Running On 2 Cylinders - Any Ideas?

[Leon 24]

Hi all

 

A long time ago I put a 1.9 Gentry engine in my 1.6 Ph1 GTI.

 

Engine was from a known runner and the car was a known runner (knackered big ends)

 

I did the swapover with no problems, couldn't get it to run properly, and then got a new toy and forgot about it.

 

A few days ago I decided to have another crack at getting it finished.

 

Current situation. Car will start and run, but it is only firing on 3 and 4.

 

Compression - equal across all 4 cylinders (the guage I'm using isn't hugely accurate but it's approx 165 PSI on each which I think is about right for a Gentry motor)

Spark - from the old "spark plug touching the cylinder head" test all 4 sparks look healthy. Leads are new. Plugs are new.

Distributor - I have 2, both used, both known good, neither makes a difference. Cap - I have 2, same story.

Fuel - I have fired the injectors off the car. All 4 appear to be spraying correctly, consistent amounts.

General electrics - Various ECUs, Throttle bodies, AFMs, ignition modules have been tried and seem to make no difference.

After running for a short while, plugs 1 and 2 are wet and clean, smell of fuel. 3 and 4 are slightly blackened as I'd expect from continual starting attempts/never getting warm. Exhaust manifold (4 branch) gets hot on 3 and 4, 1 and 2 remain cold.

 

Adjusting ignition timing/removing or blocking vacuum advance only makes the running worse.

 

Car is not in a condition to be road tested so I can't try and "drive through it" so to speak.

I do not have spares of - Rotor arm, Coil

 

The car is a bitsa, yes, but even the wildest mismatch of Gentry/1.9/1.6 parts should not cause 1 and 2 to stop firing.

 

What's really confusing me is that 1 and 2 are obviously sparking outside the head, but something is going wrong when the plugs go back in. I've checked the leads are definitely on - they are.

 

I was almost hoping for HG failure between 1 and 2, at least that's something I could fix - but no joy there.

 

Any ideas welcome, I'm almost at my wit's end!

[Alastairh 47]

Sounds like a good puzzle.

 

Have you checked the injector pin connections, as these have of coming loose. Also, have you tried testing for spark with all 4 plugs out at the same time. I have recently had a coil pack show and intermittent fault across all 4.

 

Al

 

Al

[Daviewonder 533 3 Cars]

I had a similar problem to this on a mini and it turned out that the leads were 180 degrees out on the dizzy cap, I just moved each lead round 2 places and it cured it. Might be worth checking out?

[miamichris 9]

I had a similar problem to this on a mini and it turned out that the leads were 180 degrees out on the dizzy cap, I just moved each lead round 2 places and it cured it. Might be worth checking out?

 

^^^ As Davie said, had my leads 180 degrees out on my Xs before and it acted like this.

[Leon 24]

Tried different lead orders with no joy (just more back firing!)

 

All injectors are fuelling.

 

Plugs 1 and 2 still wet after running with the leads back in the correct order.

Either 1 and 2 have a weak spark, or 1 and 2 are overfuelling. As they don't appear to be overfuelling it just has to be spark.

 

Which leaves rotor arm and distributor cap I guess - I can't see that the coil would supply a strong spark to 2 cylinders and a weak one to the other 2.

 

Might buy a spark tester and see what they are outputting.

[strobe 0]

forgive me for interfering as a newcomer but as I am no newcomer to the motor trade 20years now ,please stick with the leads in wrong position theorem

only interchange the two that are not firing leave three and four as they are ...firing orders can really confuse you make sure you know the rotor direction and take off the cam cover to see when the two lobes of cyl1 are both equally"facing up" and the timing mark is at tdc then you will be certain that you know the rotor is pointing at 1st base in the cap and then work round 1342 in the direction of rotor travel take 2 hours if you have to but be absolutely certain and I recon she'll be away