Minor idle issue, now rough idle (1 Viewer)

[fjbj40]

My 80 has a little stumble right now. Only at idle. I pulled all the plugs, they look perfect. Not going through coolant.
So I’m thinking check TPS rigging then throttle cable rigging if not those change plugs as they are dirt cheap at Toyota, $2-3 ea.
Then?

Fully baselined, all new ignition components 12,000 miles ago. OEM parts.

Plugs all looked mint when I inspected them last week.

Any other suggestions?

Very light miss at idle, seems like ignition, but disappears at above idle.

Fuel injectors were serviced at baseline as was the full fuel system.

Pulls ****ing great at highway speed, temps and pressures are spot on.

 

[JoeCova]

What kind of a stumble? Like quick super small rpm drop randomly every few seconds or something more?

 

[fjbj40]

What kind of a stumble? Like quick super small rpm drop randomly every few seconds or something more?

Steady, low level shake

 

[JoeCova]

Steady, low level shake

Hmm not sure. Maybe double check timing?

 

[LandLocked93]

Steady, low level shake

Sort of thought this was normal, at least in vintage rigs.
Although it's not steady in mine. Rather more infrequent at idle, then gone off idle.
Curious what you find out.

 

[JoeCova]

Sort of thought this was normal, at least in vintage rigs.
Although it's not steady in mine. Rather more infrequent at idle, then gone off idle.
Curious what you find out.

Same mine idles smooth then you can just feel like a slight low rev or something infrequently which I think is pretty normal.

 

[robnicko]

check for vacuum leaks
give the throttle body a good clean and pay particular attention to the IAC port area

 

[fjbj40]

Sort of thought this was normal, at least in vintage rigs.
Although it's not steady in mine. Rather more infrequent at idle, then gone off idle.
Curious what you find out.

No, not normal.

This thing was totally baselined and has purred for 12,000 miles since then.

Definitely something is amiss.

Throttle body and IAC port is spotless.

A friend suspects maybe a bad tank of fuel at last fill-up. I put in some fuel system cleaner so see what happens after the remaining 1/2 tank burns off and it gets filled with supreme.

Fingers crossed it’s that simple

Cheers

 

[fjbj40]

More troubleshooting with no faults found but still there

TPS inspected and adjusted as per FSM.

IAC valve inspected and ck good as per FSM.

Did the fault code ck, constantly blinking which means no faults.

So fuel pressure ck next, afm value measure and if there is nothing there then I will drive her till empty then fill with supreme.

If not that, change spark plugs.

 

[fjbj40]

Well, I think idle issue is resolved?

Tried a spare FPR, nope not it.

Checked every vacuum hose I could, with propane trick, nope

Started the old feel around with engine running and rough.

Noticed oil on my hands, it was my oil separator/catch can .

I should add the seperator is a water separator for compressed air. I should have realized the o-ring is probably no good for oil. It was hardened along with flattened.

O-ring no longer sealing! Not cracked, just flat and not sealing.

I don’t think the propane trick works unless it’s a substantial leak?

Anyways smooth now

As always or typically, it was something simple

 

[LandLocked93]

Pretty sure I'm running the same can as you.
That o-ring stays stuck to the top of the can when I empty it out. Probably oil exposure damage.
Good thing to remember if my idle starts to get grumpy.

 

[fjbj40]

Pretty sure I'm running the same can as you.
That o-ring stays stuck to the top of the can when I empty it out. Probably oil exposure damage.
Good thing to remember if my idle starts to get grumpy.

Home Depot Husky special

 

[fjbj40]

Problem returned. So I removed the oil separator to eliminate potential problem.

Must of just been a fluke/coincidence with the oil separator.

Swapped in spare tps, no change. Swapped in IAC, no better.

Maybe a temp sensor of some sort?

Digging into FSM and EWD

 

[fjbj40]

Function checked IAC motor and works as per FSM.

So I extended closed as far as possible. Reinstalled and started engine. Idled at 400 and would not increase.

Pulled IAC and it never moved from where I set it.

I think it’s not getting voltage or whatever communicates with it has a broken wire or is unserviceable.

Next up is check voltage input to IAC motor and go from there.

Could be wiring, ECU or engine temp sensor for computer as it’s separate from gauge temp sensor.

Hopefully have answer today after garden chores before it gets 30* again

 

[fjbj40]

Ecu temp sensor reads 2.09 ohms, supposed to be 1.5 ohms at 25*C. It’s within its range but I want to see what happens as temps increase.

So I made a jumper set-up with an old injector connector and jumpers into the temp sensor connector so I can run it and see what happens as temps increase.
Didn’t feel like draining the coolant to remove sensor and test. I have a mechanical temp gauge in the truck so I can do the same thing and look at the graph in the FSM.

Bitch of a spot to work, for me working in the wheel well is easier than trying it from the top down.

 

[fjbj40]

May have found the problem, maybe, don’t want to jinx myself.

As per the FSM, everything checked out, used all the troubleshooting procedures.

When I got to the AFM, resistance values checked out. Next step is measure voltages.

When I lifted the AFM harness to plug back in and do voltage checks I noticed water dripping out of connector.

I pulled the rubber boot back and more water. FFS, everything checked out, but there is water?

Used ACF50 to displace water and very low pressure air to force it into the wire/connectors.

Hooked it up and idles pretty much normally now!

Time for a test drive. Working on a 180*F 1Fz when it’s 30*C is no fun.

I’m drained, time for beer

 

[fjbj40]

I must add, if anybody works on a LC and doesn’t have the FSM and EWD, they are just plain old wasting time and probably throwing parts and money at it with s***ty results and not learning anything about their rig!

 

[ZackR]

At this point I'd pull the ECU fuse to reset everything and drive it around a bunch, with a lot of stop start cycles. Hopefully you found the issue, next up figuring out where the water came from....

 

[fjbj40]

At this point I'd pull the ECU fuse to reset everything and drive it around a bunch, with a lot of stop start cycles. Hopefully you found the issue, next up figuring out where the water came from....

Fuse was pulled, drove it and problem fixed.

I washed the engine after the last off-road trip, guess I was a little too happy with the hose. I usually use the mist function on the hose nozzle, not last time as it was pretty dirty.

I’m going to add a bead of sealant to the dried out rubber boot on the AFM connector.

 

[efjayatee]

My 93 was the ICM. It was fried.