I need to clean this mess up.

[BC847]

I've gone from some DDP4s to some new Scheid 6x16" EDMs.

With the current tuning and the DDP4s, when tipping into the throttle, it'd let a small puff of black smoke from the tail-pipe. Otherwise, with normal driving, one could easily control the smoke when under say . . . 10psig boost.
The 6x16's are a fair step up and with changing nothing other than the injectors, standing 15' from the truck and simply looking at it sternly has it fart a small cloud.

You folks running the 6x16's, are yours smoky with low boost?

- I'm running a set of HT3B/HX35 Hybrid turbos, heavily ported head, 100% cold air intake, Banks intercooler, 4" downpipe to 5" after the transfer case, Stock/OEM cam, etc.

- The injection pump has a 3200rpm governor spring that I trimmed by two loops. With that, I've re-indexed the throttle shaft so as to have all the slack removed from the spring and governor mechanism. The throttle linkage is tight such that there's instant throttle movement with touching the pedal. It strokes far enough to work the break-over spring.
The main fuel screw is all the way in.
The stock/OEM AFC spring has been stretched a little with the star-wheel tightened to just shy of coil-bind when under full boost conditions. The interior of the AFC housing has been machined such as to let the DennyT fuel pin come up as high as it can.
Based on the last time I put the micrometer to the injection pump, I'm gonna say the injection event is timed at about <2.5mm lift.
The fuel is supplied/returned by AN6 lines and fitting. A bypass type Aeromotive regulator holds the Walbro pumps output to 17+/-psig.

A WOT pass has the EGTs creeping on up toward 1500*F or more with over 65psig boost (measured at the intake log). Once the turbos are spooling, the exhaust presents as a fairly clear stream (if that makes sense) albeit colored with black. Matting it from less than 10psig has it present with a pretty good cloud of black (with a grey tint) smoke.


Short of an after-market cam, y'all know of any more tricks to clean up the bottom-end smoke?

NOTE: Scheid sent some copper washers with the injectors that look like they're going on .040" (or more). Ya reckon that might be contributing? I ran the DDP4s with a .020" washer.

Thanks.

[pulltilbroke]

Yeah I'd be runnin the thinnest washer possible

[soggy]

I'd be getting some bigger turbos, How about a gt3582r over gt 4508r?

[soggy]

oh you just wanted to clean up bottom end smoke, afraid I cant help you much there

[burnt_servo]

couldn't you just turn the star wheel up a bit till things cleaned up where you wanted it ?

the " fuel pin's " location is dependant on the amount of boost , so slightly increasing the spring tension on it , should lower your fuel levels till your seeing more boost .......

this is assuming your still using the "fuel pin " and haven't mutilated your injetcion pump yet


OK

just reread your post .... ( that helps some times ) ......

with vw pumps , there are at least 2 afc springs ( i've heard rumours of 4 or 5 ) , but i've only seen 2 .... a greenish / blueish one ( for a vw it's softer and more desirable )
the one you want to look for is white and very stiff . i've seen alot of the white springs in '90 '91 '92 model years of vw jetta's , it's like they made an effort to reduce the amount of smoke these cars made by changing the spring rate in the afc .

you could also regrind the " fuel pin " so that it limits the amount of fuel untill it's pushed deep enough by the boost pressure to start the heavy fueling .

fiddeling with the injection timing might also help , same thing with seeing if you can get the turbo's to spool a bit faster too .

[Richie O]

Mine haze at idle. It also hazes running easy down the road. I can't see how you could adjust anything in the AFC to get rid of idle haze other then maybe the smoke screw. Mine is all the way out, still hazes. My 89 hazes also with the stock 4x12's but the fuel screw is in pretty far. It never used to haze at a lesser fuel setting. I expected idle haze with my 6x16's so I am not upset. I am happy how they run.

[PToombs]

Put the .020 washers in there. That will help a lot.

[Richie O]

Put the .020 washers in there. That will help a lot.

Thats what I have.

[BC847]

Thanks for the replies folks.

I got to make a few passes at the local 1/8th mile track tonight for some comparison.

And things are off.

With simply pulling out the DDP4s, and slipping in the 6x16" has me down from one to two tenths.

04/30/09 Running regular DDP4s (5x<.013").
Reaction: .1050
60 FT: 1.8128
330 FT: 5.4008
1/8 ET: 8.5698
1/8 MPH: 76.83

05/14/09 Running Scheid (6x.016") EDMs.
Reaction: .1394
60 FT: 1.8231
330 FT: 5.4472
1/8 ET: 8.6654
1/8 MPH: 75.52


-> I generally allow almost an hour in between passes for cool-down. The engine coolant is "Normal" (Stock/OEM temperature gauge). The transmission fluid in the pan is right at 130*F.

-> With the DDP4s, I ran a 50/50% mix of water/meth. Tonight is was about 55/45% for what it's worth.

6400# (+/-), 3.5x gearing on 33" tires.

EGT's are going above 1450* (pre-turbo) with over 65psig boost (measured at the intake log).. Much more smoke coming off the line. Once spooled, the smoke clears a good bit but it's still heavier than with the DDP4s. I'm definitely putting more fuel in the cylinders.


What'cha reckon?

[gear jammer 91"]

I think that you are fueling too hard down low, and it's not making the power at lower RPM that it used to. I could be COMPLETELY wrong though . To try and clear up your low boost smoke I would look into a different fuel pin, one that has a real gradual slope until the top of the pin, and then a sharp cut so that it only adds fuel under higher boost. There is a user that goes by alwaysworking, I believe he is a member hear, I know he is on DTR, he makes or know someone that makes a fuel pin and they have a couple different cuts.

[BC847]

Yeah, I saw those fuel pins you're talking about. The number three or four has a slope that could be called opposite of DennyT's pin (Denny's is concave where that I'm reffering to is convex). It would certainly cut the fuel at lower boost.

But wouldn't a boost fooler for a turbo's waste-gate work the same if applied to the AFC reference line? Stock would have it at full fueling at around 19psig boost or so. Adjusting the boost fooler so it wouldn't go to full fuel till say . . . . 30psig boost . . . . . . . . ?

I'm thinking about just disconnecting the AFC's boost reference tube and see how it runs.


This blows.

[93_Fummins]

But wouldn't a boost fooler for a turbo's waste-gate work the same if applied to the AFC reference line? Stock would have it at full fueling at around 19psig boost or so. Adjusting the boost fooler so it wouldn't go to full fuel till say . . . . 30psig boost . . . . . . . . ?

I'm thinking about just disconnecting the AFC's boost reference tube and see how it runs.

Technically, there is already such a mechanism in the AFC top...kind of. If you back the star wheel out to increase the spring force, you can delay the movement of the fuel pin until more boost.

Correct me if I'm wrong...I'm still fairly new to these beasts.

[BC847]

You are correct.

But I'm WAY ahead of you there.

- The AFC spring has been stretched.
- The star-wheel has been run up to the point that, when pressing down on the fuel pin / diaphragm (as in full boost) the spring is just before binding.
- Inside and under the AFC housing, I've ground out metal so that the fuel pin can come up as high as it can.

[dpuckett]

BC847, have you had anything done to your pump in the way of springs/ seals/ rebuild? It may be time if you havent had it done yet. I realize this is an apples to oranges comparison, but smoke cleared up on the bottom end of my nonIC 91 after a rebuild. Advance piston wasnt right, and a new one made a LOT more bottom end power with less smoke, and better EGT/MPG.

Daniel

[gear jammer 91"]

I don't have any experience with a boost fooler, but it sounds like if you could delay the afc cones movement until there was adequate boost to burn the fuel I would think it would help out get out of the hole.