i have a 66 mustang with a paxton supercharged 306. Had my car dynoed the other day, and the owner of the dyno told me that my car was running dangerously lean, so we richened my car up to a decent level, and then 2 days later i fouled a plug. It has a tendency of doing this, it has done this many times. It likes to run on the rich side but then i end up pulling over on the street to change a plug. With the supercharger im kind of afraid to go up a heat range for the plugs, but its frustrating and i need to figure this out, does anyone have any suggestions?
keeps fouling plugs??
- Thread starter boosted66
- Start date
iskwezm
10 Year Member
Spend the $250 on a wideband sensor. This will help tell you exactly what's going on.
A miss often shows up as lean on a wideband sensor (lots of unburnt oxygen). If it's missing because of being too rich (which would show up as being lean on the O2 sensor) and your dyno guy ended up adding more fuel, then your problem suddenly just got worse.
My guess is that something like this is happening. Just remember that a miss shows up on a wideband as running lean. Could be missing because of fuel or spark issues.
A miss often shows up as lean on a wideband sensor (lots of unburnt oxygen). If it's missing because of being too rich (which would show up as being lean on the O2 sensor) and your dyno guy ended up adding more fuel, then your problem suddenly just got worse.
My guess is that something like this is happening. Just remember that a miss shows up on a wideband as running lean. Could be missing because of fuel or spark issues.
Iskwezm: napa told me not to touch the gaps on the plugs because of the way they are setup, which didnt make too much sense too me. Other than that i have a DUI distributor thats sopposed to be good for 55,000 volts, and i have a holley electric blue fuel pump with plenty of flow, but i do not have a boost referenced regulator, i just have the adjustable one by turns. i do have a paxton vacuum regulator that came with the kit but i did not put it on not knowing it would make a difference for a carb setup. Bottle fed: that makes a lot of sense. Thanks alot guys, if you have ne more suggestions thatd be great
TOM B
20+ Year Stangneter 
Well said Bottlefed70
I also run a wideband sensor with mu supercharger. and I tune my car with a laptop from my Holley commander 950, well woth the money with a supercharger.
There are many ways to do this so go get one before you blow it up.
I also run a wideband sensor with mu supercharger. and I tune my car with a laptop from my Holley commander 950, well woth the money with a supercharger.
There are many ways to do this so go get one before you blow it up.
When running boost you usually want to decrease your plug gap or increase ignition system voltage.
The more boost you have the more spark energy you need. If your running less than 10PSI you should be able to get away with just narrowing your gap to .030" or so.
iskwezm
10 Year Member
Dont take this the wrong way, but your very close to killing that engine. The boost referenced regulator is there to add 1 psi of fuel for every pound of boost. Mine under full boost will peg the F/P gauge at about 16 psi.The guy at Napa knows nothing. The plugs will need a smaller gap, due to the spark getting blown out, mine are at about .28. The Holley Blue will not keep up with the needed amount of fuel at its max of 14 psi, if it does indeed put out that much.I have a Product Engineering 410 GPH with max of 42 PSI free flowing.Its a bit much, but a lean condition is more expensive then a good pump.
iskwezm
10 Year Member
Do yourself a favor and ask all the questions now. I was too much of a know it all and ended up melting a piston from running lean on top end from a inadequate fuel system.I have my blower pressure port into a "T" that send the boost signal top a gauge and the regulator,if i rev the engine I can wathc the needle spike up.Make sure the fuel pump has the needed GPH as well as enough pressure to be stable under boost.I learned all this hard way last year and then HAD to build a new stroker
i now have the regulator hooked up and it seems to mabey be working backwards. When the car is either idiling or i am driving normal (low rpm) the fuel pressure is around 17-18 psi which seems very high for just an idle, and then when i stomp it and start making boost the pressure drops to about 7-10. I thought mabey something is wrong with the regualtor, because to me it would make sense for it to be low pressure at low rpm, and higher presure when i stomp it and begin to boost.
iskwezm
10 Year Member
is it hooked up to boost or vacuume????
If it was at 17 psi at idel, it would flood the engine very badly.
i put "T" into my boost guage line which is off of the intake that shows vacuume and boost, and yes it fouled brand new plugs in a few hours. Since i put the blower carb and blower on, not yet have i seen a decent coolered plug such as bronish or tan.. its almost as if i cant lean out the carb enough.. doesnt make sense to me all it is, is a 650cfm mighty demon ( the blow through model) which i thought should have been the smallest size for a blower application
iskwezm
10 Year Member
If you put the carb on out of the box, I doubt it its anywhere near "tuned" for your application. The only thing they do to them is mill the channel in the base plate,change the floats, the jetting ight be close, but i would have put on a dyno and read the a/f. I dont know what up with your f/p. I have my pressure line off the blower into a "T" to feed the guage and the regulator. i know people like to run them off the manifold, but it didnt work for me.
What does your boost guage read under load and at idle????
iskwezm
10 Year Member
its reading vac. so its working right, but is your regultor on the same port???? or off the blower????
iskwezm
10 Year Member
iskwezm
10 Year Member
thats the way mine is and it works fine. You might want to put a "nipple" on the carb hat or whatever your using so it sees the the same boost the carb sees. MIne is off the head unit so it sees 10 psi while the carb see 7 psi, so it works, but isnt exactly right.
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