2006 xc70 persistant problem

jimpierce7 · Post by **jimpierce7** » 26 Nov 2019, 06:09

A month ago or so while performing an oil change I noticed a broken vacuum line. Big port on the intake manifold. Car was running fine prior to fixing this. No warning lights on.
Shortly after fixing the vacuum line the engine service light and check engine light come on.
P0102 and P0170 were the codes. MAF and fuel trim respectively.
When light is on it runs like it did before I replaced the MAF a year ago. I've searched for a vacuum leak and as of yet not found it. (may be having to pay for a diagnostic?)
Took awhile but the Bosch MAF finally got here.
Installed it and car went a couple days warning light free.
Then it came back on. Same codes. But, with the Bosch MAF the car doesn't run much different. It stumbles once maybe but smooths out. After a short time the warning lights will go out. By themselves.
This has become a cycle. Light comes on. Same codes. Seems to self repair, light goes out.
I took it in to smog check (light out) and the fail result was do to emissions drive cycle incomplete (catalyst). Sorry, this is new to me. I'm starting to think maybe upon completion of the drive cycle light comes on. What ever goes on it goes out and the cycle takes a bit to complete as my daily driving is nothing like what I am supposed to do to complete the drive cycle.
As I am coming up on a hip replacement surgery I'm short on time to get this done. lol Any ideas?

Post by **vtl** » 26 Nov 2019, 08:14

What do you read for the fuel trims, both STFT and LTFT?

jimpierce7 · Post by **jimpierce7** » 27 Nov 2019, 06:14

vtl wrote: ↑26 Nov 2019, 08:14 What do you read for the fuel trims, both STFT and LTFT?

I'll try to find out. I'm stopping in today to have it reread again to make sure it is still the same. As it continues.
Last time I had it plugged it, it's probably a vacuum leak, is what I was told. I may be having to invest in my own diagnostic beast.............

Post by **abscate** » 28 Nov 2019, 06:27

A fuel trim code will take a few cycles to set, so the behaviour isn’t strange, it is just the fault being detected in the normal way.

Find the leaks, new parts, check trims at idle and 2500 rpm to confirm leaks are fixed

jimpierce7 · Post by **jimpierce7** » 05 Dec 2019, 17:01

Found the problem. Never would have found it on my own. Hooked her up to a smoke machine. The intake tube. There is a sensor on it down by the turbo that isn't a turbo. The mount is it on is loose. Crazy! Hopefully I can quick fix it to get it through smog and replace it after my hip replacement come February or March.