Re: RE: These dyno numbers look right?

From: Bernd D. Ratsch (bernd@dodgetrucks.org)
Date: Sun May 20 2007 - 17:52:41 EDT


The Magnum engines (and most other DC engines) are made to run rich
(10.2-11.0) under WOT...no way around that without PCM programming. As
long as you have the engine in a good tune (plugs/cap/rotor/wires/air
filter) - you'll be fine.

BTW: Those numbers are pretty much on par with the Magnum V6's (A/F as
well). The PCM will also compensate for the dirty air filter and even
that won't get you above the A/F ratio you're showing.

- Bernd

msnbcnnbcbs@hotmail.com wrote:
> ok, I left some information out....
>
> on the first run, the truck actually DIED on the dyno (at 4k+ rpms) and would
> not start. Initially we thought it was flooded.
>
> One the guys grabbed a wire from the distributor and plugged in a spark
> plug...no spark.
>
> I had done an ignition upgrade about 3 months ago. (wires taylor thudervolt,
> autolite 3923, brasss cap/rotor) and replaced the stock coil with an accel
> super coil (the one that requires an adapter). I ran down the street and bought
> an aftermarket replacement coil. crank....it started. the damn accel coil died
> on me, on the freaking dyno!
>
> The truck was running rich on the run it died and subsequent runs. now that you
> mention air filters....my air filter (cone) did look really dirty...
>
> what sensor is the CTS? and where can i get a scanner?
>
> My intial suspicion was the injectors. ive been using regular costco gas, and
> bad gas, for a long time.
>
>
> In article <000001c79ac7$2aa27dd0$2f544b0c@Dakota>, bpracing@worldnet.att.net
> ("Ray Block") writes:
>
>>
>>> -----Original Message-----
>>> From: msnbcnnbcbs@hotmail.com
>>>
>>> I was under the assumption that a/f ratio at WOT was 12.0-12.5?
>>>
>>> In this case it was 10.4, which is VERY rich. It seems to have dropped to
>>> that
>>> level after about 4k rpms(?)
>>>
>> Hmmm, yeah, that's really rich! I would expect it to be blowing black
>> smoke out the exhaust at that level.
>>
>>
>>> The dyno operator did not take the engine to redline(4800) as he was
>>> worried
>>> the a/f mixture was too rich, so the dyno chart is incomplete.
>>>
>> That's odd.
>>
>>
>>> the only thing i cant think of is the injectors are not atomizing the fuel
>>> at
>>> higher rpms (they are stock btw)
>>>
>> I wouldn't jump to conclusions just yet. You'll just end up throwing parts
>> at it that may not help. While a scanner will tell you a lot (my choice)
>> you can test your sensors (IAT and CTS) with a volt/ohm meter. The
>> resistance for various temps is in the FSM.
>>
>> The first thing I would consider is the condition of your plugs, wires, and
>> air filter. Any misfires or restricted air flow would show up as a rich
>> condition, as would excess fuel pressure at WOT. Also, was the engine up
>> to full operating temp?
>>
>> Ray
>> http://www.dragtruk.com/ENTRIES/20KM1FD2KWBP.html
>>
>>
>>
>
>
>
>



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