2001 Nissan maxima crank ref sensor corrosion on tip with rich condition

Hi all I have a Nissan Maxima which has broken my heart for the past 18 months firstly hands up I was parts changer and shotgunned the car to no avail however I finally started following scanner videos last summer and have been trying diagnosis techniques with a bit more success I apologise in advance for the lenght of this post.
The car originally had a lean condition and I discovered a significant number of vacuum leaks using water. I replaced gaskets and hoses which were leaking. The car idles without stalling, however there is a misfire and its now running rich I have scoped the ignition coils and found one bad coil and replaced it wave pattern on ignition now looks good. I also changed the O2 B2SI beacause of failed heater circuit. Compression tested 165-185 psi in all cylinders, injector wave form looks good but maximum Amps are approximately 0.8 Amps. Voltage is 70 - 80 Volts. the only code coming up is p1335. Long term fuel trims are -10.2 on bank 2 and -1.6 on bank 1 short term on both banks are negative at Idle but in around 0 above 1000 rpm and the car stinks of fuel when idling. The circuit seems fine on the crank sensor and it ohms well but the tip is heavily corroded I can't safely back probe the crank sensor because of its proximity to the alternator belt. I am obviously reluctant to spend any more on this car because on parts alone I have already paid well over a grand. I am completely lost on this one I need direction. All help really appreciated.

I have back probed a connector on the side of the engine which is connected to sub harness leading to crank ref and signal looks fine so I think this is something to do with a leaking injector or injectors. I am just reluctant to pull the intake again without being sure anyone any ideas.

Have you checked the fuel pressure/regulator? Does it hold fuel pressure, after shutting off the engine. Or, does it, immediately, begin to fall?

Hi Pole71, tanks for your reply, I tried that test on friday however I didn't block off vacuum and it yielded nothing after 5 minutes of idling with a few throttle snaps. I will check again In the morning its now pitch dark here in Ireland I cant see anything and torch died. I will post back tomorrow thanks again.

Hi guys I checked the regulator and damper this morning and both are fine I forgot to mention I changed the fuel pump last year when I first started trouble shooting the car with an aftermarket pump.

P1335 being crank position sensor?


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P1335 is a Nissan specific code I cleaned the corrosion off the tip cleared the code and it didn't come back as yet but I haven't driven the car since because it has no test which here in ireland means I cant take it out on the road legally. just let it idle during testing and increased the rpm'so blow any crap out of the exhaust T. I am going to pull the intake manifold today and remove the injectors and test them for leaks. I did however pull the spark plugs last night and discovered they were all fouled with a tar like coating on the centre electrode and the side electrode is relatively clean but the tar was spreading up the side and incorrect gap they are denso plugs rather than the recommended NGK. I will boroscope the cylinders while I have the intake off as well I presume there is significant carbonisation of the cylinders from looking at the plugs. can I clean the plugs and put them back in or would they need to be replaced.
Where I live diagnostic technicians are like hens teeth.

Just a note on fuel trims + - 10 are acceptable + - 5 is preferred , fouled plugs will cause - trims , does it still run rich and misfire after coil replacement ?

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Hi Ben, I pulled the injectors this morning and discovered the no. 2 had an iffy pin so I swapped it with a spare one I had lying around. I know + or - 10 is OK but she is just -10.2. but stft can be into the 20's
When I swapped the ignition coil on the no. 3 I re-scoped it and the pattern came up to match all the other coils. it was about half all the other ones before that.

yes there is still a miss its not registering a miss but she runs choppy and I can feel something. I still have the intake off but it started raining so had to leave for a while. I am convinced that the crank code was because of the miss which is probably down to the plugs. I am not convinced they are the correct plugs. Iam going to boro scope the cylinders when the rain lays off. Iwill post back then.
Darren

Hi Ben, I pulled the injectors this morning and discovered the no. 2 had an iffy pin so I swapped it with a spare one I had lying around. I know + or - 10 is OK but she is just -10.2. but stft can be into the 20's
When I swapped the ignition coil on the no. 3 I re-scoped it and the pattern came up to match all the other coils. it was about half all the other ones before that.

yes there is still a miss its not registering a miss but she runs choppy and I can feel something. I still have the intake off but it started raining so had to leave for a while. I am convinced that the crank code was because of the miss which is probably down to the plugs. I am not convinced they are the correct plugs. Iam going to boro scope the cylinders when the rain lays off. Iwill post back then.
Darren

Ok I like to do a cardboard test with the injectors if you don't have an injector tester tool if you pull the rail and wire tie all the injectors to it(for safety) and place cardboard under the injectors and have someone crank it while observing fuel spray to see if you have a partially plugged injector (also a good idea to disable spark) may be worth doing while you have intake off . It does sound like it's time for some plugs .

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Hi Ben I have made a power supply from an old laptop charger and injector connector and tested the injectors individually because I cant crank the car safely with the intake off I use carb cleaner and the pattern is a good cone shape with full atomisation. I scoped the cylinders and there is a layer of sticky looking crud on all the pistons. I agree the plugs are no good and I think the denso ones are burning too cold causing the fouling and carbonisation of the cylinders.
Dar

Hi Guys I ran another scope test this morning and discovered that the used coil I put into the car was no better than the one I took out or else its blowing coils the amperage is half all the other ones so I have ordered a new one and a set of NGK plugs hopefully they will sort it I am conviced at this stage that this is the reason she is running rich due to incomplete combustion. I will post back when I have fitted and rescoped the parts.

right lads I put a new coil and plugs into car and scoped, wave forms are perfect,Long term trims are still negative -10.2% and short term trims are constantly negative on both banks I then tried swapping pressure regulator with one from a breakers didn't change. Neither breaker or original regulator have fuel leak if I remove the vacuum hose from either the damper or regulator she drops back to -7.8% . I am at a loss with this car I don't think it will pass a test I need it back on the road ASAP. Any suggestions really welcome help!!! I need to get a reading on fuel pressure but my kit doesn't have a fitting for this car. Can an aftermarket pump run too high pressure.

To answer your question I would say no even if the pump put out 100 psi the regulator would dump off extra to put it where it should be , also other things play a role in fuel trims such as valve adjustment, compression, vacuum leaks, exhaust leaks, oxygen sensors , misreporting maf sensor ,on non maf engines the map sensor plays a role ,to a lesser extent even air temp and coolant temp can sway fuel trim numbers

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Ben wrote: To answer your question I would say no even if the pump put out 100 psi the regulator would dump off extra to put it where it should be , also other things play a role in fuel trims such as valve adjustment, compression, vacuum leaks, exhaust leaks, oxygen sensors , misreporting maf sensor ,on non maf engines the map sensor plays a role ,to a lesser extent even air temp and coolant temp can sway fuel trim numbers

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Hi Ben Thanks for confirming I watched Paul's video on dirty maf sensor and my symptoms are identical so I will try to clean it , if it doesn't work I may buy a new one. Can I scope a maf.

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Yes you can Paul has some vids on scoping a maf

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Hi Ben, Thanks for that I will look into it if I evr get it fixed I will post back.

Do you have a scan tool with maf data pid ? If so we can diagnose the maf sensor with it's grams per second reading at idle with a warm engine and at wide open throttle in 1st and 2nd gear

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I have a post in the diagnostic tools and technics forum Topic is known good pids it's like the 15th or so down the list I couldn't link to it as I'm on the tapatalk app but I gave a great description on how to test maf with a scan tool that will apply to most any vehicle

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