Missfires when starting, then clears after blipping throttle

m_p_rogers

Re: Missfires when starting, then clears after blipping thro

:oops: I wouldn't know where to start in order to do that..... I think i've run out of skill

Daz

Re: Missfires when starting, then clears after blipping thro

Get some jump leads, connect the black to the battery and the other end of the black to the engine somewhere..., and then connnect the red to the earth also and connect that to the body somewhere.... ,,, Just make sure you dont connect the posative of the battery to any of them

m_p_rogers

Re: Missfires when starting, then clears after blipping thro

Having I got it right ?

Black - negative terminal on battery to earth point on head
Red - Earth point on head then just clipped on to engine bay chassis

Thanks again guys for your help.

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Daz

Re: Missfires when starting, then clears after blipping thro

nearly there... go from battery to engine and battery to chassis/body..

m_p_rogers

Re: Missfires when starting, then clears after blipping thro

Gotcha !

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Will try tomorrow and see if I can check Cat at the same time

m_p_rogers

Re: Missfires when starting, then clears after blipping thro

Back again, tried the jump leads out as above, at first I thought there was a definate improvement, but after running it a couple of times, I dont think there is.

Still missing under 1500 revs and wanting to stall, am in the the process of clearing out the garage in order to get the car over the pit to remove downpipe and cat. A busted EGR valve that is stuck open wouldn't cause problems when cold would it ?

Attached a faily unhelpful video, that doesn't really show it missing as i'm mostly holding it above 1500revs apart for a couple of moments, but maybe it helps...

astra22bertoneauto

Re: Missfires when starting, then clears after blipping thro

Few thing i would try first.

1) blank off egr and install cheater. But if there is no eml then egr may be ok

2) What type of spark plug do you have? From experience the single electrode ones dont work well.

3) Fuel pressure regulator and/or fuel pump/injectors. You can check the FPR by pinching the rubber return pipe (by brake fluid reservoir) but only do it by no more than 50%. You just want to restrict the flow a bit no completely stop it.

I would try those 3 things before considering anything more serious. Might also be worth checking compression again just to make sure.

How many miles has the car done? any recent error codes?

m_p_rogers

Re: Missfires when starting, then clears after blipping thro

1) Will purchase the blanking plate and cheater tonight
2) Running on Genuine GM triple electrode plugs (changed 2 months ago)
3) Do I pinch the return pipe when the engine is running ? Or just with the ignition on so the pump is primed ? What should I expect to happen if pressure is good, heard of fuel spraying out from somewhere and hitting windscreen if pressure is good ?

Will compression test again.

Car has done 86k miles, only error code it has ever thrown are the three on page 2 of this thread, all relatedd to throttle body after performing compression test, new TB has since been cleaned and fitted and no error codes since.

Thanks for your help!

astra22bertoneauto

Re: Missfires when starting, then clears after blipping thro

Sorry should of said, you pinch it with ignition off.

There is a valve under the black cap on the fuel feed pipe. Just like a tyre valve push the centre pin with ignition primed but not running. Fuel shoots out and hits bonnett.

I was thinking it could be a stick FPR when idling. Only other thing I can think of is a valve not seating correctly but would of thought that would show up somewhere on a compression test.

MikeS

Re: Missfires when starting, then clears after blipping thro

have u unplugged the coolant temp sensor to see if it idles

i am thinking it is a fuel problem also

m_p_rogers

Re: Missfires when starting, then clears after blipping thro

Haven't tried unpluging CTS yet, but have replaced it.

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Is the pipe with the arrow pointing to it the fuel return pipe to pinch ? Comes off of the left hand side of the fuel rail and the pipe to the right to it comes of the centre of the fuel rail.

Also have Iocated the the correct valve with which to push when primed ?

Got it over the pit in the garage now, so will compression test and check precat today.

Apologies for my lack of knowledge, i really out to admit defeat and take it to a garage..... :oops:

MikeS

Re: Missfires when starting, then clears after blipping thro

circled object is for air con

the arrow is fuel lines

follow fuel lines onto front of head and you will see a chunky pipe it connects to [on that pipe is a bike valve cover thingy that is for checking fuel pressure]

m_p_rogers

Re: Missfires when starting, then clears after blipping thro

Thanks mike, the 'chunky pipe' circled ? I can't see any bike type valve on it ??

Of the two fuel lines, which is the return line ?

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m_p_rogers

Re: Missfires when starting, then clears after blipping thro

Compression test results are in...

Cylinder 1: 14.5bar
Cylinder 2: 14.5bar
Cylinder 3: 14bar
Cylinder 4: 14.5

Dry test on cold engine, compression seemed to 'build up' nicely on each turn of the crank

MikeS

Re: Missfires when starting, then clears after blipping thro

your engine sounds sweet m8

look at chunky block and follow fuel line back - u see little round cover on one of the fuel lines 🙂

unplug coolant temp sensor and let car idle btw

your fans will kick in also so dont be too worried

m_p_rogers

Re: Missfires when starting, then clears after blipping thro

Superb! I see it! I assume the one with the little black cover on it is the fuel line IN ? And thefore I need to pinch the other pipe (being the return) ?

Will try unpluggung CTS

astra22bertoneauto

Re: Missfires when starting, then clears after blipping thro

m.p.rogers said:
Superb! I see it! I assume the one with the little black cover on it is the fuel line IN ? And thefore I need to pinch the other pipe (being the return) ?

Will try unpluggung CTS

Yes undo little black cover to reveal a valve (just like a tyre). Prime system (ignition on) but dont start. Undo valve and using anything really, push centre pin for a quick second. Fuel should shoot up and hit bonnet. If it dont then try pinching return pipe.

Also try unplugging CTS.

MikeS

Re: Missfires when starting, then clears after blipping thro

could be fuel pump relay as well

m_p_rogers

Re: Missfires when starting, then clears after blipping thro

Interesting, I pulled the blue fuel pump relay out yesterday to compression test, the top of plastic on the relay was slighly dis-coloured in one spot, the type of colour plastic goes when it gets too hot.

MikeS

Re: Missfires when starting, then clears after blipping thro

the only ones that matter are purple

no blue one

should be a purple one for engine ecu management and another for fuel pump

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