LPG 100 series and misfire problems

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lionrampant

Joined
Jan 8, 2012
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5
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Folks,

What should the readings for Ignition Timing Advance for #1 cylinder be? I am trying to work my way through some diagnostic info for a misfire. The workshop manual says 5-25 at idle and mine seems to be in that range but then goes up to 40 when running.

Is this normal?

Cheers,

Malcolm.
 
Sorry for being a bit dense guys but I am not sure what you are meaning - I have a UK spec Landcruiser Amazon which I believe is a 100 series so I think this is posted in the right section.

I have a pdf manual from the internet which I believe has given me the correct range at idle but can't find anything to verify the data I am getting from a journey (pulled off the diagnostic port by a launch crecorder).

I am not a particularly mechanically minded person but trying to learn so if I have posted something which looks wrong please let me know in laymans terms.

:cheers:
 
Timing seems normal. If it is misfiring, then it is likely throwing a Check Engine Light code (CEL). Do you have access to a code reader? If not, it is recommended you get one. Doesn't have to be anything fancy.
 
Thanks for the replies. It's a V8 so if it is controlled by the ECM then that is fine. I am wondering whether there is an issue with the ECM at the moment but I'll start another thread about that.
 
Continuing misfire issue and then car dies

Folks,

Me again - having lots of fun posting on my misfire issue (still not solved) and had another issue on the way to the garage to get the car service (including LPG serviced).

Apologies for the length of the post too but I wanted to give as much info as possible.

I have the dreaded P0300 code and a really bad misfire which only seems to come on with the LPG (it was there on petrol but Toyota identified a faulty coil and replaced). It seems to happen strongly below 2000rpm and within the first 30 minutes of a journey. If I am on a long journey it clears up above 2000 rpm (definitely notice it when it kicks down a gear after acceleration) and I can sit a 60 - 70mph with no problems. If I reduce speed it can come and go but seems better the longer the engine has been running.

All coil packs and spark plugs have been replaced but the issue persists.

In the past 2 weeks the car has died twice while moving at 30-40 mph. The engine dies and all the lights come on the dash as though I had just turned the key to the first position when starting the car. Turning off and then on starts the car although it sometimes takes a push of the accelerator to get it going.

After starting there are no issue (and no related CEL codes other than the pre-existing misfire codes) but the car then seems to run perfectly i.e. no misfire occurred in the couple of miles to the garage from where this happened.

All the things to check in the workshop manual for a p0300 code look like they should affect LPG and Petrol apart from injectors which I'll get the garage to check (although I am 99% sure they have checked these before)

So I have a couple of questions:

I have found a thread where TPS and APPS issues seem to have caused a similar failure - can these two sensors be checked or do they need replaced?
Could this be an ECU issue (the LPG ECU does talk to the main ECU)?
If it is can a replacement ECU (or one from another car) just be fitted and away I go or would I need to take it in to Toyota to reprogram (I have been told certain car manufacturers ECUs need to be dealer programmed)
Does an ECU issue fit the engine dying issue?

Any help would be much appreciated as at the moment I am losing trust in the car.

Cheers,

Malcolm.
 
You can keep it all in one thread, keeps people with similar issues from having to look for 3 different threads.

I would look at the propane system. Aftermarket stuff like that can be really dodgy and take fine tuning. The TPS and APPS can both be replaced, but they would throw this own codes and wouldn't be related to a misfire. A replacement ECU can be fitted, but it would require programming the keys and security system to the new ECU.
 
Thanks for merging.

The TPS and APPS issue was reported in this thread as a possible cause of the car dying:

https://forum.ih8mud.com/100-series-cruisers/402506-1999-uzj100-intermittently-drops-dead.html

at post 18 (I realise this won't cause the misfire).

I have it at the LPG specialist that fitted the system and he can't find any issues with it at the moment - but as he hasn't seen an issue like this we are trying to get advice from anyone as to what it could be.

Does the reprogramming of keys and security system require Toyota to do it?

Of the other codes that are turning up it seems like the CATs are gone but it sailed through the emission test. The LPG guys has suggested the misfire might be caused by the failing CATs but I think it is more likely the other way around (from what I have read).

The 02 sensor readings suggest they might be away as the downstream 02 sensors never settle down to a steady reading but keep yoyo-ing the same as the upstream ones.

However, I still can't see this as the cause of the misfire.
 
TPS and APPS failure will cause the truck to go into limp mode. If you replace the ECU you need at least one key with a programmed transponder in order to program more keys. Otherwise to use your keys you'd need Toyota to do it with their laptop.

I don't think the ECU is the problem, they're solid state and either work or don't. I would still guess it's got to be an issue with fuel (propane) delivery into the system.
 
The car didn't go into limp mode - it stopped working. No revs, all lights lit up, no power steering. A problem with fuelling could cause the misfire but why would it make the car die?
 
Well - misfire sorted now. There was an issue with the LPG fuel pressure sensor, the MAF sensor and finally some of the LPG injectors. All diagnosed by a new electronics expert who opened a garage in the village - having been unsuccessfully taking it to others for a year to try and solve.

Next step is to replace the CATs - trying an engine cleaner as suggested by a toyota mech first but not holding out much hope.

Anyone think that I should change the o2 sensors while I am replacing the CATs?

THanks for all the suggestions in the past,

CHeers,

Malcolm.
 
The car is throwing P0420 and P0430 codes. My guess was the misfire was causing the cats to overheat and degrade.

I am going to run it for a few weeks in case the misfire was causing the codes but so far they keep coming back.

I am pretty sure the o2 sensors are working as there are no associated codes and from the live stream data they are changing voltages - just the downstream sensors are moving in a similar way to the upstream ones which would indicate that the cats are gone.

The car has done about 80k miles.
 
lionrampant,
Just wondering what is your mileage per tank of LPG like? Also if you don't mind me asking what is the range per fill up / price? That is a pretty cool conversion.

What year is your truck?
 
Hi Dogdays,

Difficult to tell given the misfire has meant reduced fuel consumption. When running well I think I get around 240-250 miles per fill and around 15 mpg. Costs vary but at the moment I can get LPG locally for 72.3p a litre and have a 75 litre tank.

Wouldn't have bought the cruiser (2003 by the way) unless I had been able to convert it given the cost of petrol. Ironically once I get the cats sorted - or the codes go away - I'll be looking to sell it as I need a bigger vehicle. Large as it is I could do with more room on holidays - kids, dogs, camping equipment - without the need for a trailer. A minibus beckons.

Will be sorry to see it go as it is a great vehicle.
 
lionrampant said:
Hi Dogdays,

Difficult to tell given the misfire has meant reduced fuel consumption. When running well I think I get around 240-250 miles per fill and around 15 mpg. Costs vary but at the moment I can get LPG locally for 72.3p a litre and have a 75 litre tank.

Wouldn't have bought the cruiser (2003 by the way) unless I had been able to convert it given the cost of petrol. Ironically once I get the cats sorted - or the codes go away - I'll be looking to sell it as I need a bigger vehicle. Large as it is I could do with more room on holidays - kids, dogs, camping equipment - without the need for a trailer. A minibus beckons.

Will be sorry to see it go as it is a great vehicle.
Click to expand...

Hi lionrampant

I am facing similar issues with my Land cruiser, I was wondering if you still have the contact details for this mechanic/electrician who fixed it. I have shown my vehicle to many experts and have been suggested as many solutions. Mr. T doesnt wanna touch it. Hence wondering if i can bring it down to the same guy who fixed yours only if you can forward me his details.

Your help would be greatly appreciated.

Regards.
 
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