To change or not to change--injectors?

[ChuckG]

At Cruisefest, Paul discovered a "lean" condition in my O2(new)sensor. Since then, my mind has been racing to discover why. I also have a ever-so-slight feeling of a miss at mid-range RPM.

I'm not sure it's related, but the subject of my injectors came up when talking with friends. Mine are 101,000 miles old AND have suffered through a fatal engine overheat on the original motor.

Electronically, they do report back 16.3ohms--but there is a mechanical component there I cannot test. The o-rings and caps were replaced, but not the injectors. One knowledgeable pal says the poor design of the era and mileage adds up to replacement--and then there's the other stuff too.

This all being said, what do you folks think of the logic behind replacing the injectors and with which? I have heard my cam would appreciate one size up from stock and that Ford Motorsport offers an affordable OEM quality unit in that size. Thoughts on Summit's brand? Accel?

[LLC5]

Originally Posted by ChuckG

At Cruisefest, Paul discovered a "lean" condition in my O2(new)sensor. Since then, my mind has been racing to discover why. I also have a ever-so-slight feeling of a miss at mid-range RPM.

I'm not sure it's related, but the subject of my injectors came up when talking with friends. Mine are 101,000 miles old AND have suffered through a fatal engine overheat on the original motor.

Electronically, they do report back 16.3ohms--but there is a mechanical component there I cannot test. The o-rings and caps were replaced, but not the injectors. One knowledgeable pal says the poor design of the era and mileage adds up to replacement--and then there's the other stuff too.

This all being said, what do you folks think of the logic behind replacing the injectors and with which? I have heard my cam would appreciate one size up from stock and that Ford Motorsport offers an affordable OEM quality unit in that size. Thoughts on Summit's brand? Accel?

Injectors can definately clog up. Try searching for an injector cleaning shop in your area. If you do find a shop, you simply remove your injectors and send out so they can flow check each injector and analyze the spray pattern, this way you will know for sure if they are restricted, the shop can also clean them when they are out. We use them quite often.

Carbon build up on the intake valves can also cause lean conditions. BG44k is one of the best carbon removers I have found for an in tank solution, and it can also clean mildly dirty injectors at the same time.

[ChuckG]

I have run Techtron pretty religiously every oil change and only use Top Tier fuel (Shell). I run BG44K every Spring when the car comes out of storage. The plugs and wires are also new.

Honestly, if I'm going through the tear down and find a shop willing to check my injector flow and spray patterns here in Detroit where shops routinely charge $125/hr labor, wouldn't I be better off with some new injectors? I've heard those at FIC are nicely done and they're $189 rebuilt/$289 brand new.

Corvette, Camaro, Firebird, GTO Only - L98 CORVETTE, CAMARO, F'BIRD - FIC rebuilt Bosch Design III 24 lb Fuel Injectors 85-96 Corvette, Camaro, Trans Am ,97 up LS1 - Fuel Injector Connection

My choices seem to be down to 24lbs and 33lbs ratings, but I am running an adjustable fuel pressure regulator set at 48lbs.

[LLC5]

Having the injectors flow and pattern tested would verify if an injector problem even exists, and cleaning them would be less expensive than new injectors. I personally like to verify that something is bad before replacing it, but I do understand your point that while it is apart why not just install new injectors. With the injectors out see if you can get a borescope in there to check the backside of your intake valves for carbon build up. I guess I kind of have a "fobia" with aftermarket parts, especially with runnability issues, as sometimes they can create additional problems that didn't previously exist. Seen it too many times. Good luck either way.

[ChuckG]

No doubt, I have the same phobia with aftermarket parts--even from reputable names if they're not the OEM supplier of said part.

The more I think about it, the more I think at 100k and having suffered that fatal engine meltdown, these original injectors have to be a problem, if not the problem.

I guess my point is, here it would cost $200 to check and test and I still might have a bad set, whereas with FIC, for $189, I know they're both rebuilt and flow tested. They come pretty highly recommended as re-builders from folks who have used their service.

Do you think the 24lbs stock rating is sufficient for this mild cam? (264/270 .464 lift)?

[LLC5]

I don't have much experience with modded C4's but I think you would be fine with 24 lb injectors if it ran good previous to the problem you are having now. Remember to check the backside of your intake valves with a borescope when your injecors are out, if at all possible.

[ChuckG]

That's a good tip. I have no reason to suspect the valves, but since I'm there anyway...

[LLC5]

Originally Posted by ChuckG

That's a good tip. I have no reason to suspect the valves, but since I'm there anyway...

Exactly. Check for the amount of carbon build up on the backside of each valve as the carbon can absorb fuel and cause a lean condition.

[ChuckG]

Ended up with a NEW set for $139 though an old pal in the parts business. Very happy!

[ChuckG]

Okay, new injectors are in! Some of the bolts to remove the runners are a nightmare, but after about four leisurely hours, my new 24lb Bosch Gen III injectors are in!

Problem now is, the car is surging and hunting for an idle. Drove about six miles and it didn't much improve. There's a slim chance the TPS got bumped, but not sure.

Any thoughts? Should I disconnect my negative battery cable and try to retrain the ECM, or will this self-correct?