I've read a lot here but not posted much...just been soaking up the info, but now I could use some input.

Background: I put a 350 HO crate into an '87 TBI truck, GM Vortec to TBI manifold, a new 454 TBI (with what I thought were 454 injectors), a fastchip prom from Ed Wright, and a Walbro 190 fuel pump.

Ever since I put the engine in it has been running WAY lean in closed loop, lean to the point of needing to remove the thermostat to drive it. As soon as it hits closed loop any load above an idle and the temp gets WAY out of control and the truck hesitates like it's starved. I've cranked up the fuel pressure, but all that really did was make it way too rich during idle, maybe helped a little in upper RPM but didn't cure it.

So, today I finally took a good look at the part #'s on my injectors and to my surprise they are 17084327 65# (68) injectors!!!! When I purchased a brand new 454 TBI I expected to get 454 injectors, thus the chip was burned for 80+ pound injectors. No wonder the truck is starving!! I got the new TBI from TurboCity...it would have been nice if they had told me they were going to short change me. I guess that explains why their "454" setup was a little cheaper. Needless to say I'm a bit torked and will be making a phone call in the morning.

My question: Replace the injectors or reprogram the chip? I am split right down the middle on this one. Will I lose any "make shift" tuning ability if I go with the bigger injectors, and the exisiting chip i.e. fuel pressure adjusting? If I keep the smaller 65# injectors and get the chip redone will I be throwing away power I could have had or will they handle the engine just fine?

I don't plan to mod the engine, I just want the 350 HO to run as good as she can with TBI.

I've searched through the archives but it was inconclusive.

Thanks for any input.

Mike

 

I have the exact oposite problem. I put the holley 670 and the 80 something # injectors on my 305 with vortec heads and an lt4 cam. It ran wayyyyyyyyyyyyyy to rich. So I put the stock 305 pod on it and now it runs lean.

65# are about what i need with the stock chip... Hey mabye if you're in the houston area we could swap injectors =)

 

hmmm.. usually its the other way around. The engine will run lean (and like crap) untill it enters closed loopa dn the computer can compensate for it. Wonder if its a problem witht eh chip or maybe a bad o2 sensor.

 

Sorry, not in Houston area...over the water in England.

The problem with the chip is that it is burned for the wrong injectors. It runs great in open loop because it is in warm-up mode and is running richer. I doubt that the computer is going to be able to compensate for a 15-20lb injector difference based on o2 inputs.

 

65lb/hr injectors at 17psi should flow about the same as 80lb/hr injectors running at the stock 9-13 psi. I try to get my engines to run correctly at WOT on the top end by adjusting fuel pressure and then change the too rich at idle by adjusting the chip. 80lb/hr will have a tendency to run very rich in a 350 engine. My guess is that fastchip didn't cut back the base pulse width enough to get the 80lb/hr injector to run correctly at idle.

Where you need to start is with a WINALDL setup that you can use to take some guess work out of what is going on with your engine. A fuel pressure guage would also be benefical to know how much you are adjusting the fuel pressure.

 

Thanks for the very informative post. I think the reason the fastship's chip is not working right is because it was burned for 80lb injectors when I only have 65lb injectors.

Good info about the 65lb injectors. It sounds like they should work just fine with a little fuel pressure adjustment and the chip redone.

Thanks!

 

Hoover,

Why not just set the BPW constant on the chip to 125? Then see if engine is still starving. Depending on whether the motor has a bigger cam and heads, you may need the 80# injectors anyway. I did for top end.

 

I would if I burned my own chips, but I don't. I got an email back from Ed Wright at Fastchips and he said to send the chip back to him and he'll make the changes.

So far great service at Fastchips.