Just wanting to see if anyone has had the same issue as me and how they fixed it. My 94 fz 80 is not idling properly, from cold when I start it up in the morning it doesn’t idle up high, instead it goes to about 800 rpm and then settles at about 600 within a few seconds of starting. Anyone had the same issues or know of the best steps to take to fix it ?
1fz no warm up idle
- Thread starter DesFZ80
- Start date
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I have the same problem, haven't fixed yet
Having the same issue with my 94 haven't been able to figure it.
Mine does the same thing. Though with mine itll sometimes idle closer to 400-500, im not sure why but i could see a miscalibrated TPS causing issues
You guys can easily check it, removing connector plug from IAC valve and start engine, if RPM will be high engine is ok, mine do this but won't keep nigh under ECU controlling IAC valve, also I don't have low RPM after disconnecting battery terminal as usually it should be for FJ80 93-95
Here is page from FSM how ECU is controlling idle speed
Thanks for the info, I'm not understanding the part about disconnecting the batteryYou guys can easily check it, removing connector plug from IAC valve and start engine, if RPM will be high engine is ok, mine do this but won't keep nigh under ECU controlling IAC valve, also I don't have low RPM after disconnecting battery terminal as usually it should be for FJ80 93-95
- Thread starter
- #8
Thanks for the input guys, I tried the trick of unplugging the IAC and it did idle very high. So does this mean that the problem is somewhere else in the engine? I have a sneaking suspicion it’s my air flow meter but can’t be sure.
No, VAF meter can't do anything for idle. first check TPS sensor with multimeter, should be continuing between IDL - E2 at throttle door fully closed
Pulling the EFI fuse or disconnecting the battery resets the computer memory, it takes the computer a while to relearn some settings. During this time the engine will behave with low idle. I had this in the past when my high cold start idle was working, now resetting the computer doesn't have effect at relearn program, it's WRONG
do you have low idle after disconnecting battery?
I have lowish idle all the time, no high idle at start up. Throttle body sensor cleaned and everything else checked out by my mechanic another mud 80 guy. It used to have hi idle start up 30 /45 seconds then starts slowly back down.
AC on should make the idle +300 RPM if everything is ok
The thread 2 up from this one on the main page has your answers...
Zjohnsonua
SILVER Star
Pull the IAC. Clean it and the port it mounts in. Replace the o-ring.
It'll be wise to pull the throttle body as it eases the IAC removal and helps prevent stripping out its screws.
Pulling the battery resets the ECU's learned program for IAC control. I think I pulled it for 10 mins, but Cruiserdan's posts tell the correct amount of time for 93-94s.
It'll be wise to pull the throttle body as it eases the IAC removal and helps prevent stripping out its screws.
Pulling the battery resets the ECU's learned program for IAC control. I think I pulled it for 10 mins, but Cruiserdan's posts tell the correct amount of time for 93-94s.
Did this ever get sorted? If so, what was the fix?
I've got the same problem ( sort of ) when it's cold it starts fine when it gets to operating temp it will start but rev high and.blow heaps of black smoke, it also won't do this if the tank is over half full for some reason
- Thread starter
- #17
I actually did get this sorted, literally a day ago. It was the throttle cable adjustment. It needed to be tightened slightly to just crack the throttle open. Obviously as the cable stretches over time it changes the throttle position at idle. I never had any throttle related issues so never adjusted it, but lesson learnt now.
Zjohnsonua
SILVER Star
The IAC is meant to control air at idle. Cracking the throttle is a bandaid.
- Thread starter
- #19
Seems more like a blocked fuel tank breather or maybe blocked charcoal canister. I’m thinking that could cause an increase in the fuel pressure and hence your black smoke. Perhaps try bypassing the charcoal canister or even just pulling the vacuum line off the fuel pressure regulator when you get those symptoms, just to see if you observe any change. That’s where I would start anyway.
- Thread starter
- #20
Yes I understand this. I replaced every item possible including 2 IAC valves over time. I stumbled across this solution when doing other maintenance, as I had just let this issue go for a long time. When I was adjusting the throttle cable which appeared to have slack, the problem was fixed and I didn’t mean to fix it. I’m guessing it’s more to do with how the TPS reads the throttle position and as a result, this would change how the IAC valve responds. It was a very minor adjustment.
