Coil packs

[Mɐʇʇ]

SAI removal requires a map update to the ECU.
DIY for the brave only : viewtopic.php?f=2&t=135435

[Shoppinit]

Looks like a massive vac leak to me. Did you put the airbox back on properly?

How was the SAI removed? Was it all blanked off properly?

[MattyVRS6]

The SAI was removed by a previous owner, I've had it 18 months and it throws the cel up every few weeks due to it not being there. I just scan, clear faults and it disappears for a while. The previous owner message me on here to say he used to own it and it had been properly blanked off.

The misfire error only occurred yesterday, cleared the cel and its back to normal but I'm sure it will come back when I floor it.

[srichards]

Are they SAI errors or EVAP errors? The latter I've had so I wonder if SAI removal changes other things in subtle ways too.

[Shoppinit]

OK. Check the trim then. Group 32 IIRC. If you clear the fault codes it will reset the trim to zero so you'll need to drive for 10 miles or so before it starts to give useful values.

Also log the MAF values at partial load and full load.

[Shoppinit]

Are they SAI errors or EVAP errors? The latter I've had so I wonder if SAI removal changes other things in subtle ways too.

If the vac pipes previously going to the combiner valves haven't been blocked off correctly then you can get other vac related errors, including the EVAP, I imagine. Just because the SAI has been mapped out doesn't mean that a physical fault in the system won't cause other problems.

If the SAI blanking plates aren't gas tight (no gasket for example), then you can get mixture issues because of poor readings from o2 sensors.

Anyway, if we ignore the SAI DTC and assume it's all been removed properly (other than the coding out, which doesn't inspire much confidence TBH) then we just have the misfire to consider. It's not linked to any one cylinder so that suggests an upstream mixture problem. So that's most likely either a metering problem (vac leak, bad MAF, etc), boost leak or fuel pressure problem.

[Foxmeister]

Anyway, if we ignore the SAI DTC and assume it's all been removed properly (other than the coding out, which doesn't inspire much confidence TBH) then we just have the misfire to consider. It's not linked to any one cylinder so that suggests an upstream mixture problem. So that's most likely either a metering problem (vac leak, bad MAF, etc), boost leak or fuel pressure problem.

As Shopp has said, it’s not a cylinder related fault and that’s what my coil pack had thrown up

[MattyVRS6]

Well it's been 3 weeks now and the misfire and cel has not returned. The only difference is I've been filling up with the usual Tesco Momentum.

The misfire occurred when I filled up at Esso - could this be the reason?

Glad it's back to normal now, it was a worry when I wanted to floor it and didn't know whether the fault would come up.

[steve2003rs6]

I have used shell vpower since I bought the car back in 2012.
Over the years I had to use Tesco momentum on quite a few occasions.
On the odd occasion whilst on holidays I had to use Esso.
To be fair I hardly noticed any difference in performance although I am aware of cleansing additives in different fuels.
But then again I hardly ever floor it there’s days.

I am not saying that the fuel you used isn’t your problem but I would be very surprised if it is.

Unless of course you had very bad fuel.

Years ago I used to visit forcourts to calibrate the petrol pumps. We also had to dip storage tanks with water paste to determine the amount of water present.
You would be surprised what water content readings we obtained.
However this would only effect you if the storage tank you filled up from was at a very very low level.

[MattyVRS6]

I'm not sure but it's never done it in 2 years of owning it but starts playing up after an Esso fill up.

Oh well, it's fixed itself for free which is always a bonus. Will update if it plays up again.

[steve2003rs6]

Hi Matty. That’s the sort of error that would send me absolutely nuts.
I would have to fill up with Esso fuel again (preferably from another filling station) just to see if the error returns.

[Shoppinit]

Still worth investigating a leak because the "poor" fuel might have just tipped it over the edge into putting a CEL on.

Also, who did your map? Might not tolerate lower octane fuels. Or might just not be a great map and tolerant to fuel variations (see above).

[MattyVRS6]

This is part of the message I received from the previous owner who was on here -

"It was remapped before I got it and this is the reason for maf limit exceeded codes, the limits in the diagnostics side of the software have not been increased, its never caused a problem. I also completely deleted the SAI system but never got chance to code this out."

Not sure what sort of map it had but I'd love to code the sai system out. I have full VCDS.

Strange how it can go months without the sai cel coming on and then other times a couple of weeks.

I've only ever used Tesco Momentum 99 or Esso Synergy 99.

[Shoppinit]

Mmm. I think I'd get a known good map from somewhere reputable like MRC if it was my car. Probably if your map is iffy then you're not realising the potential anyway and you might find the car drives better.