NEVER EVER EVER start a car with no coolant in it. This could ruin the engine. EVEN just starting it. Take an empty soda bottle and put a flame next to it. You melt a hole through it. Now fill that bottle with water and hold a flame to it. It will not burn through. Even a few revolutions of the engine could cause some hot spots on cylinder walls which will not wear same as rest of cylinder and hot spots on head. These could lead to cracks. Hook radiator up. and make sure there is no air in system

 

Well I got everything hooked up and still nothing. I do have a cheap vagcom but I borrowed a scantool from the body shop nextdoor that is much better than mine and it wont read the ecu at all. I have used their scantool many times so I no its good, I even tested it tonight on my other audi. My buddy said it would be a BIG coincidence that the ecu died at the same time that engine blew . I think I may know whats going on, this car was parked at an import repair place for like 6 months so I stopped in one day and asked about the car and they put me in touch with the owner so I bought it from him. Since the car sat there so long I wonder if the repair shop needed an ecu for a different audi and swapped them. If the ecu is fried i'm assuming that no signal will go to the injectors. Any ideas?

We also pulled the fuel rail and tried to start the car to check if the injectors were firing and nothing comes out of the injectors at all.

 

One more thing, I was thinking maybe bad gas so I pulled the fuel line off just before the fuel rail and turned the key to the start position and it sent a little fuel out then stopped. I thought if I did this it would keep sneding fuel until I turnedthe key off. I had to turn the key about 500 times to get 3 gallons of gas out and gave up and added 5 new gallons of gas. Is this how the audi fuel system works?

 

The new engine is from a 99a4 1.8t and my car is a 98a4 1.8t.

 

if your ecu is 'fried' your igntion wouldnt even work, you wouldnt have any lights on your dash or anything!

for the scan tool.....
when you scan for codes what does it say? cannot communicate with the ecu? you do have the key to acc right (lights on and flshing on the dash)?
do an automatic sweep and hold the cables in place at each sokcet very tightly, sometimes they can be loose and the vag-com will losses connection to the ecu.

check your ICM and coil packs!! check the ICM first. if its not getting a spark it wont send fuel.
you know that your next problem is going to be a flat battery right, inevitable. keep charging it up. just a heads up on that, hopefully that has already crossed your mind.

 

scan tool says somrthing like no connection, key is at acc position. I will check icm and swap coil packs tomorrow. Bought a new battery today.

Any other ideas?

Thanks.

 

since its a 98 im putting my money on a fried ICM. the ICM is a comman fualt in the early B5's where as the late B5's the coil packs are the comman fualt with the engine miss firing, rough idles, or not starting at all.
you should be pulling codeson all this, left, right and centre.and there'll be about 4 codes on the ICM if its fried. if it is the ICM, the price of a new one can range anywhere between $100 and $300 new. i got a used one off ebay for $25, works PERFECT and solved my problems!!

also, the scan tool not working properly could either be user error, the scan tool itself playing up, or an error in the ecu.
at this point, since you cant get the VAG-COM to work properly, it might be a good idea to get the ecu scanned by a machanic, it'll cost but i have a feeling getting the codes scanned one way or another is going to answer all of our questions.

 

spark/air/fuel you say the injectors work but no fuel? that tells me the fuel pump isnt working because there is no fuel pressure

 

Nevermind

 

I now have tried the scan tool and my vag-com about 30 times and it just wont read the ecu but it reads it just fine on my other audi. Is there anything that would cause the ecu not to scan other than the ecu being bad? I just bought another ecu on ebay just in case and it should be here Tuesday or Wednesday. I will look in my bently manul and check the wiring in between the ecu and the scan port to see if there is something else that would cause it not to scan. Thank you very much for all the replies. Any other ideas?