SSSS8

I have a 2003 s8 that is the devil. The engine blew 3 month after buying it so I bought a junk yard engine for it and swapped the intake and most of the sensors all of the plugs and coils. At the junk yard it had a hard time starting but had vacuum leaks galore After installation the car cranks and cranks and eventually after 5 or 6 try's starts runs rough and if you give it throttle it dies. It will start right up and idle for a while, on starting fluid when cold. How ever it starts right up once warmed up. I checked the fuel pressure at the rail it was 5- psi and 75 psi dead head, and it drops off to near zero over night (I now think my gauge leaks down). I pulled the injectors out after ohm testing them (11 ohm) and put each one in its own bag and pressurized and bleed the rail. Then I let it sit for 3 days checking for leaks, no leaks. I replaced the fuel pressure regulator, no change. Next I replaced the pump and filter. no change. for good measure I put a mechanical check valve in front of the pump about 2 inches away from it. Still cranks and cranks. I have no check engine light on, and it runs good but feels a little light on power at the very top end. I am Starting to think the egr or Lambota valves might be hung open just a little. Has any one ever seen something like this? I think I might have seen it in a Steven King movie once.

Y888

Crank position sensor?

SSSS8

Thank you for your input I really appreciate any help at this point. I am ready to whip one at it too. My thought was that it would trip a check engine light.

the_duke

CPS almost never presents a code.

SSSS8

Cool I will give it a try this weekend. Thank you for your help.

SSSS8

I did verify that it has spark and injector pulse when cranking and capped off the EGR. Still think it is a CPS, possibly throwing the timing out? I'm going to try one cause why not at this point. Grrrrr.

iamshayan

Did you check timing when you got the motor. Not sure if you did the belt and w/pump service before installing but its possible that it went out a tooth or two when the wrecked car was hit.

Another good place to start would be pressure at the rail. I know you said you have injector pulse but do you have fuel at the rail?

While a Crank position sensor is possible. In my experience, the engine will fire 1/5 tries as the Cam position sensor should still pick up the trigger. At least it was this way for my 1.8t - I could be wrong.

Also is it possible that wires were pinched when installing the new motor?

Have you tried preforming VCDS Output tests to make sure each sensor is working properly.

also try - key on - 12v but no start. pull the throttle body boot. check that the butterfly actuates when you move the pedal.

Have you tried hooking up a vac gauge to see if you have sufficient vacuum?

Just some things I would check. Not sure if I'm on the right track but figured I'd give me $0.02

SSSS8

Coolant temp sensor fixed it. Thank you all for your help with this.

Y888

Great,im ordering spare one just in case.