**Resolved** 1FZ-FE poor cold starts and wont idle (4 Viewers)

[robnicko]

possible that its trying to run on both fuels at the same time. Try shutting the valve on the LPG tank and start on LPG to drain residual LPG in the lines. Then switch to Petrol and see how it goes

 

[petegangies]

possible that its trying to run on both fuels at the same time. Try shutting the valve on the LPG tank and start on LPG to drain residual LPG in the lines. Then switch to Petrol and see how it goes

the LPG tank was empty and it was still doing this. I only filled up 15L of LPG on the weekend to get the car back home. Had to limp to the nearest service station on petrol. The gas mechanic that's receiving the car this weekend can definitely test all that out though.

 

[petegangies]

the mechanic has replaced the fuel filter (no change to vehicle running). He's also removed the valve cover to check the clearances, and said they were too tight, so is having those done this weekend, while at the same time replacing the spark plug tube seals and valve cover gasket which were all weeping slightly. The valve clearances are unlikely to solve this issue though, given the car runs ok on LPG. I still think there's a very good chance the issue is electrical and stemming from when the main wiring loom was replaced with a second hand unit and modified to suit. I still suspect that it hasn't been wired up correctly and the ecu is getting bung signals, causing the vehicle to run rich. Also, before it stopped running on petrol, I had replaced the engine coolant temp sensor with a brand new genuine unit. It drove home fine that day, but the next time I drove it, it started playing up pretty badly, whether hot or cold. Still not CEL light to date.

Things replaced so far:

- VAF meter x 3 (none of them made any difference)
- spark plugs (checked gap 3 times)
- new leads
- distributor cap + rotor
- checked and verified TDC with timing mark (timing wont lock in diagnostic mode)
- timing set to 9 degrees (won't run at all near factory 3 deg btc)
- fuel filter
- fuel pressure regulator
- checked for vacuum leaks and replaced some hoses
- by-passed charcoal cannister (no change)
- swapped ecu's
- pro grade fuel system cleaner run through tank
- fuel pump was replaced back in 2021
- o2 sensor was replaced back in 2020
- exhaust leak at downpipe fixed
- cleaned throttle body
- cleaned IACV (it was very clean though tbh)
- cooling system flush (new thermostat + new rad cap)
- new battery

all parts are genuine Toyota. Vehicle has only travelled 152,000kms.

Not sure if maybe TPS needs recalibrating (never been touched).

If the mechanic can't work it out without needing to spend bulk hours of diagnostic time, then it will have to go to an auto electrician next to retrace every wire from the loom to ecu and check how they re-integrated the LPG computer/system (the original auto electrician my dad used had no LPG experience).

I'll also get him to do a compression/cylinder leak down test, though motor sounds healthy, and doesn't use any oil.

Will keep this thread updated with any developments.

 

[petegangies]

Update from my mechanic..

• The valve shims – all exhaust valve were way too tight – the smallest feeler gauge only just managed to slide through on some.
• Inlet valves were tight as well – swapped most on the exhaust shims to the inlet side to get the required valve clearance and sourced new shims for the exhaust side – Needed to remove camshaft as too difficult to get #6 shims out by the normal method.
• Fuel pressure tests ok – new fuel filter fitted (old one was slightly dirty)
• Found that the EFI fuse was starting to overheat and slightly distorted. Fuse was the wrong amperage – was a 10amp, should be 15amp.
• Connected electrajet test equipment and found that idle switch contact wasn’t closing – has now been adjusted
• No visible water leaks apart form a minor seepage at one heater / converter hose connector – tightened – held pressure for over 3 days

What needs to be done now:

• Recheck base ignition timing
• Have checked at the ECU that bridging E1 and TE1 is seeing the signal on Electrajet – so hoping now that when terminal bridging and the fact the idle switch is now working it will go into setting modes to adust base timing.
• Set Air/fuel mixtures on both petrol and LPG

Final comments:
Vehicle is starting well and test driven and going much better, and should be finished by this weekend if all goes to plan.

It's now quite clear that I would have never been able to sort this myself given my ability and level of experience/knowledge/lack of specialised equipment. Very excited to see how it drives following these repairs and all the other work I've put in over the last 18 months.

I will do a final update when I receive the car back.

 

[petegangies]

Ok, I picked up the rig over the weekend, and can happily report that she's driving the best she's driven in the last 20 years. All valve clearances are sorted, tappet cover gasket and spark plug tube seals replaced. The AFM was fitted with an adjustment screw and fuel trims and ignition timing were set using a wideband sensor to monitor AFR's. Since the idle control switch and TPS were adjusted, and the EFI fuse replaced with the correct amperage, it would now allow it to lock in diagnostic mode and set the base timing properly (which I couldn't do). The old fuel filter when backwashed was dirty... not horrible, but definitely was due for a change! He's also tuned the LPG, so it's running great on both fuels. It's like a new car, my previous slug now has a bit of pep. The exhaust leak I fixed, seems to be holding too. After the last 18 or so months of work, it's finally great to see it all start to come together.

I now need to focus on removing old and redundant electronic accessories and wiring. Under the dash and behind the glovebox are a complete mess and frankenstein of wiring. I will do this work myself slowly over the next few months on free weekends.

Finally, I will be treating her to a full detail, courtesy of me. Every nook and cranny, inside and out, full cut and polish and ceramic coating, including repainting parts of the underbody all fresh black. I will do this myself and chip away at it over a few weekends in the months to come. Pics to come later once she's all done.

Thanks everyone for your advice, guidance and mainly just support, while I navigated these tricky and challenging fixes and diagnostics.

Special thanks to @Malleus, @mudgudgeon, @robnicko and @ppc — I really appreciate your help and patience! What a wonderful community, that brought back memories of car forums back in the mid 2000s—a dying breed since Facebook groups became a thing.

I hope some of the information in this thread helps someone else down the track, when they're troubleshooting their 80.

Cheers,
Pete

 

[mudgudgeon]

Ok, I picked up the rig over the weekend, and can happily report that she's driving the best she's driven in the last 20 years. All valve clearances are sorted, tappet cover gasket and spark plug tube seals replaced. The AFM was fitted with an adjustment screw and fuel trims and ignition timing were set using a wideband sensor to monitor AFR's. Since the idle control switch and TPS were adjusted, and the EFI fuse replaced with the correct amperage, it would now allow it to lock in diagnostic mode and set the base timing properly (which I couldn't do). The old fuel filter when backwashed was dirty... not horrible, but definitely was due for a change! He's also tuned the LPG, so it's running great on both fuels. It's like a new car, my previous slug now has a bit of pep. The exhaust leak I fixed, seems to be holding too. After the last 18 or so months of work, it's finally great to see it all start to come together.

I now need to focus on removing old and redundant electronic accessories and wiring. Under the dash and behind the glovebox are a complete mess and frankenstein of wiring. I will do this work myself slowly over the next few months on free weekends.

Finally, I will be treating her to a full detail, courtesy of me. Every nook and cranny, inside and out, full cut and polish and ceramic coating, including repainting parts of the underbody all fresh black. I will do this myself and chip away at it over a few weekends in the months to come. Pics to come later once she's all done.

Thanks everyone for your advice, guidance and mainly just support, while I navigated these tricky and challenging fixes and diagnostics.

Special thanks to @Malleus, @mudgudgeon, @robnicko and @ppc — I really appreciate your help and patience! What a wonderful community, that brought back memories of car forums back in the mid 2000s—a dying breed since Facebook groups became a thing.

I hope some of the information in this thread helps someone else down the track, when they're troubleshooting their 80.

Cheers,
Pete

That's great Pete. Hope you get to enjoy driving it now.

Sounds like your mechanic is switched on

 

[Malleus]

Great news, Pete!

More details on the AFM when you have a minute.

 

[robnicko]

Nice to hear you have it sorted out now Pete!!

enjoy the drive now

 

[petegangies]

Great news, Pete!

More details on the AFM when you have a minute.

I didn’t go into great detail about it with the mechanic, but essentially, you replace the metal stud located in the hole on the air flow meter with a screw, which I believe allows you to adjust the spring tension on the cog—this, in turn, affects the fuel trims. I’ve seen people adjust this on similar Toyota air flow meters on YouTube as well, usually by removing the black cap on the face and jumping the cog.

However, the method my mechanic used was simply to replace the metal stud with a screw. I rang my contact at the local Toyota dealership, and he confirmed that they do this as well—but not on all vehicles. Apparently, the workshop manager is the only person there who knows about it. He even tuned the parts dealer’s air flow meter using the exact same method.

This kind of adjustment should only be done when using a wideband sensor to monitor the air–fuel ratios after making changes.

I'm now running 10 degrees of timing with the correct fuel to ensure it's safe. LPG can take much higher timing, but I needed to strike the balance for both fuels otherwise it would ping on petrol.

Here are some pictures of what I’m talking about…

 

[Malleus]

Good stuff. Thanks Pete, and congratulations on getting the truck in shape again. It's always nice to save one from the scrap heap, and yours is especially sweet, given its provenance.

 

[petegangies]

Good stuff. Thanks Pete, and congratulations on getting the truck in shape again. It's always nice to save one from the scrap heap, and yours is especially sweet, given its provenance.

Thanks Fred... I only wish Dad were here to have driven it like this. He loved this car more than anything—he would have been chuffed.

Photo from when we stitched him up at a Lake renowned for people getting bogged on the bank. Instead of locking the diffs, we told him to just "floor it"...

Good times, and good memories! He'll be looking down and proud that I've kept the legacy going.