Technicians are at a disadvantage when a customer’s car has already been to another shop without resolution. They have to figure out what was done, and what to do next. SureTrack community member patriot tech had an Audi A4 in the shop that wouldn’t run and some parts had been replaced by another shop. They posed the question to the community, and with the help of fellow community member DAG1365 and others, they were able to resolve the issue quickly.
The following Community Fix summarizes the interaction between members of the community that led to the solution.
Vehicle
2013 Audi A4 Premium Plus Quattro
Title
Will not run, replaced timing chain and guides.
Complaint
Customer states that vehicle is not running.
Diagnostic Steps Performed/Parts Replaced
Car was towed in not running from another shop. Looks like they replaced the MAF, CMP sensor and fuel pressure regulator valve. It would crank with very little resistance. First I did a dry compression test, and all cylinders were at 30 psi. Did a wet compression test and got them all up to around 100. Still wouldn’t fire, but sounded like it wanted to. So after sitting over the week, I decided to push it in to continue diagnostics and low and behold, it fired right up. Smoking of course. So I changed the oil, which was reminiscent of diesel oil (really thin and smelled of fuel). Took it for a drive and would barely move until it got up to 3000rpm and then felt normal. But at lower RPMs it feels like the exhaust is plugged solid. Waiting for it to cool to check back pressure. But it does keep coming up with a CMP/CKP correlation code (P01600)
The only test I could find says its for P01604 but seems like the proper test. The first step says to unplug the CMP sensor and check terminals “1 to 3” for voltage. Specified value is about 5.0v. So I checked all 3 terminals and the first 2 have 4.9v but the third (black wire) has no voltage. Looking at the wiring diagram shows the black wire going back to the ECM and splitting to the knock sensor. To me it looks like this wire is a ground. It also looks like it goes to the shielding for the knock sensor. But of course there is no description in the wiring diagram at the ECM. Is this a ground or should it have 5v???
Best Answer from Community Member DAG1365
With cam/crank correlation code, and not running good until above 3000rpms, and now not running, I would check to see if it is out of time by a couple or more teeth. If you still suspect exhaust, drop it from converter or manifold, remove O2 sensor if needed.
Cause
Ended up being that the timing chain had stretched to the point that the tensioner was hyper extended.
Correction
Replaced timing chain and guides. Test drove vehicle and it operates as it should.
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