Fault codes and lumpy idle

[jesus]

Basically my idle is quite lumpy but it's not a misfire. It goes away when driving but when idling I can feel it through the seats and see it with the gearstick.

Gavin kindly plugged it in for me and it came up with:

DF018 Upstream oxygen sensor heating circuit (red fault code)
DF057 Upstream oxygen sensor circuit (yellow fault code)

Has anyone any idea what these might mean and what to fix/replace?

Thanks!

 

[Ol’ Tarby]

Lamda sensor?

 

[jesus]

Is that 100% what it is? The one that sticks into the cat?

 

[bloke]

upstream is pre cat. what were the codes read with?

 

[jesus]

CLIP. Is the pre-cat one in the manifold?

 

[bloke]

just in front of the cat, 182 is easier than the 172 (not that it's a bad one to do) worst part of it is plugging the new one in. should take five minutes on a ramp.

 

[jesus]

Just replaced the pre-cat one, still spluttering and the engine light is still on. The other was BLACK though. Does the fault code have to be reset before it'll stop spluttering? Or will it sort itself out?

 

[Tommo.]

No it should have stopped spluttering when the new sensor was fitted (if it was faulty).

Have you checked out the injectors?

 

[bloke]

a component fault should clear when it's been replaced but i've had a couple of phase 1's that have needed the code clearing to turn the light off.

 

[jesus]

Oh bloody hell! The fault code did say DF018 Upstream oxygen sensor heating circuit though.

No it should have stopped spluttering when the new sensor was fitted (if it was faulty).

Have you checked out the injectors?

How do you test for those again (I've done it once before but forgotten!).

 

[Tommo.]

I'm not sure if this was the right or wrong way to do it, but what I did was disconnect an injector one at a time and listen for a change in the tone of the engine. If the injector is in good working order, there should be quite a noticeable difference. It has always worked for me, but like I said I'm sure there is a 'proper' way to do it.

 

[jesus]

I think that's what I did last time - just disconnect the plugs from them? Cheers!

 

[bloke]

measure the resistance, you're looking for 15 ohms

 

[jesus]

measure the resistance, you're looking for 15 ohms

On the injectors? How? I have a multimeter!

 

[bloke]

unplug them and get probes on the two terminals on the injector itself, you can get to them while they are on the car easy enough.

 

[Dan]

Have you lost one fault code but kept the other?

 

[jesus]

Have you lost one fault code but kept the other?

The one I posted above (red) meant it was still active, the (amber) one (I was told) meant that it's been a problem in the past and just stayed on CLIP as a record.

 

[Dan]

Ahh right, how rough is the idle?

Does the engine light flash?

 

[jesus]

Engine light stays solid and the idle is like this:

 

[Dan]

Hmm I thought it would have sounded like mine (searched a bit) when I had an injector problem but it's nothing like it.

Is the engine tappy?

 

[jesus]

Nope! It drives completely fine (and smoothly) too. Just the idle is a bag of nuts.

 

[Dan]

Nope! It drives completely fine (and smoothly) too. Just the idle is a bag of nuts.

Hmm try swapping pre and post cat sensors around and see if that does anything.

Which one have you swapped already?

 

[jesus]

Pre-cat. That's the one everyone on here said it was... it was a right ballache too!

 

[Dan]

The only reason I say swap them round is to see if it does something, the only other thing is get yourself a working injector and swap them out one at a time and see if that works.

I would give Birchdown a ring in the morning and ask them what the fault codes actually state and what they would do with it, then guys will have the info on the top of there heads lol

 

[jesus]

The only reason I say swap them round is to see if it does something, the only other thing is get yourself a working injector and swap them out one at a time and see if that works.

I would give Birchdown a ring in the morning and ask them what the fault codes actually state and what they would do with it, then guys will have the info on the top of there heads lol

Would they mind giving that sort of info to a stranger though? If not I'll be on the blower!

 

[Dan]

Would they mind giving that sort of info to a stranger though? If not I'll be on the blower!

Hmm you can only ask, usually very helpful.

Just explain the situation your in.

If they say you need a part the least you can do after they help is buy the part through them?

 

[jesus]

OK I replaced the pre-cat lambda sensor and nothing happened. Engine light stayed on and the spluttering was worse if anything!

But, yesterday the engine light went off and it was a lot smoother at idle. Only a tiny bit spluttery.

I went to the back and put my hand over the tailpipes. Only the right hand one is doing it. I'm guessing it might be to do with the design of my exhaust system (custom with 1 backbox) and the air leaving the pipes at different times. Does that sound like it could be the case?

 

[bloke]

yup, think i said on one of your other posts that a lot of it could be down to exhaust pulses.

 

[jesus]

yup, think i said on one of your other posts that a lot of it could be down to exhaust pulses.

I couldn't remember who mentioned that, that's what gave me the idea

So it can be a common thing that? I'm happy with where it's at now. Glad I changed the lambda regardless and that the fault code disappeared on its own!

 

[bloke]

yup, had a few that sound a bit odd, even with twin back boxes.