Misfiring Bnr32 All Through The Rev Range

[Yawn]

Hey guys well i had this misfiring problem start along with idling problems when i changed my turbos,ecu, injectors etc about 8 months ago.

I figured it was to do with the tune or something so I had it brought back to the same workshop about 5 times and sometimes it improved a bit or even got worse at times but never totally disappeared.

I tried Racepace since everyone swears by Ben's work and had him diagnose the whole thing. Turns out the injector loom was falling apart and just by shaking it a bit whole cylinders would shut down. Had him make up a new one and a retune which left me with a hefty bill. Also, turns out that the MAP sensors were hooked up slightly wrong so I had him fix that too (i run a pfc djetro), which was probably to do with the tune not being able to be sorted out from the beginning.

It was running great for a week or 2 until a few days ago where it would just turn into a Scooby after about 15-20 mins of driving, no matter what rev range im in. Even happens on idle. I figured it was the plugs since they havent been changed since before Ben had a look at it and the tune was rather rich before so i reckon they might be fouled.

Today i took em out and chucked a set of NGK platinums in since my mechanic friend had a spare set lying around. It was gapped to 0.11mm and without checking we chucked em in and went for a test drive. It then was fine in the low rpms but would misfire high up. So we took em out, found out they were 0.11 and regapped em to 0.08mm. It then ran fine for like 20 minutes and i drove home.

Halfway through the journey it started again and wouldnt go away. Reached home and went for dinner and came back to start the car and it was fine again.

Also, i might add, with the old plugs which were cheap mismatched coppers (gapped to 0.08mm), I went to a track day and it would go great for like 5 laps and then it would start misfiring. I would let it cooldown for like an hour or so and start it up and it would go good for another 5 laps then happen again.

What does that point to? Im running roughly 315rwkw btw.

I have had a read of all the misfiring threads on SAU and ive come up with several possible conclusions:

1. Unsuitable heat rating? Thus the misfiring only happening after a certain period of driving?

2. Cracked coilpacks? Even if i dont see any hairline cracks can i just wrap everything up in electrical tape?

3. Need a smaller gap since running considerably more power than stock and maybe not enough spark?

4. Coilpacks leads loose? thus leading to misfiring throughout the whole rev range no matter what i do?

This is really a pain in the neck and its one of the remaining problems in my car that I just havent been able to iron out even after having so many people look at it. Someone please help, i cant seem to get it to run reliably and smoothly even after having spent a ton. Argh

Edited March 31, 2007 by Yawn

[sky-017]

check coil packs for hairline cracks, you dont need to tape them if their isnt any . you obvioulsy need a lower gap considering your running that much power.also weather is changing , might want to check up on heat rating

Edited March 31, 2007 by sky-017

[Yawn]

check coil packs for hairline cracks, you dont need to tape them if their isnt any . you obvioulsy need a lower gap considering your running that much power.

Hmm, how much lower? 0.06mm lowest? Im just wondering if it was such as obvious thing to do why no mechanics thought of regapping the plugs when they had a look at my car?

Would taping the coilpacks up work as sort of a preventive measure to future hairline cracks?

Thanks for the input

[Yawn]

Update on this, took the car out for a spin. Didnt happen this time after about 20 minutes of driving at normal operating temperature.

How does this happen on the highway at normal operating temperature (ie. earlier on in the day) but not now?

The oil/water temperature between the two times out were exactly the same. But it seems the longer i drive it the more likely it will happen. The thing is, it never happens on cold start or within the first 10 minutes of driving throughout the whole 8 months so it is likely to be temperature related im guessing, maybe the temperature of the spark plugs themselves after working for a while?

To elaborate on when it happened on the highway, I was just cruising at 100 in 5th gear with a constant throttle application and out of nowhere it started. Its doing my head in!!

[gillies2001]

Hi, I had the same thing (15 minutes starts missing) Over about 2 months I changed most things, turned out to be the POWER TRANSISTOR (coil pack igniter) I opened the back (with side cutters) of the P.T and found one of the input fine wires had come adrift. It was like a bimetal strip (broke contact when hot) I cleared away the goo and soldered the wire. WORKS PERFECT

[heller44]

Another quick check for coil casing issues is to remove your coil cover, go for a drive when it is dark to warm everything up, then pop the bonnet and look around the base of the coils whilst the engine is running and everything is dark.

Even at idle I could see blue arcs around 4 of my coils.

If nothing then follow gillies2001 advice and try a replacement ignitor pack.

Just something to try.

James.

ps. also make sure you have a good earth to the ignitor pack. The original earth can get a bit dodgy and play up.

Edited April 1, 2007 by heller44

[brother_david]

I've got the very same problem but with an ECR33, the car runs great in the first say 15-20 mins of driving, then starts to misfire more and more the longer i drive. The misfiring seems to occure above 4-4500 rpm.

Went for a 3+3 hour drive yesterday (3hours in the morning going to an event, 3 hours returning home). The last tries to reach above 4000 rpm resulted in a very fast, constant misfiring.

[Keeper]

coil packs + tape is a great idea to help cut down a possibility,

another idea is the O2 sensor(s) could be kaput and making the car run too rich and fowl plugs?

[MANWHORE]

Most likely your coil packs. Since the car is old, it is highly likely. Nothing lasts forever. Spitfires are pretty cheap anyway.

Back when i bought my car, replacing coilpacks was dreaded because they'd end up costing you 2k

[Giffo]

mate check out your coil[packs for hairline fractures, veyr easy job, and look for snapped or burnt out probes. also look for evidence of (white chalkiness) type powder or staining as this often leads to coil pack breakdown. take the valley cover off for starters to let the hot air out and see how you go, if it still happens have a look at the coil packs!

splitfires are a great upgrade mate and relatively cheap these days, check all your plugs for gap, if you dont have feeler gauges, a hacksaw blade is .8mm if the slides in and out of the gap easily, buy some iridiums and re-gap them to atleast .8mm.

any problems or further help, pm me mate!

cheers and goodluck, Garth

[BoyWhoCriedWolf]

Have a look at the NGK NOS plugs, get a 7. Coilpacks are the most likely culprit. Have a look at your afm's too.

[WogsRus]

i know this might have already been tested, but a stuffed CAS will also have simmilar results.

[skylinegtts]

sounds like the same problem i had, changed coil packs and all good now.

mine got progressively worse as u have said