Should I let Nissan diagnose my car?

[Beau]

I have a new SR swap and it's running incredibly rich. I've borrowed a friends MAF and that didn't change a thing so that is out of the equation. The CAS is set perfect, but I haven't checked other sensors yet.

It's running very rich, enough to see black smoke at idle, which is currently around 1,400rpm. Can any sensor cause it to run this incredibly rich? It drives fine, not as much power as I think it should have based on other SR cars with same mods I've ridden in, but it drives nice. I don't have a boost gauge yet, but it feels like the turbo is doing something and I can definitely hear it.

I'm fed up with dealing with this car to the point that I want to just drop it off at Nissan and let them run some diagnostics on it and tell me what exactly needs replaced. Is this a bad idea? I would hate to let them have my car for an hour and get charged $74 for them to tell me that they don't know what is wrong.

Any advice is much appreciated.

[Beau]

A friend just informed me that I shouldn't have used wire crimps to secure my SOHC maf plug. Could something that stupid be causing all of my problems?

[ItzGenX]

Possibly. The ECU in cars read data through very small voltage pulses. The MAF uses .5-5.0v. Crimps and crappy wires tend to have too much resistance, causing the ecu to get a false reading or vice versa. That is why many guides involving wiring often tell you to solder the wires, not splice or crimp.

[Beau]

I took it apart and soldered them back together, individually wrapped them with elec tape, and then wrapped them all up in elec tape.

Result: No difference.

[ride4lame]

My car does the same thing...but here is the deal, unless you did the wiring harness yourself, and know the diangnostic port will definitely work, it won't. From what i understand, you have to use the KA harness, cut off each plus, and use the sr plugs or something incredibly annoying like that, for the diagnostics port to still work. 02 sensor would cause you to run rich....try changing that, and i would assume you have good plugs and filter and such so I won't even suggest that. Did you upgrade anything in your fuel system?(ie fuel pump, filter, injectors...these will cause you to run rich, thats why i am rich i believe) I plan to get a power FC, have it tuned, and be done with it once i have money. If you find an easy solution, please let me know

[NeedCAforS13]

coolant temp sensor maybe? The CA's have problems with them, but I'm not an SR guy... Bring it down to Nissan anyways Beau... I bet they can figure it out.

If you think about it ride4lame, none of the s13's have consult ports and that is the only diagnostic tool we use at work that plugs into the harness. Therefore, it won't matter if you have a KA or an SR, the techs should be able to diagnose it using other methods.

[Beau]

I have a Walbro 255 fuel pump, stock filter and regulator for now. I have a friend with the same fuel system and he is FAR from this rich. My harness was modified by Estevan (semi-local SR guru) so I have no idea if it will work. I'll change the plugs again when I try a new O2 sensor, the filter is brand new, injectors are stock.

Tomorrow my plan is to change the water temp sensor, change the O2 sensor, change the plugs, check the TPS voltage, redo my intake plugs (holes I plugged up), and hope for the best. If that doesn't do it, then I'll let Nissan have a crack at it maybe.

[Beau]

If all of that stuff doesn't make it run right, then what?

[ride4lame]

coolant temp sensor maybe? The CA's have problems with them, but I'm not an SR guy... Bring it down to Nissan anyways Beau... I bet they can figure it out.

If you think about it ride4lame, none of the s13's have consult ports and that is the only diagnostic tool we use at work that plugs into the harness. Therefore, it won't matter if you have a KA or an SR, the techs should be able to diagnose it using other methods.

Um, i thought it was called a dataport, but thats not important. My car has one and its a '90. Its located under the dash on the driver side...

[NeedCAforS13]

We don't have that version of consult laying around anymore... I can't speak for other dealerships though:)

Sean

[solaris22]

is the ECU showing code? Might wanna try that and check it with the FSM

[240Kuminachu]

Wont that walbro cause this on a stock fuel system? I've heard it causes richness in some and not in others. Try putting the stock fuel pump back in, my stocker works fine, Ive got a walbro also but have put off putting it in for this exact reason.

[Beau]

It did this before the Walbro also.

[ItzGenX]

If the fuel pressure regulator sticks open (higher pressure) it can cause an excessive rich also. My car runs rich where you can smell it kind of, but not black smoke. It only shoots out a puff of black smoke when I punch it, and even that isn't too thick of a smoke, more of a haze. I do however have the higher idle problem which is somehow related to air temperature. When it is cold, it idles kind of high 1500+. When it is 80+ degrees outside, it idles fine at under 1000. Your TPS could also cause a rich problem as this tells the ecu to spit in fuel also (not as important as maf, but it still tells ecu something the motor is doing at that point and time). Then you have the maf that could be it, but it is out of the question as you've tried a different one. A coolant temp sensor could cause the richness also due to the fact that it tells the ecu that the motor is warm so it can switch to open loop mode. When the motor is cold, it needs more fuel to run. Then you have the oxygen sensor, but you say it is black smoke even while idling. The oxygen sensor open loop mode is above 2k rpm or so. Anywhere under, the ecu will ignore. Mine isn't effected by the oxygen sensor much because I can unplug it and notice no major difference in power or richness.

[bvanev]

I had a very similar problem, the only difference was my car was running so rich that it wouldn't start. It turned out to be the fuel pressure regulator and the BOV. I was running the Blitz DD, once I changed to the Greddy recirc type valve, problem solved. Try doing this. I also noticed a slight improvement in throttle response as well.

[NeedCAforS13]

his ecu was bad... replaced with a good one, and it works fine:)

Sean

[Beau]

This car is soooo much fun to drive!!!

I modified my HICAS pump so that the secondary pump is disabled. I still hate ZeroLift.