Help Supra Missing

[yby]

Hi all, Got a wee problem here. My brothers has a Mk3 2.5 TT R Supra and has just developed a miss at 1500+rpm. It only happens when the car is warm (eg sitting in traffic). Once the car is running on the road its fine. As soon as he gets stuck in traffic or is sitting still the miss comes back. It seems to be all 6 cylinders.

Car boosts fine, runs perfect when cold and idle's perfect when warm. Engine sounds perfect (no noises or rattles).

But every so often it will miss when you accelerate it or it will try to stall.

Any ideas guys?

Any info appreciated as the car is becoming undriveable.

Cheers

yby

[Leeky]

I always say the first thing to do when an engine acts strange is to reset your ECU(EFI).

Simply remove the fuse for 15secs to reset the computer back to the factory default.

It may not be anything to do with the ECU but at least you rule it out by doing this.

[yby]

Good advice alright but I've already tried this one with no effect.

I've also replaced the plugs, fuel filter but its still there..............

You can burry the throttle and the car won't rev above 3000rpm. It misses for several seconds then suddenly clears and you're on the rev limiter.

Any other ideas?

[adi]

Are you getting any engine codes?

Could be various things.... the 1JZ engine is heavily reliant on temp feedback from the engine from various sensors.. if one of yours isnt operating correctly it may not be getting into the correct fuelling mode causing the misfire.

Other than that its normally plugs... missing on boost (which is effectively what yours is doing) is normally down to fouled plugs.. if youve changed these though (with the correct grade i hope, and gapped to 0.8) then you can eliminate them. You could try running a cooler plug as this may help.. it depends what boost youre running.

[yby]

No ECU warning light is displayed so I assume there are fault no codes (is this correct?) or should I check?

Its missing sometimes before it comes on boost i.e. when in the garage @ 1500rpm. And its all 6 cylinders too.

The plugs are the same as what he's always used and they are gapped to 0.8mm.

[Tercel GTS - DirtWeed]

checked for vacuum leaks? when the metal warms it may open a crack, boost may be over riding it

[adi]

It could be many things.. this is going to be a hard one. As tercel says it could be a vacuum pipe, or an electrical issue, mechanical fuelling prob or a faulty MAP sensor.. anything really. You really need to get it on the dyno to find out whats going on.

All six plugs missing are suggesting a fuelling prob, which may point to vacuum probs or ECU backing off the fuel for some reason.

[Leeky]

Have you checked your Battery out? are you getting a full voltage?

Also i agree now with adi, sounds like a fuel problem. Maybe the fuel pump is stalling.

[adi]

or the ignition of course :D could be loads of things..

[yby]

Cheers guy's. I'll let you know what I find (if anything).

[yby]

Does anyone in the UK or Ireland do engine diagnostics for Jap imports? (1JZ-GTE)

Looks like I'll need outside assistance as its a needle in a hay stack to find this fault.

[adi]

Where are you based?

[yby]

Northern Ireland.

[adi]

hmmm

in that case no i dont know of anyone.. UK yes Ireland no. Sorry. Any good tuner that deals with high power engines such as the JZ series, or RB26 etc should be able to help you out. Dont go to the average hot hatch tuner like perhaps a cossie tuner as they simply wont know a thing about the engine.

[yby]

Not being cheaky but Northen Ireland is the UK. :D

I take it you mean UK Mainland? I wanna take the worst case scenero. Whats my options on the Mainland? Or even Scotland? Scotland might be easier (cheaper to get to). If there is someone who knows the engine it might be worth the trip.

[adi]

oops yep sorry :D force of habit when talking on US supra forums...

Anyway.. i dont know anyone in scotland.. i do know of someone near the top of the welsh border who is *very* good but can be expensive. He owned a 1JZ soarer and has worked on my 2.5tt a couple of times.. he knows the JZ engines well. his website is at this place

Or theres a couple of places in the South/London area..

Im sure you can find someone closer to home though.. try asking on the performance forums such as GTROC, mkivsupra.net, SXOC etc to see if theres anyone near you who can help.

It sounds like your problem is a simple fix, but finding it is the difficult part.. you could come all this way and then find out its just a broken coil or something..

good luck with it..

[yby]

With the cooler days the fault has dissappeared. He's replacing the Air inlet temp sensor but I suspect we won't see the miss fire again until next summers heat wave.

Cheers for the help guys!

yby