Firing on three cylinders

PeterRobinson · #1 6th January 2018, 12:33

Hello all,

Some advice/help needed...

My Sylva Striker 4age (Omex open loop) is only firing on cylinders 2,3 and 4. One day in the summer, cylinder 1 just stopped working. I know this because the exhaust primary pipe stays cool instead of red hot, it sounds uneven, and is down on power. It still goes like stink on the three cylinders (I just unplug no.1 injector to use it) but it is obviously nothing like what it should be.

Would really appreciate any help, advice, crazy suggestions (the crazier the better) or obvious ideas to help with this.

Many thanks in inticipation.

Peter Robinson, Sutton Coldfield, West Midlands

PS this is not a spoof - I don't know what to try at this point!!

Mitchelkitman · #2 6th January 2018, 14:28

Do you know that it's not firing on #1? I've no experience of elec control systems like these, but does it tell you it's not firing? Can you look at something which says it isn't (I'm not being flippant, I just don't know). If you know it is sending the correct 'command', then it's a case of why isn't it getting there..... Maybe check plug, lead or more likely? coil pack. Just random thoughts, but hope it helps.
ETA my first sentence wasn't written very well - I can see from the evidence you've given that it's definitely not firing the mixture - my brain was 'in computer mode'.

Phaeton · #3 7th January 2018, 07:47

You seem to think it's the injector, but have you checked out the spark plug & the HT lead, have you swapped them with ones from 2,3,4, does the fault stay on 1 or move to the other cylinder?

Exactly the same with the injector, can you swap 2 of the injectors over, again does the fault move or stay where it is?

Have you checked continuity from the Omex plug to the injector plug, never had anything to do with Omex but the Shitreon Paxo boys run them, you have to make your wiring harness, which is the most likely place for a fault, I suspect a bad joint somewhere.

Just as a matter of interest which Omex is it, there are diagrams available online for pinouts

PeterRobinson · #4 7th January 2018, 11:05

Thanks Phaeton, I've had another go at the problem of #1 cylinder.

This morning I swapped the spark plug lead to cylinder #4 and #4 still works ok.
I strongly suspected the injector and so I swapped injectors #1 and #2 and the fault is still with #1.
I bought new HT leads in case there was some intermittent fault but the fault is still with #1.
I suspected the fuel wiring but with engine running I could simply swap the connectors on the injectors so that #1 wiring was driving # 4 cylinder (it's a semi-sequential Omex 500 system). Of course it could barely keep running for the couple of seconds it took to make the switch as only cylinders #2 and #3 were firing, but the moment the connector hit the #4 injector it was back to life on 3 cylinders, showing (I imagine) that the wiring is OK.
That leaves the spark plug #1. I've changed the spark plug already to no avail, and I've seen/heard a spare plug firing normally when attached to the #1 HT lead!

I'm well known for doing something stupid/obvious and forgetting I've done it...! What might it be that I've missed or done? I'm familiar with the whole engine and it has worked until the summer, being Rolling-roaded as it stands at 195 bhp @ 7950 rpm.

Thanks again for any thhoughts,
Peter

Phaeton · #5 7th January 2018, 11:20

It appears you've covered off most of the electrical side

2 suggestions, physically change injectors 1 & 4 over, they are just held in by the rail onto rubber grommets (I think) little while since I did 4AGE, my last MR2 MK1 had a V6 fitted.

You also need to consider either a compression or leakdown test across all four, just in case it's dropped a valve or damaged a piston, unusual on this engine but you never know.

PeterRobinson · #6 7th January 2018, 17:35

Phaeton,

Yes I swapped a couple of injectors but the problem remained with the same cylinder and the other three ran fine. So it's not a non-functional injector itself.

Your ideas of compression failure are interesting as I've done the obvious things now. Although I have put my palm on the bellmouth and felt the suction alright hmm that kind of demonstrates it is mechanically ok. I know it must sound as though I'm making this up - I wish I was!

Peter

Phaeton · #7 7th January 2018, 18:32

Quote:

Originally Posted by PeterRobinson

I know it must sound as though I'm making this up - I wish I was!

Peter

Nope honestly I belive you I've had gremlins like this in the past which defy all logic. So to recap No1 has had from one of the other cylinders, spark plug, HT lead, injector, injector lead & each occasion the No1 part has worked on the other cylinder & the replacement part failed on No1.

Just one thought what coil pack is it? A Ford EDIS? Does 1& 4 share a coil, can you swap the leads over at the coil pack end rather than at soak end.