Bugger!

 

Just got the 300 out to make a start on cleaning the engine and get the tracking checked. As I started her up I noticed that she was running a little lumpy. Drove her down to the garage for the tracking and could smell she was running rich and there was an occasional back fire.

 

Got the car home and removed the coil conectors and there was a drop in revs on all but one connector (middle off side). Called Jim (at PowerZ) and he’s said check the injector connectors (look fine), remove spark plugs and check PTU2. Haven’t checked the last two items yet but is there anything else you clever fellows can recommend?

 

One the plus side the tracking was found to be out and now she drives like a dream.

 

Cheers,

Chris.

 

Got the car home and removed the coil conectors and there was a drop in revs on all but one connector (middle off side)

 

So what happened when you cleaned up that connector? Sounds like you've isolated it.

Sounds like timing to me. But fix that misfire first

Sounds like timing to me

 

How does it sound like timing to you?

How does it sound like timing to you?

Backfiring and lumpy running can be a symptom of retarded timing.

 

But as I added, fix the missfire first.

So what happened when you cleaned up that connector? Sounds like you've isolated it.

 

Nothing. Plugged back in and nothing changed, recs didn’t pick up. I did notice that the connector retaining clip has snapped off at some point but even with me holding the connector down there’s no difference.

Nothing. Plugged back in and nothing changed, recs didn’t pick up. I did notice that the connector retaining clip has snapped off at some point but even with me holding the connector down there’s no difference.

 

Ok, so move that coil pack to another cylinder and see whether the fault stays or goes. If it stays on the same pot, then it'll be injector or spark plug related.

Backfiring and lumpy running can be a symptom of retarded timing.

 

But as I added, fix the missfire first.

 

Maybe I’m not understanding you. Jim replaced all belts etc around 500 miles ago, I doubt it would be a timing issue.

Backfiring and lumpy running can be a symptom of retarded timing.

 

But as I added, fix the missfire first.

 

It's running lumpy because it's misfiring.....:lol:

 

Unlikely for the timing to just 'go' to that extent.

 

- - - Updated - - -

 

Maybe I’m not understanding you. Jim replaced all belts etc around 500 miles ago, I doubt it would be a timing issue.

 

No, it isn't that, ignore him (sorry Alic). Carry on with your process of elimination as I posted. Post your findings. :)

It's running lumpy because it's misfiring.....[emoji38]

 

Unlikely for the timing to just 'go' to that extent.

 

- - - Updated - - -

 

 

 

No, it isn't that, ignore him (sorry Alic). Carry on with your process of elimination as I posted. Post your findings. :)

 

Yeah just skim read it hence the edit. :Innocent:

 

Continue checking things.

 

Have you checked spark on the cylinder down?

So not the coil packs, they swapped ok.

 

Couldn’t get to the plugs as I couldn’t find my remover.

 

PTU looked oK...

 

That's the next thing. If the plugs check put OK then check impedance values of the injectors with a multimeter. Make sure the connectors are very very clean.

You are also running a S1 PTU which are prone to giving the symptoms you are having.

That's the next thing. If the plugs check put OK then check impedance values of the injectors with a multimeter. Make sure the connectors are very very clean.

 

What sort of ohms am I looking for Simon?

 

You are also running a S1 PTU which are prone to giving the symptoms you are having.

 

Thanks Andrew, I thought it was a 2. I’ll chase up another one. Can you get them new or is it only used now?

Injector testing : http://z32.wikispaces.com/Injector+Testing

 

If you're replacing the PTU for an S2 one you'll need the harness adaptor also.

 

I would wait before you've checked everything else first.

10-14ohms

 

My car did have backfiring issues because of the Ptu, it just dropped more cylinders.

 

Not sure if you can get them OEM new. I know you can get Chinese ones but they will probably be unleliable so easiest to swap for a S2 once you tested with another S1 and can confim it's the issue

My money is on a faulty injector plug.

Yeah, keep it simple here like funkysi says - you're very fortunate in that you've managed to narrow it down to one cylinder bank - so it's only one of 4 things:

COILPACK

INJECTOR

SPARKPLUG

COMPRESSION

 

not much else to go wrong in there..

COILPACK - swap out for a known working one from another bank - if same (on that cylinder) then move onto

SPARKPLUG - swap out as above

INJECTOR - swap out as above

 

once you've worked it out THEN replace

 

If all these fail, then do a COMPRESSION check to ensure somethings not majorly buckled.

 

You can rule these things out:

Fuel filter - affects all cylinders

MAF/IACV/TPS etc. - affects all cylinders, often intermittently

Timing will affect more than one cylinder

PTU will affect more than one cylinder (plus you can't tell anything from the outside of a MAF or PTU)

 

It's not intermittent, and you've isolated it - that's a massive bonus pal.

Additional - another quick way of checking an injector is 1) testing the ohms with a multimeter and 2) get a wee rectangle 9v battery, bit of speaker wire round each and hit the injector connector with the wires, you'll hear if it's opening and closing properly.

Ptu can affect just 1 cylinder or more. It's 6 individual power transistors in a box.

 

Also you underestimate how hard it is to swap injectors and they often break on removal.

 

But okay points.

So I’ve just done an ohms check on the injector which came back as 12.7ohms.

Next I removed the SPARK PLUG and noticed it looked a bit glossy and so double checked against another.

 

I’ve swapped the plugs round and the issue moved with the plug. Any ideas what will have caused the plug to look like this?

 

I’m now waiting for the car to warm up so I can do a compression test on the cylinder that the gammy plug was in.

 

EDIT

Just to add the plugs are new having been replaced 300 miles ago.

Edited March 29, 20187 yr by Chris300

Looks a bit wet as if fuel was on it and not ignited.

 

Throw a new plug in it.

Next I removed the injector on noticed it looked a bit glossy and so double checked against another..

 

You mean spark plug?

 

Any ideas what will have caused the plug to look like this?

 

Running rich on the cylinder it came out of which points to an ignition problem. The problem would have moved

as the plug is now so fouled.

Cheers Ali. That would make sense as it’s not been combusting down there. Any idea why the spark plug might have failed though or can it just happen?

You mean spark plug?

 

 

 

Running rich on the cylinder it came out of which points to an ignition problem. The problem would have moved

as the plug is now so fouled.

 

 

Oops, yes spark plug.

 

Why would it run rich?

What have you checked so far on the ignition system which fires that cylinder?