B18C6 Missfire.....


NIcad7

EG6
Joined
Nov 19, 2011
Messages
359
OK, before we start, I have searched the **** out of this, on this forum, google, everywhere.

I've found a few threads where people have had similar symptoms and checked their fixes but to no avail in my case.

So, at my last race at Cadwell I had second in the bag then a missfire began to develope and I had to retire.

Started at 8k rpm, then 7k, then 6k.... until it is now so bad it is completely missing on idle. So clearly something has gradually broken down.

Now one possible cause could be that the gearbox earth had a dodgy connection and was noticed to be almost arcing against the chassis... It's obviously been fixed now but could this have killed something, if so what?

So things that I have already replaced/checked;

Compression - all even and good
Timing checked
Sparks - Replaced
Leads - Replaced
Ignition Coil - Replaced
Dizzy Cap and Rotor - Replaced
ECU Chip - Replaced

I've got no CEL, sometimes it sounds like it's has a little backfire 'pop' just before it starts up then just rough idles.

Seems to me like it's getting too much fuel but I don't know. I've looked at the injectors they are all firing fuel but I don't know if they are dumping in too much. The plugs look ok when I pull them out, maybe slightly sooty.

I have also fitted thermal intake gaskets but would have thought if there was a vaccum leak like that it would high idle?

I'm going to try another standard ECU (Mine is a chipped P28) and also a complete known working dizzy asx mine is 170k miles old.

Just wanted to hear other suggestions that are a little more informative than the usual suggestions that I have already found?

Thanks :)
 
Also tried adding an extra earth to the dizzy just in case - nope!
 
Mine does the same , my problem started by having my car mapped on a faulty BWR throttle position sensor, that failed after a month, replaced with a Honda one and its effected the map badly and mines missing on idle, assuming yours pops and bangs and stinks of fuel on idle and driving ?
I swapped my Hondata for a faulty but oem mapped p28 and it stopped the shitty idle obviously didnt drive properly due to my injectors being larger and that having a C4 map on opposed to my CR but at least it stopped missing, put my ECU on the other car and that started stinking of fuel and the above problems.

Ive now got myself a stock P73 that needs the immoboliser removing then i'll see if it drives spot on from then, if it is then I know my problem, so i'd try and get yourself a stock ecu just to make sure its not the ecu.
 
Cool thanks, I'm going to try and get hold of a stock ECU and dizzy to test, hopefully be able to go from there. Just got to find a nice chap who will lend me the parts for a few hours as I don't fancy buying them right now! :D
 
But yes to add, it pops and bangs when driving although not driven it since the race it's just sat in the garage feeling sorry for itself.

Let me know how you get on :)
 
+1 on dizzy here. Some folk in my paddock advised the heat of racing affects tbe dizzy.
 
Yeh I'll give it a go when I can. I've heard the same thing about racing killing the Ignition Coil but I've tried replacing that.

Anyone have any idea how much a new dizzy would be from Honda?

Or is it worth running and external MSD coil set up?
 
Small update, I still have the issue although I have done some more testing.

Tested the map sensor - all good.
Tested the ICM - all good on both voltage and resistance.
Check cam belt hadn't jumped a tooth.

Pulled the HT leads one at a time with the engine running. Cylinders 1 + 2 it killed the engine. Cylinders 3 + 4 it kept running (like ****) even with both cables removed!

So it looks to be that the engine is only (barely) running on 2 cylinders...
 
Also I have a dizzy on the way. Was hoping it would turn up today, so when that arrives next week I'll throw that on and fingers crossed it sorts it, even though everything seems to be testing fine on my current dizzy.
 
Another disappointing update;

Put another known good dizzy on the car today, issue is still there.

It is definitely getting a strong spark to all four plugs.
It is definitely getting fuel out of each injector.
Swapped the injectors around, still missing on 3 + 4
Spark plugs mega sooty on 1 + 2 and they look brand new still on 3 + 4
Turned everything over slowly with the cam cover off, everything looks fine, no snapped springs/shut valves or other crazyness.
When I turn over the engine with the sparks out it is smooth as silk, no nasty noises.

Stinks of fuel out of the exhaust. Also noticed it kind of makes a strange blow back noise into the air filter when starting it up.

So I guess I need to look at the ECU? Unless some wiring has gone duff.

Any advice would be really appreciated, this is driving me crazy now.
 
You ever had the head off?
Done a compression/leak down test on it before? Just to clear any mechanical issues out?
I thought a new dizzy was going to cure this tbh.
 
Engine has never been apart.

Done a compression test with over 14 bar across all the cylinders, not done a leak down but I can have a go.

What could cause it to run insanely rich?
 
Injector firing at the wrong time perhaps?
Ignition timing wrong for what ever reason.
 
Hahaha
Sorry bud but that's pretty funny!

Easy mistake to make I suppose, lost count the amount of times I've had to check the firing order on such a basic engine
 
Should have thought about that, we had the same issue with the misses mx5 after we swapped blockes were completly baffled then checked done a google image check and sorted it! Felt dumb but happy it was something so simple
 
Well, for one I'm a f*cking idiot and two, whoever created this image on google is a dick!




Hahahaha so yeh, it's now fixed!
So what was the likely cause of the original problem before you mixed up the leads?
 
I believe it was the distributor that caused the original missfire at his race event.
 
It was the old leads, no. 4 lead was breaking down.

Funny though, I soon as I looked at a proper shop diagram I realised I had 3 + 4 on the wrong way round.
That image needs to be taken down!
And maybe I should have paid attention when I took the old leads off haha!
 
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