[mjeffries]

Into:

My name is Michael and I own a 2003 Nissan SE-R. The Turbonetics turbo kit was installed in September 2007 but didn't really start to see time on the road until ~Feb of 2008. I am currently running on 12psi via a GReddy EBC and have an APEX'i AFC Neo for additional fuel tuning. Full 3'' exhaust, water/meth injection and the Jim Wolf Technology balance shaft removal kit pretty much top things off. There are other mods but none of which will really make a difference to this thread.


The Problem: Inconsistent fuel delivery


I just spent about 20 minutes typing a long post describing the issue but decided that a "short and sweet" would be much more effective. Fuel delivery is inconsistent at idle and WOT. This problem first appeared just after I finished the install of my clutch and flywheel but I doubt that has any relation to the issue at hand.

Idle: 50% of the time at idle I'll see perfect A/F ratios; damn near a steady 14.7. The other 50% of the time the wideband will read "---", the leanest it will actually read is 18.0. During the lean idle times the car may studder a little but not always. Idle speed remains mostly unchanged.

WOT: Without changing any settings (boost, piggyback fuel controller, meth injection) I will sometimes see 11.5-12.0 A/F ratios (my target) and other times I will watch the A/F ratios lean out into the 13s, at which point I promptly let off the gas of course. Keep in mind that this problem doesn't always happen, sometimes the car will pull like a champ. Let me be the first to say that adding fuel via the piggyback fuel controller is not the answer to the problem; it will only mask the real problem.

These issues have been with me for a little over a month now.



What I've done so far:

I changed my plugs but didn't notice any real difference. In this post are pictures of the plugs that came out, didn't see anything wrong with them but I'm far from an expert.

Took a look at the fuel pump and fuel filter. The filter had some black soot on it but not too much, cleaned that off and reinstalled. Didn't help.


I cleaned my MAF and air filter; didn't help.


I checked my compression. Starting at the passenger side I saw 180psi, 175psi, 170psi, 175psi. Great numbers. I took it to a shop about two months ago for the same test and those numbers were lower but I can't remember exactly what they were. This was my first time peforming this test on my own but it doesn't really seem like something I could screw up.

I've added fuel injector cleaner stuff on two different fillups, don't know if it helped or not.

The O2 sensors are only a few months old, both purchased from the dealership.


(side note: In the past few weeks I've thrown a P0172 [System too rich Bank 1] code three times. Each time it was just during normal cruise conditions. Not sure if that helps at all. A/F ratios didn't look rich at the time the codes were thrown)



My "Need to check" list:

-Fuel pressure
-Coilpacks
-Injectors
-ECU relfash gone crazy?
-(let me know if I'm missing something here)




I'm pretty much just making this post to document the troubleshooting process I'm going through in the hopes that it will help somebody out if they encounter the same problem. Your comments and suggestions are certainly welcome. I usually post on MySpecV.com but any time I make a long, somewhat educated post it gets ignored. If I make a short post that sounds like a twelve year old typed it then the thread will end up being 4 or 5 pages. Very frustrating.


I'll keep updating this until I either find the problem or lose the engine.

[Robert]

I'd be very interested to see the fuel pressure numbers. I would especially check the fuel pressure at two specific points. First get a static fuel pressure reading at idle. If possible run this test over the course of a week. Log the fuel pressure at idle on a note pad. Then start checking fuel pressure under WOT. Make a mental note of what it reads each time you go WOT. Try to log it in the same notepad at each red light or when you get to your destinitation. With your current out of box setup I would expect to see your fuel pressure have a delta of 8-10 PSI from static. In other words running a returnless system you should see the fuel pressure drop between 8-10 PSI from what it is static when you go WOT. This could be the source of your issue. Out of box at 8 PSI the car does well with only a delta of maybe 6 PSI. As you start going up with boost pressure the delta increases proportianally. Most times it won't make much of a different however under lower volumes of gas in the tank if the pick up for the point starves for fuel at any point you may see a lower pressure reading which would cause an inconsistent fuel pressure to read. At the out of box 8 PSI this typically doesn't make any difference but if you have a 10 PSI or greater delta and then have an issue with the fuel pick up it could cause things to go a bit too lean. Its just a theory but its happened on Z cars when they cross the 9-10 PSI range.

[mjeffries]

Thank you for the input. I don't currently have any way of checking fuel pressure, either going to have to purchase something or wait until my buddies schedule matches mine and he can help me test that. I may eventually install a 1:1 fuel pressure regulator. Would I also need to convert to a return style system for a 1:1 FPR?

[Robert]

Originally Posted by mjeffries

Thank you for the input. I don't currently have any way of checking fuel pressure, either going to have to purchase something or wait until my buddies schedule matches mine and he can help me test that. I may eventually install a 1:1 fuel pressure regulator. Would I also need to convert to a return style system for a 1:1 FPR?

Yes you would need a way to feed the fuel back to the tank. A 1:1 FPR regualtes the pressure on the back end. In other words the fuel goes from tank to pump to rail to injectors with unspent fuel going out of the rail into the FPR and back to the tank. That way the fuel systems gets optimim pressure which is regualted based on how much the FPR allows to go back to the tank.

[mjeffries]

Question for you Robert. What are the chances that my reflash is a little screwed? I ask because during my clutch install I pulled a typical Michael move. Didn't disconnect the battery before I tried to remove the starter. Got one hell of an arc.... then tried again and arc'd again. (Sometimes I'm not the brightest shade tree mechanic out there.) What are the chances that I somehow screwed up a small portion of the reflash? The problem appeared just after the clutch install.

[Robert]

Originally Posted by mjeffries

Question for you Robert. What are the chances that my reflash is a little screwed? I ask because during my clutch install I pulled a typical Michael move. Didn't disconnect the battery before I tried to remove the starter. Got one hell of an arc.... then tried again and arc'd again. (Sometimes I'm not the brightest shade tree mechanic out there.) What are the chances that I somehow screwed up a small portion of the reflash? The problem appeared just after the clutch install.

Its entirely possible of course but I would have expected some other issues to surface as well if that was the case.

[mjeffries]

Well as it stands my next course of action is to test the fuel pressure as you suggested. Not sure when I'll be able to do that, hopefully sometime this weekend or soon thereafter. I can probably try to test the coilpacks before then but I still need to research how to test those. I've read some but nothing informative enough.

Thanks for all the input.

[Robert]

Originally Posted by mjeffries

Well as it stands my next course of action is to test the fuel pressure as you suggested. Not sure when I'll be able to do that, hopefully sometime this weekend or soon thereafter. I can probably try to test the coilpacks before then but I still need to research how to test those. I've read some but nothing informative enough.

Thanks for all the input.

For the coil packs I would trust the ECUs input. If possible try to find a Consult 2 or a friend at a dealer with access to one. I believe they can run a diag test on the coils.

[mjeffries]

Update: 04 OCT 08



Today I replaced the camshaft position sensor and the crankshaft position sensor, as suggested by zeniac. It was worth a shot but I'm still having trouble with lean conditions at idle. Haven't had an opportunity to test WOT conditions yet.

I'm in the process of setting up a Zeitronix ZT-2, going to datalog A/F ratios, EGT, RPM, TPS, MAP and there is room for a user defined 5v input which I will try to make my MAF voltage.

Have not been able to test fuel pressure yet, very difficult to match my schedule with my buddies schedule.

[Robert]

Originally Posted by mjeffries

Into:

My name is Michael and I own a 2003 Nissan SE-R. The Turbonetics turbo kit was installed in September 2007 but didn't really start to see time on the road until ~Feb of 2008. I am currently running on 12psi via a GReddy EBC and have an APEX'i AFC Neo for additional fuel tuning. Full 3'' exhaust, water/meth injection and the Jim Wolf Technology balance shaft removal kit pretty much top things off. There are other mods but none of which will really make a difference to this thread.


The Problem: Inconsistent fuel delivery


I just spent about 20 minutes typing a long post describing the issue but decided that a "short and sweet" would be much more effective. Fuel delivery is inconsistent at idle and WOT. This problem first appeared just after I finished the install of my clutch and flywheel but I doubt that has any relation to the issue at hand.

Idle: 50% of the time at idle I'll see perfect A/F ratios; damn near a steady 14.7. The other 50% of the time the wideband will read "---", the leanest it will actually read is 18.0. During the lean idle times the car may studder a little but not always. Idle speed remains mostly unchanged.

WOT: Without changing any settings (boost, piggyback fuel controller, meth injection) I will sometimes see 11.5-12.0 A/F ratios (my target) and other times I will watch the A/F ratios lean out into the 13s, at which point I promptly let off the gas of course. Keep in mind that this problem doesn't always happen, sometimes the car will pull like a champ. Let me be the first to say that adding fuel via the piggyback fuel controller is not the answer to the problem; it will only mask the real problem.

These issues have been with me for a little over a month now.



What I've done so far:

I changed my plugs but didn't notice any real difference. In this post are pictures of the plugs that came out, didn't see anything wrong with them but I'm far from an expert.

Took a look at the fuel pump and fuel filter. The filter had some black soot on it but not too much, cleaned that off and reinstalled. Didn't help.


I cleaned my MAF and air filter; didn't help.


I checked my compression. Starting at the passenger side I saw 180psi, 175psi, 170psi, 175psi. Great numbers. I took it to a shop about two months ago for the same test and those numbers were lower but I can't remember exactly what they were. This was my first time peforming this test on my own but it doesn't really seem like something I could screw up.

I've added fuel injector cleaner stuff on two different fillups, don't know if it helped or not.

The O2 sensors are only a few months old, both purchased from the dealership.


(side note: In the past few weeks I've thrown a P0172 [System too rich Bank 1] code three times. Each time it was just during normal cruise conditions. Not sure if that helps at all. A/F ratios didn't look rich at the time the codes were thrown)



My "Need to check" list:

-Fuel pressure
-Coilpacks
-Injectors
-ECU relfash gone crazy?
-(let me know if I'm missing something here)




I'm pretty much just making this post to document the troubleshooting process I'm going through in the hopes that it will help somebody out if they encounter the same problem. Your comments and suggestions are certainly welcome. I usually post on MySpecV.com but any time I make a long, somewhat educated post it gets ignored. If I make a short post that sounds like a twelve year old typed it then the thread will end up being 4 or 5 pages. Very frustrating.


I'll keep updating this until I either find the problem or lose the engine.

you could always install a fuel pressure gauge. The are under $200 for the really nice full sweep electric Autometer ones. I ran one in my car all the time. You can never have too much precaution especially if you run at the track.