Misfire/hunting on idle

[Jhonno]

Cerb was parked up for a period.. Now it is running.. Not great shall we say..

Hunting on idle, misfire below 3k on heavier throttle, stinks of fuel.. If you ease it above 3k, then floor it, it seems to go like it should. If it starts missing, it doesn't stop even when you get above 3k..

Throttles balanced/tps' set. Was all working fine before it sat.

My thoughts..

Lambdas - Need to plug the laptop in to check traces
Injector issue from E5 fuel?

I'd like to try another set of leads on it, but chucking a set at it for diagnostics is expensive and I'm currently having to rebuild my daily after I hit a deer.

It has also had 5 or 6 cans (~35L of fresh fuel).

[Imran999]

Mine always stinks of fuel when I have issues with spark (coil or leads). Surprisingly difficult to diagnose without throwing parts at it, but given the consumable nature of leads, I would start there.
Can also inspect the plugs to identify which leads might be causing the issue.

[Jhonno]

Anyone run EvoOli's latest (0.97) software and have an image of healthy lambda traces? I think both my lambdas have died.. Giving incorrect/lazy readings throwing it all out.. It's hunting from cold start now too.

[notaping]

Not from EvoOli's, but a recent trace of my Lambdas from cold start (zoomed in on the bottom trace) . . .

[Jhonno]

notaping said:

Not from EvoOli's, but a recent trace of my Lambdas from cold start (zoomed in on the bottom trace) . . .

Yeah that is what I was expecting, but I've got nothing like that.. It's more like a digital signal wandering around. 2 lambdas it is!

[Jhonno]

Hmm... Disconnected the lambdas, and it was better, but still had a miss and still was hunting a bit.. However, it definitely didn't smell as unburnt fuelly..

[fredd1e]

If the Lambdas are ok as it would be unusual for 2 to fail at the same time imo, it could be a failing NVRAM in the ECU? this would mean it would need to relearn adaptives for every cold start, or for how long it takes for the NVRAM to loose its memory .

[Jhonno]

fredd1e said:

If the Lambdas are ok as it would be unusual for 2 to fail at the same time imo, it could be a failing NVRAM in the ECU? this would mean it would need to relearn adaptives for every cold start, or for how long it takes for the NVRAM to loose its memory .

It got worse with a longer run..

[Imran999]

Jhonno said:

It got worse with a longer run..

Really sounds like spark to me…

[ridds]

Need to see what your Throttle Pot Traces are. Ideally cold and then warm. If it's getting worse when warm then I'd put money on the pots.

The ECU works off Throttle Position and engine speed.

Lamdda control is rudimentary at best.

[Jhonno]

ridds said:

Need to see what your Throttle Pot Traces are. Ideally cold and then warm. If it's getting worse when warm then I'd put money on the pots.

The ECU works off Throttle Position and engine speed.

Lamdda control is rudimentary at best.

I forgot to check the TPS traces when I had it plugged in.. Will look again!

[ridds]

If you can, log a load of channels and export it.

I think you can do that with the MBE and factory software.....

[DuncanM]

When Paul (ukkid35) had an issue, he posted the rs-ajp logs on here so we could all give feedback?

The logging option is so useful!

[Imran999]

DuncanM said:

When Paul (ukkid35) had an issue, he posted the rs-ajp logs on here so we could all give feedback?

The logging option is so useful!

Yes, just be sure to set the sampling rate at 1 second or similar. Otherwise, it logs something like 8 datapoints per second and even a couple of minutes of running results in almost a thousand lines of excel!

[Jhonno]

So.. Having swapped some leads out, I seem to have some misshaped connectors which might be causing a connection issue.

My lambdas giving unhappy readings I will readdress.. Currently running with them disconnected. I will reconnect them and see if no misfire brings things back to where they should be!

[fatjon]

Check coolant and air temperature on ECU diags. Sensors and connector fail, thinks it’s clock cold, chucks fuel at engine like you own a refinery.

[Bogsye]

I'd be inclined to fire it up from cold and see if each port on the exhaust manifold gets hot. That will soon tell you if it's spark related - ie is it a single exhaust port that stays cold or is it all the ports associated with one coil pack.

I toasted one of my catalysts due to a coil pack causing a mis-fire.

In my case I had a bad low tension connection to a coil pack, and subsequently the plug leads were a bit hit and miss for refittng securely. A new set of leads from Mr Retro Leads sorted that out. I'm sure I did a thread on those or at least mentioned it on someone else's.

I think it's also possible to soot up a lambda so be sure to solve any misfire and run it to give it a chance to sort itself out.

[gruffalo]

I have had similar after a lay up and the problem was the battery, it had started to die during the storage period so none of teh engine sensors could function properly as they were not getting correct reference voltages.

[mrniceguy351]

Pull the plugs and have a look. See if you can narrow the problem down to one cylinder in particular. Even if you don't want to fork out to replace them you can at least clean them. Mine managed to ruin a set of plugs just from many sessions of fault finding idling in the shed.

[HarryW]

Similar to another poster I too had a poor LT connection to one of the coil packs which needed the LT connector disassembling and reassembling. That was the culmination of many hours and swapping out of parts to get to that point, it was years ago mind.