2a4sowner

I have a 96 Audi A4 that I am doing an engine and transmission swap on. The car was a 2.8 with a Triptronic automatic. The engine's camshaft broke while driving so I am putting in a donor 2.8 engine (both old and new AFC enigne codes) and a 5 speed manual transmission from a same year/model donor car. I've been able to install the engine, clutch and transmission. I've figured out how to bypass the neutral safety switch to get the engine to crank and get good fuel pressure but cannot get the car to start. I get full time positive to the fuel injectors but no pulsing negative to get them to fire. I also get no spark to the plugs. I've checked the Bentley recommendations for resistance testing the ignition control module, crank position and speed sensors and they test out fine. I have the ECMs from both cars but neither changes the no injector, no spark condition. I have a good scan tool but not a VAG-COM tool. I've read that I need to reprogram the ECM, but would not programming the ECM cause the no start I am experiencing? I've been at this project for weeks and am stuck with these current no start conditions. Does anyone have any tests/ideas that I can try or sites that may help me? I really don't want to tow this thing to a stealer but I'm running out of ideas. Thanks!

mtroxel

Hate to say it but......you're really spinning your wheels without a VAG-COM. Without that you are really guessing.

2a4sowner

Mtroxel, I agree having a VAG-COM would definitely help tell me more. I am hoping that someone in the forum has performed a similar swap and can help guide me through the pitfalls they may have gone through. One of the nagging issues I've seen while researching this kind of swap online is that some folks say you have to reprogram the ECU and others say you dont. One of the biggest questions is should the car start without the reprogram, or am I chasing a ghost by trying to figure out my no-start condition without doing the reprogram. As I stated in my first post, I have the ECU for both the automatic and the standard transmission, but putting it in an automatic based car. I don't know if that makes a difference for the ECM. Also, if someone in the St. Louis area has a VAG-COM they'd be willing to hook up, the beer and/or beer $$ would be on me... no problem.

mtroxel

I've swapped some engines on Audis, but never done a sex change (auto to manual). And here's what I'm not clear on. In your first post you said you had both ECU's. I assumed you put the ECU from the manual donor car into the car that received the manual. Is that right?

If you brought over the ECU from the manual, did you also bring over the entire wiring harness? In paticular, I'm thinking of the clucth switch that tells the ECU you're pressing on the clutch. If not, that alone would put the ECU in a "don't start" mode.

Or do you have an ECU from the original auto trans car now trying to start an AFC with an auto?

2a4sowner

OK, In answer to the first question, yes I did bring over the manual ECU. I've attempted to start the car with both manual and the automatic ECU and got the same no injector-no spark condition. I put them in another A4 with an automatic transmission and that car started the car just fine. So I am confident the ECU's are good.

Also, I did bring over the manual main wiring harness from the manual donor car. This is the wiring harness that goes from the ECU box to the injectors, sensors, etc. in the engine bay. The difference between them is that the original wiring harness has one extra wire. One end plugs into the automatic transmission and the other end plugs into the blue plug in the right hand side of the ECU box. My Bentley tells me these are for the automatic transmission if I remember correctly.

I have also swapped out the automatic pedal setup with the setup for the manual clutch pedal setup from the donor car. I have not wired up a clutch pedal safety switch yet. I'm currently able to crank the car by gounding the clutch safety wire (a brown wire with a blue stripe behind the passenger kick panel).

If anyone knows how to set up or bypass a clutch pedal safety switch a better way, that may well fix my problem. I've seen bypass setups for transmission swaps for other years Audis but haven't been able to find how should be setup for a 96 A4 2.8L. If you have ideas about how I can tell if my current neutral safety bypass is leaving my car in "no start" mode that would be great too.

Thanks for the response. I appreciate your interest.

moloveshisaudi1254

My '96 A4 among others did not come with the clutch pedal safety switch. I can start the car in neutral with clutch engaged. One of my family members also has once by accident attempted to start the car with clutch engaged and car in gear. It cranked and jumped forward. There is one switch by the clutch to deactivate cruise control once the clutch is depressed. If you can still get the car to crank without grounding that brown/blue wire then your problem isn't the clutch safety switch. That wire may be for the cruise control switch behind the clutch and if so, it is unrelated to the issue at hand.

2a4sowner

Thanks for sharing your experience with the clutch safety switch. When I did the motor/trans swap, the car wouldn't crank when turning the ignition, so I was originally cranking the my car by removing the small crank starter wire off the starter and supplying 12 volts to it to get it to crank. With the ignition set to on and applying 12 volts to the starter crank wire it would crank fine but wouldnt start. I grounded the brown/blue wire so that the car can now be cranked by turning the ignition switch but still sitting at the no start condition. I've seen posts where owners have jumped wire on other year/models to bypass the switch but not seen the setup for my car. Like the user before stated, the way Im doing it now may allow me to crank, but still may leave the car in a "no start" mode. I just don't know how to determine if this is the case. Thanks for the reply.

shah 23

Hi .just wanted to know if you got the 2.8 started& if so what was the problem.