1fz-fe running rough

Submitted: Friday, Jun 13, 2008 at 18:19
ThreadID: 58726 Views:12620 Replies:11 FollowUps:1
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I've had this 80 series for about 3 months, about 2 months ago I had an impco lpg system fitted. So far it has been running great on gas.

Last Friday it started running rough on both gas and petrol, as though it has dropped a cylinder. After a bit of research I realised that you should run colder series spark plugs when running lpg, so I fitted NGK Iridium plugs. Then the engine wouldn't start at all. So I pulled the plugs back out rechecked all the gaps and refitted them, still no start. I put the old plugs back in, still no start. I then called out NRMA who couldn't diagnose it either so the next morning it was towed to the auto electrician.

He worked out the problem as the air flow meter and after having it reconditioned i finally got the car back today. The air flow meter only fixed the problem of it not starting not the rough running. But it is still running rough, the same as it was before I changed the plugs. The auto elec reckoned it was just a coincidence the air flow meter failed while i was changing plugs.

Does anyone have any ideas? It is rough at idle and under acceleration?
Any help would be appreciated.
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Reply By: DIO - Friday, Jun 13, 2008 at 18:50

Friday, Jun 13, 2008 at 18:50
Gee I'd be beating a path back to the LPG installer, after all you've only had it for a couple of months. If the wrong plugs were in it after install, have a go at them about it. Get them to check and hopefully resolve it for you. Good luck with it.
AnswerID: 309722

Reply By: Splits - Friday, Jun 13, 2008 at 20:15

Friday, Jun 13, 2008 at 20:15
I have had gas powered cars since 1988 and have never had to put colder plugs in any of them. The colour of the standard ones has always been normal.

How old are your plug leads? If they are years old then they will probably fail a resistance test and should be replaced. Disturbing them to change the plugs could have made them worse.

I would imagine the car has diagnostic code lights on the dash. They could easily show something so if you can't read them, see if you can find someone who can.

These type of problems are usually electrical and there are a few things that can cause them. If you like working on your car and don't have a workshop manual then get one. You will also need a good quality multimeter of a type that will not damage some of the parts you will have to test. Good ones are usually upwards of $200. The factory manual covering the engine and its electronics is by far the best but a non genuine one will usually do. They will list step by step procedures to trace problems like this. The tests on each individual sensor or circuit are fairly simple.

AnswerID: 309749

Reply By: Stephen M (NSW) - Friday, Jun 13, 2008 at 20:21

Friday, Jun 13, 2008 at 20:21
Could possibly be the valve/valves have become stuck down, more then likely just one and this will cause it to run rough. Common on Toyota vehicles that are fitted with gas and dont have a flash lube kit and/or have not had the valve clearance's checked. My mate was floor controller for 18 years for Toyota and he said unless the vehicle had issues they never checked clearance's although you would have paid for it when getting it serviced by the service manual, I think every 20k is when they should be done. I would be getting it checked asap as the longer you leave it and continue to drive if this is the issue then it will burn it out resulting in bigger dollars thats if that is the probelm. I may be way off. Regards Steve M
AnswerID: 309753

Reply By: newlux - Friday, Jun 13, 2008 at 20:40

Friday, Jun 13, 2008 at 20:40
Thanks for the replies.

I have tried to get in contact with the lpg installer this afternoon, but didn't get a call back before they left for the weekend, so i'll leave that avenue for monday.

The leads are 5mm spiral core leads which look to be in pretty good condition but I will get out the haynes manual in the morning and check the lead resistance. The auto elec also noted that the leads looked good and also the distributor cap and rotor.

I have no idea when and if the valve clearances have been checked, I am running a flash lube kit. After I check the leads I might get the valve clearances checked.

AnswerID: 309760

Reply By: toolman WA - Friday, Jun 13, 2008 at 21:19

Friday, Jun 13, 2008 at 21:19
hi newlex,
can you answer a few questions,
1, is the main gas line copper or a braided nylon?
2, when running rough, the only way to fix it is to go back to gas??
AnswerID: 309768

Reply By: Kiwi & "Mahindra" - Friday, Jun 13, 2008 at 21:51

Friday, Jun 13, 2008 at 21:51
get it tuned to gas...helped our 80 series...
AnswerID: 309779

Reply By: newlux - Friday, Jun 13, 2008 at 21:54

Friday, Jun 13, 2008 at 21:54

I'm not too sure about the main gas line i'll check in the morning. It runs rough on both gas and petrol. I'm going to start with the ignition leads resistance checks in the morning.

AnswerID: 309780

Reply By: toolman WA - Saturday, Jun 14, 2008 at 00:52

Saturday, Jun 14, 2008 at 00:52
when my 80 had the gas fitted , they fitted a rubber/ hore to transfer gas from the tank the the converter. The gas breaks down the rubber and very quickly causes gumming up of the converter and injectors. The vehicle stalled while crossing a h'way with some large oversized 22 wheelers heading my way. This problem took a while toidentif and then more time for the fitters to accept respocibility and fix. Since then copper was fitted and the car runs really well. another point to look out for will be air getting in after the gass is injected. Usually some not so good fitting. Good luck
AnswerID: 309803

Reply By: Debbie_115 - Saturday, Jun 14, 2008 at 07:08

Saturday, Jun 14, 2008 at 07:08
We have had our 80 series on gas for 4 years now and also had the same type of problem a couple of weeks after when we first got it. It wouldn't idle on gas at all and ran like a bucket of you know what on petrol it was also running rich on petrol - easy fix - now excuse my great explanations here but from the air filter there is a pipe that runs to the top of the motor and in that pipe is a black tube - so if the car backfires whilst on gas it blows out there - ours had a hole in it - it now has a beautiful red stubby holder with the bottom taken out and trimmed to fit but has to be a wax type inside and ran like a charm after that! Now there's always a spare stubby holder on hand and we have never had to use it!
AnswerID: 309818

Reply By: Member - Bucky (VIC) - Saturday, Jun 14, 2008 at 10:33

Saturday, Jun 14, 2008 at 10:33
Question.............what do the Gas Specialists recommend you use ??
And what condition is this list in ?

Spark Packs/Distributer cap
Any dead shorts, anywhere, what power is getting to the plug, maybe a broken wire, ( hidden )

Waterproofing, seals ect

Had a Commodore, ( big deal ) but I used to run Bosch HR7DCY , gr8 plugs

Now we have Platnimum ect,,,,so high quality plugs will pay for themselves

Cheers Mate

AnswerID: 309862

Reply By: newlux - Saturday, Jun 14, 2008 at 18:02

Saturday, Jun 14, 2008 at 18:02
I've been going over truck today with a multimeter and everything seems to be o.k.

The plugs are new, I have done resistance checks on the leads, the distributor, the primary and secondary resistance of the coil pack, the pick up coil, and everything is within the limits as outlined in the haynes manual.

One of the lead seals does not clip in tightly onto the rocker cover and another of the seals is starting to break up, but apart from this the leads are in good condition. Could this be causing the problem.

I cleaned a up a little bit of corrosion on the rotor and distributor cap contactors, but the car is still running rough. It is rough at idle and under moderate acceleration. If accelerating hard it will cough for a few seconds and then smooth out.

Ant ideas?

AnswerID: 309956

Follow Up By: Debbie_115 - Sunday, Jun 15, 2008 at 21:11

Sunday, Jun 15, 2008 at 21:11
Hubby now home and after my great explanations in past reply (no. 9 I think) he says its the air intake pipe directly above the rocker cover there should be a foam rubber sock on the air intake - check for holes and wear because ours had similar problems and it had a hole which once replaced fixed the problem. And as said in early reply stubby holder fixed it!
FollowupID: 576235

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