8V running on 2 cylinders!

hi,

The cars been sitting outside for about about 4 months over the winter, before being parked up it ran well, only issue I noticed was that revs were slow to fall sometimes, assumed that was the idle valve.

finally got it started but there's a lot of backfiring going on at idle. when holding some revs on and pulling the leads, 1 and 2 make no difference, however they are getting a good spark by the look of it. dizzy cap and rotor look ok, haven't tried swapping the leads.

so, that makes me think its a fuelling problem on 1 and 2, injectors sticking open maybe? or an ECU relay or fuse?

I've also drained the fuel and topped up with fresh super.

Can anyone help? does this sound familiar to anyone?

cheers
mike

 

Check the wiring to those injectors look ok. It's all on the same circuit - all the injectors fire together, so it's not the ECU / relay / fuse.

Any mouse's nests on the inlet manifold?

Are the spark plugs for 1&2 wet with fuel, or dry?

How much fuel was left in it over the winter?

 

thanks,

didn't see any signs of rodent residents!

didn't have time earlier to check the plugs, will do that tomorrow. judging by the amount of backfiring I assume there was fuel, too much fuel perhaps?

 

Are you absolutely sure the firing order is correct?

 

I'll check tomorrow, dizzy spins clockwise right? and firing orders 1,3,4,2?

it should be right, I haven't touched it since October when it was fine.

 

Yep, and No1 is normally around 11 or 12 o'clock, looking at the dizzy from the front of the car.

 

normally though can end up around 1-2 oclock if someones done a botched cambelt swap

would double check against rotor arm position

 

tried another set of plugs but same story, running very rough and backfiring. plugs were all fouled up afterwards.

did a compression check and were all 200psi +- 5psi.

also sat all 4 plugs on the inlet and cranked, could see them all sparking in the correct order.

It's got a 2E block, fitted before I got the car, presumably that's the 2E dizzy right? going to replace dizzy cap, rotor and leads just in case.

Thought I might replace the coolant temp sensor as well, i've got the cast aluminium radiator flange and the sensor with the white connector. are these senders still available or do i need to change to plastic.

I'm starting to think the problem may be over-fuelling rather than ignition, it ran fine before parking it up though, any other ideas? AFM, injectors?

thanks

 

one more thought, when i pulled the lead off number 2 cyl while running, i could hear an arcing sound coming from the dizzy area, could this be an indication of faulty cap?

 

^^^ might be sign of bad earth strap.. one from gearbox wears on underside so not always obvious. if its a mk2 digi be worth cleaning throttle vac inlets if not done recently.. would throw fpr out if they were blocked

 

thanks
I think its over-fuelling, possibly caused by some electrical issue so I did some more testing tonight (out under an umbrella!)

- coolant temp sensor reads 4k ohms when cold so that seems ok
- the AFM resistances are as shown in the haynes manual, 4k Ohm between 1&4, 0.55k ohm between 3&4
- 2&3 fluctuates when moving the flap

I think I read on here that measuring across the injector connector it should read 0v with the ignition on and that 12v can mean a damaged ECU. Mine showed 12v initially which slowly dropped to 0v, so not sure if that's right?

so I'm going to swap the ignition stuff anyway and check the earths, after that I'm out of ideas, any more?

cheers

 

have you pulled out the injectors to see how / if they're spraying?

 

not yet, will give that a go though thanks. I suspect it might be a bad earth which is making the ECU power the injectors when the ignition comes on and floods it

 

Why? You just said they're sparking fine. Unless it's a faint yellow spark you're wasting your time with that.

 

well for the price of the bits i think its worth doing just to make sure its all in good nick.

Does anyone tell me if getting 12v at the injector loom is normal with ignition on? It starts at 12v volts and falls to 0v over maybe 20 seconds. I don't know what happens with the injectors connected, how the resistance affects it. would this mean its dribbling fuel in all the time they're powered?

cheers

 

So you still havent pulled them out to see whats happening then?

 

yeah I pulled them out tonight, they don't leak when turning on the ignition they all inject a similar looking amount, spray pattern looks ok.

I cleaned up all the earth's I could find and that didn't help, I had to run in since a huge thunder storm appeared over my house.

so I'm totally stumped now, got fuel, got spark, got compression. So it must be over-fuelling and/or wrong ignition timing. I'll have to go back to basics and double check the timing and firing order.