When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
I’ve searched the forum looking for MAF values and RPMs it’s checked at for my car...I can find the NA version but not the SC version, I’m trying to determine for certain if my MAF sensor is reporting correctly. My scan tool reads pounds per min.
Thanks!
don't know the answer to your question, but if you find a source for the 4.0 XKR MAF at a reasonable price please let us know. AFAIK, the XKR and XJR are the only cars using the same pricey MAF sensor.
Sorry, that's not a common question, and I don't know the answer. The values will vary under different conditions ie start up from cold, highway driving, heavy load etc. I wonder why you might need it.
The Denso MAF is a pretty reliable unit, compared to the old mechanical flap valves, and maybe you feel your XKR is underpowered for some reason. Cleaning the MAF, with correct cleaner is a 5 min Zero dollar job so easy to do.
If that doesn't work it may be due to an air leak after the MAF. Common fault is at the accordion section in the air tunnel, between the throttle body and the air box. Another is the PCV breather pipe. For me it was a cracked male joint at the camshaft cover.
Maybe someone else on this forum has done this type of study and can chip in.
Definitely do the smoke test to rule out any air leaks first....
I have read there is a full throttle/full load test for the maf sensor, Don't know how good or accurate this test is but it is on this forum somewhere, Also it could be difficult to do...
HOW TO TEST......
Measure the maf sensor reading's at full throttle in 2nd or 3rd gear (3rd gear best) at 6'000 rpm (drive till you hit the rev limiter)
You need to take the peak reading of the maf at this rpm.
You then divide this reading by 0.8 and this figure should be close to the brake horsepower of your car.
E.g......239 g/s divide by 0.8 = 298.75 bhp
............300 g/s divide by 0.8 = 375.00 bhp
sorry this is in grams per second not pounds per min.
can't you change the scan tool values ?
If not there must be a conversion chart on google.
Im going to give this test a go over the weekend just out of curiosity.
I have very recently fitted a new maf part number LNE1620BB with new seals, So i will take some reading's for you to compare.
I came up with 279 g/s-divided by .8=348.75, seems pretty close...I'm looking for a under reporting MAF...I have normal fuel trims at idle, and high fuel trims under heavy load on both banks equally... which I'm told is usually not indicative of a vacuum leak, but either a under reporting MAF, or a fuel delivery problem. I'll probably call it good with this test, seems pretty close. I have carefully checked the intake system up to the split looking for leaks and have found none. Thanks for your help!
high fuel trims under heavy load on both banks equally
Make sure the AFM is itself well sealed (there was a thread recently). There is a thin o-ring involved, and it is typically not supplied with a new AFM. If this leaks air, you will read low as the air flow increases. Again, a smart smoke test would likely reveal this sort of leak.
Just found some old note's i took on fuel trims, may or may not be helpful.
Fuel trim values are based on a properly functioning oxygen sensor (o2 sensor)
So make sure the sensor is accurate and responds to fuel trim changes,
Other areas that may affect fuel trim's are...poorly functioning maf sensor ...low fuel pressure's ...and vacuum leaks.
Common fault is at the accordion section in the air tunnel, between the throttle body and the air box.
FWIW > I am probably preaching to the choir, but I use 2 throw-away gloves, plastic wires ties or such as clamps, and a ~7/8" DIA folding card table chair leg to floor protector cap. I blow in a puff of air then cap it off and check for leakdown . I think you get the picture.
Well took some reading's of the mass air flow rate coming through the new maf at different rpm's.
car in park.........engine up to temp 195f ............out side temp 64.4f.
Took the reading's twice at the different rpm's.
The difference in the g/s reading's is because it's difficult to hold the rpm at the exact range stated.
This should give some ballpark reference hopefully.
I have a final update....at least I hope! So...Thanks again to everybody here for all the help and suggestions...Here is what I did...I leaked checked the intake tube, found no leaks, I then cleaned the MAF sensor, topped off the fuel tank with fresh fuel and injector cleaner, and completed a hard reset. I drove my car for 150 miles varying the load from low to high, city speeds and highway speeds. Then I looked at my fuel trims again and noticed a significant change, which based on what I have all learned here its now normal, please see attached photo...I'm calling it good as the car seems to run better and is much more responsive.
Still have a remaining question though...(These Cats are labors of love), Way back when I first got the car I removes the SC to change valley hoses and found oil in the intake system, I posted pictures here of what it looked like before I cleaned it up. I did a compression test and all cylinders were between 148-154..on a cold engine..Seems good to me. I had a few people here tell me some oil in the intake is normal. Now for the question...after driving my car, when I park it in my garage and shut it down, my garage smells of burnt oil for awhile...Because I also had the cam covers off to change the tensionsers, I have looked high and low multiple times for leaks...it is dry as can be. No smoke visible either under hood or out the tail pipes when first started. I removed the intake tube and see fresh small puddle of oil in the intake elbow, just like the first time I took it apart. Anybody else have this oil smell problem? Its annoying thats for sure...
Jason
This thread shows why its not a good idea for two different members with similar user names to post two different problems in the same thread - who had what problem, who has done what and who has fixed what?
This thread shows why its not a good idea for two different members with similar user names to post two different problems in the same thread - who had what problem, who has done what and who has fixed what?
....2KXKR (thread starter) has the problem, No one else in this thread has stated they other than 2KXKR has a problem.....(i think).......
His problem is high + fuel trims on both banks.
This is his trims....................
2379 rpm ...engine temp 183f...closed loop..
Bank 1 STFT..+0.8
Bank 1 LTFT.. +17.2
Bank 2 STFT..--0.8
Bank 2 LTFT.. +18.0
650 rpm...engine temp 192f...closed loop...
Bank 1 STFT..+0.8
Bank 1 LTFT.. +3.1
Bank 2 STFT..--0.8
Bank 2 LTFT.. +3.1
Hope this has cleared up any confusion, With who has the issue and what this thread is about
04-16-2019, 10:28 AM
