david zavetsky wrote:
>
> Back in 93, I was one of the first folks to get the MP computer in my 318
> Dak.....It went back a couple times for this same problem...
>
> The guys at the shop which "programs" the computers suggested a few things....
>
> Checking for manifold leaks was one of the them.......Pull the breather and
> PCV valve......Tape ooff the pcv valve hole and put your thumb over the
> breather hole while truck is running......Hold a few seconds......Lift thumb
> and you otta feel a rush of air come out.....This supposedly indicates that
> all is sealed well....If the airflow is weak or not there at all, you have a
> intake leak...
>
> I did this and I dont.....But I DO have the same pinging problem......
>
> I have learned to live with it (unfortunately)....about 4200-4500 rpm heavy
> throttle....
>
> The truck runs great otherwise...
>
Well David, I too have had to learn to live with it as well. It seems
almost that the MP SBEC is a double edged sword. You get a real kick in
the pants performance wise but you also get some detonation.
It seems that Mopar designed the MPSBEC to run on just a tad more than
93 octane. I think 94 or 95 it would run great with no detonation.
Some things I have tried that have reduced my pinging substatially (but
not gotten rid of 100% of it) are:
turning the distributor (waste of time, SBEC re-adjusts the moment
you crank it back up)
180 degree t-stat (seemed to help a lot)
Headers (helped almost as much as the t-stat)
I just put in some Red Line WaterWetter wich claims reduced head temps,
which should help control the detonation even more, but since we're in
the middle of a freezing cold spell I can't tell for sure if it is
working, but the temp needle is lower than usual so I have high hopes.
One other thing to try is to go one step colder on the spark plugs.
Octane booster works great, gets rid of ALL the pinging even on high rpm
load, but that crap's $7.00 a pop, add that to the premium gas price
already and that option is out except for special circumstances (ie. the
drag strip). BTW does anyone have a recipe for home made octane
booster, that wouldn't cost an arm and a leg?
I think that one sure way to get rid of the pinging is to get an msd box
with a timing retard box, you know the one with the little knob you turn
to retart the timing. This retards the timing of the msd box and the
SBEC has no say in it. This way you could pull the timing back just a
hair until the detonation goes away. You would still be hotter than
stock, but not so much that it pinged. This would also come in handy in
the winter when the gas stations start pumping the oxegenated crap. You
might could even retard it enough to run lower octane pump gas like 89
or even 87. Granted, you would be defeating the horsepower gained by
more aggressive timing, but you would still be able to rev higher and
not worry about the 115 speed limit.
These are just some of my thoughts on our detonation problems. Also I
want to clearify that the detonation we're talking about is caused by
the MPSBEC, and I'm not sure that it affects ALL of us (I think Sam P.
said he had no more pinging after the headers). My truck with the stock
SBEC has never pinged once under any circumstances.
--
Michael Clark mike@snakebite.com
'93 MarkIII 4X2 V-8 SWB RC auto, DDBC, MP SBEC
K&N FIPK, Flowmaster cat-back dual, WaterWetter
Doug Thorley Headers, Moroso Blue Max wires
http://userv.wt.net/~mclark/dakota.html
http://userv.wt.net/~mclark/webring/ring.html
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