80 Pin To 121 Pin ECM

jackfolstam · Dec 11, 2019

What are the differences between the two ECM's in terms of options and performance (is there a point to go from 80 to 121)? I want to get a tune and am debating whether it's worth it to change over to the 121 pin first because it has to be better, right? Like it's a newer design for a reason, and hopefully that's because it is better?
So far here is what i understand:
80 pin

Immo 1 (no immobilizer), don't have to pay for immo delete when swapping or tuning
no flashing, have to chip socket, one time additional charge
metal clip connectors
spliced sensor grounds
hot start problem, left foot braking 'problem'
I think I read that the 80 pin has one fuel map (2D map) or something?

121 pin

Immobilizer: pre 2003, immo 2, 2003, immo 3.
Flashing possible over OBDII.
D shaped connectors (except pre 2003 needle lift sensor)
one ground per sensor as well as other more minor harness changes
No hot start problem, no left foot braking 'problem'
I think I read that the 121 pin has three fuel maps (3D map) or something?

Thoughts:

Immo: I don't know the differences between the immobilizers but I assume I have to pay to get them deleted, as in I can't diy them out. I have an 80 pin ALH swap in a Mk1 so I just want the delete and don't have to program the ecu or keys at the dealership.
Chip socketing vs flashing: I read here a few people say they don't think the chip sockets are durable. I want to tune my car in steps, from just injectors, to injectors and turbo. This means multiple changing of the chips, and probably more to come in the future.
Wire harness: I don't want to swap out the whole harness as it is an engine swapped car, and the harness is kind of cut and spliced into the car in many different places. If I change to 121 pin I'd rather just change the ECM connector or make an adapter at the ECM connector from 80 pin to 121 pin.
Wire harness differences besides ECM connector: Same as above.
Hot start problem: I see that Malone can tune this out but does Kerma? I'm interested in Kerma because they will tune multiple times for the price of one tune if you buy parts from them.
2D vs 3D fuel maps: Is this true or just theory crafting? Called Kerma and they said no difference, local Malone dealer said no difference. I think this is the main driver to NOT swap to 121 pin.

oilhammer · Dec 12, 2019

You forgot the change to the 4-channel glow system in 2002.

Really though, I think it is likely best (in the case of a swap) to just use whatever you have available to you. I think the later ECUs require more "stuff" to work, as they are designed to work on a CAN Bus and with ABS and stuff, but I think a lot of that can be changed with software?

The immo is a non-issue... you'll be tuning it regardless to work with your application, so if it has it, just delete it. Hot restart: same thing. Fixed with a tune.

I have both (in the cars they were born with), and there is no real difference to me in the way they run and perform. The ALH is a pretty primitive engine really. It just does not need much electronic wizardry to run, so the ECU's "horsepower" is largely unused, it was I think really more to make it more homogenized with the rest of the more advanced VAG systems at the time in 2000. The 1998/99 ALH cars used a lot of leftover bits from the A3 era, the TDI ECU was one of them, sort of a hybrid between the old and new.

BobnOH · Dec 12, 2019

You may have got a bit of erroneous information (easy to do on these forums), the 121 pin is just a model change for additional features. Not knowing your application, it sounds like you have an early ALH, passive immo, and it would need "socketed", something you can do yourself if you possess those skills. To change to a 121 pin, you'd need to match each feed to the new connector in the correct pin. It would still need sent in to tune (flash), unless of course you purchase a Flashzilla device which allows multiple tunes. The hot start issue is the fuel map, which gets re-written with a tune.

jackfolstam · Dec 12, 2019

oilhammer said:
You forgot the change to the 4-channel glow system in 2002.

Really though, I think it is likely best (in the case of a swap) to just use whatever you have available to you. I think the later ECUs require more "stuff" to work, as they are designed to work on a CAN Bus and with ABS and stuff, but I think a lot of that can be changed with software?

The immo is a non-issue... you'll be tuning it regardless to work with your application, so if it has it, just delete it. Hot restart: same thing. Fixed with a tune.

I have both (in the cars they were born with), and there is no real difference to me in the way they run and perform. The ALH is a pretty primitive engine really. It just does not need much electronic wizardry to run, so the ECU's "horsepower" is largely unused, it was I think really more to make it more homogenized with the rest of the more advanced VAG systems at the time in 2000. The 1998/99 ALH cars used a lot of leftover bits from the A3 era, the TDI ECU was one of them, sort of a hybrid between the old and new.

Thanks Oilhammer, I appreciate the advice. I have gotten a 121 ecu from the yard as well as an ecu pigtail, and early ecu socket so I could make an adapter. I haven't yet researched what is necessary to make the 121 happy enough to run with minimum equipment, such as ABS etc. You have a point, that I don't want to mess with CAN bus.

jackfolstam · Dec 12, 2019

BobnOH said:
You may have got a bit of erroneous information (easy to do on these forums), the 121 pin is just a model change for additional features. Not knowing your application, it sounds like you have an early ALH, passive immo, and it would need "socketed", something you can do yourself if you possess those skills. To change to a 121 pin, you'd need to match each feed to the new connector in the correct pin. It would still need sent in to tune (flash), unless of course you purchase a Flashzilla device which allows multiple tunes. The hot start issue is the fuel map, which gets re-written with a tune.

Thanks Bob, it didn't quite dawn on me that the hot start 0 fuel thing would be fixed in every tune regardless, but that makes complete sense. I do have access to a hot rework station, and I did get some Quick Chip to diy the socketing, but I just can't find the correct chip socket to purchase.

BobnOH · Dec 13, 2019

When you purchase your tune, don't assume anything. Those chip sockets are hard to find. You will still need to send the ECU to the tuner.

jackfolstam · Dec 13, 2019

BobnOH said:
When you purchase your tune, don't assume anything. Those chip sockets are hard to find. You will still need to send the ECU to the tuner.

The guys at Kerma said over the phone that they have done chip socketing for a long time. I understand that if I socketed my own ecu that I would still need to get a tune from someone. The Malone dealer also said that he sockets the ecus personally and that they are no big deal for him.

turbocharged798 · Dec 14, 2019

BobnOH said:
When you purchase your tune, don't assume anything. Those chip sockets are hard to find. You will still need to send the ECU to the tuner.

I found a whole sticks of PLCC32 sockets on closeout for real cheap so I stocked up. Problem is that package is pretty much at end of life in the electronics industry.

turbocharged798 · Dec 14, 2019

Digikey has the sockets in stock:https://www.digikey.com/product-detail/en/assmann-wsw-components/A-CCS-032-Z-SM/AE11105-ND/5023769

jackfolstam · Dec 22, 2019

turbocharged798 said:
Digikey has the sockets in stock:https://www.digikey.com/product-detail/en/assmann-wsw-components/A-CCS-032-Z-SM/AE11105-ND/5023769

Thanks, ordered some.

compu_85 · Dec 23, 2019

oilhammer said:
I think the later ECUs require more "stuff" to work, as they are designed to work on a CAN Bus and with ABS and stuff, but I think a lot of that can be changed with software?

The 98 / 99 Mk4 ECUs do have CAN, and do talk to the ABS / TCS / ESP systems over CAN. I think they talk to the transmission computer over CAN as well.

Unlike the later cars, CAN is not used to talk to the instrument cluster.

-J

oilhammer · Dec 24, 2019

My '99 has no CAN Gateway. I have never seen a '98 or '99 ALH that did. The ECU communicates via pins 9, 19, 29, and 35 with the TCM (where applicable). The '97 Audi A6, which debuted in middle '97 model year, was one of the first I know of that did have a CAN Gateway. Much of that car's tech spilled over into lesser VAG models as time went on. Hard to keep track of as things did not change all at once.

That is what I meant by "CAN", the application of an actual Gateway. The later cars of course streamlined this further.

turbocharged798 · Dec 25, 2019

What is funny is there is can wires running to the cluster but they are not used. I put a can cluster in my 99.5 and it worked straight off aside from the lack of airbag light.

compu_85 · Dec 27, 2019

Yup. There is no gateway, but they do have & use CAN. That's how I was able to add ASR to my 99.5.

Thanks,

-J

80 Pin To 121 Pin ECM

jackfolstam

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oilhammer

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BobnOH

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jackfolstam

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jackfolstam

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BobnOH

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jackfolstam

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turbocharged798

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turbocharged798

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jackfolstam

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compu_85

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oilhammer

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turbocharged798

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compu_85

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