bucks under boost?

ndiiorio

Registered User
i ve stated before in another thread i have a check engine light for low maf voltage, but car seems to run fine. occaisonally, when im accelerating heavily the car feels like it cuts out for a second, then its back to normal acceleration, but the check engine light goes off until i get off the gas then it comes back on. the engine was just put all back together. i havent checked the plugs yet but could all of this be related?
 
thats your problem

Get a new maf and go from there. I just bought a xr7 with no maf attached to the tube.....ran fine....but would only cut out under WOT under certain loads. A new maf from sccoa member for $20 fixed it
 
Clean the maf sensor and check your plugs....

If your running rich your oil is taking it on and your bearings next...Maybe 02 sensors as well.............
 
changed maf electronics and the same, o2 sensors brand new, i found a vacuum leak and now thats fixed, but still the same. i havent checked my plugs yet.
 
Change the plugs and wires, it's getting spark blow out under boost. Either the plugs are bad, or the wires are bad.

Get some autolite plugs and I've personally had good experience with the $30 set of plug wires from Auto Zone. They have a lifetime warranty so you can replace them for free every other year too. :D
 
im with scott change out the plug wires, Borg Warner Select / super mags CH8651 is a nice set of wires ,with some autolites, all-ways run good wires and plugs, if you just got it back together check/make sure there's, no air leaks
 
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Plugs and wires are essential on a supercharged motor. On an N/A motor, you can get by longer on old plugs and weak wires than you can with a supercharged motor. When you go into boost you are literally ramming air into the motor, so the engine has to have more fuel and a stronger spark to ignite the mixture. Weak wires that would work fine on an N/A motor can't provide a strong enough current to the plugs. Then again the best wires in the world won't make ~~~~~~ plugs fire any better.

Stay away from any of the Bosch platinum plugs, they suck for forced induction because the electrode is microscopic and sheilded into the insulation of the plug. They don't make a very powerful spark (contrary to what Bosch says in their advertising) the plugs are crap. They lasted me 6 months in my stock SC. Ever since I've ran autolites and have not a bad thing to say about them.
 
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bucks under boost?

just know that the minute you feel something like that coming on ( the bucking or or missing ) get off the throttle, and try and figure out why, it's not good for the motor any at all....( hg's)
 
changed the plugs, filter is new, and I just replaced hg and a whole lot of other stuff... this just started happening. im also getting a rough idle sometimes. I haven't found a vac leak and the factory gauge is reading 19-20 at idle. im going to get some more wires but its gonna be a while Because there is nothing local... I was convinced it was the plugs, I don't know, im stumped.
 
my 89 idles at 20,but runs great at wot 15 psi of boost,no problem their.it did however start a bucking like it was running out of fuel,got to looking the SCbelt was cutting through a wireing harness,left of water pump 2 wires tuching taped them upand zip tiedthe harness away from SC belt.fixed the problem,might be worth looking into.
 
changed the plugs, filter is new, and I just replaced hg and a whole lot of other stuff... this just started happening. im also getting a rough idle sometimes. I haven't found a vac leak and the factory gauge is reading 19-20 at idle. im going to get some more wires but its gonna be a while Because there is nothing local... I was convinced it was the plugs, I don't know, im stumped.

If your using stock wires, older ones can be damaged just by changing the plugs. Install a new set of wires (suggest Taylor Spiro Core) before doing anything else.

David
 
if you took off the lower intake manifold, thats probably the problem. i had similar problems under boost. just a thought.
 
Did you by any chance get a chip done for that setup? You've got a 76mm MAF and hopefully the right sized sampling tube for those 38# injectors, and a 85mm TB, and an s-ported blower with 10% OD on it.

I can see where the MAF low voltage is coming from so a chip will need to be done to get rid of that error. The hesitation or what ever your feeling is probably the car going way lean momentarily as you dramatically increased the amount of air thats allowed to go in at once and nothing in place to compensate injector wise, which would need to be done by a chip. Also without a chip, your load calculations will be skewed down and that number is used to calculate fuel and spark.

Frit
 
my 89 idles at 20,but runs great at wot 15 psi of boost,no problem their.it did however start a bucking like it was running out of fuel,got to looking the SCbelt was cutting through a wireing harness,left of water pump 2 wires tuching taped them upand zip tiedthe harness away from SC belt.fixed the problem,might be worth looking into.

Same issue I had, it was the DIS Harness at that...but mine was rubbing the pulley instead...
 
wires have been ordered as we speak, even if thats not the case its worthwhile for me. i was thinking too that the car is running lean and that was the problem... chip is also on its way. the wires are all clear of the belts and none appear to be damaged.
the sampling tube is correct... 38lb. inj + 76mm = orange
 
Change the plugs and wires. Scott and David on right. Most of the time its the basic problem that needs addressing. My car wouldnt even start a week ago. I changed the plugs, started right up and idles beautifully. Of course I have some of David's go fast red plug wires on it too;)

Ken
 
thats exactly what i have on its way... should have them by the end ofo the week, i will let you know what happens.
 
alright heres the update... new plugs and wires and got a chip from dave. well the bad news is the problem is now worse. and addition to the 66 code i also have 87 and 95 now. this all definately seems some sort of fuel delivery problem. i havent checked the fuel pressure at the rail yet as im trying to get a hold of a gauge. the 87 and 95 have to do with the fuel pump circuit? if the car is getting fuel then im assuming everything is getting turned on, could there just be a lack of voltage or ground issue? i need some big help, this is the last thing i need to get everything running right. thanks everyone
 
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