holley tbi problems

[85 Jimmy]

ok guy's, i just put a holley pro-jection 4 stand alone system on my truck and anytime i give it gas it backfires through the tbi, i set the timing to 0 and i've tried adjusting the ECU, anyone have any ideas?

oh yeah it's on a 290 hp gm performance crate motor that didn't have any problems with a 650 edelbrock performer carb, the only problem was on inclines it would stall, that's why i put on the FI

 

[Thunder]

Projection is tuneable sounds to me you need to do some tuneing on the ECM.
Do you have a newer digital DI or the old ECM that you tune with the screws on the side of it.
You probabally have to turn up the fuel enrichment.
Holley has tech help have you called or emailed them?

 

[85 Jimmy]

it's got the ecm with the knobs that you turn to tune it, i'm going to check the TPS to see if that's set right, then i guess it's time to start turning some knobs

 

[iwaxmyjimmy]

it sounds deff like a timing issue, since its backfiring thru the TB.

 

[85 Jimmy]

well i just got it running close to right, it won't backfire until i'm at WOT, but as soon as i got it that close i decided to check the temp and is was running hot, so i shut it down to let it cool off. i waited till it cooled off and now it won't start, all it does is spins over, like there's no spark, but there is???

i might just give in and call holley tomorrow to see what they say

 

[iwaxmyjimmy]

I still say its in the timing. Im not really familure with the holley set ups, but does it use a CM sensor for timing? Or does it use a distributor?

 

[85 Jimmy]

it uses the dizzy

 

[iwaxmyjimmy]

what kinda ignition are you running?

 

[Thunder]

Backfireing at WOT is also a symptom of a lean condition. running lean will also contribute to overheating.
Are you using the right fuel pump?
Did you plumb in the proper size return line back to the tank?

 

[vortec]

Backfireing at WOT is also a symptom of a lean condition. running lean will also contribute to overheating.

x2.

richen the idle and you shouldn't have to worry as much about it leaning out just off idle.

 

[dyeager535]

I agree with calling Holley.

Does this thing have adjustments for a "pump shot" to give it more fuel when you hit the gas? All factory EFI I am aware of has this "feature", it allows you to run a clean idle while getting the added fuel to the engine quickly when demanded.

 

[85 Jimmy]

Backfireing at WOT is also a symptom of a lean condition. running lean will also contribute to overheating.
Are you using the right fuel pump?
Did you plumb in the proper size return line back to the tank?

it's the fuel pump that came with the setup and the return line is 1/4", which they say is ok in the manual

i'm running stock ignition

as far as i know there is no adjustments for a "pump shot" but they left the direction very vague, all the tuning and trouble shooting seems to be more figure it out yourself type stuff

 

[loafer]

it's the fuel pump that came with the setup and the return line is 1/4", which they say is ok in the manual

i'm running stock ignition

as far as i know there is no adjustments for a "pump shot" but they left the direction very vague, all the tuning and trouble shooting seems to be more figure it out yourself type stuff

1/4" is too small IMHO, but it will only cause you to run a little rich if anything. The smaller ID creates a restriction and increases fuel pressure. Watch your fuel pressure at idle, if it slowly starts to creep up, or it is higher than when you step on the gas your return line is too small.

Acceleration enrichment is done with the TPS and with the MAP sensor; The faster you move the throttle (TPS) the more enrichment you get. Works the same way with the load based enrichment; the faster the engine load changes (increasing that is) the more enrichment you get. I have no idea if these parameters are adjustable on you setup. They are adjustable on the Commander 950, but you usually only need to screw with it on heavily modified engines...and I've never messed with those.