Running like <beep>...

[Mark-RS]

She's running really rough ! To the point where she is now laid up on the drive whilst I use a dirty diesel

The little engine ? light has come on and it's idling quite rough. Surging so to speak. Also upon accelerating it's pretty much totally gutless.

Upon scanning it says issue with Coolant Control module and a misfire on Cylinder 1.

Two questions.

Could these issues be linked ?

And, I do have a small coolant leak from somewhere, is there anywhere around the coolant control module that would be a possible source of the leak ? I only ask as when I bought the car I had the coolant control module replaced and the whole area cleaned up as the pins had corroded. My issue at the time was a cold start one, but car ran fine when it eventually started, so although it's saying the module again, the effect this time is different.

The only garage I really trust that's within a reasonable distance is closed, which is an ass

Any thoughts please ?

[Shoppinit]

What's a coolant control module?

Post up the fault codes.

Presumably you've got a Vagcom?

[srichards]

Do you still have the SAI on? If you leave it to run and warm up is still rough as a badger's bum or does it go more normal?

Surging might be air leak somewhere. Usual check the air box applies.

[Muggy]

Fastest test for air leak is to get a can of carb cleaner and give it a few shots around any vacuum lines, sensors, intake, etc. while the car is idling. If you have an air leak, the car will surge/stumble noticeably different for a moment. When I blew out my suction jet pump under the intake, I had all kinds of codes that the vac leak caused.

[Mark-RS]

I'll post a bit more on friday, My day off. It's parked up at my parents right now as my drive is getting a little full

Come to think of it./... So is theirs ! Haha !

FYI_ Coolant Control Module, I believe is what tells the engine the temperature so it knows how much fuel etc to add. My last issue with it was it was constantly reading 99c so on a winters morning the engine thought it was already hot and never got enough fuel to start.

The light I believe is emissions ? So wondering if it's now over fueling ? Temps reading low from the module so dumping loads of fuel in ?

And no, it doesn't get any better when running. If anything for the first few minutes of driving it's better.

[airtite]

pretty sure I have an intermittent coolant control module fault on mine as well but my car still runs fine...

[Shoppinit]

There is no coolant control module. Did you mean the coolant temp sensor G2 / G62? This is why the fault codes are needed.

[Mark-RS]

Right here are the codes that I have that I think are relevant.

First I think is an old code, the one with the coolant control module. After clearing all codes and rescanning it didn't come back. But it does state coolant control module, bit could also be known as the temp sensor ? Possible I guess ?

Sorry they are on the side ! Any way to flip them using site code ?

[Shoppinit]

Ah, I see. You are using an extremely old version of VCDS hence the non-existant coolant control module. The J671 in fact is the controller for the small fan. Not an uncommon failure, but has no bearing on your problem.

The misfire code has put your malfunction light on. Since there are no other codes, then I suspect that the problem is either a faulty plug, plug not properly torqued, faulty ignition coil or faulty injector. All of those are fairly easily eliminated by swapping things between banks.

Going further, if you've got a borescope, stick it down cylinder one and have a look for wetness / other anomalies. Might indicate head gasket. Could do a compression test, too.

[Shoppinit]

Suspect if it was a leak bad enough to cause a misfire you would have other codes for mixture / lambda. Wouldn't hurt to check your trim values, though.

[Mark-RS]

Thanks for the info.

Since I'm pretty much a mechanical idiot, I'll have to wait to put it into the garage. But at least I have an idea of the issue so can better be placed to assess any come back they give me.

I cleared all codes a few times and re ran the tests and it's these same ones that keep coming back. Hopefully it's not going to be an expensive fix as I'd like to maybe have the CamBelt done sometime this year, just for piece of mind. I think it's been 4 years now since the last one. Also need my Box sorting or Manual conversion, still toying with that !

[Mark-RS]

A little update on this.

My regular garage is still closed, so I chanced my arm and just popped into a small garage around the corner.

They said they could take a quick look on the spot, so was quite happy.

They swapped the coil pack from the front left of the engine as you look at it with the bottom right as you look at it. They said bottom left was Cylinder 1 (Closest to you), which was where the missfire was logged as coming from.

Codes were all cleared and I took the car for a spin. Initially I had the engine light flashing under hard acceleration and the car felt hesitant. But the longer I drove this seemed to get less and less.

After maybe 15 minutes it was like it was perfect, with no issues that I could feel and no light flashing.

Took it back to the garage and the Fault code came up again on Cylinder 1.

Next step is compression test which will tell me if it's an Engine rebuild (Car Scrappage) or Injector.

[simonpoulton]

Definitely worth buying a new spark plug for that cylinder and checking the new one is torqued up. I had the same problem on a set of plugs with less than 4k on them and went through all of the above and replacing the plug sorted the problem. Initially discounted the plug due to the low mileage on it. Also cylinder 1 which is weird...

[Mark-RS]

I did think about trying another plug.. He did remove it and it didn't look bad. Was a little sooty, but wasn't wet or gunked up at all which I was thankful for, but it's certainly worth the cost just to put another one in.

I'm shitting myself about the compression test. My luck usually is not the best.

[Mark-RS]

Just taken it for another 30 minute run up and down the A45 and it's faultless still. Hard from second it's flawless all the way to the legal limit for such a road