max89

My Audi Q5 shows misfire with check engine lights on. I have replaced all 4 spark plugs and OEM Coil. But still it shows the same. I experience this issue when I go for a log drive. How many more miles I can drive with this condition?

A6Gary

Which engine do you have and what is the mileage? The misfire(s) could be due to carbon buildup on the intake valves. Also, did you replace all coils only only one that was suspect?

S4'ed

Does it only misfire when the engine is cold?

jaims

Less likely cause is head gasket leak between cylinders.

The OBD II system will identify the cylinder(s) that are not contributing their *normal dose of power and set a code that corresponds to the firing order. A P0303 code, for example, would tell you that the No. 3 cylinder is misfiring.

max89

Thank you so much for all your input. I am not very familiar with the hardware, service parts and diagnosis. Audi dealer changed the spark plug and OEM coil as per their primary troubleshooting as they could not find the root cause and they took more than 5 days to complete this. Which did not work. Then after the second diagnosis, they told me that its the time chain (Needs replacement) which might cost around $4000. I did not fix it from Audi. I took the diagnostic report and show it to the local garage where I visited last 2 time. The Mechanic also pointed it to the time chain after his diagnosis and said this is a common issue with Audi when hits around 100k miles and the mechanic quoted me $1400, but he said he needs 3-4 weeks as this is a major engine works and he does not have enough staff. Could you please help me to confirm that is it normal to take 3-4 weeks to work on engine to replace time chain? Will there be an issue soon after replacing the time chain? Mine is 2013 Audi Q5 with 115K miles now. I have almost spend $10K in the past 4 years just for the repair in which I spent almost $4K in the past one year (or when miles exceeded 100k). Honestly, I loved this Audi, Its so comfortable to drive when there is no breakdowns. Do you think its time to get a new car for me? or continue using the same car after fixing the issue with a 3rd party warranty? Thank you so much.

uberwgn

Max, how much oil is it consuming?

It sounds like timing chain stretch is part of the problem. The actual "stretch" can be measured with a diagnostic tool. Once the chain is too far gone, the engine can no longer compensate for the stretch and the car doesn't run right or won't start.

The timing chain replacement might be the tip of the iceberg for you when it comes to near-term engine repairs. You're likely right at the point where things are about to go critical...

max89

@uberwgn
Thank you. It consumes a decent amount of oil. I have to top up 1 Qtr every 3-4 weeks or every 500-600 miles.

uberwgn

Max, it seems like this has to figure into your overall repair thought process and how much you are willing to spend to correct these somewhat serious problems.