I am posting this for a friend that is looking at replacing the injectors on an 1986 L-98 Z-51 car. When looking at the various brands, there are numerous injector options from 24 lbs to 80 lbs. The car is stock with just a chip and exhaust. Can anyone tell me what the best injector is for his application and what would be the best poundage for a stock non modded L98?. Any help would be greatly appreciated.

 

I just got a set of 24lb Bosch type IIIs from Fuel Injection Connection for my stock 85 that are amazing! 3 of my stock injectors had broken pintels and they all looked pretty rough. My idle is much smoother and I'm seeing improved performance too! FIC is the way to go!

 

For a stock engine you have to use the stock size fuel injector.

Remember, this is a computer controlled engine. If you start mix-matching various parts the ECM gets lost and cannot run the engine. The "tune" is in the prom, and that tells the parts that its tuned for, how to operate. Its about data and what the ECM thinks is there. If you stick bigger inj in the stock engine the ECM will end up running it wayy rich and cause a multitude of problems, from fouled plugs to failed emissions and premature engine failure from the excess fuel washing the lube oil off the cyl and valve guides...You can't add fuel until you have air available to go with it...that means intake & exhaust work. In ECM engines...the AFR is the key to success.

22 lb/hr is what you want, But ask Jon to be 100% sure. There was one yr in the 80s that used a 24 and the rest were 22lb/hr.
FIC is where you call and Jon is who you speak with. $250 gets you late model Bosch-III injectors, all the gaskets and all the O-rings for the fuel rails. Replacing the o-rings is a MUST and cannot be over-looked when doing an inj swap.

 

I also used the 24lb Bosch III's from FIC. Talk to John he guide you in the right direction. I also have a 1986 and the car runs 100% better.

good luck

 

With my recent running rough problems I was looking at replacing the injectors on my 1989 L98. On checking around it turned out that in California if you want to be legal with your replacement injectors they have to be listed by the injector manufacturer as a replacement for your make/model. If not they ain't legal - although they may work. When I sent an email to FIC asking if their injectors were legal for my car they didn't reply. Just fyi.

 

Tony I'll bet the farm you will hear from Jon. Been dealing with him for quite a spell, jon hasn'steered me wrong yet. About 99.999% of the folks here will say the same thing.

 

And you can run different size injectors. You can change the flow rate with an adjustable fuel pressure regulator. Of course, you would need to be able to measure AFR under WOT conditions. The computer in closed loop (cruising) will adjust the AFR plus/minus 15-20 percent by changing the pulse width of the injector, via the o2 sensor. Some individual stock injectors can be off as much as 25 percent or more! That is why it is nice to have a flow matched set. It is much easier to pick a set that matches your stock flow rates, if your motor is stock. 86 is 22 pounders, 85 had the 24's. Call FIC....he will hook you up.

 

Your L98 ECU can and will compensate for slightly over/undersized injectors and will let you know if it can not compensate enough. Of course this happens in Closed Loop Mode only, which is when the coolant temperature reaches a pre-set value programmed in the ECU. If you modify your fuel system without modifying your ECU, you will only see changes before the car is warm. This includes fuel pressure regulators.

When reading your L98's ECU data, your INT (integrator, or short term adjustment) and BLM (block learn mode, or long term adjustment) values are injector pulse width modification values. Your computer will adjust those values based on O2 sensor data. (So it's just as important to know that your O2 sensor is working properly.) If the computer's adjustments reach their high or low limits it will set codes 44 or 45, O2 lean and O2 rich.

As a result, you will not gain or lose power (or pass/fail emissions) simply by installing higher flowing injectors. There is a possibility of gaining power (and improving idle/emissions) if you replace your injectors with a new or matched set, particularly if your old set had a few bad ones. As O2 sensor values are averaged, the ECU will run the car slightly rich to compensate for a clogged injector or slightly lean to compensate for a leaky one. Fuel injector cleaner works, but I do not recommend it if, like me, you're unfamiliar with your 20+-year-old car's service history.

 

tony sorry bud, I did not see your e mail. I have been away since last wed trying to rescue some family members from Queens, NY..
not sure what legal means, they are certainly not Illegal as far as emissions etc. I thought in California and all states that the car must pass their smog test, not the parts. Especially in older car. Not 100% sure. please forward any info. We have tons of customers in California and never heard of that.

 

Thanks for following up, the way I found out about this was when I went to an autoparts store (OreillyAutoparts) and looked at their catalog, they showed one particular injector for my 89 L98 Corvette, when I asked about others I was told they aren't legal in California (off-road use only) but probably would work and would pass smog. So I did a little research and here is what I found

Here's a link to the site I found, the California Air Resources Board, http://www.arb.ca.gov/msprog/aftermkt/replace.htm
....and here's the text from that page relating to injectors
"Fuel Injection

The manufacturer of replacement fuel injection systems determines which of their systems are considered replacements for original equipment. These replacement fuel injection systems are then listed by vehicle year, make, model and engine size in the manufacturer's catalogue. Fuel injection systems not listed as replacement parts require an Executive Order to be legal. Modifications that change a vehicle from fuel injection to carburetion or from carburetion to fuel injection also require an Executive Order to be legal."
Regards,

Tony

 

The important distinction is whether the manufacturer considers the parts to be "replacement parts". I'm sure as long as the flow rates match OEM, they are considered replacements.

 

I live in Cali and a seriously doubt anyone is going to notice the injectors on your car. I've had nonstock, 30lb injectors in my car for years, tuned to run with them. Never had an issue passing smog.
Also 24lbs will work fine in a car that came with 22s, not enough difference to cause a problem.

 

The smog techs are looking for obvious mods like headers and cats.
Chasing an illegal fuel injector is outside their scope of visual inspection

 

the way i read that "chapter & verse" is, since you have the factory GM L98 TPI system on your car, you don't have a "replacement fuel injection system" from another manufacturer (e.g. Edelbrock, etc). you're not replacing the GM-original system, you're replacing a component of the original factory OEM system, you're still retaining the factory EFI. i think where they get really strict on component replacements is catalytic converters.