What's up guys? Need some help here. Ok, here it goes........

I just purchased a 99 Maxima GLE, the previous owner had changed a few things. The car was originally an Automatic, he swapped it to a 5 speed manual and changed the motor also. I looked up the VIN on the transmission and its coming up from a 97 Maxima (dont know what trim and dont know if that matters????). I dont know if he took the transmission and engine from the same car or if he got them separatley. Anyways, the car is running like S***, it idles around 500 rpm and the oil light flickers at idle. The car has a great loss of power, it accelerates like a Geo, stutters and backfires through the entire RPM band (especially higher rpms). He said he never changed the ECU, I also looked at the wire harness and its all hacked up. It looks like he never changed the wire harness either, most of the wires are spliced together. There are also alot of connectors on the harness that are not connected to anything (the rear O2 sensor is one of them). I had the car hooked up to an auto scanner and the list of codes go on forever. Most of them transmission codes, (guessing...because the harness is from the orginal auto trans and its not hooked up to anything???) one is for the MAF sensor another for the O2 and one for a cylinder 3 misfire.

Any suggestions here?? Everyone is telling me to replace the whole harness and I would like to get the correct wire harness for the engine/transmission but I cant get a hold of the previous owner (surprise surprise) to find out what year Maxima the motor is from. Is there a VIN or engine code on the motor that I can access?? Will that number tell me exactly what kind of harness I need or what year/model Maxima the motor came from?? Does the ECU have to be changed if the motor and trans where changed and they are not the same year Maxima? Not sure if the ECU would work now since the car is no longer an auto transmission and the motor was changed plus they are different years??

Any help would be greatly appreciated!!!!!!


Thanks!!

 

jeez why would you even buy a car like that?

You are probably getting all those transmission codes because the last owner never put in a manual ecu when he swapped transmissions.

You say there are a bunch of connectors that are not plugged into anything, other than the rear o2 sensor, what are the other empty connectors? Are they near the transmission? When you do a 5speed swap you are going to have some extra connectors because the 5speed doesnt have as many sensors as the auto.

Get a list of all the codes in the ecu and start fixing them. You say you are getting maf and o2 sensor codes, well test to make sure they are bad and then replace them. A bad maf and bad o2 sensors are going to make your car run like ****.

 

O2 sensors will not make your car run bad. But a bad MAF will.

www.car-part.com sells them for cheap.

 

Three bad o2 sensors sure make my car feel like crap.


I have a MAF for sale if yours is bad: http://forums.maxima.org/showthread.php?t=406117

 

Most of the connectors are near the trans......should I also replace the ECU and get one that is for a manual? If so, does it have to be the same year and trim as the engine and trans? How can I verify what year/trim the current engine is off of?? Also, what about the cylinder 3 misfire? Thanks guys!

 

O2 sensors have no input to ECU parameters when WOT.

 

Yes, get a 5-spd ECU, make sure you get the correct emissions. (check the multiple plugs in front of your front valve cover, right by the intake snorkel, if you have 4 plugs it's a cali, 2 plugs it's a fed spec). Try to get an ECU from your engine year, just to be safe.

The misfire could be a bad coil/spark plug, since it's a 99, you should expect ignition coil problems.

 

^^^yes i agree get man ECU...coudnt have said it better man^^^

 

http://jimwolftechnology.com/wolfpdf/ECU-ID.PDF

 

Ok.....so MAF, O2 and ECU. How about the harness? Also, is there a code on the motor that can tell me what year and trim its from?

 

Harness should be ok. Check the door jamb for build date. Also, remove the ECU and use the code in the link I provided to match a similar, albeit manual ECU when looking for one on www.car-part.com.

 

I think there should be a VIN # somewhere on the block.

 

Theres an ESN number on the block. To get a vin, you would have to call up NissanUSA and they can look it up. Its located on the BLOCK, rear bank, right near the rear valve cover. Drivers side

-matt

 

The motor is not original, it is from another Maxima.....dont know what year or trim......so its hard for me to know what ECU to buy......tried looking for the VIN on the block......dont see it.......anyone know where it should be?

 

On the block near the knock sensor valley.

 

You don't need a manual ECU, the car can run perfectly without it - it is not your problem. Two of my three 4th gens did (do) it, I've done it on two other 4th gens as well, and tons of people on this board do it.

I'd check out the MAF, don't worry about the O2 sensors yet either - though if you need to pass emissions where you live you will have to do something about those. But the car can run perfectly fine without those too, two of the three 4th gens I've owned had no O2 sensors at all and ran (run) perfectly.

Oil light flickering at idle is not good - means low oil pressure. Could me a bad oil pump, could mean another problem in the oiling system, or could mean just extremely low oil level (low enough to drop the pressure down below the threshold at which the light turns on).

 

How about the harness being all hacked up?? Almost everything is spliced together, including the injector wires. If I replace the harness would it have to be compatibale with the ECU? I am wondering if any wire harness would plug into and work with any ECU. Reason is, I am thinking about the wire from the harness into the MAF sensor......what if its not the actual MAF sensor but the spliced wire that goes from the harness into the MAF. Thanks buddy.

 

For obvious reasons, then you would have to inspect all the splices etc. That could be where some of the codes are coming from.

 

Yes, there is a vin on the block, however it is irrelevant, if your car is '99 you MUST use a '99 ecu (of the correct cali/fed emmisions also, see above comment about o2 connectors near front header), but as mentioned the only benefit to the 5-speed ecu is that the codes can be eliminated, and the annoying temporary high idle while pushing in the clutch will go away.

Now, yeah, sounds like you have some hack wiring going on, also the oil pressure could be, in addition to all the things that nealoc mentioned, wiring/ssensor/low idle from your car running like crap.

Now, to help you sort things out, my best advice for you is to follow the instructions and wiring diagrams listed for each individual code you have, also, I bet you there's a 95% chance that the duesch dpo was an .org member, albeit not one we are very proud of some way of finding out his name and being able to search his posts might be of some help. But here is the link to somewhere that you will need to spend ALOT of time to work out these issues (The Factory Service Manual)

http://www.vq35de.com/ESM/Nissan/Maxima/

 

oh yeah, I totally forgot about the hack wiring. I'd fix that up if it's fixable, it's very possible that your problems are due primarily to that. i've had to deal with hacked wiring in the past, it's time consuming to fix but it's not hard, and it can clear up a plethora of problems.