Ok.....wheres my problem

[Forcefedperformance]

We are haveing a problem with a car that has us a little stumped and i was wondering if there was any one out there that might see something in this file and data looking that we are over looking...the problem is at 191 kpa. The car is acting like it is blowing out the spark or it is hitting a rev limiter. We have played with timing, A/f spark plug heat range and gap( from .20 to .45 ) with no changes . Can Anyone :help2:

Background on car

04 Z06 converted to a auto 4L60E with a 2600 Stall
LS1 383 Fast 76mm Patirot 72CC Heads Siemans 60lb Injectors
Jesel Valve Train , Kooks 1 7/8 Stand alone Fuel System

Bill

[johnv]

Could try upping the spark dwell time B 6001 from 11v to 15 volts.

VE numbers seem low, maybe just boost ref fueling thing though.

Map sensor scaler is high , are you 3 bar map sensor ?

[5.7ute]

Maths isnt exactly one of my strong points, but is it possible that you are exceeding the pcm's hard limits.(512G/sec)
The way I see it G/CYL = G/SEC*15/RPM
Since you logged predicted cylinder airmass we need to back calculate what the G/SEC is at your problem area. I was never any good at transposing formulas but I get
G/SEC=G/CYL*RPM/15
This shows that you are hitting the limit right where the flat spot occurs.
Obviously this would only be the case if a) my maths is correct & b) if the hardlimits are the same in that os.

[9secVette]

I have had problems in the past with Jesel valve trains being heavy. It would cause an intermittent valve float that I guess was off of harmonics of some sort. Try swapping out the rockers, it has worked for me in that same scenario.

good luck with it.

[Forcefedperformance]

Found the Problem..It was the valve springs

Thanks to Everyone that i talked to about this

Bill

[exploder]

good find

[Forcefedperformance]

Well we thought we found the problem but we were wrong:help2:


The Car "pops" at that rpm like a rev limiter....The Motor is a 383 ci about 9.1 compression Ported "Patriot" 72 cc heads

Soild Roller W/ 200lb seat pressure, Jesel Valve Train , 60 lb injectors, Custom Fuel System..stock fuel pump with a A1000 that kicks on under boost( We used the fuel return blockers from Lingenfelter)

boost ref fuel system ( 68-69 Psi at WOT) . We have tried everything in the book to try and correct the problem....spark plugs, wires, coils ( stock) pcm, injectors, Valve Springs , more gap, less gap . we were running about 15 psi so we droped the boost to 11 psi and the problem was still there, Same rpm everytime.

If there is anything you can think of that we have missed or if we need to make a pull on the dyno and log something specific please let me know....


This Car just makes me want to beat my head against wall.

I have included a newer copy of the tune

Thanks for your help!
Bill
www.forcefedperformance.com (http://www.forcefedperformance.com/)
916-331-1611 Shop
916-331-1711 Fax
530-682-7974 Cell

Please call with any questions

[exploder]

I don't know if you remember me or not. I called you and had you help me with my tune over the phone and over email. I have a very similar car aside from injectors. I was wondering if you still had a copy of my tune or not. My car was running 15psi and also it is a Z06 that was converted to an auto 4l60 I figured you could change the IFR tables for the injectors and the VE scaled for whatever percent difference my injectors are from his (96lb.ers here) and just try it.