 20-22” is tits.

Nice thanks! I’ll check that once I buy a vacuum gauge.

 

[MissahPapaJ]

Should be higher than 15-16” and not fluttering during idle should be steady run it to 1600 RPM and hold, check cold and up to temp for scientific purposes 20-22” is tits.

Also if I had a 91-94 80 series I’d have a FSM for sure. I got a 96 and a FSM / Alldata / identifix through my work and all the tools at my disposal and I still have a hard time fixing old whips at times. Good luck report what you find out. I wouldn’t rule anything out. Also if you have a throttle plate shaft issue you can usually push it from the throttle linkage side and help it seal better by spinning it in reverse of WOT or applying inward pressure or outward pressure if that makes sense.

 

[Curtis Briggs]

Also if I had a 91-94 80 series I’d have a FSM for sure. I got a 96 and a FSM / Alldata / identifix through my work and all the tools at my disposal and I still have a hard time fixing old whips at times. Good luck report what you find out. I wouldn’t rule anything out. Also if you have a throttle plate shaft issue you can usually push it from the throttle linkage side and help it seal better by spinning it in reverse of WOT or applying inward pressure or outward pressure if that makes sense.

Copy that, yeah it is way harder to diagnose these rigs than any of the newer ones I’ve worked on with obd2. I’ve been meaning to pick up a service manual they are just kinda expensive haha.
Ahh okay I think I see what you are saying about the throttle shaft. If I can’t find anything else wrong I will probably take off the throttle body and see if there is a seal or bushing of some kind on there that I can replace.

 

[MissahPapaJ]

Copy that, yeah it is way harder to diagnose these rigs than any of the newer ones I’ve worked on with obd2. I’ve been meaning to pick up a service manual they are just kinda expensive haha.
Ahh okay I think I see what you are saying about the throttle shaft. If I can’t find anything else wrong I will probably take off the throttle body and see if there is a seal or bushing of some kind on there that I can replace.

There’s nothing to fix if the throttle plate shaft is leaking bad enough to actually cause a problem. There used to me a guy who used to repair the throttle plate shaft issue but he has passed away but he would machine the plate bore out a smidge and and machine the shaft bore out a bit and machine a new shaft and throttle plate bringing the tolerances back to spec, but he passed away a few years back. I would maybe source a better throttle body if that’s really the biggest suspect part. There’s a guy on marketplace who parts out FZ80 and FZJ80’s in Menifee CA and he parts out 80 series and he has a bunch of 91’s reach out to him he may have a throttle body for you.

 

[MissahPapaJ]

Copy that, yeah it is way harder to diagnose these rigs than any of the newer ones I’ve worked on with obd2. I’ve been meaning to pick up a service manual they are just kinda expensive haha.
Ahh okay I think I see what you are saying about the throttle shaft. If I can’t find anything else wrong I will probably take off the throttle body and see if there is a seal or bushing of some kind on there that I can replace.

If your shaft leak is bad enough to cause an issue you’ll have a high idle too is your vehicle idling over 1,000-1,400?

 

[Curtis Briggs]

There’s nothing to fix if the throttle plate shaft is leaking bad enough to actually cause a problem. There used to me a guy who used to repair the throttle plate shaft issue but he has passed away but he would machine the plate bore out a smidge and and machine the shaft bore out a bit and machine a new shaft and throttle plate bringing the tolerances back to spec, but he passed away a few years back. I would maybe source a better throttle body if that’s really the biggest suspect part. There’s a guy on marketplace who parts out FZ80 and FZJ80’s in Menifee CA and he parts out 80 series and he has a bunch of 91’s reach out to him he may have a throttle body for you.

Gotcha, do you happen to know the guys name that parts out Fj80S? Only reason I think it is the leak is because of the smoke test I can see a good amount coming out around the shaft, and have no other leaks. I do have a pretty good machine shop near me that might be able to bring things back to tolerances.

 

[Curtis Briggs]

If your shaft leak is bad enough to cause an issue you’ll have a high idle too is your vehicle idling over 1,000-1,400?

I think it is leaking just enough to where the computer is trying to compensate and the idle is lower than it should be around 450 rpm in gear.

 

[Curtis Briggs]

Or maybe I’m just being way too sensitive and I should just stop worrying about it and run it until I have worse drivability issues lol. I think I’ll pick up a vacuum gage today and if that comes back good I’ll just not worry about it.

 

[ColoradoBoy]

Copy that, yeah it is way harder to diagnose these rigs than any of the newer ones I’ve worked on with obd2. I’ve been meaning to pick up a service manual they are just kinda expensive haha.
Ahh okay I think I see what you are saying about the throttle shaft. If I can’t find anything else wrong I will probably take off the throttle body and see if there is a seal or bushing of some kind on there that I can replace.

Look in the resources section for FSM.
Cheers!

 

[Curtis Briggs]

Look in the resources section for FSM.
Cheers!

Oh sweet, I didn’t know that section existed. Thank you!

 

[Curtis Briggs]

I am reading about 16” on my vacuum guage at idle when cold and it goes up to around 17” when warmed up. At 1600 rpm it sits at about 17-18”. It does flutter a little bit but barely noticeable.

 

[MissahPapaJ]

Ya it’s Danny Ashely out of Menifee, CA he seems to have a slew of 91’s in his pimp stable. Smoke tests aren’t the most accurate way of testing some times. Alternatively you can attempt to isolate intake and exhaust introduce compressed air ( regulated ) when cold and use soapy water in a spray gun to find vacuum leaks. Sometimes it’s a better tool or at least another tool to find vacuum leaks. Vacuum leaks should get better when the vehicle warms up unless it’s real bad.

 

[Curtis Briggs]

Sweet thanks man! I actually ended up finding a used throttle body on eBay for cheap so I’m gonna experiment on it a bit and see if it works better or if I can find a way to reseal one of these units. But yeah I dunno if it’s really even what’s causing my issue, still just another thing to narrow down. From what I’ve read on these forums it seems like the most likely issue is a small vacuum leak tripping out the air to fuel ratio and causing it richen up the mixture and idle low.

 

[MissahPapaJ]

Sweet thanks man! I actually ended up finding a used throttle body on eBay for cheap so I’m gonna experiment on it a bit and see if it works better or if I can find a way to reseal one of these units. But yeah I dunno if it’s really even what’s causing my issue, still just another thing to narrow down. From what I’ve read on these forums it seems like the most likely issue is a small vacuum leak tripping out the air to fuel ratio and causing it richen up the mixture and idle low.

worth trying for sure. Like I said I had a 99 Tacoma leak bad enough from the throttle blade shaft to cause a high idle couldn’t get it to drop past 1100 RPM so it was throwing codes ( can’t recall which ) but after trying IAC and EFI relearns etc. lots of other tinkering got a used TB and wham, bam, Christmas ham got the idle to drop to spec. No more codes. Intake leaks usually cause a higher idle but maybe different on early cruisers. Lots harder to narrow down on OBD1 units without scan tool data ( glad I have a 96 ). When you checked engine vacuum did you pull off of the feed line for the booster?

 

[Curtis Briggs]

worth trying for sure. Like I said I had a 99 Tacoma leak bad enough from the throttle blade shaft to cause a high idle couldn’t get it to drop past 1100 RPM so it was throwing codes ( can’t recall which ) but after trying IAC and EFI relearns etc. lots of other tinkering got a used TB and wham, bam, Christmas ham got the idle to drop to spec. No more codes. Intake leaks usually cause a higher idle but maybe different on early cruisers. Lots harder to narrow down on OBD1 units without scan tool data ( glad I have a 96 ). When you checked engine vacuum did you pull off of the feed line for the booster?

Damn yeah sounds like I might be going in the right direction. Fingers crossed this used throttle body is better than mine. From my research I’ve found a lot of people have had leaking intake tubes on the older cruisers and it caused similar issues to what I’m having. I put new intake tubes on mine when I first got it because it was crusty as hell haha. Yeah I pulled off of the feed line for the booster.

 

[Curtis Briggs]

To update the thread, I got the new-used throttle body and it is in really bad shape. There is a hole in one of the hard coolant lines… I did take it apart and there are seals around where the throttle shaft goes through the throttle body.

Like everyone says they are not available anywhere so looks like I am out of luck there unless I take measurements and can find something else that will fit. I am thinking some chainsaw crank seals possibly.
For now I’ll just run the throttle body I have on there and deal with the issues until they get worse or I find something else that could be causing my idle issues. Thanks everyone for the ideas and help!