ok i have been trying to figure this problem out but i just dont know what is going on.. i have a 94 firehawk M6 cc503,le2 heads,lts,42lb inj,port matched intake,full exaust,1.6 rockers,ram air,nitto DRs.. and i cant seem to get it to run right ..it put down 312hp &344tq dynojet.. i am working on tun ing it beter but..i have to fix this prob. first..it has no power as soon as it hits 5300rpm..on the graph it just goes strait down...why???? and those #s suck for this setup and a tune wont fix that much... it runs fine... DD i took it to the track and the best i could get is a 13.8 at 102... and yes on Drag raidials.. i should be trapping at like 114-116 please help...why is it falling off at 5300... and sugestions...

 

Who tuned it?

 

it is a buddys tune that has the simmilar setup as me but im tweaking it with lt1 edit but i just dont see a tune making that bigg of a difference i mean u usaully only see max 20 hp out of a tune

 

What kind of vacuum are you pulling at idle? Should be in the 15-16hg range.

 

How's your fuel pressure at wot? A tune that is way off can make a hugh difference in performance.

 

Yes definitely chk that fuel pressure as if it shows only 20@wot your fuel pump is dying,also monitor if any k/r is present as this kills top end performance;since you have a 94 your opti maybe is on it,s way out as well and yes w/your mods your trap speed should be 112-114.Btw what was your 60 ft?

 

i dont think its fuel pressure prob. cause it is going rich at 4500 up like 12.2afr and it is picking up 5.0 knock at 4300 up would that make that bigg of a difference i think im getting it due to a exaust leak at the head..

 

Chk to see if you can get a 02 reading.I remember that a project car in PHR had a exhaust header gskt leak thus causing rich #,s and poor drivability,etc.And k/r can be caused by many things like r/r,loud exhaust,or in my case just stupid phantom knock.Btw you can hook a fuel pressure gauge and verify for sure if pressure drops.

 

What is the altitude where you live? Was the dyno pull corrected to SAE or STD conditions?

 

it was uncorrected...and im in texas i think the altitude is 420-450ish

 

will 5.0 knock hurt it that much??

 

DUDE ! you're leaking at the header flange?
Not only is it flowing poorly, but it's probably also pulling in oxygen before the O2 sensor.

And make sure those rockers are not overtightened.
Overtightened rockers will hold the valves open at high RPM when the lifters plump up and cause significant power loss.

A 503 and LE2s should still put down over 375 when set up properly.

Yes, it will retard your timing and cost you a lot of power.
I faught with bust knock when I did mine. Ed's tune made 30rwhp more VS the street tune I was running.

 

If you have an exhaust leak and the car thinks it is running lean it will add fuel to make it run rich. Fix any leaks first and then see how it is doing. It is a good idea to monitor the fuel pressure after you have the leaks fixed. Take this one step at a time and you should be fine. My rockers were adjusted by someon else when I bought the car and they were 2 full turns too tight. I made a hugh difference when I loosened them. I figure I picked up a 1/2 second alone.

 

1 degree of knock is typically 1-3whp.

 

and i understand the exaust leak is what im probably picking up knock from but..the o2 sensors dont work under WOT..so this is why i think it is something else..and my rockers are set at zero valve lash..1/4 turn.. is it possible im atooth off on timing??? would it still run ok beeing off a tooth..cause honestly the car runs great..just not the power it should be putting out...any other thougts??? im gunna work on it all day tommorrow to try and figure it out...while my buddy intalls my 4:10s i would love to get it fixed at the same time..lol i couldnt imagin the the difference about 80hp and 4;10s all at once would feel like:0