Please help! Running rich and I don't know how to fix it...

[dhen]

I'm getting really frustrated with this fuel injection system. First the car would't start after it ran out of gas. I reset the ECU and it fixed that, now it's running so rich that it fouls out spark plugs after about 10 minutes.

So here's a little background; I moved some gauges around to a place where I could see them better and installed an AFR gauge. It's one of those with red/yellow/green lights from SunPro. To attach it to the sender wire of the O2 sensor I spliced it and heat shrinked it.

I drive for about 15 minutes and noticed the plugs fouling out (bogged down engine, loss of power, etc.). I get the car home and notice that the sender wire wasn't attached properly. So I attach that, drive it around again, and the same thing happens. I look at it again and notice the heater wires weren't connected right. (Please don't ask how I managed to screw this up twice.)

So tonight I make absolutely sure they are connected, go for a drive, and sure enough the spark plugs foul out. The AFR gauge was in the highest green (rich) line possible.

Here is my setup:

- 10 psi of boost- walbro 255 fuel pump- VPC engine management

I've tried leaning it from the VPC, and while I can tell it's doing something, it hasn't solved the problem. My AFR gauge is telling me that I'm rich, so I'm guessing that the O2 sensor works, though to be honest, even though the gauge is new who knows if it's working right. The injectors were recently cleaned and flow tested by a reputable company, so I don't think that's it. The only thing I can think of is the the fuel pressure regulator, though it would be a weird coincidence for that to fail all of the sudden. (I have one on order.)

So I have no idea what to do. I realize that this is probably because I screwed something up, but I have no idea how to unf*** what I did. If anyone has any ideas I'm all ears. Right now I'm just so frustrated and disappointed I can't describe it.

PS I don't know if this is relevant, but it runs better at 4000+ RPM. Maybe I just have to boost it all the time.
Modified by dhen at 8:51 PM 8/25/2009

[rico05]

For starters, remove the VPC so that you have a reliable control system (aka stock ECCS) to be working with. Next, check for vac leaks, mechanical timing, CAS integrity and TPS integrity (check the FSM). How is your fuel pressure? And that narrow band gauge is nothing more than a cheap light show.

[dhen]

Thanks, I appreciate the help. I think I may have to stick with the VPC for now because I have a custom setup and don't have a MAF.

I will check the CAS and TPS, but if my mechanical timing were off, wouldn't that be clear in other ways? The car starts right up...

I don't know my fuel pressure yet. A gauge is in the mail.

Thanks,

Darian

Will a KA TPS work?
Modified by dhen at 9:45 PM 8/25/2009

[rico05]

GL with the VPC. Seems to be giving you a lot of headaches. I run a CA18DE TPS that I picked up at a parts house for like $60. And I had my exhaust cam advanced 1 tooth once and the car started and idles just fine, but ran very rich and backfired a lot on accel.

[mydato]

How did you hook up the traffic light? Did you use solder on the send wire from the O2 sensor. If you did that's probably the problem. You should only ever crimp O2 sensor wires. Soldering them will screw the impedance up big time.

[dhen]

Well, I got my fuel regulator and installed it at 36 psi. I thought mydato might have been onto something with the sensor wire, so I uninstalled the traffic light. I cleaned off the spark plugs with a wire wheel and installed them. It ran fine for about 10 minutes and then the problem came back...

Tomorrow I'm going to check and see if the timing belt dots line up.

I think the computer thinks that I'm starved for fuel. Why, I don't know. O2 sensor?

By the way, that traffic light IS worthless. Even when it was disconnected from the sensor wire it said I was running rich.
Modified by dhen at 10:01 PM 8/26/2009

[mydato]

Okay next step change over temp sensor and check the pins inside the sensor plug are not corroded. If they are get some sand paper wrap it around a very small flat head screw driver and clean them up. Next step after that is the MAF and a double check of all piping and vac lines.

[dhen]

Thanks to everyone who gave advice. Unfortunately, I don't know what else to do and I'm going to take it to a fuel injection shop. I know that they have to make a living but I really hope that they don't try to bend me over because they know I can't fix it myself...

[mbmbmb23]

Just to clarify as suggested in your other thread, you did set the fuel pressure to 36lbs with the engine off correct?

[dhen]

Yes I did.

Thanks,

Darian

[mbmbmb23]

You sure you got all the bits and peices for the VPC? I know it has multiple components and sensors.

-m

[dhen]

Nothing is certain, but I'm pretty sure I've got it all.

Thanks,

Darian

[NismoBgt]

Its not the VPC. I installed it and it came from a running engine. The engine ran, car drove fine until the Oil pan was replaced. I had to pull the motor to get all that sorted out. I still belive its a sensor. Im almost 100% its the temp sensor as it fouls out after the car warms up.

Check the plugs make sure none of the wires are coroded away to non working.. If all else fails I will pull my temp sensor yuo can try that.

[s13_ono]

Hmmm ive been having a similar issue. Not to the same extent of fouling out after 10 minutes. but close. I just finished a bone stock rebuild. I think the only aftermarket parts are a cheap cone filter and a moonface style downpipe/ turbo elbow.everything else is stock, including the entire fuel system, and still im running rich. Wtf...... occasional plumes of black smoke a when i hit boost. and i feel like every time i drive my car, im losing a year of my life from the fumes lol. I too have checked all the sensors vacuum lines and whatnot.... the ecu isnt even throwing any codes. but, i am getting roughly 10mpg good luck, my motor is hanging in the balance of this thread as well haha. if i can be of any help pm me.

[float_6969]

You said you ran the car out of gas. Maybe some debris passed through your fuel filter when you ran the tank empty and you fouled an injector and its stuck open?

[s13_ono]

on that note, I pulled my injectors out, on the rail, and primed the system. No leaks..... Im not implying that that isnt the case for the op. Just a thought though, I've been discussing this issue with some of my friends, and my injectors sat out, kind of unprotected in my garage for a long while. We discussed the possibiliy of them getting kinda fouled inside, but not to the extent of being permanently struck open. I dont know exactly how injectors work on the inside, but maybe they got a bit gummed up after sitting out for so long, and now maybe they arent open all the time, but when they do open, they could stick open longer than they are supposed to? just a theory i dont know if this kind of problem could affect fuel consumption that badly. I just feel the ops pain in that sense. Not trying to thread jack, just figured i would chime in since im running into the same problems

[dhen]

I thought I would give an update.

I've had the sensors checked out. The contacts on the wires look dirty, so that's possibly my problem.

But I think it might be my tuning. I got a wideband 02 sensor and with my ECU I'm running 9.8:1 at idle. I tried a Tomei ECU and it went up to about 11:1 at idle. Ditto for an ECU which was chipped for 440 injectors and more boost than I'm running. I'm running stock injectors with 10 psi of boost.

Does this sound like tuning to anyone, or do I have a bad connection somewhere? Any ideas are welcome.

Thanks,

Darian

[Ca_Silvia]

Are those cold motor #'s?

[dhen]

Yes. When it warmed up it went to 12:1 on the Tomei, but it was running like s***. I'm sure it's an easy problem to fix. The problem is finding the problem...

Darian

[float_6969]

Are you sure you have stock injectors? If you have stock injectors, and put a computer on there that is chipped for 440's, it should run very lean.

You either have a bad ECU, the tune on the ECU isn't what you think it is, or you don't have the injectors you think you have.

[dhen]

The injectors fit in the stock head, so they should be stock. I suspect the VPC is off somehow or it's a connector. Could an 02 sensor do this? It only runs rich at lower RPM.

Thanks,

Darian

[ca18detgabby]

The injectors fit in the stock head, so they should be stock. I suspect the VPC is off somehow or it's a connector. Could an 02 sensor do this? It only runs rich at lower RPM.

Thanks,

Darian

lots of different injectors fit..... speically with a swap of o-rings

maybe your nock sensor has changed timing?

a fresh set of plugs may do you a world of good as well.

[float_6969]

Yea, a lot of off-the-shelf, or even injectors from other motors (not necessarily Nissan) drop in with a new set of o-rings.

Can you post some pics of the injectors?

[dhen]

Yea, a lot of off-the-shelf, or even injectors from other motors (not necessarily Nissan) drop in with a new set of o-rings.

Can you post some pics of the injectors?

Sure. Here is the injector on the #4 cylinder:



I'm beginning to suspect the VPC. It was pulled from a working car, but something may have since broken, not be connected properly, etc. Unfortunately I don't have a MAF to test the stock system with.

I read that you can use the KA-E one, so I may hunt down one of those.

zerothread?id=65531

Of course it's also very possible that my 20-year-old wiring harness has a problem somewhere that I haven't been able to find yet. Megasquirt is starting to look good right now, but I'm afraid that would just trade one set of problems for another...

[mbmbmb23]

Megasquirt is starting to look good right now, but I'm afraid that would just trade one set of problems for another...

There are a number of fairly smart Megaquirt guys on here who could help you....thats the main difference with the VPC (and the fact that they still make Megasquirt).

[dhen]

There are a number of fairly smart Megaquirt guys on here who could help you....thats the main difference with the VPC (and the fact that they still make Megasquirt).

Something to think about if I do take the plunge. Right now I think I'm going to ditch the VPC and see what happens. I installed a new O2 sensor. It didn't do anything, although you should have seen how much soot was on the old one.

I'm running a Euro 4-port cylinder head, though I've heard that doesn't matter.

[dhen]

For those who are following this, the problem seems to have been fixed by a new ECU. We'll see if the Nissan wiring gremlins appear again, though...

[s13_ono]

been following your troubles. Bad ecu huh? im still running rich. my ecu is socketed for chips, but according to the guy i bought it off of, it is in stock form. Maybe i should try out another ecu. See if some magic happens like it did for you. unfortunately, im in socal, and ca stuff is rare around here for some odd reason. like, i know the handful of people in this area that own cas.... and no fresh stock ecus to be had.....so fail. good luck hope nothing else goes wrong for ya. *knocks on wood*