Hi all....

nope, my problem is still not solved. now I am seeking professional help from Turbo95Max because he has a scan tool. Anyways...as titled. so at open loop, O2 sensor is bypassed and everything is now relied on the MAF? I noticed that my EGT increase in about the same rate when I nailed the pedal and open the throttle slowly to half open without downshifting. Everytime I hit 100mph, the EGT hits 800c. Does throttle position sensor affects injector duty cycles at open loop?

Does this mean my MAF is sending a constant voltage to the ECU and making the injectors stay in the same duty cycle all the way till redline. I noticed that my AFR drops a little from 5500rpm but I thought that is because the high fuel pressure.

thx

 

No...TPS doesn't affect injector duty cycle.

I'm almost positive MAF is all the ECU uses as an input to specifically control injectors. It uses other things for timing, but for fuel only the MAF.

My guesses according to your description:
1)MAF voltage peaks and doesn't increase anymore, so the ECU doesn't add more fuel.
2)Fuel pressure/flow is inadequate, but your FP gauge disagrees.
3)Injectors aren't providing enough flow due to whatever, clogging, age, size, etc...

To eliminate the MAF as a culprit you could either A)hook up Turtles' scanner and monitor the MAF to see if it's measuring the increasing air flow or B)rig up some LONG leads to a multimeter, so you can watch it in your cab as you go WOT. If the MAF peaks at a value and doesn't climb as RPMs do, you've found your problem.

 

BTW, I'm going to(I keep forgetting!) try and hook up my multimeter to an injector in the "Duty Cycle" mode to see if it measures it. If it does, you could see what duty cycle your injectors running and see if it changes or not once you go WOT.

Also, you *COULD* pay a Nissan tech to ride-along with you with a Consult-II to tell EXACTLY what your injectors, MAF, fuel-pressure(I think), timing, etc. are doing. I know...I know PITA, but it would really help.

 

Also, do you have a check engine light?

 

According to the FSM for a "too lean" condition:
Possible Cause:
1)Intake air leaks
2)Heated oxygen sensor 1(front)<~~~Closed loop only though.
3)Injectors
4)Exhaust gas leaks<~~~~Closed loop only, I think.
5)Incorrect fuel pressure
6)Lack of fuel<~~~Out of gas?
7)MAF

Out of that list, I'd suspect:
-Intake air leak
-Bad injectors
-Bad MAF

 

FSM "Check Injector"(Need new O-rings):
1. Confirm that the engine is cooled down and there are no fire hazards near the vehicle.
2. Turn ignition switch “OFF”.
3. Disconnect injector harness connectors on bank 2 (for DTC P0171), bank 1 (for DTC P0174).
4. Remove injector gallery assembly. Refer to EC-51.
Keep fuel hose and all injectors connected to injector gallery.
The injector harness connectors on bank 1 (for DTC P0171), bank 2 (for DTC P0174) should remain connected.
5. Disconnect all ignition coil harness connectors.
6. Prepare pans or saucers under each injector.
7. Crank engine for about 3 seconds. Make sure that fuel sprays out from injectors.

 

Really.. hmm.. that may HELP me.. thanks

sorry for the thread jack. It would be better if icy started it, since he jacked my OT thread

 

This is ONLY during OPEN-LOOP, startup, and warm-up.

 

see other thread

 

bags - dont worry about thread jacking, I do that sometimes too

thx for your help, Alex.....but things didnt go as expected this weekend.
anyways, back to the subject:

I went to turbomax's place this weekend and all we could do was a continous reading on MAF during WOT. The MAF read up to 107 g/cm2 near redline @ 3rd gear. The EGT is reading high too, went all the way up to 815c (1500f) No CEL codes, no knock sensor codes, no nothing and only thing that I am concerned is that the reading is not real time. Turbomax's scan tool has a slightly delay with OBDII vehicle. Now I am hitting a wall again and I hate to see my theory is once again, incorrect.

thx turbomax for your help. He didnt charge me anything for the diagnostic

now, I am looking into getting Nissan tech to help with a consult 2. but I have a few questions.

1.Is the reading I have on turbomax's scan tool the same as the MAF voltage reading at ECU? I mean, if I see the MAF reading increase on a scan tool, the ECU should receive the same voltage increase, right?

2.can consult 2 monitor each injector's duty cycle? I am not sure if it is a general fuel delivery problem on all injectors or just a single or 2 injectors.


I dont have any clue on approaching this problem. I am getting tired and I really want a way out.

 

fuel pressure-wise...I put in a new inline pump not long ago and I am getting a bit higher fuel pressure at idle and WOT. I am pretty sure it is not a mechanical problem because how my AFR richens when near redline....even though it is a lean 13:1.

injector wise....if I can get them to test the injectors and they all run at 80% duty cycle, then I am doomed and it is time for new injectors. But I didnt notice this problem until recently and this problem didnt show up just overnight......it took time. so either the injectors cant handle that much of fuel pressure and aging time after time of high pressure abuse or the MAF is somehow damage when the fuel pump is wired to its 18v power source.


Another thing that turbomax mentioned is that my car bogs a little at low end and pulls hard after 4000, not very linear.....he said it feels more like a turbo charged than a superchagered....probably it is running to rich at low end and for sure it is lean at high end....I wish it is the other way around

 

alright....just called a nissan dealer and they can do it for an hour with consult 2. winthin that hour, I can do anything that I want...but they ask for 110 dollars

alright guys....should I go for it?
if so....what should I do within that hour? injectors, MAF, ignition......


again $110 dang!

 

And on the MAF reading, did the numbers start high and go low? Or did they start low and go high?

The reason I ask is that dixit came over and we hooked up his laptop and I saw like 258 gcm. This was at idle nand when the car was not even running.

So it sounds shorted to me, but I was trying to get a refference gcm. That is why I am asking.

Thanks.

BTW what is the problem your having?

And check EVERY LAST THING for $110.

 

the reading went from low to high. idle was 25.xx and peak was 107.xx. Turbomax's scan tool is not real time so I couldnt tell the rate of increase.

I think you see 25.xx during idle, not 258.

I am having lean problem even the fuel pressure is boosted.
just some FYI for my rich dyno and lean dyno....not taken on the same day, but 8 months apart.
http://home.earthlink.net/~doctorkiw...o-14vs10-1.jpg



$110 is still to pricey for a test ride. I would save that money to get the injector duty cycle indicator that Stephen Max uses. we will see.....<sigh>


plan for now - monitoring the MAF input voltage with a long wire and multi meter as Alex mentioned.


if everything is good.....then I guess maybe I should go back to 3.33 pulley. 2.87 maybe too much for my little car.

 

it's possible dixit and I did not see the decimal point. It was 3am..lol

Hmm what about the 02 sensors?

Checked injector resistance?

The duty cycle thing sounds good.

Any vaccum leaks? Couls cause the FP to be lower.

What is your FP?


sorry if this has been covered before

 

O2 sensors look white....so my car is running lean. Turbomax checked the voltage and they are working fine. because it is in open loop, my lean problem cannot be detected by ECU and will not generate a code. plus, ECU never know that I am boosted, so she thinks 14:1 is pretty normal

havent check injector resistance - havent done it. you just check the connector, right? if it is bad.....what does it mean? Do you have to replace the injector? and you have to take off the intake manifold to check the injectors in the back, right?

vacuum leaks....I doubt it. if there's leak in the intake manifold, it will raise the fuel pressure because the fuel pressure regulator reads off the same vacuum from intake manifold. It will think that it is at WOT (no vacuum) all the time and pump extra fuel to injectors.

FP - idle, 39psi. 0 vacuum - 45psi. 10psi of boost - 110psi.


thx for your help