4x4 cos, stage 3 set up, revs fine upto 4000rpm then gets misfire, have changed

Plugs
Rotor arm
Dizzy cap ok
coil ok
new phase sensor
rewired fuel pump


any ideas what else to look at to rectify this

Thanks

 

Sure its not overboost?
Crank position sensor

 

fuel filter ???
crank position sensor...
remove the 3 loom plugs along the back of the engine bay and just check they are not corroded .. push them closed and pull em apart a few times ..

 

When you changed the plugs did you gap them to 0.6mm rob?

 

Oh dear

 

Dude if u just want to try it with my plugs out of interest your welcome to!!

 

Stu, i put my plugs in it which are gapped as you said and still missfired and its been to a local tuner today and another new set fitted, fully checked over and they said it was phase sensor, changed that tonight but aint cured it. ill try crank sensor 2mrw for him. getting annoying now lol

 

Rhys

Cheers mate, ill txt u if i need them...........

Feel guilty now about txt you earlier trying swap a scooby for your cos

 

lol cunt, i knew it was wind up so didnt reply to lst txt lol

 

lol i was about to post that mine is having the exact same problem, but i'm pretty sure it's the same car - i bought from Finny yesterday

We also replaced the amal valve with a new one today but no joy. So we tried by-passing it instead and then when it mis-fired / jutterd it would suddenly rev on past 4.5k and pull on very strongly to the limiter, we set the boost to 22 psi and it runs fine before and after 4.5k revs but it seems to be when it comes on full boost it misses / boost cuts in and out. We turned the boost right back down and reconnected the amal valve.

We re-checked everything again today from plugs and leads through to coil etc and no joy, checked all the sensors we could think off too.

If the boost is set to around 8 psi it pulls smoothly with absolutely no missing right throughout the rev range but alas i'd hoped stage 3 would see me into at least double figure psi


Terry

 

double / duplicate post by accident

 

Hi Terry, is the rev counter ok? Doesn't wobble or anything when it missfires?! Leads not knackered?

 

Rev counter kind of drops and wobbles as the boost cuts in and out.

Swapped all leads again today while we where double checking distributor cap and coil etc

 

i've got this problem with one... the rev counter wobbles around all the time when coming on boost, but goes off the scale when its on boost properly... any ideas?

 

up

Dave

 

I would guess something within the distributor. Phase sensor, rotor or the lid itself.

 

Hi,
I had this problem on my LT Ecoss, Changed:
Coil
Plugs
Leads
Phase Sensor
Crank Pos Sensor
Fuel Filter
Fuel Pump
Rota Arm
Dis Cap.
Soldered the 2x multi Plugs on inner wing. etc etc

Had my snap on diagnostics pluged in, all ok, in the end it was the Multi-Plug to the crank Position Sensor, Cut it off replaced it with another one, been perfect ever since. Remember how old these cars are guys, the wiring has to put up with Turbo Heat, Water, road salt etc. for like 15+years!

Hope this helps,
Sean

 

well... thanks to smit, my missfire is now solved

turned out to be the earth from the engine loom to the inlet manifold! i'd recommend trying it

 

Cheers for the replys,

The only thing on your list Big Man that we haven't changed is the fuel filter but as it pulls strongly when the missfire clears i'm not sure if it could be it?

Today we double checked all we'd done again. Also changed the crank pick up sensor with another one from my mates Saph. Changed the Injectors to another set of 803's and cleaned the connectors etc.

After that it seems to pull past the missfire easier in 3rd and 4th (when the amal valve is bypassed) but first and second it's still like hitting a brick wall of boost cut out.

One other strange thing is when it's building boost it just sits at a constant 10psi on the boost gauge and then when it clears the miss, it shoots directly to peak psi instead of gradually progressing but i wonder if this will improve when the amal valve is reconnected.

Just finished fiddling with it so going to try to get some sleep and not die from the all the fumes i stink off

Terry

 

Any news

Dave.

 

I've had this problem, now trying a new Ign Amp ???? When it arives.

 

rob fit my loom and see if that fookin cures it

you've only had it for a year

 

No good news i'm afraid.

Still got the Misfire and not only that, it's now developed a knocking noise / vibration to the front left, almost like a wheel isn't on tight. However cause there's a bigger disc conversion and the anti-rattle clips wouldn't fit behind the wheels due to the clearance, i'm hoping it's the caliper. Taken it all off, greesed it up etc but still there so the car isn't being driven at all. It's not a warped disc , and there's no play in the wheel so i don't think bearing etc either, also checked bushes and had a poke about at the drive shaft.

I have the car booked in with an RS Specialist over here for the 5th of September so if all else fails and i can't get any of it fixed then i'll leave it with them and just fork out the money. Plus they can set it up properly too

The joys of owning an RS


Terry

 

change your TPS

 

I was advised it probably wouldn't be it as on full throttle when the boost is turned down to about 8 psi, the engine revs out perfect.

But if there's a slight chance i'll give it a go


If anybody manages to solve this, there's a few beers in it for them (depending on if they hold a valid paypal account)

 

I had a horrible missfire and replaced almost all of the above. Turned out to be a dodgy fuel tank and filter! Tank was fucked and full of shite. Filter was old and shit.

Try it its an easy change

 

try gappin the plugs smaller! .6 think mine woz .4 ticked over bit rough but never missed on 35 pounds of boost !

 

gapped the plugs to 0.6mm and no joy

Going to try changing the fuel filter too for the hell of it but the miss isn't random etc, always at the same rev when it's running above 8-9psi on full throttle, i thought it may have been more sporadic if it was the likes of a filter problem, but then i'm obviously no mechanic

 

have a look at the map sencor if you have,rnt all ready matey their go 4 fun

 

yeah changed the map sensor too.

I Just bought the IAW Monitor Software some of you may have seen in Fast Ford, bit like the Pectel Monitor from years old i'm told so this may help in my fight against gremlins, now and in the future lol. I got the version that allows you to data log etc so hopefully i'll get that on the go tomorow evening and i'll post up the results for someone to explain to me what most of them mean

www.remapping.co.uk






sounds like a great bit of kit and was a toss up between it and a SECS monitor