Wow, Jon, you hit every point that I was about to write in answer to Mike's
problems! I agree 100%. Thanks for saving me all that typing! As the
owner of a '00 Grand Cherokee 4.7 with a K&N FIPK (73,000 miles) I'm
intimately familiar with this engine's performance in daily driving, towing
and drag racing (as in Hundreds of passes over the years). Mike, change
your spark plugs to either the stock Champions or Autolite equivalent in the
stock heat range.
Concerning the FIPK and "premium" spark plugs....thanks to aggressive
marketing, consumers are let to believe they will achieve noticeable
performance or fuel mileage gains from these products. Nothing could be
farther from the truth. While I can vouch for the K&N FIPK picking up a
little performance on my 4.7 (as noted in my drag strip records) the
difference is comparable to replacing a really dirty air filter with a clean
one. Ditto for fuel mileage. You'd have to keep really tight records to
in order to see the gains.
I've also tried exotic spark plugs in other cars we race and have not found
any measurable gains in performance or mileage. A waste of money in my
opinion but marketing is hard to overcome.
And Jon, concerning your suggestion to disconnect the battery after the K&N
install....while it won't hurt anything, I have not found it to make any
difference on any of our cars unless you're doing some internal change such
as a cam.
Ray
http://www.dragtruk.com/ENTRIES/20KM1FD2KWBP.html
> -----Original Message-----
> From: jon@dakota-truck.net
>
> MICHAEL CABE <mikecabe@prodigy.net> wrote:
>
> > Mike,
> > I replaced the whole stock air box with the K&N setup . It just
> > seems that it is dogie and falls on its face like a lean condition .
> > I see no gas mileage gain . I put new plugs in at the same time as
> > they were shot . I used champion iridium plugs .
>
>
> You changed 2 variables at once, so its not possible to blame the
> K&N without first eliminating it or the plugs from the equation. The
> FSM says that the 4.7L is equipped with copper core plugs from the
> factory and warns that preignition will result if another type of plug
> is used. I'm not familiar with the Iridium plugs, but they could very
> well be the cause of your problems. Frankly, the fancy spark plugs
> usually cause more trouble than they are worth, and that might be the
> case in your situation. Its a bit of a hassle to swap plugs, but one
> thing you could try is to put the stock intake system back on, and if
> the truck wakes back up, that could be an indication that the problem
> is indeed the K&N. If not, it might be the plugs. Did you gap them
> to .040"?
>
>
> > The truck has about
> > 62000 on it .It idles smooth as silk and cruises fine . I think it
> > sucks too much air .
>
>
> With an EFI system, it isn't really possible to suck too much air
> - the engine will only use as much air as it needs, regardless of the
> flow capability of its intake tract. Unless you're using some sort of
> forced induction, I would not expect the engine to lean out simply
> because the intake has more flow capability.
>
>
> > I have had the K&N setup on it for about 3000
> > miles I would think it would have learned by now .
>
>
> Probably, but if you did not disconnect the battery during the K&N
> install, I'd recommend doing it now, just to make sure the computer is
> starting out from scratch.
>
>
> > The truck has no
> > mass airflow sensor or an air temp sensor .
>
>
> Unless you have modified the engine from stock, the air temp
> sensor is located in the intake manifold, near the left side of the
> throttle body.
>
>
> > After I installed the
> > fipk i read an article some where I don't remember where that said
> > without a mass airflow the computer doesn't know what to do with the
> > xtra air and could create a lean condition .I just wanted to know if
> > anyone had heard this or had the same problem Mike Cabe
>
>
> No, a mass airflow sensor is not necessary - our engines use the
> speed density system which uses a manifold pressure sensor and engine
> RPM as inputs to a lookup table to calculate fuel requirements. The
> oxygen sensor compensates from there (within certain limits) to keep
> the air/fuel ratio right. A K&N intake is well within the operating
> parameters of the stock programming and will not lean it out.
>
> Also, you mentioned that the truck feels "dogie" and falls on its
> face. I assume this is during hard acceleration? Under those
> conditions, the truck is in open loop and the stock fuel mapping is so
> rich that there's no way a K&N intake could lean it out to that
> degree.
>
> It sounds like there is something else going on here. Possibly a
> sensor which wasn't plugged back in or got knocked loose during the
> install. My gut is telling me to suspect those spark plugs. Since
> swapping the intake out is really easy, my recommendation would be to
> slap the stock intake back in there and see if the truck goes back to
> normal. If not, I'd yank those plugs and install a set of the
> recommended copper core plugs. (Champion RC12MCC4, or possibly the
> Champion 4071 truck plugs)
>
>
> --
> -Jon-
>
> .- Jon Steiger -- jon@dakota-truck.net or jon@jonsteiger.com -.
> | '96 Kolb Firefly, '96 Suzuki Intruder, Miscellaneous Mopars |
> `-------------------------------- http://www.jonsteiger.com --'
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