Misfire on boost over 5krpm - Single Turbo Setup

Chaps,

Bought the Supra last Saturday, it ran absolutely fine when I first got it apart from the boost hose popping off a couple of times.

Last Sunday, took it for a drive in the evening and it started to misfire on full load over 5krpm through 2nd/3rd/4th - Quite bad spluttering and you could not push through the misfire.

I whipped the plugs out at the start of the week, and they were all very badly dry fouled - Plugs were Denso IK22's, which I believe would be too hot of a heat range for setup specification.

Therefore, I've bought some IK27's, i've just fitted them and taken the car for a Run (A bit hairy in the rain) - However, the problem still lies.

I'm really stumped as I can't understand how when I first collected the car it ran superb, and within the space of 24hours, it's throwing a major wobbler! The only change I can currently think of was putting £20 of Vpower in, as to which, I have not yet added anymore - Nearly on empty so will be refilled and I will try another fuel station.

I've looked at all of the coilpacks and they 'look' in good condition, likewise with the coilpack clips - They are not brittle of broken and wiring looks secure.

The car spec is as follows;

T04Z @ 1.7bar

HKS CAMS & PULLEYS

HKS FCON V pro & HKS EVC

Aeromotive fuel system & fpr - Denso 840cc Injectors by the looks of it

Usual other bits like Trust intercooler, HKS Ti exhaust etc...

Is there a way to check individual coilpack plugs & clips for issues? Could it be something else?

Pics of the removed IK22's

Many thanks for any help,

Harry

Bad news on the misfire bud.. my old single kept doing this and I think it turned out to be dodgy coil packs. The extra power puts more stress on them I think. And if they haven't been replaced in a while it's probably worth doing just to make sure

Does it misfire at the same rpm in each gear? Could be worth checking for errors codes as the ecu might be cutting the ignition to prevent any damage.

Thanks for the advise Lee,

I've just taken it out, she was low on fuel so i've just put £30 Vpower in at a different Shell garage. Let the fuel settle/mix for a fuel miles and tried giving it some beans, asking for trouble in this weather with this power though, need balls of steel and hands of Senna!

From what I can gather, I did manage to get a bit of a run in 2/3/4th even though it was spinning up drastically, but the misfire seems to have dissapeared from the run an hour ago?

Really need to get it out in the Dry to be sure.

Big Supes - It's n not at the exact same RPM every time, it's very hit and miss! When she has misfired though, or you hit the rev limiter (8000rpm in this) The engine management light comes on, then flicks off again. However, a lot of high power supra videos i've seen tend to do the same thing?

Again, any help would be great, but I think a run in the dry is needed to confirm if it was a shit batch of fuel!

When my single was just under a quarter of a tank in fuel it would run like crap. Stuck a full tank in and it didn't happen. I put the full tank in after I changed the coil packs so it was either coil packs or low fuel.

Hope it's just a fuel issue for you bud and not the coil packs

Just taken it out this morning in the dry for a good 20mile run while it was very quiet, I'm still baffled, I took it through 2nd/3rd/4th on Full boost;

1st gear - No issue

2nd Gear - Not really an issue

3rd Gear - Tended to be mis at around 5800rpm +

4th Gear - Started to mis around 6000rpm +

So I believe the issue is load dependant and for how long it's climbing through the rev range, which to me, may point towards ignition breakdown?

The misfire is very noticable, as you hit the RPM thats effected, it ends up backfiring through the load area - Would the ECU be pulling the ignition to prevent damage? Are HKS FCON's up to that?

Surely if it was only one coilpack that was the issue - Only one/two spark plugs would be badly fouled?

Unsure which action to take next - Dyno or Coilpacks...

Change the coipacks mate.

Misfires at higher rpm or higher boost are a sign of faulty coil packs.

I think that may be the best option - Will buy new to prevent buying twice.

Where would be the best place to buy them? I've looked on Whiftbitz but they're £90 each, found some here http://www.daytonagblimited.co.uk/ignition-coils/239-genuine-toyota-supra-ignition-coils-90919-02205-.html for £62... Unsure if they are a reliable source or not though?

Best to bite the bullet and pay for genuine toyota ones. Just so you know there's definitely nothing wrong with them

Think you're all correct chaps,

Just been out to do some more fault finding - reviewed the settings on the boost controller, high was set at 1.7bar , I've gone on the low settings and turned it down to 1bar - did a few pulls, spiked and held 1.1/1.2bar to well into the redline with no misfiring - Pulled like an absolute train!

So I think we've sussed it to be the coilpacks degrading on high boost! Cheers for the help guys! Will buy some new ones when I get paid and let you know the outcome

It'll probably work out cheaper to buy from Denso in the US, Denso make the OE coil packs for Toyota.

http://densoautoparts.com/find-my-part/vehicle-selection

We had a similar issue on dads last year. Bad missfire at 5k rpm but we could power through it, swapped out the superspark coilpacks and fitted a set of brand new OEM coil packs and its been fine ever since.

Why not do proper diagnostics and get a garage with a rolling road to test the coil HT under load?

That was my original idea Chris, unsure of any reputable garages with a set of rollers in the Midlands area....May give my old lecturer a bell see if he'd let me use my old Uni RR.

Next best shout is to get it booked into TDI down south.

It'll probably work out cheaper to buy from Denso in the US, Denso make the OE coil packs for Toyota.

 

http://densoautoparts.com/find-my-part/vehicle-selection

Cheers Nic,

Managed to find some for $450 delivered to the UK - Will get them ordered next week!

Right guys,

I've fitted all new ignition components apart from the igniter pack, the misfire is still present. During the time the vehicle has been off the road, I have rebuilt all of the turbo to inlet pipework with new hoses & clamps, so I can be certain there are no air leaks. So Ignition and Air I believe are okay, which just leaves fuelling.

Symptoms;

Vehicle when up to operating temperature misfires/hesitates after 5k RPM on WOT - Boost appears to make a small difference to symptoms, I have ran it at 1bar - 1.7bar and the issue is still the same, albeit predominantly worse on the higher boost setting, similar feeling to fuel cut on high RPM High Boost and you cannot rev through this hesitation. As soon as you hit the load site whereby by the hesitation begins, the check engine light comes on and stays on, then dissapears upon returning back to normal load conditions.

I am due to be going to Nurburgring on August 12th, so need to get this resolved by then. Are there any reputable dyno's within the Midlands area with a good set of facilities.

I am going to try and obtain the map from the HKS FCON and review its settings.

Many thanks,

TDi North aren't too far away, and there is also Whifbitz south Wales branch.

The igniter packs are a known failure point though, maybe worth seeing if you can borrow one from someone and test it.

Didn't see this until now, have you got a wideband fitted? as it looks to me like the fuelling too rich which can cause a high load misfire, and by the look of your plugs its running quite rich, I would get it on the dyno and have the map checked.

Hi Guys, an interesting thread but struggling with what some of the componets are.?

Ignitor pack.?

Wideband. ?

Also does the NA's have the coil packs.? if no, then why.?

Hi Ricky,

No wideband unfortunately - There's an EGT gauge in the car but that is not hooked up. There is a bung available at the top of the downpipe right after the turbine exhaust housing that looks at though it could cater for a wideband. I think as you say the car may be overfuelling at high RPM. Only problem with having the MAP checked is it's a HKS FCON V Pro on the car, which not many people map I believe? TDI & Abbey at a guess?

Proving to be a bit of a PITA.

Hi Guys, an interesting thread but struggling with what some of the componets are.?

Ignitor pack.?

Wideband. ?

 

Also does the NA's have the coil packs.? if no, then why.?

The TT runs a coil on plug ignition system so coil packs and ignitors etc. are all parts used in the TT ignition.

The NA uses a distributor method of ignition. NA-T's will also work fine with this method as long as it is healthy so don't worry about ignitors etc. for now

A few NA-T guys have done a coil pack conversion as it allows you to install TT cams as well as carrying other benefits. Something I'll definitely be considering one day.

Wideband is an aftermarket gauge setup that measures the o2 to fuel ratio in the exhaust. Again, quite handy for NA-T but not essential

Is there anybody in Derby who would be willing to let me try out their igniter pack on my vehicle?

Have you checked the coilpack connectors? They are notorious for falling to bits and causing bad connections.

All in good condition Ian and in one piece with no broken ends.

Spoken to TDI in Essex - Advised to have a look at the igniter pack, as somebody may of over compensated on the spark dwell on the map to try and hide a misfire which may of come from the coilpacks breaking down. If this solves the issue, then we know it could well be the mapping.

The TT runs a coil on plug ignition system so coil packs and ignitors etc. are all parts used in the TT ignition.

 

The NA uses a distributor method of ignition. NA-T's will also work fine with this method as long as it is healthy so don't worry about ignitors etc. for now

 

A few NA-T guys have done a coil pack conversion as it allows you to install TT cams as well as carrying other benefits. Something I'll definitely be considering one day.

 

Wideband is an aftermarket gauge setup that measures the o2 to fuel ratio in the exhaust. Again, quite handy for NA-T but not essential

Hi Style, Many thanks for a good technical reply. I have had my NA from new 20 years back and it is only now, prior to my impending NA/T conversion with Dr Jekyll in Cardiff that i have taken such a deep interest in these cars, this is a great club with great members.