missfire gone with spark plug change but back a week later?

[mellonman]

Having a pain of a misfire on my supra at the moment , seems to be one cylinder only on boost .I changed the coil packs with some spares but cant 100% say they are perfict ,but I did check them for leaking spark on the housing and jump distance which seemed fine . still had the misfire so I got a new set of plugs as they where due a change , car run the best it had in years I was surprised of the change so the car was happy for a week but the miss is now back again.

odd thing is the afr's with the miss still seem to be at 11.2 which don't seem to point to a spark more a injector.

any thoughts anyone ?

anyone willing to lend me a set of coil packs to test for 10minutes just to prove.

Dartford / bluewater area

[Mike2JZ]

Got loads of spare coil packs you can try.

 

Is it happening at low boost/high boost or all the time?

[Mk4Gaz]

My misfire ended up being two boost leaks gaz, it might be worth checking all of your vac lines, just in case.

 

But, I also have two sets of oem coil packs (used), that you're welcome to try

 

 

[mellonman]

Thank you the response guys.

Seems to be through the rev range from 4000 onwards.not had a miss like this before its like a complete lose of a cylinder very clear .

Very few vac pipes on my single to check to be fair gaz . The one I would be worried about would be to the piggy back and I had checked that .

Mike that's a good point I will check at wastegate boost and if it's the same

Mike you still at the same place ? Think I remember you saying you have moved

Gaz where abouts in Essex are you mate ?

[Mike2JZ]

Thank you the response guys.

Seems to be through the rev range from 4000 onwards.not had a miss like this before its like a complete lose of a cylinder very clear .

Very few vac pipes on my single to check to be fair gaz . The one I would be worried about would be to the piggy back and I had checked that .

Mike that's a good point I will check at wastegate boost and if it's the same

Mike you still at the same place ? Think I remember you saying you have moved

Gaz where abouts in Essex are you mate ?

 

I'm about 10 minutes down the road from the last place you visited. Let me know if you want to come down and ill shoot you a postcode

 

Also what spark plugs, and spark plug gaps are you running?

[mellonman]

Went with the NGK BKR7EIX didn't adjust the gap as they are iridium. These are the same as I have had previously but they did have a new marking after the code . I'm pretty sure it's not the plugs as it's the same fault as before the plug change

That's ok then might have to take a trip down to you mate and have a borrow of your coils.

[Style]

I'm getting the same sort of thing so I'm interested to see how you get on dude. I changed plugs and there wasn't much difference. My cam cover seals had gone as well which I've now cleaned up and fixed. That helped things but I'm still getting the misfire at the top of 3rd gear onwards. Pretty sure I've got a vacuum leak somewhere as the idle hunts quite a bit when cold.

[Mk4Gaz]

I'm near Southend bud, just past Rayleigh. But I'll be in South Woodham Ferrers on Saturday at my workshop

 

 

[mellonman]

just a quick update on this went to check the low boost to see if i still had a issue and its fine upto 0.7 bar anything over i get a miss, when i went to start the car cold it was running on 5 so i could pin point what cylinder which is 6,i swapped the coil still the same so checked the injector plug still the same but when i clicked the plug on the injector it cleared , so this is looking like a sticking no6 injector possibly .

[mellonman]

another update cold start still on 5 for a short time today I expected it today so had bonnet up and was tapping the injector on 6 its missing on and it didn't change unplugged it no change moved the stock loom made a difference moved it again went back to 5 , the went on all 6 but still had fault on boost bloody thing is doing my head in , tomorrows quest listen to the injector when cold start miss fire is happening with a long screwdriver.

 

another note to add

just tried a different igniter same fault

Edited October 9, 2018 by mellonman (see edit history)

[j_jza80]

Pull the affected sparkplug out, it's condition may indicate your issue.

 

Also, have uou replaced your coilpack connectors? These are a common fault.

 

Failing that, i think my first move woukd be a compression check, followed by getting your injector tested.

[mellonman]

good point tonight I will pull the plug out straight away if its running on 5 again to see if its wet and read it .I will also have at the ready a spark plug and coil to see if its getting a signal,a injector to see if thats getting a signal.

coil clips are maybe 5 years old but in good condition , compression is good as its running sweet upto 0.7 bar . a sticking valve could be though

[mellonman]

well it started fine for the last couple of days , today I cable tied my phone under the bonnet and done some runs to see whats happening with the fuel pressure which looks to be ok so not pump related , im going to bite the bullet I think and take the intake off and make a rig to test for injector discrepancies.

[mellonman]

ok time for a update with this with resolution, After mike2JZ kind offer of lending me so coil packs to test my car and try and resolve the misfire I thought it was best to go visit him at Hidden performance where we went through my coil packs with the spares that mike had at his work shop , replacing all the leaking coils the car still had a misfire , being it was the simplest of things to do it had to be done first, but mike didn't want to leave it there he wanted to get it sorted, I did have my suppressions of a bad injector so it was on the cards to swap the suspected injector out with a spare I had , mike said lets do a compression test just to prove the mechanicals of the car which was the obvious choice to make to know we was working from a good starting point . compression come back with good results all with 185 excepts 5 with 175 which i knew was down from my last compression years ago. mike and I decided to remove the throttle body and intake just to get at the suspect injector. once we replaced the injector the car run sweet as can be , and after a race challenge mike the supra got a good work out with no faults miss or anything bad to report back .

so thank you mike for your time on a sunday dragging you away from other things to help me out , there are more people like you needed in this club with your knowledge and helpfulness

[mellonman]

another update

misfire is coming back car started the other day on 5 again for a couple of seconds thought what ? no way ? but drove fine . today started on 5 again but didn't clear so quick when on full boost could hear the miss again and feel it later on in the drive .

I will disconnect the battery and see if it makes any difference as this is weird how it works fine for a week then slowly comes back.

if no joy will try see if its the same cylinder on the start up if it is will rewire the injectors pain the butt .

[Mike2JZ]

another update

misfire is coming back car started the other day on 5 again for a couple of seconds thought what ? no way ? but drove fine . today started on 5 again but didn't clear so quick when on full boost could hear the miss again and feel it later on in the drive .

I will disconnect the battery and see if it makes any difference as this is weird how it works fine for a week then slowly comes back.

if no joy will try see if its the same cylinder on the start up if it is will rewire the injectors pain the butt .

 

is it on the same cylinder again or has another injector shit the bed

[mellonman]

could be another injector seems the same as it started before not sure yet mate was the first time it misfired while driving tonight , but as it does the 5 cylinder thing when starting I can assume that its that cylinder that's giving me problems , so when I start it tomorrow will be at the ready to pull the injector plug to find out what cylinder, could be with what we done taking the intake off moved a bad connection in the loom ? odd fault I must admit which would point to a wiring degrading issue in my experience but they are always the worst to find when so intermittent.

to be expected with such a old car / wiring with many heat cycles

[mellonman]

so this misfire continues , today I swapped out all the injectors cleaned and fitted the best ones I had out of the 12 I have got still the same , one thing im noticing is the car runs good for a while then goes bad after a 15minute drive with booting it , noticed this the most the other day when I was clearly running with bad misfire , swapped coils to pin point but still the same , pulled off injector plugs to try and pin point but its not as bad as a full dead injector and couldn't tell a difference between cylinders was still worse when getting boost, unplugged the battery for half hour then it was running with hardly a misfire .

starting to think that the aem fic is playing up as I don't get a error code from the stock ecu.

think it might be time to get it to somewhere with a rolling road to test this fault

[mike33]

Hello matey mine was also at 4000 revs and I thought it was pipes or ssv valve but it turned out as I had had enough of it of trial and error I took it to srd and on there diagnostic system it was running lean at 4000 rpm and it was the fuel pump was knackered! But when they took it out of the fuel tank you could see it was falling to bits and covered in rust! Luckily I had another new one at home!

[mellonman]

Ok just a update on this misfire sorted swapped out the iridium plugs with new copper type and boom misfire gone . I can only guess that the bad injector failed the plug or I got a duff set.