Have a 2001 QX4 with 125k. Took it to the local dealer for an injector cleaning. It was running a little rough. Servive manager came back and said there is more than that wrong. Said the MAF sensor was bad and all the coils needed replacing. I told him I would bring the car in when I had the $1500.00 they wanted to fix it. On the way home I used a half tank of gas to go 45 miles and so so much black smoke I could hardly see out the back. Barely got the car home would idle or run smooth. I called the dealer when I got and asked the service mgr what he did to my car. He said all they did was a a diagnostic check. I put my obdii on the car and got P0171, 0174, 1148, 1168. Any help with this would be appreciated.

You got injector cleaning at the dealer and now have "FUEL INJECTION SYSTEM" and "CLOSED LOOP CONTROL" codes. I'd wager the cleaning and codes are related somehow. Go back to the dealer and tell them to fix whatever they broke.

Why does your title say P1320 code but you do not list P1320 as a current code? Is it gone? Did you end up having the MAF & all 6 coil packs replaced at the dealer? New OEM parts alone are approximately $630 before shipping online, and the labor DIY is maybe an hour total...

Thanks for the come back. The P1320 is still there. Dealer never did not do an injector cleaning, said they wanted to do this instead. Dealer said they did not diconnect any plugs or sensors. I told him except for few times where it was hard to start but cleared up after a few minutes the car ran smooth. Dealer is not cooperationg about fixing because they claim all they ran was a diagnostics code check.

Ah, I see. There are no TSBs about this combination of engine codes. I'd begin with verifying that the upstream oxygen sensor harnesses, coil packs, and coil pack harnesses are secure and that there are no air intake leaks (be sure the engine air filter is still present as well). Loosen and retighten these ground screws also. Here are the locations of the oxygen sensor plugs:



P1148 & P1168 can only be caused by oxygen sensor faults according to the FSM, so something with the harnesses, wiring, or possibly both O2 sensors themselves (but the chance of both failing at the same time seems remote) is to blame here. Nonfunctional upstream oxygen sensors will throw the air/fuel ratio off and can certainly cause your other two codes and other associated effects (black smoke out the tail pipe).

Hopefully those will be gone and then we can deal with P1320.

I'll check all that you mentioned. Also, are non oem (NAPA)coil packs reliable or is Nissian the only one I should use. Same with the MAF sensor?

The MAF sensor you would use would be this OEM Maxima MAF which is only $90 + shipping online, and even a new Beck/Arnley sensor is $90 + shipping from RockAuto. NAPA's Echlin line of ignition parts are made by Standard Motor Products and should work fine, however the coil packs appear to be in the $90-ish range each which is the same price as OEM coil packs, so I'd just go for OEM coil packs. Please provide the VIN of your QX4 so I can provide links to the correct OEM coil packs.

However, before you shell out a ton of money for new MAF & coil packs, first retighten ground screws as I mentioned above and clean the MAF sensor with MAF cleaner (don't use anything else). Were the spark plugs replaced with OEM NGK PLFR5A-11 plugs around 105k miles?

The VIN is JNRDRO7Y6W103313. Idid replace all the spark plugs at 100k ,18 months ago and used NGK Platiniums. I also replaced the MAF sensorabout the same time and got it from a local online parts guy, but never really felt good about the transactuion. I have cleaned this sensor about a year ago with Napa,s MAF cleaner. This was suggested by the guy I got the part from(Yearly cleaning was recommended by him)

Are you sure that VIN is correct? I can't pull it up.

Was the MAF sensor you purchased an OEM part, or aftermarket? Generally a MAF would throw a P0100 code if it were faulty, but cleaning it may help regardless.

Were any other codes ever thrown along with P1320 (besides your other four current codes of course), such as a specific cylinder misfire (P030x)?

The VIN number or letter before the seven is either a zero or letter "o" I am not certain but would guess it was not an OEM part. All he sold me was the sensor, he said changing the housing was not necessary. I get no P100 code. There .are no misfire codes for any cylinders

I tried both "O" and "0". Was this QX4 possibly originally from Canada?

Could have been. I called the local Infiniti dealer today and it came back a March 2000 production date. I was able to determine the right MAF sensor I need with your help. Thanks again. A side note, I got a call from the Nissian dealer that I took the car to. He wanted to make it right for what they put me through. He offered to sell me the parts a his "cost". He did say not to use NAPA coils should I decide to change out the coils, only Nisson parts, something to do with resistance in the coils. Have you ever heard of that. He said to start with MAF first because that controls eveything else.

The Maxima MAF sensor will almost certainly be cheaper than the Pathfinder MAF. The two are equivalent, just with huge price disparity. Many members here have used the Maxima MAF on their VQ35DE equipped Pathfinders without issue.

I've heard of issues with some aftermarket coil packs, yes. Hitachi is the maker of the Nissan OEM parts and if you can get Hitachi branded parts cheaper than OEM parts, that would be the way to go.

Here are the OEM part numbers for your coil packs:

[22448-4W000] COIL ASSY- (qty: 1)
[22448-4W010] COIL ASSY- (qty: 5)

Thanks again for your help.

There are two types of coils for 2001 make sure you check if they are black or grey. Yours should be grey.

Black 1-6

Grey Coil 1

Grey Coil 2-6

Thanks for the info on the coils. I picked them up and they were all the grey color. What I can't figure out is why I wasn't getting any misfire codes for any of the cylinders only the ignition primary circuit fault code. According to the guys at Napa the number one coil is what sends the info to the pcm which inturn the pcm sends the firing sequence to the remaining coils. Boy, what I would give for the old ditributor, points and condensor.