just failed emissions test in PA, no codes are present but the I/M status on the o2 and CAT are not setting..

now I just replaced the ALT and had the battery off for two days, but have driven over 100 miles in the past week. hoping this would reset any codes and the ECU would relearn the default settings.

I have noticed that I have the throttle wall syndrome, so not sure if its the MAF or the O2 sensors causing the problems otherwise the car runs really good.

So I want to avoid spending cash to replace everything, is there any way to test the MAF or O2 sensors? I can say I unplugged the MAF and the car did not like that at all , hissing and popping, so I reconnected it. ( cleared the code after I plugged it back in )

I have a code scanner and will be taking a long ride this weekend to see if they will reset , ill start with a full tank of Premium and hit the road.

suggestions?


thanks,
Louied

 

If your code scanner reads live data and you can save the O2 sensor and MAF data then you have something to go on. The FSM for the vehicle has specifics around O2 sensor readings and MAF readings as far as verifying if they are working. You can get this from a code scanner that reads and saves live data.

Here is the FSM for 2001.

http://boredmder.com/FSMs/Nissan/Maxima/2001/

 

Copy of emissions readout? Were any codes present prior to alt/battery change? Mileage on vehicle? Has it ever had maf or o2's replaced prior?

Throttle wall syndrome? Is your code scanner also a data logger?

 

Thanks,
my cen-tek scanner does not log data, shows me I/M readiness, codes, erase codes.. the basics.

I just replaced my MAF.. and the throttle wall is gone!
I still have two monitors that need to clear: CAT Monitor and o2 monitor, the o2 heater monitor is ok.

i have 948xx miles, the coils are the original w/o the grey dot. so i replaced the plugs just because.. with the NGK step below the oem plug just to test, the coils seem fine no codes , when I unplug one it throws the code and can feel the miss in the engine.. found a nice set on Ebay that I might pick up just because.. I think i will replace the o2 sensor in in the manifold closest to the firewall since I pulled a code for lean bank1, I wanted to think it was associated to the MAF , it never came back but I need to get my car inspected ASAP.


EDIT: link to new coils:
http://www.ebay.com/itm/280657216122...84.m1423.l2648

 

I passed my emissions inspection.. i have done the following since the last post.

replaced alt, replaced MAF, replaced PCV, replaced f+r Rotors/pads, replaced the rear calibers, installed a dual sim for the cat O2 sensors, replaced the O2 sensor precat by the radiator.

ran half can of sea foam through the intake via the brake boster vac line!! big plus.

new gas cap,new tires. car runs great!

on order : IAC, driver door window regulator, fuel pump filter and new filter bag.

future repairs, fix heated seats, window tint, new head unit with sat radio and back up camera. New headlight bezels and 55 Watt 4500K Hids.

thanks members for the great info provide to help me make informed decisions.

louied

 

I had this same thing happen after a cleared a code and drove it for a day or so thinking I could get it inspected and the tech asked If I had the battery disconnected recently and I said yes I swapped batteries......(LIE!!!!) Well the O2 sensors and other sensors were in the "ready mode" only but not communicating the way they should....You may have to do idle relearn on that....I know you just can't swap in a new MAF of 2000-on up without setting up the TPS and IACV thru some sort of Idle relearn,....GL

 

All problems solved! Turns out my no start condition was a result of a bad fuel pump.

I replaced the filter and shortly after the car refused to start.. I did not even think of replacing the pump at the same time. Turns out the pump quit working.

had it replaced and then it too was defective( i had the same no start condition) ( it would start , idle give it gas and it stalls right out).. replaced it one last time and presto cars starts every time and runs strong!

so when in doubt not knowing when your pump was replaced its a simple tune up to your overall engine management. Replace it!

And a note to everyone: when trying to get the 5" o-ring for the fuel tank assy. I had to get one for a 99 Altima. Apparently the parts data bases at every single store is wrong.!!!

go with this:
Airtex Master/Fuel Pump Tank Seal
For your 1999 Nissan/Datsun Altima 2.4L SFI DOHC 4cyl
Price: $4.99 ( autozone )
Part Number: TS8027