Hi all,

After installing a JDM ITR replica header (4-1, 2.5" collector) and a magnaflow 2.5" high flow cat, I've noticed that my car runs really rich above ~6000rpms (when the secondary butterfly valves open up). My other engine mods are an AEM SRI and thermal R&D catback exhaust. No internal engine modifications yet.

I have reset the ECU (3 times now) and checked the resistence of the two O2 sensors (15 ohms and 13 ohms). The Helms manual says that the sensors should read between 10-40 ohms so I think the O2 sensors are ok.

All maintenance is up-to-date (i.e. plugs, wires, distributor cap, fuel filter, PCV valve, all fluids, etc etc). It ran perfectly just before the install

I was just wondering if anyone had any idea why its running so rich above 6000 rpms? Is it tuning? I didn't think bolt ons could have such a dramatic effect on the car.

I should also mention that I just had a compression and leakdown test done on the motor. The results are as follows:

B18C1, 161 240 kms, Warm motor

compression: 250psi, 245psi, 250 psi, 240psi
leakdown: 6%, 8%, 10%, 5%

thanks for your time and help!

 

maybe you think it's running rich because you smell the gas out of your exhaust. that's what happens with a high flow cat/test pipe.

 

yeah, I was wondering how do you know it's running rich?
did you do a wideband test, or do you have some other type of meter?

 

I think its running rich because I can actually see the black smoke from my rear view mirror as I go above 6000rpm. There's that much black smoke. Also, my back bumper has black residue all over it from the unburnt fuel everytime after I drive it hard. I never had this before the install.

 

any help/advice is appreciated!

 

Sometime when doing header/exhaust the o2 sensor(s) can be damaged, but you said the two o2 sensors are working properly. You also did a leakdonw and compression test.

Next I would sugest taking it to a dyno with wideband, and finding out exactly where it's running rich, (and probably running lean in some places as well), then tackle the problem from there once you know exactly what's going on.

 

a resistance test of an o2 sensor means basically, absolute ****..

you need to graph the signal out and see what its acting like, a straight line of constant volts or bouncing back and forth between rich and lean

 

**** man hows your compression so high? Have you rebuilt the motor or anything? I have a b18c1 with only 120k kms and im at 210 all around. Whats stock? I heard 270 but i was told no way on that but im thinking 270 is stock.

 

my civic has a 96 gsr swap and seems to have same problem. i can see black smoke in mirror at over 6k and it leaves residue on bumper. i am throwing a cel for 02 though but im not sure if this is the problem. if you figure it out let me know thanks.

 

the carbon deposits/smoke is pretty normal for GSRs with h/e....just ask anyone with a white GSR how fast the carbon builds up on the rear bumper above the exhaust

 

First, I'd like to thank you all for your help/advice.

The car is going for winter storage in about a month so tuning will probably come next year after I do some more engine mods.

I'm thinking that maybe I didn't notice this before because my stock cat (which flows a lot less and is more clogged) would "catch" and burn off a lot more of the unburnt fuel than my new high flow cat. Does that make any sense at all or am I on some cheap crack?

I was just alarmed when I first saw it because that much smoke coming out of my exhaust just scares me! hehe....I was suspecting that all I needed was just some tuning but I just wanted to ask you guys for your opinion just to see if this was normal because I tend to worry too much!

 

oilguzzler, I just checked the helms manual and it says for B18C1 and B18C5 engines and found these specs for the compression

nominal: 270 psi
minimum: 135 psi
max variation: 28psi

 

Yea thats what i saw in mine to, but everyone here that i talked to said 270 is crazy. And im running 210 so i dont know if thats bad or good. I also get alot of build up on my bumper w/ my gsr but i thought it was oil in my case lol.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by oilguzzler &raquo;</TD></TR><TR><TD CLASS="quote">Yea thats what i saw in mine to, but everyone here that i talked to said 270 is crazy. And im running 210 so i dont know if thats bad or good. I also get alot of build up on my bumper w/ my gsr but i thought it was oil in my case lol.</TD></TR></TABLE>

yeah, most of the GS-R's I've seen and heard of get between 200-220psi on their compression tests.

 

well...the problem may have just presented itself...I just got a check engine light and it says code 61 which I believe it to be the primary O2 sensor circuit

this occured while I was cruising (~2000rpms) so I wasn't giv'n 'er or anything like that. How believable is this code since the resistance of it was fine and within spec just last weekend?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Silver2000GS-R &raquo;</TD></TR><TR><TD CLASS="quote">well...the problem may have just presented itself...I just got a check engine light and it says code 61 which I believe it to be the primary O2 sensor circuit

this occured while I was cruising (~2000rpms) so I wasn't giv'n 'er or anything like that. How believable is this code since the resistance of it was fine and within spec just last weekend? </TD></TR></TABLE>

Update: I just reset the ECU, the check engine light is gone and I went for a good rip (up to redline in 2nd and 3rd) and no codes came up. Also, the black smoke that I always saw above 6000 rpms, was not there.... so now I'm confused! LOL

 

lol wtf^^

Anyway, I came to this thread to say what you already said about your cat.

So have fun :D

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Silver2000GS-R &raquo;</TD></TR><TR><TD CLASS="quote">

Update: I just reset the ECU, the check engine light is gone and I went for a good rip (up to redline in 2nd and 3rd) and no codes came up. Also, the black smoke that I always saw above 6000 rpms, was not there.... so now I'm confused! LOL</TD></TR></TABLE>

just because you reset the ecu doesnt mean the problem is fixed.. once you throw an o2 code then that means you should fix the o2 sensor(s), it doesnt mean reset the ecu and hope the problem goes away

same to the other guy, if you throwing a CEL for o2 that means you should fix that before trying to diagnose other problems

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by FULLY_BUILT_NA &raquo;</TD></TR><TR><TD CLASS="quote">just because you reset the ecu doesnt mean the problem is fixed.. once you throw an o2 code then that means you should fix the o2 sensor(s), it doesnt mean reset the ecu and hope the problem goes away

same to the other guy, if you throwing a CEL for o2 that means you should fix that before trying to diagnose other problems</TD></TR></TABLE>

you're definitely right and I already have the part priced out at a local shop....I'm just trying to rule out the possibilty that it was a fluke CEL (since the O2 sensor read within spec just last weekend). I, in no way, will ignore the problem and hope it resolves itself. I'm just trying to eliminate possibilities

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by JH4DC4-2GSR &raquo;</TD></TR><TR><TD CLASS="quote">a resistance test of an o2 sensor means basically, absolute ****..

you need to graph the signal out and see what its acting like, a straight line of constant volts or bouncing back and forth between rich and lean</TD></TR></TABLE>


Thats the real way to test an O2 sensor! I prefer using a Vantage for that... awesome tool.