- Thread starter
- #41
They are always really hot…but I thought the CEL would cut out which would be a sign that EFI Relay is getting baked…my CEL always lights up…
What’s the solve for this heat wrap?
‘93 FZ80 Engine shuts down randomly only after it’s warmed up… (1 Viewer)
- Thread starter Nbndallastx
- Start date
This site may earn a commission from merchant affiliate
links, including eBay, Amazon, Skimlinks, and others.
What’s the solve for this heat wrap?
I have 2 VAF's. One I need the other was for backup. They both work. I will send it out if no one else has one closer. I think your high idle is one of the contributors to the engine dying.
The high RPM could be advanced timing, an air leak, IAC, or TPS setting. The air leak presents as un-metered air getting past the VAF. This usually presents as a fast idle. Or the throttle body base idle screw setting is not correct.
If your intake tube has no cracks or leaks. loosen the TPS screws just enough to move it by hand (BTW: TPS can have dead spots as well, same moving arm on copper contact). Start the rig, and rotate the TPS until the idle settles at 650 +/- 50. I do not think I have ever been able to set the TPS correctly...If the TPS is on the edge of it's contact patch it will also kill the engine as RPM's dip.
The high RPM could be advanced timing, an air leak, IAC, or TPS setting. The air leak presents as un-metered air getting past the VAF. This usually presents as a fast idle. Or the throttle body base idle screw setting is not correct.
If your intake tube has no cracks or leaks. loosen the TPS screws just enough to move it by hand (BTW: TPS can have dead spots as well, same moving arm on copper contact). Start the rig, and rotate the TPS until the idle settles at 650 +/- 50. I do not think I have ever been able to set the TPS correctly...If the TPS is on the edge of it's contact patch it will also kill the engine as RPM's dip.
- Thread starter
- #43
I really appreciate the offer in the VAF…I’ll keep you updated!
My intake hose is brand new and OEM so it’s nice with no cracks.
I’ll try out the TPS adjustment first and then double check my IAC again…
I have a new OEM TPS that just arrived…should I throw it on just too see what happens?
Install the new one. Just so you don't have to do it twice.
If I take the condition of the ECT in to account. Install the new one. Follow the install steps, if the idle does not fall back to 650 +/- rotate the TPS slightly to see if you can get to 650rpms +/-. The curious thing is, the IAC should take over the idle control... Your almost there...
If I take the condition of the ECT in to account. Install the new one. Follow the install steps, if the idle does not fall back to 650 +/- rotate the TPS slightly to see if you can get to 650rpms +/-. The curious thing is, the IAC should take over the idle control... Your almost there...
Keep in mind that if the battery gets disconnected during any of this maintenance, the ecu has to relearn the idle speed and that take several start cycles. This info is printed in the FSM.
This would seem to go along with warming up and quiting,, so baldi is on to something I think?
How about starting with the basics before using the parts cannon.
During a no-start are you getting spark?
During a no-start are you getting fuel?
During a no-start are you getting spark?
During a no-start are you getting fuel?
- Thread starter
- #49
I replaced the cable months ago with a new OEM
- Thread starter
- #50
Confirming we have spark and fuel during no-start…albeit tough cuz each time I open the hood it restarts much quicker…
- Thread starter
- #51
Ok team…some updates…went back through the troubleshooting guide to attack components that involved my high idle and engine stall (mentioned by someone) from earlier and I was doubting my IAC testing from last week.
Well pulled the IAC and S1 to S3 failed the test per FSM at 42.8ohms….all the others passed between 10-30ohms.
So per the FSM it means to replace right?!
Well pulled the IAC and S1 to S3 failed the test per FSM at 42.8ohms….all the others passed between 10-30ohms.
So per the FSM it means to replace right?!
- Thread starter
- #52
Also here’s another video of after testing, then cleaning, and reinstalled the IAC…idle is way lower…lowest idle ive ever hear on this rig. Then slowly dies lightly…still might be the VAF per FSM troubleshooting guide but need to rule out the IAC first.
Anyone in central texas have an good IAC for ‘93-‘94 FZJ80 I can borrow before blowing $$$ on a new one?
I’ve recently been chasing a similar issue with my 96. It only happens after it warms up and then either while driving or trying to start after it’s been warm she acts like yours. I’ve gone through the fuel system and checked all the sensors and I also know it’s getting spark. I have landed on it being a wiring issue up against the firewall. I don’t see any wires fraying, and I also have had my harness heat guarded for the past couple years while also having the EGR disabled. But after being stranded twice yesterday, I finally figured out poking around the engine bay that if I wiggle the harness in the right way, it’ll restart totally fine. And the same thing when I was on the road when it would randomly die I pull over adjust the harness a little bit and it would restart totally fine. Instead of going through and trying to repair the brittle harness I ended up just ordering a new a whole new wiring harness. I’m going to install it this weekend as all my connectors are brittle and gross and I figure while they still make the full wiring harness it’s not a bad thing to check off the bucket list. I encourage you next time it does this to get out and wiggle the wires by the firewall and see if that changes anything. Unfortunately I don’t think they make the harness anymore for the OBD1 trucks but who knows maybe you could find one.
Cheers
Why? It's holding approximately the correct idle until something kills the engine. Why would something suddenly spam the IAC with signals to close it? It's not like it's spring-loaded and just going to slam one way or the other. It's a stepper motor.
I would be testing fuel pressure with a gauge on the injector rail and looking for fried wiring near the EGR valve.
The TPS needs to be set by, if I recall correctly, putting a feeler gauge somewhere and rotating the TPS until your multimeter deflects.
- Thread starter
- #55
but didn't my IAC fail its terminal test per the FSM?
S1-S3 was 42.8ohms...which is outside the 10-30ohms tolerance...reference pic a few posts up...
The FSM says to replace it if any are outside the range...i guess i'm confused why you think i shouldn't look at the IAC if it failed its bench test?
Do whatever you want, man. Personally, I would start with the free tests of much more common failure points before throwing money at a discontinued part.
- Thread starter
- #57
That’s why I posted looking to borrow one…
- Thread starter
- #58
After I exhaust all the sensor testing this is probably the only thing left
Understand that you are reading across coils in a stepper motor. Coils will open or short. It is extremely unlikely that they will slightly increase in resistance. I'd be willing to bet that the ISC is just fine.
You can also test it with a 9 volt battery pretty easily. This is explained in the FSM.
You can also test it with a 9 volt battery pretty easily. This is explained in the FSM.
It is good to see your idle back were it should be (check).
I do not remember all your posts. Did your rig die at idle or while driving at speed as well?
The VAF sends a fuel pump on when air is pulled into the engine. The flapper opens and turns on the fuel pump via the "Circuit Open relay". Please swap the Circuit open relay. I think at least 2 of the same relay. So just swap them around. They are in the driver foot well.
No change, go for the TPS adjustment or install your new one.
I do not remember all your posts. Did your rig die at idle or while driving at speed as well?
The VAF sends a fuel pump on when air is pulled into the engine. The flapper opens and turns on the fuel pump via the "Circuit Open relay". Please swap the Circuit open relay. I think at least 2 of the same relay. So just swap them around. They are in the driver foot well.
No change, go for the TPS adjustment or install your new one.
