Motor swap tuning issues
 

Hello All

I bought a 99 A4 quattro some time ago. It had a burned up 2.8l 30v in it. Recently I replaced in with a 30v from a 2000 A4.

I cannot get this thing tuned. It wont start unless i give it some gas. Once running it idles at about 400ish rpm. It hesitates really bad down low, once over 2000 rpm all is good.

I did plug in a obdII scanner and it pulled a p1545 code which is a throttle body code. I have been reading that I need to hook it up to a VAG-com to get the throttle body reaquanited with the ECU. Wondering your guys opinion.

I did do a timing belt swap on this car. I did not use the cam holder. I marked points on the gears and the old belt. I counted teeth on the belt, transfered that to the new belt and lined everything up. I rotated the motor over a few times, everything seems ok. I am going to do a compression test on it, to see where my numbers are at. That should verify if I am a tooth off????

I did notice the engine wiring harnesses were different. I could not get the 2000 harness to plug into the plugs by the ecu, so i have to remove it and use the 99 harness. Also the throttle bodies look different from the two motors. Is there a difference between these motors? are they not compatible?

Any help or insight would be appreciated
Thanks in advance
-Jason

They are different the 99 is a AHA motor and the 00 is a ATQ

Attachment 35844

Are you using the harness/ecu/sensors/TB that are for the 2000 motor?


Yes a compression test will tell you if your off a tooth, compression will be low if the valves are opening at the right time.

Thanks for the responses. I looked on the passengers head, and it is stamped AHA, so I am off on the year, maybe a 98 then. So far all I have noticed in differences is the engine harness, and possibly the throttle body. Im still trying to remove the tb from the new motor so I can look at it close up.

In my efforts to tune this car, I did notice the tb and the intake tubes from the new motor were extremely dirty (for an intake). I wiped out the tb (which I cant tell how clean it is, since its on the car) and used the old intake tube.

I am using the harness and ecu from the original motor set up. TB and sensors are from the new motor. I cant use the harness from the new motor, it will plug into the ecu, but it will not plug into the other four plugs in the ecu compartment.

Can anyone comfirm the VAG-Com.

I am much more accustom to wrenching on Japanese stuff, Audi is becoming frustrating

Thanks again
-Jason

THe list above shows the AHA is used on both the 98 and 99.

Might want to try all of the sensors and TB from the old engine if your still using the old ECU. But if the sensor/TB part numbers are the same it shouldn't matter.

Ok, I pulled the tb, it looks identical. other than it is dirty. I did a comp test with the tb removed, cold motor, all plugs removed and counted ten revolutions for each cylinder. High was 195, low was 175, all others were in the 185-190 range. Would I see these numbers if the timing was off? Seems like they would be really high, or really low if it was.

So I am thinking it could be,

-this Vag-Com thing
-stuck/dirty injectors
-Dirty fuel filter.

The new motor and the car have been sitting for a long. the car was sitting for over a year. I got damn near all the old gas out of it, which smelt like varnish. It does have new gas now. But when I comp test, there really wasnt a strong smell of gas.

The plugs (which have all of ten minutes of time on them) are sooty, more so then they should be. And I noticed a lot of sooty watery exhaust coming out the exhaust (didnt smell like coolant)

-Jason

bumps son. No one has done a motor swap before? I am sure the ross tech equipment is awesome, but shelling out the $ for it and not solving the problem will awful

-Jason

Just to update, cause I know when I am searching, I hate coming to a thread that doesnt have an ending. So you never really know what happened, if the problem got fixed, the car burned up in a fire, the owner died...etc.

I cleaned the Throttle body, and tried to do a manual adaptation. Was never successful. It did start and idle better. Made no power and had a back fire.

I took it to an audi specialist, they hooked it up to the VAG-COM and all is well.

-Jason