Standard ABY ECU and over boost function in Type 85 Audi 80

[HenryG40]

Hi,

I recently picked up a Type 85 80 with an ABY fitted, off this forum as it happens.

I'm in the process of sorting out lots of little issues with the body/wiring/conversion bits. The engine seems to run OK on the road but I have a few questions:

What is the standard boost pressure for an ABY motor?
What controls the overboost function?

For example, my boost pressure peaks at 0.7 bar but not once have I been able to reach an overboost function. I'm trying to hunt down a boost leak test kit but I'm curious as to how the overboost is activated.

My short term goal is to rectify this issue and swap out the EPROM when the engine is running OK. Do aftermarket maps run increased boost pressure all the time? or is the Overboost setting mapped out of the car at this point? I appreciate that this may be different depending on each map.

Thanks

Henry

[K Simmonds]

I'm pretty sure you should be seeing around 1 bar normal max boost with up 1.2 bar on over-boost, 0.7 is low do you know if that's with the N75 plugged in and has the top of the wastegate been tampered with?

It's quite likely that you have a boost leak.

[5cylinderman]

From memory, to activate over boost you must have WOT before 2,000rpm.

[HenryG40]

The N75 appears to be connected and wastegate untampered with but I will double check this when I get home. I really need to get my hands on a boost leak kit to at least rule this out before moving on.

Thanks for the info.

I think I made an error in my first message, I meant to say
"Do aftermarket maps run continue to run the overboost function? or is the Overboost setting mapped out of the car at this point? I appreciate that this may be different depending on each map.

[UrS4boy]

What is the standard boost pressure for an ABY motor?
What controls the overboost function? For example, my boost pressure peaks at 0.7 bar but not once have I been able to reach an overboost function. I'm trying to hunt down a boost leak test kit but I'm curious as to how the overboost is activated.

There is boost and overboost. Overboost is 2.15 Bar (for 15 seconds, if the engine is at 2000 RPM or more when the throttle is mashed down completely). This is absolute pressure not not relative pressure so

Overboost = (2.15 x 14.5)-14.7 = 16.48 psig (about 1.14Bar (17 psig) on a mechanical gauge). At 0.7 Bar, you are just over the stock waste gate mechanical boost max of about 0.4 Bar. You have a boost leak. See link below.

ABY boost leak testing (you can make your own kit BTW):http://www.s2forum.com/forum/showthr...t+leak+testing

[mouse]

"Do aftermarket maps run continue to run the overboost function? or is the Overboost setting mapped out of the car at this point? I appreciate that this may be different depending on each map.

No, as far as I know all (?) tuners delete the overboost function (certainly Homefried and Prj chips).
It is an annoying marketing gimmick anyway as you are never sure if/when it will kick in on a stock car.

[HenryG40]

Managed to build myself a boost leak test kit and found a leak on one of the injector seals. I'm not sure that it's big enough to cause the loss of boost i'm seeing but it bubbled up a fair bit when sprayed with a soapy solution. Have ordered a pack of ten from here:

http://simplybearings.co.uk/shop/p512710/BS203+3.53mm+Section+7.52mm+Bore+VITON+Rubber+O-Rings/product_info.html

Will replace these and then carry out the test again to see if I can find any other leaks.

Cheers

[UrS4boy]

Injector inserts and seals info

Managed to build myself a boost leak test kit and found a leak on one of the injector seals. No idea if it was big enough to cause the loss of boost i'm seeing but it bubbled up a fair bit when sprayed with a soapy solution. Have ordered a pack of ten from here:
http://simplybearings.co.uk/shop/p51...duct_info.html

Ha. You made me check with my friend Kate, the friendly parts girl, who is in at work on this lovely Saturday. She says Item 20 below, PN 035906149A, is the one to order and that the O-ring seal size is 7.52 x 3.53, the same as the aftermarket ones you are getting. She says that they are about 2 GBP a pop in her system.

Boost leaks can also occur through cracked injector inserts. Here is a link to a post I did about replacing and sealing these injector inserts on an AAN:

http://forums.quattroworld.com/s4s6/msgs/266127.phtml

[HenryG40]

Yeah, I saw the price of the deals from the dealer and had to look around, £2 for a little rubber ring is extortionate!

Thanks for the link by the way, a very useful guide for many things. I think I'm going to go and do some more boost leak checking whilst it's setup for it. I would be surprised if i'm losing 0.3 bar through the injector seal/seat. It doesn't help that the airline has a slight leak which makes it difficult to listen out for additional leaks!

Cheers

[HenryG40]

So 2 more leaks found, 1 of them fixed and the other is what appears to be the ISV casing, much like the other in the photo on your guide. Is this fixable or is the only way to replace?

So no significant leaks, but I guess the combination could certainly cover the total loss.

ISV leaking




Injector leak - you can see someone has tried to seal this with sealant before


Homemade test kit