They also work for OBD-I systems Ray...have already installed them on two
OBD-I models ('94 and '95 Ram) without any issues. Expensive...not that
much as compared to other options. The ARC-1 is very limited in what it can
do but yes, it does work for very minor adjustments.
- Bernd
-----Original Message-----
From: Ray Block [mailto:bpracing@worldnet.att.net]
Sent: Wednesday, March 19, 2008 7:57 AM
To: dakota-truck@dakota-truck.net
Subject: RE: DML: Fuel Mix Computer
> -----Original Message-----
> From: Jamie Calder
>
> Ray,
> It's a '93 318, 30 over, Comp Cam 604 specs:
> http://www.compcams.com/Technical/Search/CamDetails.asp?PartNumber=20-604-
> 8
> 4bbl M1, ported throttle body, FMS 19# injectors, ported heads, MP PCM,
> 1.7:1 RR's...
Very similar combination to mine:
'92 318 (stock), Hughes Engines cam...
Intake Valve Lift 1.6 .520".
Exhaust Valve Lift 1.6 .544".
Intake Duration at .050" 214°.
Exhaust Duration at .050" 218°.
Lobe Separation Angle 114. (a little more PCM friendly than 112).
2-bbl MI, 52mm TB, Accel 19# injectors, ported/milled heads w/1.97" intake
valves, MP PCM, Doug Thorley headers w/3" single exhaust.
> Isn't it that cam that causes it to run rich at idle?
Cam and head work both contribute.
> I'd like to have it run with the proper air/fuel mix. Sounds like a
> piggyback fuel controller is the answer but I'm open to any suggestions.
Well, I've read the other responses posted and I find it interesting that
people whose primary experience is with OBD-II systems are so quick to give
advice to others who have OBD-I systems.
Apexi and AEM controllers are for OBD-II systems! Not to mention expensive.
You do NOT want to use larger than 19# injectors on a N/A 318. I shift at
6000 rpm and cross the finish line at 5900, yet I have had to LEAN mine out
for max performance! Oh yeah, and on our systems the fuel pressure is 29-
30psi at idle/cruise and 39-40psi at WOT. (somewhat lower than OBD-II
systems)
James, your stated problem is rich idle so my solution for that is raising
your idle speed. If you trust me on this, I'll give you instructions for
setting it and making it stick. (it's different than OBD-II systems) Cost
= free....unless you need to buy a torx driver. ;-)
That's about the only thing that will work on ours during warm-up (open-loop
mode). Once warmed up, you can lean things out a bit by using a 195*
thermostat and putting the IAT sensor back in the intake manifold. Use
stock heat range plugs as well.
If you were going to keep the truck I'd recommend getting a scanner so you
know what all your sensors are reading. From there you can exercise a
little control over air/fuel ratio with a Split Second ARC-1 A/F ratio
calibrator. (http://www.splitsec.com) Nothing huge mind you, but it
helps a little at cruise and WOT. I can't vouch for the control over idle
because my higher idle speed (750 rpm) solved that problem and I just
haven't experimented with it there. The leaner setting I use for WOT works
just fine at any rpm.
As far as I know, this is about the best you can do for an OBD-I system
short of a standalone controller and wideband O2 sensor. It works for me!
:-)
Ray
'92 Dakota 12.98 @ 105 (street driven, through full single exhaust)
http://www.dragtruk.com/ENTRIES/20KM1FD2KWBP.html
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