Hello all. Happy Holidays.
I keep getting Codes P0171 and P0174 - Lean mixture on both banks.
I did a smoke test, vacuum check, fuel pressure test, replaced fuel filter, cleaned the MAF sensor with MAF cleaner, checked for air ingress after the MAF and the codes keep coming back. My thoughts are that maybe the MAF sensor is not doing its job and based on many posts on the forum maybe I should replace it .
The MAF sensor on my car is a Denso # LNE1620CB and the other # is 197408-0011. On the Denso site they have # 197-6040 as the part for my car. Has anyone used this Denso Part successfully?
Searching the internet I see lots of MAFs for the XK8 . The prices range from $30 to $ 270. for different brands.- used, remanufactured and new.
I would love to go with the correct one for my car so I am seeking your learned advice on which one I should purchase. I do not want to buy one that would result with the same issues I am having as is the case with many posters.
Anyone with the correct info, please post.
Thank you,

 

Ideas:
1. check freeze frame data to see when the codes flag
2. check fuel trims (hot engine, at idle & then rev for a few secs to about 2500)

With #2 if they're not within 5 of zero and then drop when you rev you're almost sure of air leak(s)

 

Years ago when I had P0171 and P0174 codes on my wife's 2006 XK8, it was due to failing external VVT solenoid O-ring seals. If yours are seeping oil, you can bet they are also leaking air. They sit there and bake in the engine bay heat and get hard and brittle in just a couple of years. I believe I am on my fourth pair now....

 

As stated in POST #1 "I did a smoke test, vacuum check, fuel pressure test, replaced fuel filter, cleaned the MAF sensor with MAF cleaner, checked for air ingress after the MAF"
Engine was rebuilt last July and all gaskets and o-rings replaced with new ones.
Given that I have no air leaks and every other item is within specs, I am only surmising that the MAFS is not performing as it should. I am going to keep test driving the car until I figure out what's going on. Given that the MAFS is 24 years old, I think its time to replace it with a new one.
So back to my original question. Which MAFS brand/part number is the correct one for my 2001 XK8. I don't want to buy one that only works for a short period of time.
Some MAFS have been proven good by forum members and other MAFS not so good.
Even though well intended,the ideas of checking fuel trims, air leaks and every other test does not apply to the original question.............
"Which is the correct MAFS to purchase for my car? Should the brand be DENSO or DELPHI
Thanks.

 

I would buy Denso.

. The Denso 4.0 XK8 MAF is not expensive, as it is shared with some Mazda models . The 4.0 XKR MAF is a different story, AFAIK, only the XKR and XJR share that MAF. It costs $300+

ouch ….

 

Genuine Denso only....