ecu questions

[dslg60]

Is anyone aware of any list of ecu part numbers and the vehicles they were available in? I have a 1z with a bk ecu and someone suggested swapping to an fa ecu. I'm new to this stuff and I'm not sure where to look for info about compatability and pros and cons of any such swap.
thanks, Jason.

 

[paramedick]

The A3 Jettas came with either an ED or JB suffix. ED suffix ECU was failure prone, and replaced directly with a JB.

The B4 Passats came with either a BK or FA ECU dependent on year. 1996 came with BK, which was replaced with a GQ if you had the smoke recall done. The 1997 only came with the FA ECU.

If you put a FA ECU in a 1996 Passat, you will get error codes. You need a GQ.

 

[G60ING]

Good list of the ECUs. I'll be adding this to the swap thread, Thx

 

[joskoh]

Hi Everyone,

I have a 96 Passat TDI with the BK ECU. I managed to get my hands on a GQ ECU and spent this afternoon doing the swap.

After the swap the car started fine but had a very shaky idle. Although the car did not stall and seemed to run fine on my test drive, whenever I came to a stop the idle was rough.

I have VAG-COM and logged in to find that there were NO FAULT codes generated.

I swapped back the original BK ECU and the idle is completely back to normal (nice and smooth).

I am I missing a step in doing this swap??

Any help with this would be great.

Thanks,

Joe

 

[luceberg]

The GQ is designed for a higher injector pop pressure. In effect, this means the timing will be retarded.

 

[Lug_Nut]

The BK, once the 5th injector had been 'neutered', is a nice controller, and was my preference for the 96 B4.
It does have limitations, but provides better driveability and fuel economy (post 5th injector defeat) than the GQ.
The cracking pressure difference (190 bar for the injectors intended for the BK, 220 bar for those intended for the GQ) is so small that the effective delay in the injection timing event will not be detectable. The fuel pressure ramp up is such that the time, (or fractions of a degree) difference between reaching 190 and reaching 220 is minuscule. Both of these are 300 bar full open bodies.
I had both BK and GQ, and freely mixed them in combination with 190 and 220 bar bodies (and with stock and Sprint 520 tips) without the idle symptoms described.

 

[joskoh]

Well thanks for the replies everyone. I am not confident enough to be messing with my timing so until I can find some time with my mechanic I will leave the BK in.

The idea was to change to GQ and then in the spring install 520 tips. Then, maybe getting a chip for the GQ which I understand is much easier than trying to get one for the BK.

 

[joskoh]

Hi LugNut,

I keep thinking about what you said about not having any issues switching between BK and GQ.....

Any ideas of what could be causing the issue?? Do you think it is a bad GQ ECU??

Thanks.

 

[paramedick]

What is the IQ setting in the BK vs. GQ ECUs? You might have to adjust the IQ for the GQ to get everything right.

That value is stored in the ECU.

 

[luceberg]

My experience of this comes from swapping out a european AT for a GQ. It picked up poorly and felt retarded to me. As it was, I swapped back to the AT, so didn't adjust the timing. It may be something else, but it definitely is something.

 

[joskoh]

I thought about the IQ and used VAG-COM to modify it. It was originally set to the default of 32768. However the reading was jumping around from 0.0 to 1.x to 2.x then back to 0.0.

I tried changing the value (both up and down) which immediately changed the way the engine was running but it was still rough. I don't know if I can describe it properly here but the engine was pulsing about every second. This caused the whole car pulse.....it was actually hard to use the laptop while sitting in the car!!

It also seemed unable to get down to just above 900 rpm which is where my idle usually is with the BK ECU in there and without ANY pulsing at all. The GQ seemed to keep the engine going just around 1000 rpm.

 

[john.jackson9213]

When I changed from a BK to a GQ I had bad idle and stumbling. I had injectors rebuilt with the higher pop pressure and new sprint 520 nozzles. Did not help.

Finally had the IQ adjusted. That did the trick. Have not tried going back to the BK ecu. Yes, the 5th injector has been removed.

Just my limited experience.

 

[Windex]

The BK, once the 5th injector had been 'neutered', is a nice controller, and was my preference for the 96 B4.
It does have limitations, but provides better driveability and fuel economy (post 5th injector defeat) than the GQ.
The cracking pressure difference (190 bar for the injectors intended for the BK, 220 bar for those intended for the GQ) is so small that the effective delay in the injection timing event will not be detectable. The fuel pressure ramp up is such that the time, (or fractions of a degree) difference between reaching 190 and reaching 220 is minuscule. Both of these are 300 bar full open bodies.
I had both BK and GQ, and freely mixed them in combination with 190 and 220 bar bodies (and with stock and Sprint 520 tips) without the idle symptoms described.

Sorry to dig up this thread.

LugNut, can you elaborate on your preference for the BK over the GQ? my 96 B4V project has a BK, and I will be defeating the 5th injector shortly. I assume this is as simple as plugging the fuel line to the 5th injector and removing the line down to the manifold?