Im not to sure about the fuel injector side of my enginge. But after I installed my cc305 cam and headers with other variuos upgrades I couldnt get this annoying ticking out of my engine. After replacing the lifters I finally found that the 2,4 cylinder injectors was were the noise was comming from. So I ordered a set of 30# injectors and just wanted to know the affects of running these injectors without getting my computer retuned. Will it run fine or will it ruin my spark plugs or make my car run like crap?

 

You really need to get the computer tuned for the new injectors. It's going to run very very rich on 30 lb injectors when the computer thinks it's pushing 24 lb'ers. 15% to 20% more fuel flow across the board with no letup from the pulse width. I'll betcha it idles like a monster, but runs like crap (at WOT). The PCM will adjust to a certain degreee based on what it see's from the O2's, but it wont be enough. Call Brian @ PCMforless and have him reflash your combo. You'll be glad you did..

Dave C.

 

You have to have it tuned otherwise it could wash down the cylinders dilute the oil and destroy the motor, at the very best it will run like crap carbon up and wipe out the cats and O2s. That is far too much for the O2s to compensate for.

 

Suppose you put 30#'s in. It'll run like crap for a bit, until the computer adjusts. If the computer cannot sufficiently adjust, your PCM will throw an L/R O2 sensor rich code. Meaning your computers tried to adjust all the way down to 100 or so and cannot go any more down to adjust. "If" your car never throws a code, it means the computers actually happy and has adjusted. I doubt it'll be happy though

Stock injectors are actually 24.9#

 

A fallacy in that logic - the PCM can only pull about 15% fuel out with the long term corrections (BLM's), then it has to rely on the short terms. You might barely get by on the PCM's ability to adjust with the 30's in place of the stockers.... but ONLY in closed loop.

Since the BLM's will have been "reducing" fuel (below 128), when the PCM enters PE mode (often mislabeled "WOT"), if the BLM's were below 128, it ignores them and (as a general rule, there are exceptions) locks them at 128. Hence, even though the long term corrections are capable of making the corrections in closed loop/normal driving, as soon as you put your foot on the floor, its going to run pig rich - definitely rich enough to foul the plugs and wash down the cylinder walls.

N&MZ28:

Just curious.... why did you feel you needed larger injectors? I don't see anything in your signature that would indicate that.

 

I actually dont know anything about the fuel injectors and when two of mine went bad I called and that is what the tech told me to go with hince the bigger injector size. But then again they told me it had 26# injectors stock wich in here you guys have told me its actually 24#s. So would you recomend buying the 24# injectors or what would you recomend. Thanks again for all the help.

 

If you already have the 30's, all you need to do is have the correct flow constant and offsets programmed into your PCM. That can be done for reasonable $$$ by one of the mail order tuners, like pcmforless or madZ28. They will also be able to pick up at least 15HP by leaning out the stock traget A/F ratio in PE mode.

 

Just to be curious, what would happen if your computer was tuned for 30# injectors and you are running the stock injectors? If the opposite causes a rich condition does this cause a lean condition?

 

Short answer: yes.

 

Is it possible for a car tuned for 30# injectors but using 24# injectors to run rich?

 

Injuneer corrected my post above, I fergot to think about it PE mode.
If i recall though, if one of the last cells (fergot which one) is detecting a lean condition before PE mode, it'll go into PE mode at whatever offset that cell was at (or something similar to that). Preventing the engine from going "too" lean. It doesn't do that if the engine is on the rich side, in that case as injuneer pointed out it'll go right on 128.

 

Interesting...I was just asked about my 30#er's in another thread as to why?
http://web.camaross.com/forums/showthread.php?t=315082

My car doesn't foul plugs,can't make a call on the cats seeing as how they're nonexistent. 02's are fine also.

 

You dialed down the fuel pressure, which will have an effect on how much fuel they are dumping. It'd be less fuel than a car running SVO #30 with stock fuel pressure. But if it were tuned it should still run better at WOT because of the reasons posted by injuneer above.

 

I think I'll wait to install the SVO #30 until I'm ready for the tune.

Just rebuilt my motor, so need to break it in for a bit before a tune, worries me to run to rich while still breaking the motor in

 

Could I think ahead and get some 30# injectors, install and program my PCM from them even though I won't really need them until I get my heads ported? If so, could I lean out the stock target air/fuel ratio and pick up the extra ponies, as mentioned by Injuneer?