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Discussion Starter #1 (Edited)
I could really ise some insight into this issue.

94 G20, Original ECU and Distributor.

MAF will not work, car runs in safe mode when MAF disconnected, tried Z32 MAF same issue, DTC MAF code is thrown by ECU when MAF disconnected but not wwhen connected, car no run when MAF connected, runs in safe mode when disconnected, tried two ECU's

PLease Help
 

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As promised, I just posted a link of this thread as noted hear:

http://www.g20.net/forum/showthread.php?t=112746

Unfortunately, it's in the sponsors only section, and I see you're not a sponsor. However, I've noted this for Snickers and I hope he'll chime in. You might also want to contact member 'p10det'
 

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Discussion Starter #4
I Appreciate it. I will follow up with P10Det
 

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Check the power to the maf. Get a volt meter and check for Batt voltage as well as ground. Then check continuity from the maf plug to the ecu. If the ground wire does not have a good ground then try to ground it directly to the chassis.

Then also check the actual voltage going to the ecu (signal voltage) with the key on engine off.
 

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Discussion Starter #6 (Edited)
the voltage imput wire reads just under 12v ignition on and just under14v engine running, both in the stock maf plug and the z32 maf plug.

the ground wire on the z32 maf plug closest to the signal wire is grounded to the chassis and has continuity with all vehicle ground points in the engine bay, the ground wire closest to the voltage imput wire on the z32 maf plug is connected via splice to the stock maf ground wire and has continuity with all ground points.

the stock signal wire and ground wire have continuity to the ECU harnes plug positions 58 and 57, the12v voltage imput wire does NOT have continuity with any of the ground points (so no short).

As I said the engine falls and dies once the maf plug is connected to the maf, but I have tested it as it is being connected, I am reading an approx. 1.6 to 2.4v as the engine dies, depending on how fast it dies before I can read the signal voltage.

I was reading a code for the intake temp sensor with the stock maf as well so I tested that for voltage and continuity as well as testing resistance of the sensor everything checked out clear,
I also tested out the two water temp sensors sense the intake air and water temp sensors kind of define each other for being in good working order, all tested clear.

I no longer am having any intake air temp codes though.

When I do disconnect the plug from the maf and test the signal voltage wire (not the grounds or the voltage power imput wire) with the ignition on, engine off, it reads -0.06. Should there be voltage on the signal wire when the ignition is on, engine off and the plug disconnected from the maf? or does it need to be connected but engine off to see voltage?
 

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so, just to be sure, you have 2 maf plugs in your engine bay? (thats what it sounds like)

other than the Z32 MAF, which other MAF are you using?

when checking signal voltage, the MAF MUST BE PLUGGED IN

Depending which MAF you have you wuill get a different voltage.

IIRC Z32 is about .7V KOEO, 1.1V Engine running
STOCK maf is about 1.1V KOEO 1.5V engine running (or there abouts)

Also, when did this problem occour? recently all of a sudden, or after making a maf swap?
 

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Discussion Starter #8
I am getting a reading of 0.45 on the signal wire when the plug is connected to the z32 maf and the ignition is on, egine off.

I had the Stock 94 G20 MAF in the car connected with the Stock Wiring and harness.

I had issues with that, I recently repalaced the stock MAF with a Z32 maf and cut out the stock plug to the original maf but used the existing 3 wires to splice into the new z32 maf plug (the forth wire needed for a Z32 maf, I grounded to the chassis)


http://i87.photobucket.com/albums/k149/fliple_niple/Z32Mafsplice.jpg


this is how I wired it up
 

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Discussion Starter #9
The issue has always been there,

I bought the car with a blown engine, and swapped a w10 avanir DET into it, I kept the original Distributor and ECU, once it was done and I tried to get it running it has always had this issue.

I've had the car since 08 swapped the motor in 10 and it has been like this since then.

it almost feels as though it cuts the gas when the maf is plugged in.

Also the idle is insanely high 1400rpms (when the maf is disconnected) (when the MAF and tps are disconnected it sputters around 800rpms)
 

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Discussion Starter #11
only thing is, I had the exact same issue with the stock maf, I can swap it back and trouble shoot that way for the mean time.

My original ECU has a NIStune Type 4 Board in it, but I can't seem to get the car running with out the ECU being in safe mode, so I haven't been able to connect yet to change the settings to the new maf.

I think for now I will revert back to the stock maf and troubleshoot with that.


One other thing, when I recieved my Type-4 board from NIStune it came with a consult cable fitted with a harness that connects to the harness just bellow the fuse panel, under the driver side dash this one has the tx and rx and power and ground and clk pins and that is it. However, I do have the OBD-2 code reader and diagnostic harness plug on the passanger side just bellow the glove box which is wired into the wiring loom (with the ECU wire harness wires) This is where I am able to connect to read codes and such using an OBD-2 scan tool.

My question is, do I have the right connection type? or do I need to connect my NIStune consult cable up to the same port that I use the OBD-2 scan diagnostic tool on (on the passanger side of the car near the ECU)?

Thank You,
 

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Discussion Starter #12
I'll do some more digging around and troubleshooting and change the configuration.
 

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Discussion Starter #13
I reverter back to the stock maf and connector, I tested the stock MAF to find
-0.06v at the signal waire KOEO, I inspected the sensor fillaments. the tallest one has a bubble in the coating so I tested for continuity from filament pole to pole on the sensor and found non, however the shorter filament has continuity from pole to pole, I tested for resistance and got 0.026 on the shorter filament and nothing on the taller one. I am guesing the bubbling effect in the coating on the taller sensor fillament was due to overheat and burn of the fillament it's self.

I happen to have another stock maf laying on the shelf, I installed that as well and tested at the signal wire, again -0.06v KOEO, I took the second stock maf out and inspected.

Lo and behold after testing both short and tall sensor fillaments for continuity and resistance I discovered the tall sensor fillament was defective on this maf as well, it had come off of one of the poles (the same tall maf fillament as the last stock maf which had an issue, although this one was not burned as the last was).

After some very very delicate saldering using very small silver salder, I managed to re attach the tall maf sensor fillament to the pole, I retested for continuity and resistance, both short and tall maf sensor thermastor fillaments have continuity pole to pole and both test resistance out between 0.024 < 0.026 ohms

I installed the now newly repaired stock maf into the intake and tested out at a perfect 0.70v KOEO

the ECU is no longer in limp home (safe) mode, unfortunatelywhen I start the engine it now revs to 2000RPMs for a few moments goes to die down to idle but instead dies completely.

I thought possible it might be something to do with the avenir injectors working with a p10 ECU except that I realized I replaced the fuel rail from a 95 P10 including the injectors so now I am not sure what it might be.

The only code I get now is DTC 34 knock sensor but I think I broke the holder to secure it during the engine swap.

So besides that I am stuck.

Possibly a fuel inj. issue, ect... Any Ideas?
 

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sounds normal except that maybe the cold start valve isnt plugged in? or that fuse is blown. check the ECCS electronics fuse and those under the dash. One of them supply's power to the cold start high idle valve and the idle valve as well and that is what keeps it idling when cold.
 

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Discussion Starter #15
I thought of that also, so as a short cut I disconnected the maf sensor and used the safe mode to warm the car up, then plugged the maf in and it died instantly, I will be checking through the IACV and cold start silynoid.

I've noticed the avenir has a different IACV then my stock motor, is that usually an issue with a p10 avenir swap?
 

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Discussion Starter #16 (Edited)
I am sinking way too much money and time into a car that I never get to drive.
I have tested virtually every sensor, swapped ECU's, tested the injectors, the fuel pump, took all the vacuum hoses off; read the diagrams, put them back together regrounded all the grounding sources, ect...
I can't connect with nistune, I can't connect with datascan.

All I can do is keep dropping tons and tons of cash and wasted time on the POS! which is wasting my time.

I am starting to F'ing! hate this car!

I took the manifold and planum off and checked the IACV-AACV and Air Regulator,

it's like one of those Sh!t ass movies you watch and watch thinking it will be worth the the wait and it must be leading to something really good and then you get to the end and realize you have just erravokably lost 2 and a half hours of your life, which you can never get back!

Sorry, I am married so some of my frustration is coming from that.
 

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I am not familiar with nistune so I can not help you there.


I would swap in a stock ecu, maf, and injectors and see how it runs with that. It can quickly eliminate a lot of things. I have seen ecu's with cracked solder joints and other bad drivers. That will eliminate a lot.
 

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iinteresting also might want to try useing the nistune on a known good car.also was the nistune bought used?

the nistune can only be adjusted in the consult port. if your greay consult port is not working you want to get it working.
if you bought this used and have no clue whats on the ecu its best to connect data scan copy down ecu part # than with nistune burn it back to factory rom for now
 

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Discussion Starter #20
NA, I converted back already to the stock injectors and stock maf and an ECU from Ebay (no luck still when the maf is plugged in it dies BUT without any codes now). My original ECU has Nistune saldered in and the jumper already moved, I haven't tried placing that one back in recently.
Since I recently regrounded everything and tore everything apart and reconnected, now it turns over and over but does not start with or with out the maf connected, I already re-tested the injectors the voltage and resistance is perfect, so I need to go and retest everything untill I find out why it won't start at all now.

I don't know anyone near by who owns a P10 to try to use my nistune on, if some one would be willing to help out and has nistune saldered in and known to work that would be pretty sweet. Man, I could really use the help.

the nistune was bought brand new unused.

Man, I wish this thing would just work, so I could spend all this frustration on upgrades rather than dead ends.

One of my concerns is that the Consult port DOES NOT work but I am not exactly sure how to see if it is working or not, like in a fool proof way. all the cables tie into the wiring loom and run toward the ECU, non are cut.
 
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