[George1]

This has been an ongoing issue with my car for years but I've never got to the bottom of it.

Under load while building boost from around 2000rpm to 2800rpm there's a misfire.

The only original parts in the engine bay are the inlet manifold, wiring loom and ECU. Everything else has been changed including the engine and all sensors and ancillaries.

I had the car on the rolling road the other day for further diagnosis and we got it to happen once. It happens every time on the open road but we found it difficult to replicate.

Here's the data logs from 3 of the power runs:

datazap.me | George Irvine | Rolling Road

datazap.me

datazap.me | George Irvine | Rolling Road

datazap.me

datazap.me | George Irvine | Rolling Road

datazap.me

I can't see anything really wrong with the fueling or ignition advance so I've ruled out any mapping issues.

I've attached a couple of the Dyno charts, one where we got the fault to happen and one where we didn't. You can see the missfire where the unburned fuel comes out the exhaust and then the ECU shuts down the injector for a fraction of a second. You could hardly feel it on the rolling road but it presents on the open road as massive hesitation. The rolling road operator suspects it is an ECU fault where one of the coil drivers is breaking down under load.

Anybody seen anything similar before?

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[dethbrd]

What are your plugs gapped at?

 

[George1]

I've tried various gaps. They were NGK ILZKBR7B8Gs gapped to 0.56mm but I've got ILKR8E6s gapped at 0.7mm the moment

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[dethbrd]

Well that sounds about right.... my car did what yours is doing and i couldnt figure it out either... turned out to just be the gap... too much boost. mine was about 1.1 mm. Always check the simple things first.

 

[George1]

According to 1320 they don't need to gap the R56 down at all when running higher boost, the standard gap seems to be fine. They do with the R53.

It's weird that your plugs were gapped wrong out of the packet. I always check new plugs before I fit them but the gap is always right.

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[George1]

A replacement ECU sorted it. I cloned a second hand one today and threw it in. The engine is much smoother now. The smell of fuel on idle has gone too. Hopefully not too much bore wash on the new engine before I got it fixed! That's been about 7 years to figure that one out.

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[George1]

Does anybody have a schematic for the circuit board in the MED17.2?

I want to identify the MOSFETs which drive the injectors and coils so I can upgrade/ replace them on my original ECU.

It will maybe be obvious when I open it up...

Looks like they're on the back of the board though, didn't see them when I cloned it.

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[George1]

Here's the little b*stards. Anybody know of an upgraded part?

I'm having trouble finding a data sheet for them online. The brand name is Fairchild

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[George1]

I'm having trouble tracking down anyone who sells these in the UK. They are Fairchild 00211 MOSFETs and they typically get used for coil drivers in Bosch ECUs. I can't even find a data sheet for them.

There's sellers in the US and China but can't see them for sale here. Anybody know where I can find some?

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[E-R53]

I have heard of others having the same issue, here is one closer to home.

00211 Fairchild MOSFET Semiconductor | Package: TO-252 (minitools.com)

This one has a datasheet linked, although it looks like you need to register to see it.

Fairchild 00211 TO252 Mosfet

00211 MOSFET Integrated Circuit Semiconductor, Brand: Fairchild, Package: TO252. Discover the wide range of semiconductors on the Minitools STORE.

store.minitools.com

 

[George1]

Thank you! I've sent them a message

£135 minimum order. I only need 4

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[George1]

I got some advice in the MHH Auto forum so I'm going to give these a try. They seem to be more readily available and they should serve the same purpose.

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