Help! Bouncing idle then Dies.

[SammieH]

Hey Guys. I have a 1993 80 series with 150km on it. On my way to work it decided it was going to die when I stopped at a light. Had to limp it to work and it will bounce between 400-1000 for a minute and then die randomly. Ohmed out the IAC and had two pins within spec (10-30) and two at 47. Would this cause a bouncing idle that that?

Also have had 83 84 85 codes for a while which gives me nightmares. Hoping that this is not contributing to the idle problem. Any thoughts? Can post a vid if it helps.

Thanks guys.

 

[voodu3]

It’s probably your ECU. Do you know if it’s ever been replaced? I had a similar issue on my 93 I got an ecu from a 94 and it fixed it. As a temporary fix try resetting the ecu by pulling the EFI fuse.

 

[SammieH]

It’s probably your ECU. Do you know if it’s ever been replaced? I had a similar issue on my 93 I got an ecu from a 94 and it fixed it. As a temporary fix try resetting the ecu by pulling the EFI fuse.

I believe the Ecu was replaced in 2021 but I’m not positive. Tried to track down old owners but had no luck. I have been researching what ecu I can swap mine with. It is a Japanese truck so it has a 89661-60160. I’m not sure that a us spec 89661-60221 is compatible.

I also haven’t changed my fuel filter in the 2 years I’ve owned it and not sure it’s ever been changed. Could this be causing it?

 

[voodu3]

I don’t know about the differences in the ECUs but yours does look newer. The codes you have made me think it was the ECU. It won’t hurt to change the fuel filter but I doubt it’s causing the issues. I’d try resetting the ECU and see if clearing the codes changes anything.

 

[voodu3]

Thread 'CODE #83 #84 #85 93FZJ80 issue help'

Aug 25, 2005

the 80 has been developing a stumbling issue when first being driven.

usually in the morning (maybe colder and moister)
usually happens if you don't let it warm up for 3-5 minutes or so first

Situation:
I gave the engine bay a thorough hosing down after the pig run here and had a sprinkler under it for an hour or so trying to clean some of the mud and such off.

the next morning (a good 15 hours later) I drove the truck but it was faltering horribly! acted a LOT like fuel starvation, but could have been anything.

The *check engine* light came on a couple times and went...

• Klunky Chris
• Replies: 42
• Forum: 80-Series Tech

This is an old thread but it has some good info but nothing on JDM.

 

[SammieH]

I don’t know about the differences in the ECUs but yours does look newer. The codes you have made me think it was the ECU. It won’t hurt to change the fuel filter but I doubt it’s causing the issues. I’d try resetting the ECU and see if clearing the codes changes anything.

Will pull it now and get back. What kind of problems were you having with yours before you changed it? Mostly idle issues and odd gear shifts or a multitude of things?

 

[SammieH]

Thread 'CODE #83 #84 #85 93FZJ80 issue help'

Aug 25, 2005

the 80 has been developing a stumbling issue when first being driven.

usually in the morning (maybe colder and moister)
usually happens if you don't let it warm up for 3-5 minutes or so first

Situation:
I gave the engine bay a thorough hosing down after the pig run here and had a sprinkler under it for an hour or so trying to clean some of the mud and such off.

the next morning (a good 15 hours later) I drove the truck but it was faltering horribly! acted a LOT like fuel starvation, but could have been anything.

The *check engine* light came on a couple times and went...

• Klunky Chris
• Replies: 42
• Forum: 80-Series Tech

This is an old thread but it has some good info but nothing on JDM.

Unfortunately I spend my nights reading these forums hoping that there is some oddball issue and it’s not the ecm. It’s concerning to me that it was potentially replaced 4 years ago and already has these codes again.

 

[SammieH]

I don’t know about the differences in the ECUs but yours does look newer. The codes you have made me think it was the ECU. It won’t hurt to change the fuel filter but I doubt it’s causing the issues. I’d try resetting the ECU and see if clearing the codes changes anything.

I pulled the fuse for 20 minutes at replaced it. Codes are gone and bouncing idle is gone but it’s idling at like 300-400rpms. I will have to drive it and let it relearn. Will post an update later on. Thanks for the help,

 

[Malleus]

I'd look long and hard at the crankshaft position sensor pigtail.

 

[landtank]

I'd look at the air tube going from the filter to the throttle body for cracks and then I'd disconnect the brake booster hose from the booster and plug it,

 

[SammieH]

I'd look long and hard at the crankshaft position sensor pigtail.

I have Checked connections on most of the sensors and they looked pretty good. Maf and tps sensors ohmed out correctly. IAC was high on a few pins. I will recheck that pigtail and retest the tps. Have you had/heard of an issue like this that was a bad TPS connection?

 

[SammieH]

I'd look at the air tube going from the filter to the throttle body for cracks and then I'd disconnect the brake booster hose from the booster and plug it,

Did a smoke test for vacuum leaks. Found and fixed them. My main intake hose was good. What is the reason behind plugging the booster hose? Should I run it while doing so?

 

[Malleus]

Ignore that; I just reread your first post. You don't have a CPS.

 

[Malleus]

Did a smoke test for vacuum leaks. Found and fixed them. My main intake hose was good. What is the reason behind plugging the booster hose? Should I run it while doing so?

That just takes a potential non–engine related problem out of the root cause analysis matrix.

 

[Malleus]

Check the BLUE wire on the distributor pigtail; that's the ground. Also, check the BLACK wire on the igniter pigtail. Those are the two easy to check failure points.

You need to examine the wires and not just the connectors. Check the terminal connections, as best you can. The connector housings are sealed, so it won't be immediately obvious if there's a terminal–to–wire problem.

I'm not suggesting this is the problem, but I'd want to rule these out before I started worrying about the ECM.

 

[landtank]

Did a smoke test for vacuum leaks. Found and fixed them. My main intake hose was good. What is the reason behind plugging the booster hose? Should I run it while doing so?

I just diagnosed my poor running, hard starting, sometimes no starting situation to a bad booster. Pull off the hose, plug it with a 10mm bolt and try to start the truck. In my case it was a night and day difference and only takes a minute to do.

 

[SammieH]

Check the BLUE wire on the distributor pigtail; that's the ground. Also, check the BLACK wire on the igniter pigtail. Those are the two easy to check failure points.

You need to examine the wires and not just the connectors. Check the terminal connections, as best you can. The connector housings are sealed, so it won't be immediately obvious if there's a terminal–to–wire problem.

I'm not suggesting this is the problem, but I'd want to rule these out before I started worrying about the Ecu

I just checked those connections and they seemed solid. Had good ground on both. I started the truck and it was idling very low(200-400 but didn’t die) as the Ecu was reset. Is this normal? I drove it for a while holding it at 650 at stops. It slowly brought itself back up to a 650 idle and is running well as of now. However the 83 84 85 code came back almost immediately. No other codes. I will keep checking things as I’m sure the issue will return.

 

[Fj80oregon]

A dirty IACV will have these symptoms.

 

[Malleus]

Have you checked the neutral safety switch connector?

 

[SammieH]

A dirty IACV will have these symptoms.

I was planning on pulling everything tonight and cleaning. Not sure how it looks on the inside. I checked the IACV with a meter and it was ohming out high. Around 45-50ohms on a few pins which is above the 10-30 it wants to see. Do you think this is out of range enough to also cause the issue?