Dynoed my car today
Thread Starter
Joined: Apr 2005
Posts: 1,456
Likes: 0
From: Brockport NY
Dynoed my car today 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
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
Thread Starter
Joined: Apr 2005
Posts: 1,456
Likes: 0
From: Brockport NY
Nope the car starts right up. and will drive around great until you load the engine pretty good. It gets worse with the cutout open. As you saw on the dyno i lost 20 hp by opening the cutout from the 2nd to last pull and the last pull. And as far as the teacher he is pretty much one of the coolest teachers in UTI. He is the hotrod instructor, i have been real lucky to get along great with all my instructors in the 6 months i have been here. something else i forgot to mention is the car pulls 5-6 degrees of knock at wot. Another added mystery to my lt1 problems. 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?
Last edited by Jditlfm; Jan 16, 2007 at 09:26 PM.
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Banned
Joined: Apr 2006
Posts: 1,875
Likes: 1
From: Naperville, IL
Originally Posted by Jditlfm
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?
yeah dude, an LT1 shouldnt drop more then around 5psi during a run. the hotwire kit is a good suggestion, since its a good mod to have even at the same time as adding a pump. Id get the hotwire kit AND a fuel pump though. cheaper if bought together. and you'll need the pump sooner then later anyways even if the hot wire kit fixed the current fuel pressure drop problem. but I also dont think thats your only problem. however Id just start with that, and retest and go from there.
good luck.
good luck.