Black Smoke Between Shifts at WOT/Boost

[GoldÐiamond]

Profile up to date. Current compression roughly 140 across the board. Car has NO catalytic converter. At idle you can place hand in front of exhaust and collect black particles despite running 14.7/1 AFR @ idle. Also, as mentioned above there is a noticeable poof of black smoke when shifting and boost. Oil dipstick never gets pushed up.

I just started noticed this on the long drive to and from Shootout, and want to try and figure it out. I've searched and it looks like there are at least a couple things I need to do. Would this be a good checklist for this problem? ...

1. Leakdown Test
2. Check PCV Valve
3. Replace PCV Valve w/OEM Unit
4. Install Check Valve before PCV Valve
5. Convert to Catch Can Setup
6. Reinstall Catalytic Converter

[GSTurbo1]

might be time for an overhaul, mine was doing this big time. Take in mind I have a boosted 420, make sure you get an oil catch can, head is built right, and I would re-ring the motor too.

[GoldÐiamond]

Well I just had the cylinder head rebuilt and the motor is at 60k from a rebuild. So, I don't think I'm ready to rip it all apart again if not necessary.

Also forgot to mention, I'm currently tuning for 23psi w/zero knock.

[SkyGrowsCold]

Have you checked your turbo for any excessive shaft play and what is your A/F ratio at WOT?

[GoldÐiamond]

Oh, yeah. Good questions.

• I recently checked the turbo and there is little to no shaft play right-to-left and none in-and-out.
  
• At WOT, I'm roughly between 10.5/1 - 11.2/1. I've fine-tuned the WOT fuel slightly at a few RPM points just to achieve zero counts of knock. Otherwise, its all Keydiver.

[cjridert1]

Originally Posted by GoldÐiamond

Profile up to date. Current compression roughly 140 across the board. Car has NO catalytic converter. At idle you can place hand in front of exhaust and collect black particles despite running 14.7/1 AFR @ idle. Also, as mentioned above there is a noticeable poof of black smoke when shifting and boost. Oil dipstick never gets pushed up.

I just started noticed this on the long drive to and from Shootout, and want to try and figure it out. I've searched and it looks like there are at least a couple things I need to do. Would this be a good checklist for this problem? ...

1. Leakdown Test
2. Check PCV Valve
3. Replace PCV Valve w/OEM Unit
4. Install Check Valve before PCV Valve
5. Convert to Catch Can Setup
6. Reinstall Catalytic Converter

You aren't by chance running a vented BOV on a stock MAS are you?
The 'black particles' during 14.7 idle is probably just normal carbon, that seems reasonable enough Id think.
Catch can setup - wouldnt hurt, but I dont think the $ will help your inter-gear smoking.
You said it's not pushing the dip-stick - is it using oil?
PCV - wouldnt hurt, but thats venting crankcase pressure thru your head - not necessarily extra fuel (or whatever) in your combustion chamber. The PCV is easy to check - the time it took to type that thought is about the test time; I assume you've done it already?
Let us know what you come up with and good luck!

[GoldÐiamond]

Thanks for the PCV info, for some reason some other threads made the connection between inter-gear smoking and excessive crankcase pressure. And I kind of figured the black exhaust soot at startup and idle was normal sans catalytic converter.

Let me answer a couple questions:

• No, I am not venting the BOV with my 2G MAS/Keydiver setup.
  
• And yeah, the dip stick does not pop up on me like I've had with other DSMs. As far as oil consumption, I went about 800 miles and I think it used about a half a quart of Castrol HD-30 non-synthetic oil. However, I think I have some seepage off the pan as well as the pesky turbo oil return line - small leak.

What about plugs?

From what I've read I should be running the NGK BPR-7ES which I am. But how do I know if they are fouling out?

Also, could this possibly be my rewired 190lph Walbro overrunning the stock FPR?

[hazmat6135]

Black smoke is unburnt fuel. 10.5 is super rich and yes an upgraded pump will overrun a stock fpr. Get an upgraded fpr and tune closer to a 12afr on WOT and that should fix it. And btw what compression pistons are u running? 140 is pretty low even if its cold. Most 100k motors with 7.8:1 pistons are still in the 160's cold.it might be time for a good hone and rings at least. Good luck

[GoldÐiamond]

Thanks for the info. I have the stock 7.8/1 compression pistons.

Firstly, I know the 140psi or so is on the low side but I don't think I'll rebuild the engine until it gets lower than that or my goals go higher.

I see what your saying that this may just be a tuning issue and I should tune for a less conservative WOT AFR. And I think I can do that even with my old-school SAFR/Pocketlogger tuning setup.

But why would an AFPR help with that, and how do I know if its being overrun?

Lastly, what is actually happening when black smoke is released through exhaust?

I mean, bone stock 4G63's run like 11:1 AFR at WOT, right?

[cjridert1]

Originally Posted by GoldÐiamond

Thanks for the info. I have the stock 7.8/1 compression pistons.

Firstly, I know the 140psi or so is on the low side but I don't think I'll rebuild the engine until it gets lower than that or my goals go higher.

I see what your saying that this may just be a tuning issue and I should tune for a less conservative WOT AFR. And I think I can do that even with my old-school SAFR/Pocketlogger tuning setup.

But why would an AFPR help with that, and how do I know if its being overrun?

Lastly, what is actually happening when black smoke is released through exhaust?

I mean, bone stock 4G63's run like 11:1 AFR at WOT, right?

Rebuild - sure, Im on your side. Let it do its thing.

10.5 is rich, I tune for mid 11s, I keep away from anything leaner than that. Its up to you - boost, timing, load, knock (most importantly) will determine whats safe and whats not.

190s arent often reported on here for over-running the stock FPR, thats usually a rewired 255. Disclaimer: I dont have any first hand experience with 190s. Over-running will occur at idle and low cruise where you have your highest need of near full fuel flow RETURN (which is still not enough with bigger pumps because your stock FPR cant flow enough back to the tank compared to the rate it's receiving fuel). What this ends up doing is making your idle real rich, so you have anything but linear 1:1 FP:Boost occurring.

Bone stock is 9.3:1 (all things considered) under heavy load for 1g cars. Mitsu was a bit conservative too.

[GoldÐiamond]

Great info, thanks.

So why don't stock setups smoke between shifts if they run so rich at WOT?

[NHerron]

Most of your problems are due to no catalytic converter. At idle (and cruise), the AFR is always changing from slightly rich to slightly lean so the ECU can determine if the O2 sensor is working. The minute amount of leftover fuel is burnt up in the catalytic converter at idle. So no cat= raw hydrocarbons released out the tailpipe.

During WOT, there is added fuel to lower the air charges' temperature effectively reducing the chances of detonation. Again, no cat = unburnt hydrocarbons so much its visible. The excess smoke between shifts might be the bypass system not being 100% efficient. And on a high millage engine, valve guides/seals might have something to do with it as well.

It's doubtful an overunning FPR will cause that rich a condition though, because in closed loop the 02 sensor sees the rich condition and can subtract a fair amount of fuel via closed loop fuel trims to accommodate. Its a different story in open loop operation.

[GoldÐiamond]

OK. That idle/cruise explanation makes sense.

The cylinder head is rebuilt so so valve guides and seals are brand new. (about 1500 miles)

Yeah, from what I have read the 190lph pump is probably not overrunning the stock FPR, I have good idle and cruising tune without any real issues.

Stupid question: What do you mean by the "bypass system"?

[NHerron]

When the throttle is closed (between shifts) the BOV is opened, and releases the excess air from the pressurized pipes, to the turbo intake pipe, after the MAF.

My theory is, yes the airmass has not escaped, but its being sent at a later time. The different times may effect AFR, but thats just my theory and the 'bypass system' might work as perfect as we all think.

[Spoolin92GSX]

It might be worth checking that your idle switch (AKA throttle closed switch) is still working/adjusted. If not the injectors will keep dumping fuel while you're off the throttle between gears. Assuming you have a wideband (I checked your profile and already forgot ) just let off the throttle above ~1500rpms in gear and see if the gauge goes full lean. Hope that proves somewhat helpful, at least to eliminate a suspect!

[GoldÐiamond]

Yes I do have a wideband and yes it does go full lean (3 dashes). It does this until you slow down to the point where its essentially idling. (under 1.5k rpm)

Does that mean the switch is in working order?

Also, SAFC says 0% on decel.

[NHerron]

It must be working then.

Have you gone through the list you mentioned in your first post? 1-6?

Also, what is your AFR during WOT?

[GoldÐiamond]

No, I'm still doing research on it. I really don't do much wrenching during the week.

I'm currently at about 10.8 - 11.2 at WOT, which is mostly just how the Keydiver chip came out of the box.

[Spoolin92GSX]

Originally Posted by GoldÐiamond

No, I'm still doing research on it. I really don't do much wrenching during the week.

I'm currently at about 10.8 - 11.2 at WOT, which is mostly just how the Keydiver chip came out of the box.

That's really not too far off for WOT AFR, I shoot for 11.2:1 across. Another thought I had, is possibly check your recirculation tube for any obvious leaks. Other than venting, idle switch, or junk tune (which are all eliminated) that's the only thing I can think of that could make you run black-smoke-rich between gears.

[NHerron]

After reading a bit more into it, I still think it's perfectly normal to have black smoke from the exhaust during WOT, especially if there is no catalytic converter.

Reason being is like I said, we have a rich AFR during WOT to combat detonation. Only a portion of that fuel is actually burned and the rest is sent out the exhaust. Normally, the catalytic converter would take care of this but since you don't have one, the excess fuel is not burnt up.

I have no functioning converter as well. Although, I do all my tuning at night and that's the only time I've driven it since hollowing out the cat. So I can't say for sure that I get black smoke. But I'm almost positive I do because my AFR's are 9-9.3:1 between 5600-7000RPMS due to mad boost creep.

Anyway, here's some links of interest
Black soot from exhaust?
The official "Why is there black smoke coming out of my exhaust?" thread - evolutionm.net

[GoldÐiamond]

Thanks. I've read through most of the threads after searching "black smoke" and I think the consensus was that this was normal without a catalytic converter. I actually have a high-flow cat laying around that I might throw on there but not sure yet.

It would be interesting to test a stock DSM and pull the cat off just for comparison reasons.

Spoolin92GSX: Yeah I was thinking of maybe targeting 11.5:1, and I noticed that during 3rd gear pulls it sometimes hangs out in the 10.2 - 10.5 range. During 4th gear WOT is when I get the 11.2. Not sure the reason for the difference. (More engine load?)

Its going to be tough for me to nail down a steady, targeted AFR with just my SAFC/Pocketlogger, but I still have faith in the old tuning technology.

Oh, and like I said I run BPR-7ES plugs - how do I know if/when they will foul out?

[Spoolin92GSX]

Originally Posted by GoldÐiamond

Thanks. I've read through most of the threads after searching "black smoke" and I think the consensus was that this was normal without a catalytic converter. I actually have a high-flow cat laying around that I might throw on there but not sure yet.

It would be interesting to test a stock DSM and pull the cat off just for comparison reasons.

Spoolin92GSX: Yeah I was thinking of maybe targeting 11.5:1, and I noticed that during 3rd gear pulls it sometimes hangs out in the 10.2 - 10.5 range. During 4th gear WOT is when I get the 11.2. Not sure the reason for the difference. (More engine load?)

Its going to be tough for me to nail down a steady, targeted AFR with just my SAFC/Pocketlogger, but I still have faith in the old tuning technology.

Oh, and like I said I run BPR-7ES plugs - how do I know if/when they will foul out?

Yeah, air fuel controllers are tough to dial in. Since they just pull/add fuel from the stock map, it will still follow the enrichment, which is a lot less steady than you would think. If you can run the car out in 4th to tune that's better since you get a better effective resolution on your logs, if you run richer in other gears you'll have to live with it until you can get a more inclusive tuning solution - I'd rather run rich than lean If the plugs are fouled out they'll be black and sooty, you should be able to clean them up with a wire brush, check gap and reinstall no problem. Best of luck!

[NHerron]

How the heck do you guys tune in 4th gear? That would have to be a pretty long stretch of road right? I start a log in 2nd gear from a 1k RPM roll and punch it up to 7K and it gets tiring doing that over and over for an hour+. Plus cops don't dig me speeding... and second gear is barely under the speed limit

[Spoolin92GSX]

Originally Posted by NHerron

How the heck do you guys tune in 4th gear? That would have to be a pretty long stretch of road right? I start a log in 2nd gear from a 1k RPM roll and punch it up to 7K and it gets tiring doing that over and over for an hour+. Plus cops don't dig me speeding... and second gear is barely under the speed limit

I live near the base of a mountain range, so a 5-10 minute drive gets me to fairly unpopulated, straight roads but I still tune in 3rd which is enough for most people. 2nd is way too quick, I would try to find an industrial area or something nearby where you can get it to at least 6000rpm in 3rd. I've tried 2nd gear pulls and even with my little 14psi 16g the rpms just go by too quick to get a good picture.

[GoldÐiamond]

Originally Posted by Spoolin92GSX

if you run richer in other gears you'll have to live with it until you can get a more inclusive tuning solution - I'd rather run rich than lean

Yeah, I agree with that. I basically want to get all I can out of my current setup. The only exception would be maybe to find an old Dejontool big SMIC. (One day I would like to have a true sleeper 1G. Factory wheels, muffler, no FMIC, nice paint, find an old windown sticker, etc. At that point I would just find an old VDO boost gauge to cleanly mount in an otherwise stock, clean interior. But still have ECM link. Kinda like Buschar's white 1GB I saw at Shootout)

Originally Posted by Spoolin92GSX

If the plugs are fouled out they'll be black and sooty, you should be able to clean them up with a wire brush, check gap and reinstall no problem.

Are there any symptoms, or just a gradual reduction of performance?
Should I stick back in a set of BPR-6ES's since I daily drive?

[Spoolin92GSX]

The different "temperature" of the plug shouldn't affect it's susceptibility to fouling, just rich conditions. If you're over stock boost (or pushing more air than stock) I would stick with the 7's, they certainly won't hurt anything. I daily my GSX with BR7ES's (yes, non-protruded) with no problems whatsoever

EDIT: You won't really be able to notice a huge difference when the plugs get fouled, but when they start to get really covered you might start getting ignition misses. I usually check them after a tuning session and then every couple thousand miles if everything else is kosher. Obviously sooner if something else goes haywire.

[GoldÐiamond]

Sounds like a plan on keeping in the BPR-7ES's.

So what would be my best approach on achieving roughly 11.5 AFR during WOT. Should I just set all RPM points on my SAFC to -5 and start datalogging for no knock?

For guys still running the SAFC: I know the fine tuning kicks in pretty quickly for idle and cruising conditions, is it usually the same when tuning for WOT?

[NHerron]

Just thought I'd drop this by

Spark Plug FAQ

[Spoolin92GSX]

Originally Posted by GoldÐiamond

Sounds like a plan on keeping in the BPR-7ES's.

So what would be my best approach on achieving roughly 11.5 AFR during WOT. Should I just set all RPM points on my SAFC to -5 and start datalogging for no knock?

For guys still running the SAFC: I know the fine tuning kicks in pretty quickly for idle and cruising conditions, is it usually the same when tuning for WOT?

The process may be a little different with SAFC, but when I'm tuning fuel (and MAF since mine is garbage) I start with global settings to get fuel trims dialed in, and then start logging pulls and pulling fuel out until I hit my target AFratio.

[GoldÐiamond]

Yeah I don't think that is possible. I can't directly affect fuel trims with SAFC, I think those get calibrated over time. I think I just have to go in and pull back like 5% fuel and then tune for no knock. I'll try it after I get a better Palm Pilot that doesn't eat batteries so fast.