Misfire need help

[stevebow]

hi hope someone can help with this,

I've got a misfire on two cylinders, car was running fine all day then it stalled after being parked up for 20 mins. I've taken it to my local garage and they say the compression is fine and the spark is good. I changed the coils after reading peoples similar problems on the forum, but not the module they sit on.

They did some further tests and say two of the injectors are not opening as much as the other two and these two have low voltage (i'm not sure if they tested this or are just assuming low voltage), but they are not sure why there is low voltage it could be due to ecu or wiring loom fault, has anyone had this on their cars ?

Would connecting the car up to elan scan show any possible problems ?

thanks in advance

[epipete]

Don't know how easy this is but if you swap the two good injectors around with the two 'bad' ones and the problem 'moves' then it will be the injectors at fault and if the problem 'stays' then it'll be the electrics (I think that's logical, int it?).

[Brit-Car-Nut]

The power is fed directly to each injector and the ECM switches the ground on and off. Not sure why the power could be low on some.

If one of the injectors has a bad winding and is drawing more power when fired, it might cause the matching other feed to show lower voltage.

Remember the M100 uses Wasted Spark and twin cylinder injection. Plugs 1 and4 fire at the same time and plugs 2 and 3 fire the same way. Injectors also fire two at one time but it is cylinders 1 and 3 then 2 and 4. Each pulse gets 50% of the needed fuel so the second rotation makes it a full charge. Each cylinder fires a full rotation after it's twin.

There are affordable injectors at Rock Auto MFI559 for a single injector. That is MFI, not MF1. They sometimes have 4MFI559 which is a slightly less expensive pack of 4 injectors.

The injectors are made by TRW and are the correct 3BAR injectors compared to the lower pressure injectors used for the non-turbo models.

[stevebow]

Thanks for the replies, Ok so the consensus is that it's likely to be a faulty injector, are these available in the uk, and would you suggest replacing all four?

[Brit-Car-Nut]

The RockAuto injectors ship from the USA but another UK member that pudchased earler this week got them in 2 days. Maybe he paid extra for special shipping

I would probably replace at least the two that make up the pair. I bought a set of 4 for future needs.

[mitreklov]

Rock Auto is your best bet for these injectors.
I hunted hi and low to find a UK source but no joy. I had a similar problem with one of my injectors that would stop working when it had been left after a run. On restart only two of the cylinders fired. The dodgy injector would stop the other injector in the circuit too hence only two pots.

I figured that all my injectors were getting on so I opted to replace them all.

Good luck wit it.

Tim

[stevebow]

Ordered the injectors today diners crossed thanks for all the help I'll let you know how it goes

[epipete]

Most of us cross our fingers but if you think it helps I'll buy a lottery ticket and find some way of crossing my diners

[stevebow]

Bloody auto correct

[Enright]

Steve, it would be worth you putting your location in your profile.
I have a known set of good injectors just sitting around - if you were close you could simply have tried them to eliminate the fault, or I could have taken a look at it.

[stevebow]

Thanks for the offer of help enright I'm a bit to far from you in Beccles a few miles from Norwich. I've added it to my profile also.

[stevebow]

Thanks for the advice it was the injectors so she is running nice again. However since the change of injectors the turbo doesn't seem so fierce, if that's the correct word. It used to kick in around 3000 rpm with quite a kick, now it seems more progressive and the turbo wine seems to me more high pitched. Just wondering if that's how its supposed to be? The exhaust seems more poppy than before to.

[Enright]

Did you use new sealing rings? Could be an air leak I guess...

[stevebow]

i assume so i didn't fit the injectors but the old ones still have o rings on them, as my car is now running very rich is there anyway i can alter it, does elan scan have any readings for fuel mixture ?