Running rich... This one's got me stumped - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

mRclARK1 · 05-19-2007, 01:36 PM

I'm kind of embarrassed to ask this... lol. But time is a factor here so I need some help on this one to fix it fast.

Two days ago I installed a test pipe on my friends gf's car, and it immediatley started running rich, and it was fine before. It's not overly rich, there is puffs of blackish/gray smoke on accel and decel, and the occasional little pop. The plugs are a lighter tan color, and don't have any raw fuel on them when pulled. I cannot figure out why it's doing this... I've checked everything I can think of. To start, the setup is: Redtop SR20DET, T25, Walbro 255, NGK BKR5EGP plugs, stock FPR, SR20 MAFS, 3in turbo back, and Blitz atmospheric BOV.

The timing is good.

MAFS checks out and looks clean.

The BOV might be a cause, but it's not the only culprit, as it still does it with the BOV vac line removed and plugged to keep the BOV from opening.

The O2 sensor is kinda dirty, but the ECU doesn't throw any codes. I'm gonna replace it anyway.

Injectors are good: Cleaned and do not leak.

Could it be a faulty FPR? If so, how would installing a test pipe cause it to malfunction? I'm also going to check for any boost leaks as well, but I have my doubts as it boosts just fine.

Any suggestions of things I may have missed that could be the problem, or really any help of any kind, would be appreciated.

King 240 · 05-19-2007, 06:22 PM

Even though you said the MAFs check out, how did you go about checking them. Unplug the MAF when the car is running then plug it back in, how does the car act?

mRclARK1 · 05-19-2007, 08:25 PM

I swapped the MAFS with an extra one I have. Didn't change anything. I doubt they're both bad.

I DID find a couple pinhole size boost leaks in a couple of the welds on the IC piping. I just put RTV on them for now until they can be welded shut. That improved it a very little bit, but it's still running slightly rich. I have a new O2 sensor on order that should be here by Tuesday. I guess I'll have to wait and see if that fixes it.

drftwerks · 05-19-2007, 08:27 PM

it will do that with a test pipe, the cat does alot of clean up

mRclARK1 · 05-19-2007, 08:30 PM

^^^True, but I run a straight 3in test pipe on my car as well, and I run SLIGHTLY rich, but not as much as her car is. I'm betting the new O2 sensor will improve it greatly.

Thanks guys.

auxoura · 05-20-2007, 09:12 PM

Did it throw any error codes in the ecu?

My car running quite rich on WOT and the car feels sluggish....
The gas pedal also tends to gets physically heavier and worsen when it rains.....

aznnay · 06-30-2008, 01:26 AM

im running really rich too....can exhaust leak lead to running rich?...rich enough to make plugs go bad?

05-19-2007, 01:36 PM	#1
mRclARK1 Post Whore! Join Date: Sep 2005 Location: Location? Posts: 4,205 Trader Rating: (0) Feedback Score: 0 reviews	Running rich... This one's got me stumped I'm kind of embarrassed to ask this... lol. But time is a factor here so I need some help on this one to fix it fast. Two days ago I installed a test pipe on my friends gf's car, and it immediatley started running rich, and it was fine before. It's not overly rich, there is puffs of blackish/gray smoke on accel and decel, and the occasional little pop. The plugs are a lighter tan color, and don't have any raw fuel on them when pulled. I cannot figure out why it's doing this... I've checked everything I can think of. To start, the setup is: Redtop SR20DET, T25, Walbro 255, NGK BKR5EGP plugs, stock FPR, SR20 MAFS, 3in turbo back, and Blitz atmospheric BOV. The timing is good. MAFS checks out and looks clean. The BOV might be a cause, but it's not the only culprit, as it still does it with the BOV vac line removed and plugged to keep the BOV from opening. The O2 sensor is kinda dirty, but the ECU doesn't throw any codes. I'm gonna replace it anyway. Injectors are good: Cleaned and do not leak. Could it be a faulty FPR? If so, how would installing a test pipe cause it to malfunction? I'm also going to check for any boost leaks as well, but I have my doubts as it boosts just fine. Any suggestions of things I may have missed that could be the problem, or really any help of any kind, would be appreciated. __________________

05-19-2007, 08:25 PM	#3
mRclARK1 Post Whore! Join Date: Sep 2005 Location: Location? Posts: 4,205 Trader Rating: (0) Feedback Score: 0 reviews	I swapped the MAFS with an extra one I have. Didn't change anything. I doubt they're both bad. I DID find a couple pinhole size boost leaks in a couple of the welds on the IC piping. I just put RTV on them for now until they can be welded shut. That improved it a very little bit, but it's still running slightly rich. I have a new O2 sensor on order that should be here by Tuesday. I guess I'll have to wait and see if that fixes it. __________________

05-19-2007, 08:27 PM	#4
drftwerks Nissanaholic! Join Date: Mar 2004 Location: california Posts: 2,343 Trader Rating: (1) Feedback Score: 1 reviews	it will do that with a test pipe, the cat does alot of clean up __________________ giantroboteyes.wordpress.com/

05-19-2007, 08:30 PM	#5
mRclARK1 Post Whore! Join Date: Sep 2005 Location: Location? Posts: 4,205 Trader Rating: (0) Feedback Score: 0 reviews	^^^True, but I run a straight 3in test pipe on my car as well, and I run SLIGHTLY rich, but not as much as her car is. I'm betting the new O2 sensor will improve it greatly. Thanks guys. __________________

05-19-2007, 06:22 PM	#2
King 240 Banned from the Marketplace Join Date: Nov 2002 Location: College Station,TX Age: 40 Posts: 449 Trader Rating: (0) Feedback Score: 0 reviews	Even though you said the MAFs check out, how did you go about checking them. Unplug the MAF when the car is running then plug it back in, how does the car act?

05-20-2007, 09:12 PM	#6
auxoura Join Date: Apr 2007 Location: Asia Posts: 13 Trader Rating: (0) Feedback Score: 0 reviews	Did it throw any error codes in the ecu? My car running quite rich on WOT and the car feels sluggish.... The gas pedal also tends to gets physically heavier and worsen when it rains.....

06-30-2008, 01:26 AM	#7
aznnay Zilvia Member Join Date: May 2006 Location: la puente, ca Posts: 234 Trader Rating: (5) Feedback Score: 5 reviews	im running really rich too....can exhaust leak lead to running rich?...rich enough to make plugs go bad?