Dear Forum,
Please could someone tell me whether or not the following increase in MAF Airflow rate with increased revs (car is stationary) looks 'normal'?
Regards,
Ray

 

Here's a chart that may help:



From what you have posted, it looks "okay" from what I'm seeing. MAF readings will generally be higher when you're on the road driving. What issue are you having that you suspect the MAF?

 

Hello Michael,
Thank you for your reassuring reply. I will take a look at my driving MAF numbers as well.
I am just casting about, really......I have somewhat lopsided Fuel Trims, with Bank 2 fine and dandy, showing small movements in LTFT to keep STFT to around zero, but bank I appears to need a higher LTFT and still fails achieve the same objective (STFT stays in low-ish negative territory despite LTFT of 6% plus)?
For your interest, I gave up trying to figure out whether my PCV valve was functioning correctly or not and replaced it! I have also fitted an Oil Catch-Can to try to overcome my periodic clouds of grey smoke. I will post with results when I have them, but so far, so good!!
Thanks to the fantastic help I have enjoyed on this forum from a number of members like yourself, I now have NO DTC's, but I still have a slight tremble and shake at idle and my Timing Chain Tensioners are going to be my next fixation!
Regards,
Ray

 

I wouldn't suspect MAF if you have a bank-to-bank difference. That would affect both banks equally.

So if I understand, on bank 2 you have 0% LTFT and STFT oscillates as expected. But bank 1 you have a +6% LTFT and -3% STFT? That would give a total trim of 3%, indicating the PCM is trying to enrich the mixture slightly.

If that's correct, I wouldn't worry too much. The long term trims will come in line eventually so STFT hovers around zero. +/- 3% is really well within the tolerance of a normal engine. Beyond 10% you should be concerned. The PCM won't set any codes until total trim gets to approx. 25%. However, if you want to figure out a slight leak, I would get the engine smoke tested.

For your idle shake, have you looked at the motor and trans mounts? I had mine go bad around 60k miles. They don't last very long as they are the hydraulic type with a liquid in the center. I would do all 3 if you suspect one, I had to do mine in series every 5-10k miles, should have just done them all at one time.

 

Thank you Michael - I'll look into the mounts.....100,000 miles ....very possible.

 

Ray,

It would be a good idea read the fuel trim primer document, located here

https://www.jaguarforums.com/forum/g...17/#post304460

It explains a lot but if have any questions or need something explained let us know.

Cheers
34by151