William,
It sounds like your injectors are too big...Lean it out a bit and pull more
fuel in the PCM as well (or talk to Duner about his best N/A flashes!)
Bruce
----- Original Message -----
From: "William H. Hiatt III" <william@hiatt.net>
To: <dakota-truck-moderator@bent.twistedbits.net>
Sent: Sunday, November 17, 2002 7:53 PM
Subject: DML: Re: Disappointing day at the dyno... Advice needed!
>
> Well, I hooked up my OBD-II scanner on my laptop, and read the short term
> fuel trim. It seems to be running rich (Average was about -12% for bank
one
> and -11 for bank 2). I would however constantly see -18% or so on both
> banks, with peaks of -25% on the banks. I can't read the long term fuel
trim
> (It's at 0) because the PCM hasn't learned yet.
>
> The reason I bring this up is after about 200 miles after the PCM learns,
> the truck will start to surge about 200RPM here and there while driving
not
> under acceleration. Then it'll throw a a few 20X codes (Injector control
> malfunction)
>
> Could this be because it's running way to rich? I do have those 21# FMS
> injectors, coupled with the extra fuel in the LEACH PCM flash, minus the
> extra timing in the flash?
>
> I'm going back to LEACH on Tuesday, and Tom is going to flash my box and
set
> the timing back up to 28.5 (Where he sets them all). Is the extra 3.5
> degrees enough to burn the rest of this fuel causing the truck to run
rich?
>
> Thanks
> william
>
> ""news.verizon.net"" <wE@.com> wrote in message
> news:ar1i83$dr9$1@bent.twistedbits.net...
> >
> > Well I had a disappointing day at the dyno today. Only gained 1.4RWHP
and
> > 5RWTQ, this is after the HO cams. This brings me to 225.4RWHP and
> 283.5RWTQ.
> >
> >
> >
> > My guess is that 3.5 degrees of timing out of the PCM is making a big
> > difference! Also, you can see a steady decline after 4400 RPM of the of
> the
> > TQ/HP curve.
> >
> >
> >
> > Changes between this run and last run:
> >
> >
> >
> > - HO cams
> >
> > - 21# FMS injectors
> >
> > - (-3.5) degrees timing on the PCM
> >
> >
> >
> > Other things that may make a difference between this run and last run:
> >
> >
> >
> > - I have a bolt in cat for the third cat now. There is a minor leak
around
> > where the cat bolts to the exhaust. I can tell this because water leaks
> out
> > from where you bolt the cat in (I got ripped on the install job I had
this
> > crappy shop do)
> >
> >
> >
> > - I'm running a Robertshaw 330-180 thermostat. The problem is it's such
a
> > HIGH FLOW tstat, the truck doesn't warm up a lot of the times, and trips
a
> > check engine light. I'm thinking I should change it to a GT755-180
> > thermostat? Could this be affecting HP/TQ?
> >
> >
> >
> > Here are my questions:
> >
> > 1) I think I need to get that timing put back in! 3.5 degrees must make
a
> > big difference
> >
> >
> >
> > 2) HO intake?
> >
> >
> >
> > 3) I'm going to remove third cat, and weld in some pipe between the Y
pipe
> > and muffler. My question is, should I go 3" between Y pipe and muffler,
or
> > go 2.5" to like halfway to the muffler. I DO NOT want to loose any more
> > power, and I know our engines aren't that large, so we need to be
> > conservative on pipe size. Is this even worth doing?
> >
> >
> >
> > 4) Anything else you can suggest based on my mods. Do I need to change
my
> > exhaust?
> >
> >
> >
> > Again, my mods are as follows:
> >
> >
> >
> > - Mike Leach PCM (With 25 degrees of timing instead of 28)
> >
> > - FMS 21# injectors
> >
> > - HO Cams
> >
> > - 4" Z-tube
> >
> > - Magnaflow 3" IN 2x2.25" OUT exhaust
> >
> > - F&B Throttle body
> >
> > - Robertshaw 330-180 Tstat (180 degrees)
> >
> >
> >
> > Sorry for the long post, this whole thing was kind of frustrating.
> >
> >
>
>
>
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