More R50 woes, need help.

[Empty V]

So the trans has been rebuilt and is shifting as it's supposed to. My other big problem is the dreaded P1320 Ignition Primary code. I've replaced all of the ignition coils, spark plugs, supposedly the wires going from the ECU to the coils have been tested for continuity and have passed and I'm pretty sure the ECU has been swapped out. I'm still getting dropped RMP's at idle and occasionally it'll drop low enough for the engine to cut out. What else can it be? I finally got it back tonight after almost 3 weeks in the shop and the dude who's been working on it says he wants it for another week to find the issue. I'm almost ready to take it to the stealership for a diagnosis but obviously that's not the economical route. Does anyone have advice/suggestions for else it could be?

Thanks!

Billy

[Pwnin O'Brien]

The problem with P1320 is that it can be generated so many different ways that it can be really difficult to pinpoint why the ECM thinks something is wrong. Now, the FSM specifically states that a DTC is generated when "the ignition signal in the primary circuit is not sent to ECM during engine cranking or running." My suggestion would be (and you may have already done this or your mechanic may have done this already) is to use an OBD-II reader or an oscilloscope to datalog each primary ignition signal. You need to monitor the activity of each ignition signal and look at when (or even if) the ignition signal isn't present during cranking or starting. This will at least tell you if the problem is with the coils or any part of the ignition circuit. If all of the ignition circuits test out perfectly, then that is great news, maybe.

Also, just to cover all of your bases, you should run the diagnostic procedure for the crankshaft position sensor. The FSM states that this could be another reason for the P1320 and I doubt this is your issue since I'm sure it would throw another DTC for the crankshaft position sensor anyhow, but you never really know.

The unfortunate thing is that when you take it to the dealer they will basically perform the above steps to try and solve your problem and if they can't figure it out they will just throw parts at it until it fixes the issue.

[alexf20c]

clear the code and see if it comes back. a P1320 can easily be triggered by trying to crank the vehicle with something disconnected, like the primary or secondary coil, even just the fuse to the coils. it's possible that the code is just an artifact from the work done on the transmission.

in the meantime, you can mess around with your IACV - Idle Air Control Valve. i bet you're only dropping rpms while idling in Drive or Reverse, and not in Neutral or Park (no load). and does it make it worse if you have the A/C on?

a faulty IACV will not compensate the engine under load while idling, and cause a rough idle, dropped rpms, and even a stall.

you can easily counter it by reclocking the TPS - Throttle Position Sensor. just loosen the 2 bolts, and you should have a few degrees rotation of adjustment. after every adjustment, you need to shut off the engine and restart it to allow the ECU to reset its base values, then you can see if it fixes your rough idle under load.

it's a very tricky process, especially when you start messing with the idle adjustment screw in conjunction with the TPS.

of course, inspect your IACV first; it's a little motor on the underside of the throttle body. the harness connector is the opposite side of the throttle body. it wouldn't hurt to remove the two, clean them up, shake them, blow on them, then replace them.

[Empty V]

Thanks guys for the info! It doesn't drop at first startup when cold, only after running for 10min or so. I drove it to work and it cut out while in park and neutral, it's not just when at load. So does this mean the IACV is okay or can that still be a factor?

Billy

[nnorton44]

Just throwing this out there, my car would die and have rough idle when stopped when the engine was warm. If it was cold it wouldn't die. Replaced MAF which fixed the problem.

[Empty V]

Just throwing this out there, my car would die and have rough idle when stopped when the engine was warm. If it was cold it wouldn't die. Replaced MAF which fixed the problem.

Would it only die while in Park or neutral because that's what mine does. While under load it'll drop but not completely cut out.

Thanks for the help.

Billy

[Empty V]

UPDATE

So I finally got my code reader back from my dad's friend(6 weeks late) and I'm seeing another code:

P0420 Catalyst System Efficiency Below Threshold (Bank 1)

Does anyone know what this means? I'm dropping it off tomorrow and would love to have more info for the dude trouble shooting it.

Thanks!

[Pwnin O'Brien]

P1320 is causing the P0420.

[Pwnin O'Brien]

Have you figured out the P1320 yet? I'm curious to see what is causing this code.

[Empty V]

Have you figured out the P1320 yet? I'm curious to see what is causing this code.

I spoke with the dude diagnosing it and he says that they found an issue with a "wire harness" and his electrical guy is soldering it back together. To be perfectly honest I have no idea what that means and I'm somewhat scared that he's stripping wires and soldering them back together. He said he'll call me tomorrow with an update but I doubt that'll happen. Unfortunately I'm so slammed at work I don't have time to try anything myself. He did rule out the MAF as it "tested" okay. I'm flying out to DC next week and I'd really like to have this month long chapter closed before I leave.

I just thought of something, could it be a leak from an old vacuum hose? They're all original (200,000+ miles)

Billy

[Pwnin O'Brien]

I just thought of something, could it be a leak from an old vacuum hose? They're all original (200,000+ miles)

I doubt it since the P1320 is strictly an electrical issue somewhere between the spark plugs and the ECU (or between the spark plugs and ground). Did they tell you specifically what wire harness they were working on? It's pretty random that this would happen all by itself.

[Empty V]

I doubt it since the P1320 is strictly an electrical issue somewhere between the spark plugs and the ECU (or between the spark plugs and ground). Did they tell you specifically what wire harness they were working on? It's pretty random that this would happen all by itself.

I just got off the phone with him and he said they were working on the main harness. Is there a main harness? I asked him if he found voltage on the ground and he didn't know. How many things are there between the coils and the ECU? It's just wires right? He swapped out the ECU and had it flashed at the dealer and that didn't resolve the issue. He said he'd call me at 5PM PST, with a prognosis. I've got a feeling it'll be another "we still don't know what's going on" conversation.

Thanks for the help Mr Mod!

[Pwnin O'Brien]

Hahahaha damn right! You can all call me Mr. Mod herein.

Assuming the ECU power circuit and the coil ground is good (also assuming your coils and spark plugs are all operating properly), then the issue is with the coil output signal which is the wires which the ECU uses to turn each coil transistor on and off; it's also the wire used to detect proper functionality of the coils (and each coil transistor). I just don't understand how there could be a problem with the coil output signal out of the blue when it's not related to the coils or spark plugs.

[Empty V]

Hahahaha damn right! You can all call me Mr. Mod herein.

Assuming the ECU power circuit and the coil ground is good (also assuming your coils and spark plugs are all operating properly), then the issue is with the primary circuit (or the coil output signal) which is the wires which the ECU uses to turn each coil transistor on and off; it's also the wire used to detect proper functionality of the coils (and each coil transistor). I just don't understand how there could be a problem with the primary circuit signal out of the blue when it's not related to the coils or spark plugs.

The first thing I did in attempting to fix the problem was change out all of the coils and plugs but the issue persists. So right now I'm at a loss, figuratively and literally.

Billy

[Pwnin O'Brien]

Did they at least datalog each coil output to see which one is not working?

[Empty V]

Did they at least datalog each coil output to see which one is not working?

Well I had to head out to DC for a week and was hoping that dude would have the problem diagnosed and fixed by the time I returned home. Not a chance! So last Thursday he said he had good news. He reported that the #3 engine coil(which was just replaced) had blown again which pointed @ the main harness and they found a short. Apparently a wire had worn out due to rubbing and bare wire was exposed. So I called yesterday and he said that the infiniti dealer and his electrical guy suggested replacing 2 of the 4 crank sensors. One in the engine compartment and the one at the transmission. What do the crank sensors do and how on earth would they contribute to burning up an ignition coil? Ohh yeah and he said that he was datalogging the coils but if he was I think he would have seen that #3 blew immediately.

Thanks!

[Innovazn]

Well I had to head out to DC for a week and was hoping that dude would have the problem diagnosed and fixed by the time I returned home. Not a chance! So last Thursday he said he had good news. He reported that the #3 engine coil(which was just replaced) had blown again which pointed @ the main harness and they found a short. Apparently a wire had worn out due to rubbing and bare wire was exposed. So I called yesterday and he said that the infiniti dealer and his electrical guy suggested replacing 2 of the 4 crank sensors. One in the engine compartment and the one at the transmission. What do the crank sensors do and how on earth would they contribute to burning up an ignition coil? Ohh yeah and he said that he was datalogging the coils but if he was I think he would have seen that #3 blew immediately.

Thanks!

your truck really likes to be a bad b****..... werent you considering replacing or trading it? or are you going to run her to the ground?

[Empty V]

your truck really likes to be a bad b****..... werent you considering replacing or trading it? or are you going to run her to the ground?

No dude I was never thinking about replacing or trading it and I don't intend on ever running it into the ground.

Billy

[Pwnin O'Brien]

There is no way that any of crankshaft sensors could have caused the failure of your #3 ignition coil. I'm assuming that your mechanic tested the crankshaft sensors while trying to troubleshoot the DTC and they tested out of spec or something. If the crankshaft sensors aren't throwing a DTC, I would recommend just having them finish with the coil harness and get the car back. The sensors aren't super difficult to replace but they won't be cheap (about $80 per sensor). In the following picture you can see the locations for the various cam/crankshaft sensors. Numbers 4, 5 and 7 are your crankshaft sensors (whereas the two #2's are your camshaft sensors).



So you should ask your mechanic why he thinks the sensors should be replaced. Ask if they are actually throwing DTC's or if he thinks you should replace them because they could fail soon or are damaged. If you took the vehicle in there without a DTC for any crankshaft sensors and now there are crankshaft DTC's then your mechanic has some explaining to do.

[Empty V]

There is no way that any of crankshaft sensors could have caused the failure of your #3 ignition coil. I'm assuming that your mechanic tested the crankshaft sensors while trying to troubleshoot the DTC and they tested out of spec or something. If the crankshaft sensors aren't throwing a DTC, I would recommend just having them finish with the coil harness and get the car back. The sensors aren't super difficult to replace but they won't be cheap (about $80 per sensor). In the following picture you can see the locations for the various cam/crankshaft sensors. Numbers 4, 5 and 7 are your crankshaft sensors (whereas the two #2's are your camshaft sensors).



So you should ask your mechanic why he thinks the sensors should be replaced. Ask if they are actually throwing DTC's or if he thinks you should replace them because they could fail soon or are damaged. If you took the vehicle in there without a DTC for any crankshaft sensors and now there are crankshaft DTC's then your mechanic has some explaining to do.

I just spoke with the shop owner which is who I've been dealing with and asked him about the necessity of changing out the sensors. I also asked him if they were throwing codes and he said no. Then I asked him why we were replacing them and he really didn't know. He said that he doesn't understand why the "electrical expert" working on the car and the dealer suggested it. I'm guessing there's kick backs involved between the dealer and the mechanic but that's completely unfoundedn(despite the fact that the dealer stated they know me and my vehicle which they don't because they've never seen my vehicle).

Apparently the vehicle is at the dealer right now where they're putting in my old ECU because it won't start with the other ECU. That I don't understand either.

Thanks again for the help!

Billy

[fleurys]

Thanks guys for the info! It doesn't drop at first startup when cold, only after running for 10min or so. I drove it to work and it cut out while in park and neutral, it's not just when at load. So does this mean the IACV is okay or can that still be a factor?

Billy

If this can be any help for you troubleshooting.... This 10 minutes thing behavior is typical of an o2 sensor... When you first start your engine, the o2 sensor signal is ignored while the sensor heats up. While this is going, your ecu will mix fuel and air at a predetermined amount considered as safe. It is usually richer just to be on the safe side.... They when the 5 or 10 minutes has elapsed, it will start adjusting the mixture according to your pre-cat o2 sensors... One easy way of knowing if the o2 sensors have anything to do with it is simply unplug them... This will bring a code, but it will also force your ecu to run in safe mode (rich mixture)... if the problem goes away, you'll know it is related...

Again, if everything goes well for the first 10 minutes, I don't see why it will start going ruff afterward with the rpm apart these sensors... These are the only ones that are not taken into account by the ecu when first started (cold).... It's worth a shot and it takes 2 minutes to try.

Good luck.

[Empty V]

If this can be any help for you troubleshooting.... This 10 minutes thing behavior is typical of an o2 sensor... When you first start your engine, the o2 sensor signal is ignored while the sensor heats up. While this is going, your ecu will mix fuel and air at a predetermined amount considered as safe. It is usually richer just to be on the safe side.... They when the 5 or 10 minutes has elapsed, it will start adjusting the mixture according to your pre-cat o2 sensors... One easy way of knowing if the o2 sensors have anything to do with it is simply unplug them... This will bring a code, but it will also force your ecu to run in safe mode (rich mixture)... if the problem goes away, you'll know it is related...

Again, if everything goes well for the first 10 minutes, I don't see why it will start going ruff afterward with the rpm apart these sensors... These are the only ones that are not taken into account by the ecu when first started (cold).... It's worth a shot and it takes 2 minutes to try.

Good luck.

Well I'm pretty sure it's not a sensor because the only code I'm getting from a sensor is after the cat. Speaking of O2 sensors, I've got more to the story.

So I called yesterday and dude says he left it at the dealer to diagnose the issue because it's beyond his skill. Then he tells me that the #3 coil burned out and he traced it to a short in the main wire harness whic his guy fixed. I had him replace all the coils and my bank 2 position 2 O2 sensor a month ago so now I'm out a brand new coil. I drive out to the dealer to discuss the truck and possibly pick it up. The dealer was pretty cool and hadn't touched it yet. BTW I did not authorize the mechanic to give it to the dealer to diagnose which would have tacked on a minimum $240 starting diagnosis fee. The dealer had no problems handing the keys over and I brought it home with the same misfire problem still occurring. I figured I would call the mechanic and thank him for putting the time into the vehicle and since I owed him for an O2 sensor and he owed me for a coil we'd call it even. I stop to get gas, popped the hood, and dude replaced the wrong O2 sensor!!!! I couldn't f-ing believe it! After all of this time he did not diagnose the problem, burned up a brand new coil and replaced the wrong 02 sensor. So I'll probably just lick my wounds instead of going after him for a new coil.

I took it to my local dealership(the other one is 20 miles away) with whom I know most of the people there and they usually give me a mechanics discount on parts. They quoted me $125 to start the diagnosis which is fair. My trusted local mechanic also agreed that the dealer would probably be the best place to go as this is most likely an electrical issue.This is one of the most frustrating things I've ever been through.

Billy

[Pwnin O'Brien]

I'll be honest, the dealer is definitely the best place to get most electrical system issue taken care of (besides taking care of it yourself). The CONSULTII computer can diagnose most electrical issues within minutes with around 100% accuracy; of course it all comes down to the competency of the tech operating the CONSULTII computer. That really sucks about the coil and O2 sensor that would really piss me off, no mechanic should allow a vehicle to leave their shop that is still getting DTC's for the original problem (or at least comp for all associated costs). Did they figure out the problem with the ECU?

[Empty V]

I think the ECU is okay. They swapped it out with another one but I'm not sure how they would have started the engine because they would have needed to program the key into the "new" ECU which can only be done on the CONSULTII right? I know they took it to the dealer before to re-flashed but I'm not sure which one they were re-flashing. I'm 80% positive Ive got my original ECU and an extra one sitting in my back seat which I think I'll keep.

[Empty V]

UPDATE

So I dropped it off at the dealer and they were able to diagnose it one day. They told me that they're 99% sure the drop in idle is being caused by the MAF. Which was one of the first things I told the 6 week mechanic to check but I don't think he had the tools to do so. The stealer wants $1K to replace it so I just ordered a brand new one off of ebay for $89 and will spend an hour on replacing it myself. If anyone has any tips to this job I'd appreciate it. To say the least I'm f'ing furious!

Billy

[fleurys]

did you monitor your MAF with an obd2 software to see the what's the volume of air that it thinks it's coming in ?? Usually a bad MAF will limit your revs just under 3000 rpm... On the other hand it might just be half-damaged :-) did you buy a used maf for that price ?? I mean they are 500$ ususally new... Changing the maf should not be very hard, Just make sur to not touch the element in the middle ... any grease, debris or other thing will make it fail... good luck and post pictures if you can...

S.

[asnorton44]

^ He is probably buying a Maxima MAF which is 100% compatible for a fraction of the price, that's the route I went.

[fleurys]

^ He is probably buying a Maxima MAF which is 100% compatible for a fraction of the price, that's the route I went.

Yeah I know, but even the maxima one is usually 200$....not 89 .... That's quite a saving.... we need to know about this...

[Empty V]

^ He is probably buying a Maxima MAF which is 100% compatible for a fraction of the price, that's the route I went.

Yeah I know, but even the maxima one is usually 200$....not 89 .... That's quite a saving.... we need to know about this...

I did order a brand new maxima MAF from Victory Nissan in Chesapeake, VA off of ebay Ebay Auction for 2001 Maxima MAF Super cheap and already on it's way. They've got tons of good feedback, seem to be an excellent seller, and are a legit Nissan dealer. Man I hope this works because if ti doesn't I'll be at a serious loss.

Billy

[Empty V]

UPDATE

Well I put in my new $89 MAF yesterday and it fixed ALL of my problems! My truck is like new and ultra improved.