1.4 petrol poor idle issues
- Thread starter Azim
- Start date
PlasticMac
Admin Team
I'm not able to answer the question in detail, others may do.
The big difference that I'm aware of is that the AUA has a single coil pack, and fires two cylinders at the same time, both the one that is charged any ready to burn, and the other that isn't. This is not a problem, in the AUA, as it's as designed. The BBY has individual coil packs, one per cylinder. The interface between the ECU and the coil packs must be different.
That's why I've wondered if the ECU was swapped. It is not a simple plug and play swap, so if it was done the job would need special software, not just VCDS, and a degree of expert knowledge.
Apologies for going on a bit!
Mac.
I just spoke to the garage that installed the engine .
The owner brought a AUA engine complete and asked the garage to fit it .
Tha garage fitted it as requested and the engine failed to start .
So it seems the A2 has a AUA engine complete fitted with the original BBY ecu .
The car failed to start after the conversion .
What do I do now ?.
The owner brought a AUA engine complete and asked the garage to fit it .
Tha garage fitted it as requested and the engine failed to start .
So it seems the A2 has a AUA engine complete fitted with the original BBY ecu .
The car failed to start after the conversion .
What do I do now ?.
PlasticMac
Admin Team
Isn't it the other way around, started as AUA, then had a BBY, (individual coil packs), fitted?
Mac.
PlasticMac
Admin Team
According to 7Zap:
The AUA ECU is either 036997034AB, or 036906034EH.
The BBY ECU is either 036906034CA, or 036906034FE.
Mac.
The AUA ECU is either 036997034AB, or 036906034EH.
The BBY ECU is either 036906034CA, or 036906034FE.
Mac.
It seems the original engine was a BBY and was replaced with a AUA
Yes it does have single coil packs .
Im also confused now .
I dont know how different the heads are on these two doffent engine codes ..
Weather you can fit single coil packs on a AUA engine ..
Ill check what my ecu is and get back to you ..
My ecu code from my vcd scan confirms its the 1st one on your BBY code list 036906034CA
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PlasticMac
Admin Team
That's promising, hopefully the physical part will match.
Mac.
birtyA2
A2OC Donor
This is useful from German wiki
wiki.a2-freun.de
If I have understood correctly the original engine was a BBY and was replaced with a AUA. Certain parts from the original BBY were swapped on to replacement AUA. From this article there would appear to be subtle differences with the fuel rail, air box and of course a move to individual coil packs but otherwise broadly the same
J
Unterschiede AUA BBY – A2-Freun.de Wiki
If I have understood correctly the original engine was a BBY and was replaced with a AUA. Certain parts from the original BBY were swapped on to replacement AUA. From this article there would appear to be subtle differences with the fuel rail, air box and of course a move to individual coil packs but otherwise broadly the same
J
Yes BBY to AUA .This is useful from German wiki
Unterschiede AUA BBY – A2-Freun.de Wiki
If I have understood correctly the original engine was a BBY and was replaced with a AUA. Certain parts from the original BBY were swapped on to replacement AUA. From this article there would appear to be subtle differences with the fuel rail, air box and of course a move to individual coil packs but otherwise broadly the same
J
Im not sure how much of the BBY parts were used .
Yes it does have the individual coil packs and possibly other parts from the BBY engine .
How ever the garage did tell me they installed a complete AUA engine .
The parts list does show 4 brand new coil packs installed .
Proghound
Admin Team
Reading back through this thread, the car is a 2002 and therefore originally an early BBY. The engine in that's in the car now still has individual coil packs, but the replacement engine was an AUA from a 2001 car. So to make it run at all, they must have had to fit the BBY coil packs to it so that it still looked like a BBY to the ECU. They must have been able to do that without having to change the entire head, as the BBY head would very likely have had bent valves after the cambelt failure and the labour even to investigate would have been prohibitive. So it now has single coil packs again, but possibly not fitted the way Audi intended.
A couple of possibilities occur to me. One, might there be some difference in the output of the various sensors attached to the head and/or block between AUA and BBY, that's causing the BBY ECU to struggle to fuel it correctly? Or two, if there is any difference between them, have the correct spark plugs for an AUA rather than a BBY been used in the recent replacement? I once had a recon engine in one of my cars, and the place that supplied and fitted it used spark plugs where the nose was shorter than standard. It was OK-ish out on the road, but idled roughly.
A couple of possibilities occur to me. One, might there be some difference in the output of the various sensors attached to the head and/or block between AUA and BBY, that's causing the BBY ECU to struggle to fuel it correctly? Or two, if there is any difference between them, have the correct spark plugs for an AUA rather than a BBY been used in the recent replacement? I once had a recon engine in one of my cars, and the place that supplied and fitted it used spark plugs where the nose was shorter than standard. It was OK-ish out on the road, but idled roughly.
You may have something there .
I did order spark plugs for my original BBY engine using my reg number at the motor factors .
I wonder if the spark plugs for a AUA are different to those of a BBY .
PlasticMac
Admin Team
That's a bit of deduction, Poirot himself would be proud of Ian.
That the engine could well be a mongrel.
Looking at 7Zap, the head, camshaft, (but possibly not the crankshaft sensor), seem, to me, to be the same parts, on both AUA and BBY engines.
So it might not be such a bad combination. After all, it did start and run, albeit not very well.
I reckon to give it the benefit of the doubt for now, and concentrate on the basics, fuel, compression, and sparks.
Mac.
Edited in italics
That the engine could well be a mongrel.
Looking at 7Zap, the head, camshaft, (but possibly not the crankshaft sensor), seem, to me, to be the same parts, on both AUA and BBY engines.
So it might not be such a bad combination. After all, it did start and run, albeit not very well.
I reckon to give it the benefit of the doubt for now, and concentrate on the basics, fuel, compression, and sparks.
Mac.
Edited in italics
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PlasticMac
Admin Team
Looking at 7Zap, there's a part called the trigger ring, which drives the crankshaft sensor. Although it is marked 14, it doesn't appear in the parts list, looks to be part of Group 13. What caught my eye, is that there are two alternatives, one of the few parts that have alternatives.
That may tie in with the different spark timing, (two at a time versus one at a time), that seem to be the main difference in the two engines.
I think you'd need a BBY crankshaft sensor trigger ring, to match the BBY ECU, and 7Zap has several options for the crankshaft sensor, too but the dates along side them don't match the build dates.
As the only DTC we have refers to the crankshaft sensor signal, the sensor and it's trigger ring need further investigation.
Both parts pictured below.
Mac.
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birtyA2
A2OC Donor
Interesting. @Azim, whilst testing for sparks would it be possible to take a few photos. In particular the BBY cam cover has a vent that isn’t present on the AUA and the fuel rail and air box is also different. It would be useful to establish if possible what may have not been swapped. @PlasticMac That is a good find, I wonder if it is related to the fact that the AUA fires twice as often?
J
J
PlasticMac
Admin Team
My guess would be yes, but it could be in the ECU itself. Can't find any details of the trigger ring though, as no part number to play with.
Mac.
I might take the new spark plugs out and compare them with the old ones.
Heresa picture of my mongrel AUA enine
Attachments
PlasticMac
Admin Team
Might be able to see what's coming from the Crank Shaft sensor via the appropriate measuring block, while turning the crank by hand. (plugs out).
You'd expect 4 blips per rotation ... if all is well down there. Other than a lot of spannering, probably the only way to check, and rule it in or out.
Engine Group 001, Block 1, I think.
Mac.
how about trying the BBZ which is similar in the 9N Polo - does this help at all?
Bit of a parts number swerve, but is it possible that if you get the appropriate flange / seal component that it has the appropriate magnets integrated into the seal for the sensor to detect (similar to ABS rings inside the hubs)? So you just need the one-piece seal component?
ie, a similar part on the 1.9tdi :
so we don't need to know the part number for the trigger ring itself as it should be built in.