OK boys and girls, I still have a stumble problem. Have changed F/P, timing anywhere from 4 deg to off the timing mark, or 12 deg plus, several chip comfigurations, and nothing. Starting to get discouraged, ready to swap back to modded TPI set-up. Can't believe I cannot get rid of the stumble. Here are my specs

91 Z-28 5.7
Bored .030 over
TPIS ZZ-9 cam
Ported vette alloy heads, mild port job, stock size Stainless valves
24 lb. SVO injectors
Aeromotive AFPR
SLP 1-3/4 headers
F/P right now about 46, Have driven car and checked F/P while driving, no drop off in press, screams up top. Have bounced off the 6500 rpm rev limiter
Next mod is heated o2 sensor

Anyone with imput or info or any suggestions would be appreciated
Mike

 

You will need lots of acceleration enrichment when swapping to the HSR.
Whomever is doing the chip isn't adding enough or it's still decaying away too fast.

 

Tried the enrichment thing, it got so rich it died, even had tuning on the fly and could not get rid of it

 

I have a LSRacingchip.com and the tuner there(Jamy) got mine right the first time.....no stumbles at all. The HSR does have a stumble/surge problem at low rpms. I run a 6* base timing then 20* at idle and 36* max at WOT through the chip.

With you set up...you might need to lower your FP a little to 43 or so.

 

Dataloging along with a WB is a tried and true method for those that lack the "feel" for tuning. That lets you see exactly where your rich or lean.
Except for the big cam guys.
But it won't fix tweaking the wrong table for the problem.....

 

post a link to your bin and a datamaster log. I'll give ya a hand. You wouldn't believe the **** I just went through with my miniram. Thing was worse to tune than the singleplane.

-- Joe

 

Send me your e-mail and I will send you a copy of my tunerpro. Realmac4@aol.com

 

Joe uses TunerCat I think. So he'll want a copy of your bin.
He has an email link in his profile.

 

Not too sure who this Joe is. Need an e-mail address. Mine is Realmac4@aol.com