no, we are talking about a truck with a lot of modifications that gets 8 mpg.

if you are happy with getting about half the mpg you should be getting then do not listen to suggestions like mine.

the jacobs box is really a band aid on your truck, it is firing those crappy trick bosch plugs and i would bet if you pulled them at least half are fouled.

do what you want but my truck gets 15 mpg in the city and your does not.

 

OK.. so forget the fancy diagnostic tools, does it flash codes on the check engie light if you ground the STI wire and turn the key on? This will tell you if the computer has lost it's marbles or not, if you get codes.. any codes at all it's probably fine, and if you do then you have a starting point at least.

 

Yeah, Its dead.


And 15 mpg in town out of a 90 351. Please. you had me on the plugs but Im calling bull****. Most people are lucky to get that on the hiway, myself being a lucky one. as for in the city, you must have been on a free way passing thorough.

 

quicklook, are the bosch plugs really that bad? I havent had anything but them in my truck, so I wouldent know of it acting any different. Sounds like maybe I should change em out. Even though mpg doesnt really concern me from the sounds of it they probably will make it run a whole lot better.

 

Some people have had back luck with the gimmicky +2 or +4 platinum plugs, but that's more to do with the design of the plug, not the name on the side. A copper core plug is a copper core plug, it doesn't really matter what name is printed on the side.

 

I was told autolites and motor craft were the same thing

 

That's correct...Autolite makes the plugs for Motorcraft.

 

i never said i got 15 mpg in the city with a 90 351.

i said i got 15 mpg in the city in my truck, 94 auto 4.9 long bed driven like it has an egg under the accelerator.

plenty of 15 mpg in the city from a bunch of members here with v8s and sixes.

now if i had said 20 mpg....

 

I wish I got 15 mpg city.

 

this summer they just started adding like 10% ethanol to gasoline. This will deff drop your fuel milage. Prob when your on the highway you won't notice it as much.

 

Did you ever back probe the voltage at the TPS ? ,1 volt < @ idle

 

393 Stroker, I havent had time to try the back probe yet. Im going to my shop this weekend and ill try it then. I am wondering if maybe my O2 could be shot and by not throwing a code if the computers dead its not operating at full circut. I have a few diagnostics to run this weekend and get a new fuel filter but I guess we will see.
And as for quicklook2. You drive a 4.9 and you are lectureing me on my plugs. They wouldnt help you becuase you drive a six man, your getting 15 in town when I have heard of others getting 17 so dont be so quick to judge what you think. Im sorry but a six is completely different than a v-8 no matter what you are looking at. the only similarities is they use spark plugs and have ford stamped on the case.

 

well against my better guess, my ford Mech, says to try the O2,. Its at 4 or 5 years and he said thats all your gonna get with a after market one. So well throw one on and see how it ends up.. Low end and idle meters are off he thinks.

 

i can see by your posts that you know everything and reasoning has not helped so.... good luck.

 

+1 for ditching the bosch plugs. Quicklook knows what he's talking about, whereas you seem to have an attitude. That's too bad, you can learn a lot more from people who are trying to help you if you listen to them rather than argue with them.