I've been trying to find as many solutions to this problem as I can, and I want to get some opinions on what's up here. Sorry for the long explanation (I think it's all relevant), but here goes:

My new GSR has a chronic black smoke problem (see below for pictures), where after a day or two, there's already black dots/dust on the rear bumper above the exhuast. I have reason to beleive that it may be running rich for a few reasons (just a heads up, I don't have a Wideband a/f) :

- Black marks on bumper
- Poor Gas mileage (22mpg)
- About a week before I purchased the car, the owner installed a 3" AEM CAI to replace his old Icebox (which he already sold). After he drove it for a week, the plugs fouled, so he got a new tune. I later realized that more/ denser air shouldn't have made it run rich, but leaner (I think?). So maybe the plugs fouled due to a rich condition.

The car was tuned after the above ^ and runs fine throughout the power band and through different throttle levels. He says that it was both WOT and partial throttle tuned (all on a dyno, so partial throttle numbers might be a little off). I had them put the catalytic convertor back on, and now it smokes a lot less, but I'm still getting these marks on the bumper. I'm a little concerned that I'm clogging the Cat with this junk too.

Possible solutions:
- Bad thermostat, causing engine warm up slowly and more fuel to be dumped
- Rich tune at partial throttle

What do you guys think?

Relevant mods:
Engine:
B18C1 Engine and transmission
B16 pistons w/ hastings rings
Balanced GSR crank
GSR rods
Crower Stage 3 cams
Manley Retainers
Supertech Valvesprings
3 angle valve job
Head milled .01"
ACT Stage 1 clutch
Exedy 9.4lb flywheel
Blox Intake manifold
Generic SRI
Rage 4-2-1 Tri-y header
Custom stainless 2.5" Mandrel bent piping, Carsound 2.5" cat, SNL 2.5" twin loop muffler
Controlled by a P28 with the help of Hondata S200, tuned by R/T Tuning on a Dynojet 224x.


Pictures:

 

See if you can get it on a dyno to check **** out. If everything seems good there, maybe fine tune partial throttle conditions on the street, and just kinda go from there.

 

Thanks Forty. That was kind of what I suspected was th next step, but I wasn't 100%. I'm going back and forth between finding a different tuner (it was tuned 3 weeks ago, supposedly partial and WOT) or maybe even getting a wideband and tuning software to tackle this myself. I've got a whole heck of a lot of research to do before I dive into that.

What do you think on the stage 3 cams? The tuner said that because they're so aggresive, it was very difficult to tune. Could this be the issue at partial throttle? Having to richen it up, or retard timing due to the high lift/ high revs (8800)?

 

Yeah man thats very possible. I don't have a lot of experience with N/A applications. If you haven't already, maybe toss up a post on HT to see what they think. I know theres quite a few guys over there running really aggressive cams

 

Will do, thanks!

 

Good luck bro!

 

Alright well, I think I'm going to change a couple things and then get it tuned at Evans Tuning instead of the place it was at before. Dyno + street tuning ftw.

I found out the stage 3 cams have an idle of 1200, which might be hurting the mileage also. In the end this is my DD, so I'm gonna have them swapped out for some milder ITR OEM cams.

The exhuast is hella loud, so I'm going to try to squeeze a 2.5", 14" resonator on behind the cat. After that, I'll probabaly replace the 2.5in muffler with a 2.25 in/out Magnaflow race muffler (so it still has a 2.5in core) to quiet it down a bit more. Do you think the restriction at the end of the exhuast would be an issue? I really don't want to run all new piping + a smaller cat since it's almost brand new as is.

And finally, I'm going to replace the thermostat, just in case that's causing a slow warmup with rich conditions.