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If you installed ecu maf injectors from stock DE and it still doesn't start. Then I'd say you have another problem. (assuming those are known good parts you bought)
 

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Discussion Starter #22
I started the car today and was tinkering but it dies pretty quikly, after a bit I had it running today on it's own for about 5-10 minutes before it died. The ecu throws no codes any more and all sensors are connected and in good order, the idle kept adjusting lower and lower untill it reached about 1400RPMs and fluctuated about 150 up and down but in no particular pattern such as with a MAF sensor problem i.e. no rev stall, rev stall ect.... I think that it has to do with the map and needs some ecu tuning now. or possable the z32 maf and a change in niztune to read for that maf, since I am using the turbo on the stock maf.

there is a possability it is something else.
Does anyone know a fool proof way to troubleshoot a consult port like with a volt meter or something short of finger tracing each wire to the source?


it also sputters alot and hesitates when gas is applied suddenly, then rev's
 

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if you are runing the z32 maf and the ecu is not set up for it than you will have all kinds of runing problems.

verify with oem components everything is working fine before adding new parts and modifiying the rom on nistune

once all is good for shits and giggles do boost leak check and verify all is good than add the new parts maf injectors and so on.

if you dont have experience with setting things up I recomend you seek help from someone who does. prolonged running the engine to rich at idol will hurt piston ring sealing

for consult port you need to check its power and ground and verify rx tx clk conections are good . you can not conect nistune from the obd2 port their is only one comunication wire on obd2 port and is not able to work with the board

if you run into a wall and can't figure something out I can offer verble help. Im just really no good at typing so its hard for me to pas on helpfull info
 

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Discussion Starter #24 (Edited)
Hey, yeah the verbal help would be good. I've looked over all the basics as far as I know what to look for but this is my first time doing a swap.

I am at the stage where everything in the car is stock with the exception of the turbo which is pushing air through the stock maf.

I have set the timing at +16 deg. at idle but as I said I can't get the idle down past 2000 RPM's so idle is more like rev.


So I have everything set up the way it is suppose to be (as I understand it) I may be missing something and in that area I am looking for some good old fashioned commen sense basics help, not throwing codes, no more limp home mode, but I can't get the car to stay running and when the few times I am able to it is idleing too high and doesn't sound stable, as I said also when gas is applied it goes to die first (rpms dropping from 2000, starts to sputter around 750rpms) then rev's up.

So basically in checking the consult port after checking for
1. battery voltage on pwr,
2. continuity on ground to grounding sources,
then I should check what? 3. continuity of tx between consult and ECU harness pin,
4. continuity of rx between consult and ECU harness pin,
5. continuity of clk between consult and ECU harness pin,
6. Continuity of pwr between consult and ECU harness pin?,
and 7. Continuity of gnd between consult and ECU harness pin?,

and by the way p10det, I am interested in the idea of burning back to factory rom for now but in the mean time I need to try to get the consult working. I have tested everything else i.e. sensors injectors ect.. they all test clean according to the fsm and hayens. The ecu is the only thing I can't be sure of so I do like that idea and will try it when as soon as I am able. in the mean time I'll be working on the consult port.

Thanks you guys for all the help so far
 

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Discussion Starter #25 (Edited)
I am curious, the consult port in my car has a 6 wire config instead of 5 (pwr, gnd, tx, rx, clk, ?) I believe it is the check wire.

How ever my consult cable only has a 5 wire set up.

1. Is this a possibility why data scan will not connect?
2. Does data scan work through the consult port from a laptop; on ecu's which are completely stock? or do I need an ecu with a chip?

I checked ground, to ground and ecu #39 = continuity fine, I checked pwr to ground = battery voltage and pwr to ecu #56 = continuity fine KOEO, I checked rx to ecu #64 = continuity fine, I checked tx to ecu #65 = continuity fine, I checked clk to ecu #68 = continuity fine, and the 6th wire to ecu #38 = continuity fine KOEO (though I am not sure what this wire is for, it has the same color markings as the rx wire i.e. yellow w/ black stripe and silver dots.
 

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Discussion Starter #26
All righty, I thought I'd update.....

The car is getting closure to a solution, I figured out I had multiple (un-metered) air intake leaks (hoses) I plugged them all up, untill upon plugging the last one the car died which I concluded was the last leak. (it was running w/ out the maf plugged in; in safe mode, it was idling at about 2200<2500RPMS each leak I plugged brought the idle lower and lower untill at the last one it was down to 1000rpms when that one was plugged it died. p.s. I had also already plugged the IACV hose just to find the leaks)

I connected the IACV hose to a nipple I had previously welded onto my intake piping post MAF, pre throttle body. When the MAF is unplugged and the ECM is in safe mode, the leaks are plugged and the IACV hose connected to the intake post meter, the car when warm idles at 750<800rpms a little roughly.

When the maf is plugged in the car will not idle at all and dies when trying to start it with out giving it gas. If pushing the gas peddal while starting it the car will start and RPMs change with gas peddal presure except that the car when rev'ed past 3500<400 rpms the peddal does not mantane responce and the engine slowly dies regardless of throttle, although it will pick up once it gets to lower rpms if the throttle is feathered but will not exceed 3500<400 rpms before loosing power (not fuel cut of) if peddal is steadly applied from start it will rev to 6000rpms.

The timing is set as far as I can turn the distributor and it is at max 13 degrees, as well.
 

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Discussion Starter #27
Any one interested in buying my G?

It comes with a few extra's
I am pretty sure it just needs to be tuned proffessionally

It runs steady untill warm then as the IACV valve closes the idle drops but then the IACV closes and it dies and will not restart untill cold again.
I am sure the car needs a tune and some one who understands tuning things such as A/F mixures and timing and such.
I just don't have the time or more money for it. At this point it seems the hard stuff is over it just needs some one intelligent to finish it up and run it.

I'm asking $2,450.00 O.B.0
There is a full write up in the CFS section, including the good the bad and the ugly plus about 30 pics through out.
 

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I know this is a little old but how did you handle your splicing, more what I wanna know did you cut back in the harness far enough to expose the shielded wire? or not? Really sounds like a wiring problem....also what ECU do you have Nistuned?
 

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When you say
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.
, does the ECU need to be plugged in? Or is it correct to test for continuity when the ECU connector is unplugged from the ECU?
UPDATE:
  • There is Battery Voltage 12.4 -12.88V on MAF plug at idle, Power Supply wire (Terminal B). I put one lead on this wire and the other on Battery Ground
  • Ground voltage is .01V, Engine running, leads on Chassis Ground and Ground wire (Terminal C).
  • There is continuity between the MAF plug and the ECU, both when ECU is plugged and unplugged.
 

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Could some one please tell where it says the correct voltage for the middle (ground) wire on the MAF sensor connector?
This source says if more than .009V are present, re-grounding of the MAF sensor is in order. MAF Sensor Grounding
I would like to know where this information comes from. Is it in an SR20DE engine vehicle's Field Service Manual somewhere?

In my FSM for '91 Infiniti G20, it says that there should be 1-3 -1.7V on terminal A, when testing the MAF.

Terminal "A" has no wire running to it, so maybe Terminal "A" is either Terminal B or D, depending how you look at the drawing of the Connector X-B-C-D or X-A-B-C. ??
There are 3 wires, Orange, White, Orange. The middle wire is white and in understood to be the Ground wire.
I believe Terminal B is the relevant Terminal "A".


With ENGINE at ILDE -weak idle, I get the following voltage (From MAF sensor to Battery Ground):
Connector looks like this ---> [ X-B-C-D ]
Terminal A (X) ---> 0V no wire running to this slot on the connector
Terminal B ---> 12.4V
Terminal C ---> 11.10V
Terminal D ---> 10.5V

I've been following the instructions from this thread, posts #5 and #7 -----> MAF Sensor
There is CONTINUITY on the MAF sensor GROUND wire with the ECU connector UNPLUGGED and PLUGGED.

I have a Known Good MAF sensor which I switched with the stock one that I have been testing.
Below are the voltage readings, comparing both MAF sensors' results in the same problematic G20.
Testing, MAF SENSOR CONNECTOR to ECU Pin 16, MAF connector connected:
[ X - B - C - D ]

MAF #1 (from problematic G20)
KOEOFF
:
Terminal D (input signal wire) --------> .60V
Terminal B (power supply wire) ------> 1.23V
ENGINE RUNNING AT ABOUT 1,000 rpms
Terminal D ---------------------------------> .66V
Terminal B ---------------------------------> 1.24V

MAF #2 (Known Good MAF sensor)
KOEOFF
:
Terminal D (input signal wire) --------> .61V
Terminal B (power supply wire) ------> 1.26V
ENGINE RUNNING AT ABOUT 1,000 rpms
Terminal D ---------------------------------> .68V
Terminal B ---------------------------------> 1.26V
  • Basically the same numbers, Is it that the MAF sensor not the problem? There is a Knock Sensor code as well as the MAF code in the ECU, and KS came first.
  • Could the KS code cause a MAF code?
  • Could a vacuum leak cause either of these codes? ( I have been hearing a hissing, but have thought it is due to air getting sucked into the power steering system. A separate issue)
 

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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.
There is CONTINUITY on the MAF sensor GROUND wire with the ECU connector UNPLUGGED and PLUGGED.

BACK-PROBING the MAF connector (CONNECTED TO MAF SENSOR) with the other lead touching Chassis Ground:
-- KEY ON, ENGINE OFF:

Terminal B (power wire): 11.8V (battery voltage)
Terminal C (ground wire): 10.5V
Terminal D (signal wire): 9.96V

--ENGINE RUNNING: voltage at -- voltage at -- voltage at

struggling 400 to 500 rpm -- 850 rpm -- 2500 rpm
Terminal B (power wire): 11.27--13.27V , 13.93V , 14.21V
Terminal C (ground wire): 11.05 --11.6V , 12.83--12.87V , 12.70V
Terminal D (signal wire): 10.42--11.04V , 12.17--12.20V , 13.94V


 

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I have a p10. I was getting 9.77V on the Signal wire and 10.38V on the Ground wire with KeyOnEngineOff, and normal battery voltage on the Power wire. The engine could barely hold an idle, and timing seemed like it had been hugely retarded. I fouled out my spark plugs just trying to let it idle while I tested voltage. I also had the Knock Sensor code present in the ECU.
What led me eventually to the MAF sensor was I was getting crappy gas mileage and the engine did a big miss. I thought an injector was going out, but there resistances were all within spec , and the voltage on their harness was what it should be. I thought I had put the plug wires on out of order by accident.
I swapped MAF sensors with a known-good MAF sensor and got the same sort of numbers that I did with the original. The ECU is only sending 3.32V to the Knock Sensor, but it's supposed to be sending 5V, from what I have read. I was suspecting the ECU was bad. The fuel filter is new, and the fuel pressure is at spec. I cleaned the MAF sensor and changed the air filter, switched out the crankcase ventilation hose because it had a split at the top. The engine was running crappy, but rich, not lean. Nonetheless, I was thinking something was making the MAF sensor act up and the ECU throw the MAF code, so I was thinking maybe a vacuum leak, or the ECU is bad. I did not see teh Exhaust Gas Sensor circuit code on the ECU, so I did not suspect the O2 sensor.
In either case, I knew the MAF sensor was good, so that left me suspecting the ECU or the MAF wiring.
That HIGH ground voltage at KOEO suggested the ground wiring was getting voltage added onto it somewhere between the ECU and the MAF sensor. After reading a lot of threads on MAF grounding, folks' symptoms sounded very similar to mineit sounded like it could only benefit my situation. I cut the ground wire a couple of inches behind the MAF connector and spliced/soldered a new ground wire in place and ran it around the airbox to the negative battery terminal clamp.
Now, the voltage reading in Signal wire is .78V and .007 on the Ground wire. I reset the ECU (cleared the MAF code), put KOEO and checked for codes again. 55, No problem codes present. Amazing.

To secure the new ground wire to the negative battery terminal, I used a "mechanical connector", a flanged metal cube with a worm screw into the middle of it, but not out the other side. The flange has a hole through it for mounting. The ground wire goes into the cube and the worm screw is tightened down onto the wire (14 gauge) strands. I then, soldered the empty space around the worm screw. I used Ultra Grey RTV and a bit of rubber vacuum hose to give the wire reinforcement where it meets the flanged cube. I used a long, thin bolt to tighten the negative battery terminal, and the flanged cube is secured onto the bolt between a spacer and a tightening nut.
I have not cranked the engine yet but will tomorrow. That code 55 is so nice to see.
 
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