Jump to content
The mkiv Supra Owners Club

Weird missfire problem...Please help


garetheves

Recommended Posts

I have EXACTLY the same symptoms as yourself. Missfire but a lot more prominent when warm/hot. I had a 12 years of service lexus technician listen to it yesterday. It took him all of 2 seconds to look up and say 'number 3 injectors fooked mate'. :search:

 

Mine deffinately worse with temperature. For about 2-3 mins after turning the car on there is nothing. as soon as the temp creeps up or i start reving the engine then it kicks in.

Link to comment
Share on other sites

  • Replies 161
  • Created
  • Last Reply

Top Posters In This Topic

Mine deffinately worse with temperature. For about 2-3 mins after turning the car on there is nothing. as soon as the temp creeps up or i start reving the engine then it kicks in.

 

I'll let you know if the injector change cures it. :D

Link to comment
Share on other sites

have been going over mine this week and have found one problem, checked both the TP sensors and they were working fine so mved onto the IAC and found one possible cause...

a little while ago i found that the gasket for the IAC, little did i know back then, wasn't on properly and was leaking a little air so i undid the bolts and put it on correctly but my chunky fingers knocked the rubber out and when i put it back i have just confirmed that i put it the WRONG way round, thanks to Ian C for that confirmation.

as to whether thats the whole problem or not i am yet to find out as my luck is running short and TT in the wet is a big chance of disaster real quick. given a clear and dry day i'll take her out and see if the problem persists.

 

 

Rob

Link to comment
Share on other sites

Possibly, is there an easy way to check this or is it just a case of buying a new one and seeing if it makes a difference.

 

 

You could take it out and give it a clean to see if that helps. I have been told to try soaking the end in a bit of lemon juice (concentrate) as a way to clean it, not sure if that works or not though. In the end I just swapped it with a used one I bought that I knew was working.

Link to comment
Share on other sites

hope you get it sorted gaz is the biggest technical thread without a resolution.

 

Haha i know tell me about it. Its booked in at a local tuners for 2 weeks today so if i cant sort it out in the meantime then im hopful they should be able to. Am trying swapping the Ignitor this weekend and maybe the O2 sensor now its been mentioned, see if either of those work.

Link to comment
Share on other sites

You could take it out and give it a clean to see if that helps. I have been told to try soaking the end in a bit of lemon juice (concentrate) as a way to clean it, not sure if that works or not though. In the end I just swapped it with a used one I bought that I knew was working.

 

Cool ill give that a go. cheers.

Link to comment
Share on other sites

So, the cars only exhibit this when its hot, whats the exhaust readings when the cars playing up?

 

I dont have a wideband so cant check afr's, but its definately leaning off. Mine's strange though as its only on 50-60% throttle that it missfires and hesitates. Floor it during the miss and it clears??

Link to comment
Share on other sites

Sounds like a buggered TPS mate, I think they work on a stepper motor variable resistor type thing, so it may be that the signal from it is wrong when its at half throttle.

 

When the engine is cold, The fast idle valve may be compensating for the knackered part of the TPS, which is why its only affected once warmed up.

Link to comment
Share on other sites

Sounds like a buggered TPS mate, I think they work on a stepper motor variable resistor type thing, so it may be that the signal from it is wrong when its at half throttle.

 

When the engine is cold, The fast idle valve may be compensating for the knackered part of the TPS, which is why its only affected once warmed up.

 

Next on the list then. :D Cheers mate.

Link to comment
Share on other sites

i di check the Throttle Position sensors, both butterflies, the one attached to the throttle worked how the diagnostic said it would but i wasn't too happy as it was a series off 10 leds and should move from one end to the other, it did this but very quicklywith hardly any movement of the sensor.

if theres anyone who done this test before, is this what you got or is the sensor too sensitive

Link to comment
Share on other sites

Hmm, everycar I've had cuts out or runs like a bag of shite without the tps plugged in.

 

I am however also aware that if the tps is faulty, the ecu can compensate with other methods although it will still run rough.

 

Check your ecu fault codes, the tps error code should now come on because you disconnected it while the engine was running. This will need to be reset to get rid of the code.

Link to comment
Share on other sites

Ok had a quick check of my Ignitor this afternoon, thanks again for bobbing over Ian. Although a different ignitor didnt cure the problem completely it deffinately changed the "Symptoms" for the better. With mine in it was missing intermittantly on idle and when revs increased sounded like a machine gun going off. Driving like that was bloody awful and it would cut out at lunctions. With the new one in it was the same initially but after about a mile or so it cleared up during "Cruising" speeds, no miss that i could detect at all, didnt cut out at junctions etc. The miss was still there at WOT but not at Idle or "General driving". Got home and when parked and revs applied (ie under no load) there was still a slight miss but a million times better than before.

Swapped mine back in and tried again and the miss was back at idle and sounded like the gun again under revs.

 

Ive therefore concluded (please correct me if im wrong) that it looks like the ignitor could well be on the way out but there is deffinately a secondary problem going on. There was a fair amount of black smoke out of the back and even what looked like unburnt fuel so it may be a fueling issue, but also with it only really happening on WOT could it be a gapping issue with the plugs being new.

 

Any help much appreciated as usual, if i can avoid this having to go to the garage in a weeks time then id prefer it.

 

Cheers, and thanks for being patient. Wonder if ill get an award for longest Technical thread. :)

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Restore formatting

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue. You might also be interested in our Guidelines, Privacy Policy and Terms of Use.