2001 Automatic acceleration stutter at 2.5K RPM

[jkoch53102]

Have seen a lot of similar posts but no answers. What causes a 2001 Maxima automatic to "stutter" at 2.5K RPM when hard accelerating. Otherwise transmission is smooth and engine is running good. Will stutter when in drive and also in park or neutral. As RPM gets above 2.5K there is a "cut out of power" and tach drops back to 2.0K whereupon the engenine revs right back up to 2.5K and again cuts out. Very repeatable cycle. Current codes are P0505 (IAC) and P0403 (EGR).

[Nahkapohjola]

Originally Posted by jkoch53102

Have seen a lot of similar posts but no answers. What causes a 2001 Maxima automatic to "stutter" at 2.5K RPM when hard accelerating. Otherwise transmission is smooth and engine is running good. Will stutter when in drive and also in park or neutral. As RPM gets above 2.5K there is a "cut out of power" and tach drops back to 2.0K whereupon the engenine revs right back up to 2.5K and again cuts out. Very repeatable cycle. Current codes are P0505 (IAC) and P0403 (EGR).

Mileage?

Lack of maintenance; swap plugs, coilpacks, MAF, fuel delivery restricted. Start from checking charge voltage. Oxidized connector pin(s), gnd ... (see linky)

[jkoch53102]

Thanks for general info. Plugs and packs good. Replaced MAF and IAC. Still needs to be retaught and will repost after this is done. Still has same acceleration issue upon test drive.

[Nahkapohjola]

Originally Posted by jkoch53102

Thanks for general info. Plugs and packs good. Replaced MAF and IAC. Still needs to be retaught and will repost after this is done. Still has same acceleration issue upon test drive.

IAC just for idle adj

Have you measured and/or diagnosed Throttle Pos sensor TPS for linear resistance while turning? The bits are structurally different but u get the idea for test possibilities from here: http://www.cardomain.com/ride/748507...maxima/page-6/

There are two features 'changing' between 2-3k.
- The O2 sensor 'cant follow' in full exhaust flow to higher rpm, and thus 'only' MAF & rev sensor is used for input. This happens somewhere after 2.5k. If supply voltage or their signal is poor, then the problems may start to appear 'at 2.5k'. Check chargeV at batt (min 14.2V), then at ECU ... also while revving. Voltage at MAF. Start cleaning wiring groundings/contacts...
- if critical sensor fails, the 2.2k rpm ceiling

Note that you may get multiple bad spare MAF's ... Basic test is just to unplug, but here it wont help as that causes the 2.2k rpm limit.

[jkoch53102]

Excellent information Nahkapahjola. Much thanks, and will post as soon as I have had a chance to do these checks.

[jkoch53102]

Found out that this car had an incorrect ECM installed. Was a A56-P34-Z45 whick I believe goes to 2000 models. I replaced with a A56-P70-Z62 which corresponds to the Nissan part number 23710-5Y000. Took to dealership for software install and reteach. Note now the computer reads back it is a 23710-5Y006 which is the upgraded model number Nissan now has for this car. Upon initial test drives this did solve the acceleration problems. However, I still have a fast idle problem that the dealership said did not get resolved with the reteaching of the ECM and that further diagnostics is needed. Suggested I replace the IAC and the TB. However, this problem first showed up when I replace the IAC. Will probably need to open another thread on this issue, but still looking through some of the existing ones first. Again thanks for the help.

[Nahkapohjola]

Originally Posted by jkoch53102

Found out that this car had an incorrect ECM installed. Was a A56-P34-Z45 whick I believe goes to 2000 models. I replaced with a A56-P70-Z62 which corresponds to the Nissan part number 23710-5Y000. Took to dealership for software install and reteach. Note now the computer reads back it is a 23710-5Y006 which is the upgraded model number Nissan now has for this car. Upon initial test drives this did solve the acceleration problems. However, I still have a fast idle problem that the dealership said did not get resolved with the reteaching of the ECM and that further diagnostics is needed. Suggested I replace the IAC and the TB. However, this problem first showed up when I replace the IAC. Will probably need to open another thread on this issue, but still looking through some of the existing ones first. Again thanks for the help.

Seems 'some' history facts were omitted...

One cause for high idle is air leak. Ten year old car has definitely brittled air hoses, leaking. And with such no-history, maybe totally missing hoses, widgets, seals, whatever.

[jkoch53102]

First I want to better describe the idle problem the car was having: Would be steady but around ~1k when cold, but would be oscillating between 1200 and 1500 rpms when in park after being warmed up. The fix for this was to correct the throttle valve position. This was done at the shop I brought the car to (since all the threads I read warned not to touch this). The car is now running excellently. Does anyone have the procedure for how to set the throttle valve position?

[Nahkapohjola]

Originally Posted by jkoch53102

First I want to better describe the idle problem the car was having: Would be steady but around ~1k when cold, but would be oscillating between 1200 and 1500 rpms when in park after being warmed up. The fix for this was to correct the throttle valve position. This was done at the shop I brought the car to (since all the threads I read warned not to touch this). The car is now running excellently. Does anyone have the procedure for how to set the throttle valve position?

This constitutes as an air leak (which could be also coming from myriad other places.)

TB: The Factory manual doesnt tell... Main issue is that the flap wont touch the wall while throttle closes fully. This means that the flap never touches anything and wont face any mech stresses possibly causing wear or screws getting loose.
Axle assy has a stopper. Theres an adj screw that the stopper rests on. One could use a thin 'paper' shim while adjusting...