So, for the past year I had 24# injectors on my car & the car ran fine. Til recently, it started to lose fuel pressure, which later diagnosed that the injectors were leaking. I proceeded to return them under warranty. I got a brand new set of equivilent injectors (Venom 24#) and re-installed. The engine (stock 350 w/Trickflow heads) idled very poorly & I was wondering WTF???? I tried everything, I replaced cap, rotor, plug wires & plugs. Plugs, btw, were black like charcoal. Previously running rich apparently. So, anyways I knew the 24# injectors were brand new, so I didn't want to point the finger at them right away. They all had an ohm reading of 15.3 on my voltmeter. I checked to confirm pulsing at my harness for each individual injector connector and all was good. Timing was right on so what else can it be? Well, out of curiosity, I replaced the Brand New 24# injectors with my factory TPI injectors, what 17#ers? Keep in mind, I have a 58mm & Miniram with a ZZ-409 cam (.520/.520). NOW with the factory injectors, it runs phenomenol!! Never better! Does any of this make sense?

 

Are you sure your regulator is fine?
Might want to do a fuel pressure test.

 

Some things to think about.

Whats your pressure set at? Is your regulator adjustable?

What kind were your old injectors? They are both rated at 24lbs, but perhaps they are rated at 24lbs at different pressures. If you're running a higher pressure than what these are rated at, they could be dumping in a lot more fuel.

Has your chip been adjusted for the change in injectors?

good luck

 

The stock injectors were replaced with Venom 24#ers about a year and a couple months ago. Just recently, the Venoms started to leak, so I sent them back for direct replacements (venom 24's) under warranty. The replacements ran worse than the leaking ones. The fuel rail was set at 51psi with the leaking ones and remained unchanged when I put the replacement ones in. When I placed the stock injectors back in, I backed the pressure on the rail down to 45. All pressure values were with no vacuum to the regulator. The chip was burned by a fellow Thirdgen member & is accurately programmed to my 24#ers.

 

what made you back the pressure down for the smaller injectors? That would make you run VERY lean, wouldnt it?

Since the ECM thinks you have 24s, putting in a lesser poundage injector with the ecm set up for 24's would make you even leaner than if it thought you had 22's (or whatever your stockers are). Lowering the pressure would only aggrivate this.

 

I put my stock ones in because I KNOW they were operable. A way to pinpoint the problem in this case was to put the operable injectors in & see how the motor reacts. The reaction was positive & it delivered exactly what I needed, a smooth idle & outstanding performance. Better than what I had before. The 24's provided me with rough idle & alot of backfiring/missing. I lowered the pressure because do to the nature of the smaller injector & modifications I have, I didn't want to overwork them. My question I guess is that was my 24 injectors too much for the set up that I have. The stock ones seem to perform better than what the larger injectors perform at.

 

Maybe it's the venom injectors. Where in Wisconsin are you? I have a set of Accel 24's you could try. I pulled them off my engine when I needed to upgrade.
24's don't look like they'd be too big for your mods.

 

Yah, I sent the Venom's back for evaluation earlier this week and I should be receiving a replacement set. I appreciate that offer, but will just put the replacement set in once I receive them for testing purposes. Now that i've been driving w/new plugs in there with the stock injectors, i'll pull the plugs to see how they look. Maybe it'll be better if I were to just leave the stock ones in. Another guy on a different board mentioned that my stock injectors are 22#'s, I always thought they were like 17 or 19 or something, but thats for the 305. When I had the 24's in all along, the old plugs came out black. Maybe now they'll come out clean. Thanks for everyone's input, its all starting to make a little sense now.

 

Do you have access to a scan tool? You could see where your BLM's are and see how rich you're running.

You could try putting the 24s back in and lowering the pressure, and checking it with the scan tool to see the change. If they're rated at 24 pounds at a low pressure, and you're running as high as 51, they could be putting out way more than 24lbs. Maybe up in the 30s. (not sure exactly of the formula to calculate it)

You could try contacting bosch, and seeing what fuel pressure they rate the poundage at. That could give you an idea if you're putting too much pressure to them.

Also you could contact the guy who modified your chip for you, and ask him what he changed for fuel.

24lb injectors shouldn't be too big for your application.