I've been running a 2BBL Holley Pro-Jection for the last few months (much better than the old Holley carb ;-> ).

Ever since the install I've had a problem with WOT.

Idle, choke, acc.pump, cruise and part throttle (up to 3/4) are almost perfect. But as soon as I go over about 3/4 throttle it starts breaking up BAD! It sounds/feels like an MSD rev limiter (pop-pop-pop).

If I back off to 3/4 throttle it hauls a$$ (if I do it near the torque peak the car launches forward HARD).

I've rerouted the return line (no restriction now), installed a new Earl's high flow EFI fuel filter, played with the fuel pressure (everything from 10# up to 25#).

I tried adjusting the TPS, when its set at .640V closed throttle/ 4.60V WOT (4.9 signal) everything is fine but WOT, when I upped the TPS so that it was just on the edge of hitting 4.90V @ WOT it ran like crap ALL the time.

Any ideas?


Thanks,

JK

------------------
'88 Camaro- Originally a 2.8, 7/98-3.1, 11/99- L-69, 8/00- Twee-Fidy!
Goodwrench350, Performer RPM intake, Holley670 "stand-alone" Pro-Jection, Hedman shorties, no cat, 2chamber FM under pass seat,MSD ProBillet, 6AL, HVC coil, TH350 w/2400 stall and shift kit, Chassis Engineering adj. Torque arm, 2"X1"X.110 fully welded SFCs (homemade) NOS SuperPowershot- going on SOON!, 3.42 Open, 8.8" 3.73/locker in the works.

"If it don't make it faster, it ain't got it!"
(no PS,PW,A/C)

 

I have TONS of experience with the ProJection pieces, from the older analogs to the newer digitals... I'll assume your is the 2D version.

You're going to have to find a way to measure the air/fuel mixture in your exhaust to do anything right or the diagnostic procedure of the Holley will be long and costly...

Measuring the AFR wii let you know if you have fuel delivery and/or ingnition problems.

Problems I have seen with the ProJections that may cause your symptoms:

o Bad connections will cause SEVERE operational problems with the units...

o The "small-block/big-block" wire(s) that determine the mode of operation MUST be a perfect connection or you WILL see problems.

o Holley's injectors SUCK! They could be misfiring/not firing at all at higher rpms. They do not like high rpms at all, and Holley may or may not tell you that... that is a reason for the low rpm-limit imposed on the system.

o Dirty injectors/screens

o bad/weak fuel pump. Do not use their pump to suck through your OEM tank pump. Also, how are you measuring your FP!????????

o Plugged return line would make you run RICH, while your conditions sound lean.

o Bad distributor/module/pickup coil. Also, bad coil-to-ProJection connection could give the ECU a bad tach signal. Are you using an older-style vacuum-advance one-wire HEI??? I hope so. You cannot use an OEM electrically controlled distributor (ie, TBI or TPI). Also a REAL BAD spark curve and/or bad weight springs may cause weird stuff, I guess, along with WOT loss of power. Also, check the vac canister for leaks/proper operation...

o Ground-loops can cause havoc on this system. Only have ONE source to ground, ie, don't run a engine-to-batt ground along with a batt-to-body ground if you have a ground strap (engine-to-body). You only need engine-to-batt and ground strap (engine-to-body) to provide one path. Long story, so don't ask...

Probably more, but can't think of anything right now...

EDIT: I must also add that if/when you get the system running properly, it will run VERY well. I suggest adding on the closed-loop kit if you are serious about keeping the unit. Best hundred'ish bucks you can spend and helps mileage a lot.

[This message has been edited by fast_broker (edited September 26, 2001).]

[This message has been edited by fast_broker (edited September 26, 2001).]