corvet786c

Had my 02 auto dynoed. I post graph up when I can take a photo of it. anyway my Max TQ was 440 and Hp was 430 in 80 degree. Florida. Its on a mustang dyno. The dyno operator says maybe time to change valve springs ,but drops from 433 tq @4868 to 415 @ 5226 and is not the normal curve. Any explanation for this? Pulley is 4.38 only running 5lbs of boost. Are my numbers normal for my set up? Also the lines look choppy.

corvet786c

Here is the dyno graph some please explain what is going on with the lines and drop off of tq thanks.

Other than that the car drives very strong.

corvet786c

Some are saying valve springs though, the cylinder heads are patriot 243's with there dual valve springs, could it be something else. Need advice.

corvet786c

Does anyone know if the rear tires could be slipping the dyno to make erratic wavy lines like this? Because the rear tires are old and warn in the middle of them and possibly dry rotted. Never had a chance to change them out.

corvet786c

Over a hundred views and No replies or help that is sad.

C5 Pete

.......
You need to post this in the FI section. Those guys know a thing or two.

chaase

Nevermind. I confused the curves up. The TQ curve looks wrong. The numbers don't look bad but that is Mustang Dyno which read notoriously low.

js23881

Crappy tires probably gave you the jerking lines on graph. I had same thing on mine a long time ago but it was because I pushed 800 HP and dyno could not hold it with my racing tires. I changed them to my street tires and believe it or not.......they worked well/better when dyno my car. Don't let my avitar fool you......I run mid to upper 5's in 1/8 and very low 9's in quarter.

corvet786c

I hope that is the case because they were dry rotted when I bought the car and a lil bald on the inside, dont know if this made the lines or not maybe someone else could chim in?

mxguy1286

If your car was a sound running car previously I would try a new tuner. That graph looks terrible. Choppy and erratic.

neutron82

graph does look horrible... do you have any other mods?... I made 12psi with a 4.38 pulley on my d1 and I also have longtubes and a cam so I would think you would see more than 5psi... I would go over the car and make sure you don't have any boost leaks or other mechanical issues and once that is all good to go then start looking at the tune... if the car isn't in good shape to begin with then a tuner won't be able to do much with it

corvet786c

Problem fixed, it was not valve float even though the chart may point to that direction, but it was a combination of a spark plug gapped to .20 and a spark plug wire defective and 1 of the cylinders was not getting proper air/fuel mixture.

Now I bought new MSD's and gapped all plugs to .35.

The car idle's much better being consistant and is not choppy meaning being up and down (RPMS) sound is a lil deeper to, seems like I have all my power back. I took it to over 5000 rpms and car kept on pulling.

neutron82

how much boost are you seeing now?... was the car tuned at the same of time the dyno graph you posted?... if so and it wasn't running properly when it was tuned I would take it back and have it cleaned up since the car is running better now or you risk the chance of messing something up

corvet786c

Very conservative about 5lbs, yes it was tuned by the same shop. Well, I believe it is running better than it was. Meaning the air/fuel mixture is still the same as tuned, but now it is fully being utalized on the compression stoke. Instead of unburned fuel popping out the exhaust, it is being fully burned, what it is supposed to do.

I just changed the gap from .25 to .35 and bought brand new plug wires.

neutron82

I still think you should see more boost with that pulley on a d1

neutron82

what other mods do you have done to your car?... as I stated above I saw 12psi with a 4.38 on my d1

corvet786c

Unless the shop is lying to me this is what they said. about 5lbs. Then maybe it is more. Forged 347, fast 102, 100lb injectors, 243 patriot heads and a blower cam. Automatic with 3.42 gears

neutron82

I'm assuming you don't have a boost gauge then?... check for belt slip and boost leaks... I think your car should be making more boost and more power than what it is making... 100lb injectors also seem awfully big for your power level but a good tuner could make them work I suppose... if you aren't capable of checking these things out yourself then I think you should take it to a better shop that can properly look the car over and fix any mechanical issues and then get a good tuner on it