172 PH1 a few issues.

[Baer]

So I've driven the car almost 2000 miles since picking it up a week ago out of necessity (looking for a new apartment etc).

About 500 miles ago up in scotland I got a check engine light, along with code P0420 (on my cheap £20 reader). The car is running alright but with a slight misfire/cough and I had to drive it out of necessity unfortunately as I was stuck up north with nowhere to stay otherwise.

I also got P0711/B0500 and I can't seem to clear these. They are not the cause of the CEL, when I clear P0420, the CEL goes out. For reference if it helps the gearbox whines in 2nd and makes a squeal going into 5th, think it needs a rebuild.

Anyone know what these might be on a ph1? The car does splutter occasionally as I say and sounds a little rough so I am starting today by changing the HT leads, and if it needs it, the injectors too.

 

[chazza114]

I'd pull your spark plugs and check to see what condition they're in, they can cause some rough running when they're old and gunked up.

Seems someone else had a similar problem in 2020: https://cliosport.net/threads/obd2-codes-p0711-and-b0500.830001/

Might be worth messaging them to see if they cured it?

 

[Baer]

I'd pull your spark plugs and check to see what condition they're in, they can cause some rough running when they're old and gunked up.

Seems someone else had a similar problem in 2020: https://cliosport.net/threads/obd2-codes-p0711-and-b0500.830001/

Might be worth messaging them to see if they cured it?

Thanks, I dropped him a message.

I took the plugs out today and cyl2 was completely white all others were only slightly pale brown on the ends. They all almost looked new. So the car is clearly running lean.

I replaced the HT leads whilst I was in there but now I'm a bit scared about having driven so many miles with the car running lean! Really hope I haven't damaged any of the cylinders or pistons.

I've ordered 4 new injectors and will fit them when they arrive.

I smell fuel when idling (only with the windows open) which is a bit worrying, could that be related to an injector? I thoroughly inspected the entire engine bay and couldn't find anything leaking anywhere.

 

[chazza114]

Thanks, I dropped him a message.

I took the plugs out today and cyl2 was completely white all others were only slightly pale brown on the ends. They all almost looked new. So the car is clearly running lean.

I replaced the HT leads whilst I was in there but now I'm a bit scared about having driven so many miles with the car running lean! Really hope I haven't damaged any of the cylinders or pistons.

I've ordered 4 new injectors and will fit them when they arrive.

I smell fuel when idling (only with the windows open) which is a bit worrying, could that be related to an injector? I thoroughly inspected the entire engine bay and couldn't find anything leaking anywhere.

Did you take note of which plugs were in them? Should've been NGK PFR6E-10, most people find that running anything other than these can cause problems.

As for the running lean, as long as you haven't spent the last 2000 miles banging the limiter I don't think any damage will have been done. If you're really worried, a compression test would help to see.

To go with the injectors, you could order a new fuel filter as the Phase 1 has an external fuel filter compared to the later 172/182 which are in the tank I think.

With regards to the fuel smell, does your car still have the stock catalytic convertor on it? Mine's running a decat so it definitely increases the smell of fuel when idling. If not, you could have a small exhuast leak. You'd notice if fuel was dripping when idling.

This is a year old plug in mine for reference:

 

[Coops Mk1]

It'll more than likely be an injector, they lunch them for fun

 

[Baer]

@chazza114
Compression test is a good idea, might pick one up from Euro's over the weekend. What psi should the cylinders be at on these?

Thanks for the pic of your spark plugs, to be fair mine looked identical! I think it was cylinder 2 that was whiter than the rest, so that's probably the injector that's given up.

The P0420 code does seem to be cat/emissions/misfire related, my cat is original but I have a feeling the downpipe or cat itself are blowing. Bloody shame I've spent so much money apartment hunting or I'd just order a PMS/SuperSprint full system. I'll get one in a couple months.

@Coops Mk1
Cheers! It's looking like it's definitely an injector.

I've just spent an hour trying to get the bloody fuel guard off. The bolts seem to be completely seized and/or rounded, so that's another fun thing to deal with. Sprayed them with wd40 and will leave overnight and try again first thing, failing that I'll visit my mechanic mate and get him to cut or drill the bloody stupid thing off. (Why is it even there 🤣).

 

[Coops Mk1]

It's there for front end impact protection so the thing doesn't split and shoot fuel everywhere and set in fire

 

[Baer]

It's there for front end impact protection so the thing doesn't split and shoot fuel everywhere and set in fire

Ah yes, what a stupid oversight by me. I'm used to working on extremely basic engines (Volvo redblocks) didn't even cross my mind.

 

[Baer]

Well this has developed a bit, I tested my injectors with a multimeter and inspected them and honestly all of them are fine, I think they might have actually been replaced only a couple thousand miles ago by the previous owner.

I've realised when I turn the AC on the misfire stops. Anyone ever seen anything like this?