Rough idle

[Ardent]

What ctm said.
Ecu operates a two trip logic.

[treeroy]

ECU was reset on Monday, i've since driven 40 miles and no warning light has come on. I thought it would be back on pretty soon. Yesterday I would have said that it was still rough on idle and not staying still on revs, but it's fine today. I'll keep driving it and see what happens.

Thanks for all the advice and I'll report back soon!

Was that just one trip of 40 miles? Generally it'll take two or more trips for the ECU to convince itself there's a problem and throw a code.

Fingers crossed though.

I've now done about 50 miles I think? Over 5 or 6 trips. So admittedly none of them especially long.

[Call the midlife!]

ECU was reset on Monday, i've since driven 40 miles and no warning light has come on. I thought it would be back on pretty soon. Yesterday I would have said that it was still rough on idle and not staying still on revs, but it's fine today. I'll keep driving it and see what happens.

Thanks for all the advice and I'll report back soon!

Was that just one trip of 40 miles? Generally it'll take two or more trips for the ECU to convince itself there's a problem and throw a code.

Fingers crossed though.

I've now done about 50 miles I think? Over 5 or 6 trips. So admittedly none of them especially long.

Yeah, barely getting warmed up at that rate this time of year probably, need to get the cat nice and hot for a period of time to burn off.

[treeroy]

ECU was reset on Monday, i've since driven 40 miles and no warning light has come on. I thought it would be back on pretty soon. Yesterday I would have said that it was still rough on idle and not staying still on revs, but it's fine today. I'll keep driving it and see what happens.

Thanks for all the advice and I'll report back soon!

Was that just one trip of 40 miles? Generally it'll take two or more trips for the ECU to convince itself there's a problem and throw a code.

Fingers crossed though.

I've now done about 50 miles I think? Over 5 or 6 trips. So admittedly none of them especially long.

Yeah, barely getting warmed up at that rate this time of year probably, need to get the cat nice and hot for a period of time to burn off.

So basically, in order to Save The Planet, and ensure that my Co2 emissions are as low as possible, I need to rag my car to its limits. Might try it tomorrow.

[shnazzle]

@Carolyn your comment:
"A bit of tissue taped to the end of something long and thin (so it can flap about) and then held close to the joints, is an excellent way to track down a leak".

Reminded me of an old post where I "introduced" the sticky stick and @Enjay introduced his "sucky stick".

Perhaps we could name your invention a "flappy stick".

https://www.mr2roc.org/forum/index.php?msg=765455

PS
I would remind the reader that the Poor Man's Patent is still in force!

It's all the same stick in various stages. 

Flappy stick -> sucky stick -> sticky stick.
Old news. No new patent needed.

[treeroy]

Haven't had to use the car much, but sure enough, is now showing the engine light again. Took a good 200 miles of driving to kick, though!

I will do some checks/tests over the weekend to try and diagnose it.

In the meantime until it's fixed, do I have to put up with the fuel economy? Having the emissions fault obviously makes the car overfuel horrendously. However - will it do this only after it's triggered the EML light? Or will it be overfueling regardless of whether it's caused the light to go on.

If I reset the ECU with an OBD reader every time the light comes on, would that prevent the car from using lots more fuel?

[Call the midlife!]

The EML is triggered by the ECU detecting the fault so yes, the fault will be there regardless of the EML or not, clearing it/resetting the ECU won't give you your normal fuelling back as the ECU will run with base settings while it learns and then triggers the EML again.

[treeroy]

The EML is triggered by the ECU detecting the fault so yes, the fault will be there regardless of the EML or not, clearing it/resetting the ECU won't give you your normal fuelling back as the ECU will run with base settings while it learns and then triggers the EML again.

Hm. Thanks.

I asked as I managed to do 210 miles (from full) to half a tank, so that's pretty normal behaviour from the car. It only  plummeted down after the engine light came on.

Whereas when I did a full tank with the EML on 2 weeks ago, the fuel usage was very high right from the get go.

[Topdownman]

Have you taken it back to the garage that did the work to tell them of the problems that have started since they worked on it? (I dont mean blaming them, just stating whats going on and see what they say).

They may tell you something useful or discount some possibilities which may help get to the bottom of it even if they say it is nothing to do with them?

[toyoda]

If you run with no front cat then I would buy a cheap code reader, just so you can knock your own light out and keep an eye on the codes. If the code for cat not working comes up again it can be a mix of small journeys or that the mid cat is not operating as good as it should be. But I think it was probably wahat carolyn said ,all the paste/gaskets/new exhaust heating up and causing incorrect essisions to trigger the code. Since I decatted mine a few years ago I have had codes on and off for a while but mine are bank 1 or 2 o2 sensor out of parameter and im sure it cos I have the standard manifold still. My codes strange in that I can get 2 in a month and then its ok for up to 8 months.
But more importantly I dont think that code would cause you're car to have rough idle.
I would be checking the basics , plugs,coils, electrical connections and all intake and vacume pipes especiall the last two as these could have been knocked when exhaust was fit.
One more thing ,I have a normal air filter and a K and N (it was in car when I bought it), when I take the k&n out to clean it I fit the new standard filter and the car runs lumpy, it develops a flatspot off idle that is quite bad causing you to press the accelerator, after a few days it gets better on its own and never happens again until about a year later when I swap the k@n back in. I'm sure they "learn" and adapt a small amount.I know the bmw's I work on definately do, you can pull a vac pipe off the manifold on one cylinder and it will run lumpy and rough but if you ride it like this for a while it adapts (in this case by injecting more fuel and altering the butterfly angle for that cylinder) then when you put the vac pipe back on it runs rough again until ridden.
I'd put some plugs in it then you can check the coils at the same time.
But buy a code reader for under £20 or that download/bluetooth thing.
Hope you fix it.