3FE high idle help (1 Viewer)

[Krondor]

Hey.

So my 1991 FJ80 is having some high idle in park but changes to the correct idle in drive.

I have swapped out my TPS thinking it was faulty and correctly set it with feeler gauges. , changed the O2 sensors, adjusted the timing (as best as I could, it was difficult to see the sight window), Adjusted the "brass screw" as far as it can go clockwise.

Starting to run out of ideas. If anyone has any knowledge they would like to share, or would want to come poke and prod at the engine, please feel free to send me a message or respond.

Thanks,
Alex

 

[Bryanseye]

Intake free of splits? They get hard and crack inside the accordion section near the TB.

 

[Krondor]

I temporarily wrapped the intake with electrical tape to cover any cracks I couldn’t see. It dropped the rpms slightly but not much.

 

[Krondor]

It runs around 1100-1200 rpm at idle at park then drops to 750 ish while in drive.

 

[DFWMatt]

It runs around 1100-1200 rpm at idle at park then drops to 750 ish while in drive.

Exact same issue here. I’ve done everything you have without luck. Any progress? Thanks

 

[Krondor]

No progress. I can't figure out what it is. I'll take it into the shop at some point. It just hasn't been a high priority since it drives fine.

 

[DFWMatt]

Does yours idle higher when you start it up cold and slow down when it warms up?

Mine starts up at 1000-1200 and stays there regardless of temp. As soon as I put it in gear it drops to normal idle range. I also installed a tps and set it per fsm but think I may revisit that.

 

[Krondor]

Mine is the same as yours. It's high while in park or Neutral and stays at 1000-1200 then drops down to about 700-750 when in drive. Turning off the AC drops it slightly but not much.

 

[dbenke]

It's most probably 1 of 2 things.
Either the cold enrichment (like a choke on a carb) or a vacuum leak.
Lots of vacuum lines to check, a small crack will make it idle high.

 

[toy_tek]

I had the same issue when I bought mine, would lurch when I put in in Drive. While attempting to adjust the TPS, found the TPS was not snapping to the idle position fully, needed to remove it to notice this. Removed, cleaned thoroughly, reassembled... Also found the PCV valve caked up with crud.

Also make sure your throttle cables (both pedal and hand) are routed correctly, once I had moved mine to work on something else and forgot to reseat it in the bracket... I had a high idle for the next 2 days until I realized what I had done.

 

[DFWMatt]

Great ideas, I’ll look into them. Thanks

 

[toy_tek]

Great ideas, I’ll look into them. Thanks

Did you get it sorted out? just found my old post about high idle on 3FE, maybe it will help:

FJ62 engine miss at idle (3fe) where to start?

Members, This will be my next project on the 62. I have a slight miss at idle and a little as revs climb to about 1000. Did be the obvious such as wires, plugs, cap and rotor. Injectors were rebuilt about 2/3 yrs ago from PO. Truck is smogged. Have FSM and just looking for advice of where to...

forum.ih8mud.com

 

[Krondor]

Good suggestions! I have not fixed mine yet. but I did remove the TB and it was very clean. I replaced the TPS sensor and clocked it per FSM. , I'll have to check the PVC valve, IAC valve, and dashpot.

Thanks for the suggestions!

After the changes, did you have to readjust the brass screw at all? or did you leave it all the way in like it was?

 

[Krondor]

Success! I finally had a chance to rebase the cruiser.

- I started off retiming the FJ80 per the FSM (I used a mirror from harbor freight to allow me to see the dimple in the flex plate. I realized that I was looking at the flex plate bolt before hand.)
- I then cleaned the IAC valve with brake cleaner then reinstalled.
- I removed the Throttle body and reset the TPS per the FSM. I used two multimeters to verify the correct position.
- I replaced the throttle body, cleaning all the surfaces really well.
- I adjusted the brass screw out 1/2 a turn.
- I then retimed the FJ80 again per the FSM.

The idle is much lower, hovering around 700 in park and neutral and it drops down to 650 in drive. I took it on a quick drive and the response is much better, the idles stayed lower, and I am a happy camper.

 

[Krondor]

thanks again @toy_tek for your detailed response.

 

[DFWMatt]

I need to dive into mine. Hopefully this week. I was going to start with my timing then tps. Was there a big difference in the valve clearance on the second retime? Awesome response

 

[Krondor]

I never adjusted the valve clearance. Just twisted the the distributor until the dimple on the flex plate lined up with the needle. It will need a valve job at some point in the future though.