Jditlfm

iTrader: (26)

Well I have been having a gremlin in my car since i moved to Florida to go to school so my instructor at UTI said he wanted to put it on the dyno and see if he could see anything wrong with it. The car bucks at low rpm under load and also has a stumble at wide open throttle. He said that because of the torque numbers being so erratic that my spark plug wires might be to blame because they are throwing the probes on the spark plug wires off. I also noticed that the car was running at 14.1 a/f ratio under wot so im thinking maybe my stock 140 thousand mile fuel pump cant keep up. What do you guys think. The car also ran worse with the cutout open. Maybe i am fighting two problems and not just one?



car has:
New ac delco optispark
New ac delco plugs
new ac delco o2 sensors
New autolight spark plug wires
new Coil
new ignition control modual
Egr is tuned out of the pcm and all vacum lines capped off but egr is still on intake manifold
Long tube headers
madz28 tune
cutout
new fuel filter
Cleaned maf
newer K&N filter

9sec93

iTrader: (67)

just because the opti is new doesnt mean it isnt bad. either way, it definitely sounds like an ignition problem.

flame

iTrader: (13)

best look into the fuel problem first before you do damage to the motor

the_hunted

If you are looking at your fuel pump, then you should put a guage on it and see what kind of psi it has at idle and at wot. then go from there on the pump. dont just replace it, check it first.

Mattybz28

294hp / 922tq

Looks like your problem is someone swapped a diesel into your car when you weren't looking!?!?

Jditlfm

iTrader: (26)

Ya thats what i was saying, the out of whack torque numbers are possibly from the spark plug wires messing the probe up on the dyno causing false torque numbers. When i scanned it the other day with data master i found i was getting 5-6 degrees of retarded timing due to knock. I am thinking maybe that it is running lean (14.1) a/f ratio and then it is detecting knock and then retarding timing causing these problems?

solid95z

iTrader: (7)

With the numbers showing what they do, the dyno may have been set for a 4 cyl (which will double the tq multiplication & show goofy tq #'s). If there was deisel in the tank, he car would barely run & would be smoking.

I would check the fuel pressure at WOT. That'll let you know if you need a new pump. Also, check and make sure you dont have a cracked spark plug or that one of the plug tips is not loose or missing.

Jditlfm

iTrader: (26)

Well i got the fuel pressure gauge hooked up and it dose 41 psi at idle and will drop as low as 30 psi under wot in a 3rd gear pull. Is this around normal?

Rebob5

iTrader: (3)

solid95z: Mattybz28 Meant that by the HP/TQ numbers it looks like somebody put a Detroit deisel in it. Detroit MBE 900, 7.2L 250 BHP, 860 lb feet of torque

95zpro

I say you need a new fuel pump; pressure shouldn't drop that low under wot.

Mens Rea

iTrader: (2)

I'd say you just go around bragging about your 900rwtq to everyone...

camar0corey

iTrader: (22)

Your fuel pressure should increase under WOT, not drop lower.

LT1MAN

iTrader: (6)

i dont see how a dyno could read 922 lbs of tq like that.

The Big Show

iTrader: (2)

Actually you can make a dyno read whatever you want...

Jditlfm

iTrader: (26)

From what i understand, the dyno uses the spark signal and the speed of the drums to calculate torque. When your spark signal gets all crazy like bad plug wires because they are arcing everywhere you get ridicules torque numbers because it throws the inductive prob on the wires off (signal wise).

LT1MAN

iTrader: (6)

o i c i do c.

titter

iTrader: (5)

got to love dyno tq spikes. like said, your fuel pressure should go up, not down during wot.

LT1MAN

iTrader: (6)

this is funny, the guys putting in my motor did a baseline run on my car before the new motor. and it did the same thing as yours did, 292rwhp, 940rwtq. i had never heard of that happening before yours and then it turned around and happened to mine.