reconditioned maf driving car really rich

Hi Guys, I have spent a lot of time diagnosing this car I have a Nissan Maxima that is running rich at idle(-10.2%)long term but balances out with increased rpm, I bought a reconditioned Maf from rock auto and now the car is perfect at idle and runs really rich at increased rpm.(-25%)long term.it even triggered a catalyst code on both banks. has anyone experienced this. I have spent alot of time and money on this car and just need it running right. please help I am running it through a test on Wednesday hopefully it will pass if not I will get a gas analysis readout. I have tested injectors for spray pattern and wave form all fine also coils are perfect I had to replace one last month. I am convinced the problem is maf because the g/s are all wrong and the fuel trims back this up but the remanufactured maf readings are throwing me

What year is it? What led you to replacing the MAF? codes? Performance issues? -10% won't set code

Hi Bruce, I bought car in 2016 its a 2001 2.0 V6 European model Maxima QX looks like an I30 and have only gotten to drive it for about three months. It failed its test on a bouncing idle, so test was cancelled I was a parts changer and did swap out parts including the fuel pump for an aftermarket one to address the car stalling which is still in the car and didn't work which made me start using Pauls diagnostic methods . The car initially had a lean condition and wouldn’t idle below 1200 rpm without stalling within a week of purchasing car which I bought privately, and seller disappeared. Car is approaching classic status, so I do want to hold onto it. Thanks to Paul I have bought a lot of diagnostic equipment and have successfully diagnosed several issues the main one being the intake gasket leak and used the bottle of water trick the knock sensor had also failed threw code and tested bad, replaced. The car had a faulty gasket on the IACV as well, but I replaced the entire unit because of horror stories of ecu's blowing. TPS spring failed at WOT on motorway which was SCARY. Compression is 170 to 180 across all cylinders, fuel pressure regulator Mechanical diaphragm type has no leaks from vacuum side I have no way of testing fuel pressure no adapter 2 injectors were showing low amps so replaced them also spray pattern was iffy when tested. 1 Ignition coil low amps as well, replaced, also fixed. Stuck closed thermostat replaced, replaced second one as preventative maintenance, ECT -40C replaced. Car exhaust is stinking MAF has very erratic g/s ranging from 2g/s to 3.2 g/s at idle and a max of 21g/s at WOT. B2S1 O2 was slow response throwing codes so replaced it as well. PCV valve replaced with full service including plugs last month. The car owes me too much to scrap it at this stage so need help I have spent a lot on body work and brakes have been overhauled as well . I have a Hantek scope so nowhere near the accuracy of PICO but its only for DIY and techs locally are not very good, so I must work on this myself. Thanks for your patience on this post but I think the more info the better. If I think of anything else I will post Back. as I said I have a test on Wednesday so need it to pass.I hope it will pass with current trims but there is still something causing this issue. Thanks again, Dar.

Ok so drive it and record the engine rpm and MAF g/s. WOT until it shifts to 2nd gear. What is the max g/s and what is the rpm at that g/s. Then we will do some math. Take the engine size in liters x rpm x .8 = minimum g/s. So let's say your max RPM was 5827 rpm.
2.0 x 58 x .8 = 92.8 g/s. Doesn't have to be exact because we aren't taking everything into account that can affect the MAF reading but it is close enough. If it is low look for an air leak between the MAF and throttle body. Be careful doing this test. If you don't have a scantool that you can select a custom data list or that you can pause or record then get someone to drive it while you watch. Just make sure they go to WOT

Lets stand back and sift the facts
(1) The engine is running rich at idle and the computer computer maxed out trying to take away fuel but the fuel trims and general running are better at higher rpm and load ? --- this dosen't suggest an inlet trunking leak intake or vacuum leak.
(2) The MAF flow rate is jumping around between 2 and 3 g/s ---- I think this just down to the very erratic idle speed caused by the rough running.
(3) The rich condition got much worse after the "remanufactured" MAF was fitted.
Check the vacuum pipe to the fuel pressure regulator is connected

If I was looking at it I would look at the MAP and IAT in live scandata, also the TPS output (scan data should be okay -- if any doubt scope it).

However although the g/s numbers you are getting from scan data look okay I am really cynical about the wisdom of fitting a MAF not from the original manufacturer , the sensor unit that is in the MAF has to match the characteristics of the engine both electrically and aerodynamically also some MAF types have the IAT built in and some don't but look identical.

Thanks guys I will do all you have suggested The TPS has been tested several times and I am happy to say it is fine I wasn't clear earlier and I apologise for that, my idle is fine at 675 rpm now since I repaired the vacuum leaks. I will post back when I have tested again.

can you put the old MAF and and have different results?
Cardone MAF's i have had horrible luck with and refuse to install anymore.
Typically bad maf's will cause lean, not rich. not always but usually.
You should step back and look at what controls fuel. maf, cts, tps, a/f sensors etc. there isnt usually too many big players in that group to figure out which one is the cause of the a/f issue.

yes I put old MAF back in which I have done -10.2% LTFT at Idle and perfect trims at higher RPM the Remanufactured MAF is a cardone so I have returned to Rockauto and I am using credit to buy a Hitachi MAF instead apparently they were the OEM supplier

I was thinking the erratic idle was from vacuum leaks. I have a smoke machine and that saves the day quite often. I'm with you on the MAF issue. I think there's something to these Cardone units. I have a 5.0 Ford truck that has serious running issues. Let us know when you get the factory unit and tell us the results.