From what I have read over the years, Accell injectors are the one's to avoid.

 

Okay, I thought that they were the ticket. I use RC Engineering injectors in my LT5 and I'm not very savey on the L98/LT1/4 series stuff. I would think that 22.5 or 22.0 or even anything close would do the trick. Just watch the flow rating vs at what psi, flow rates will vary as you vary the psi...not by much but bear that in mind when you shop. Better to know what the OEM's flow rates at what psi first and then compare that # to the aftermarket injectors. Don't go too far away from the OEM specs.

Jim maybe you should look to see what everyone else is using. The injectors are not hard to swap out if you have a place to work. If it's the first time I'm sure it will take ya some time to do it...ya know because first time ops are time until you know the drill. I would think that it would be a day for the first timer...a pro wrench could proly do it in 4 hrs.


Tom

 

Thanks Tom...it looks like I have to "bite the bullet" here.
Ok so I go with aftermarket injectors...Icorrect me if I'm wrong, but 22#or 22.5# will work?

 

do you think there could be a problem installing 21.5# or 22.5# injectors? I'm not having any luck finding 22# injectors.

 

Jim, I'm not fluent in L98.....I ain't even fluent in C4's so I'm using what I learned about the replacement injectors in my LT5 as a base for my guess as to what an L98 needs. I proly shouldn't do that as the motors are too different.

I would do a search over in the Tech & performance section first. See what the general concensus is. The way I understand it the flow rates vary slightly as different mfg's use different psi's to run the flow tests.

Also are you gonna do this yourself? If yes ya gotta have a Helm FSM...or at least I wouldn't do it without a FSM...but I'm a backyard hack...not a pro. If you are wanting a shop I would call Corvettes of Westchester.com and talk to Chuck. He is well respected and has been down this road with regular C4's before.

I can offer you my 90 helm set as it covers both motors...if you want to do this yourself. Let me know I'd be willing to help but I've never worked on any C4 except my Z! So we'ed be two novices doing the job. I did my injectors myself and my car still runs!


Tom

 

It might also be worth having your Ignition Control Module checked. Many parts stores can check it for you. The Ignition Control Module resides under the rotor inside the distributor. It will look something like this:



When they go bad they are first affected by heat. You will drive a while until the engine warms up then suddenly the engine stops dead. It will restart after the module cools down. Mine went bad last summer and my symptoms sounded a lot like yours. Just an idea.

 

jimmyu2: I too have a 89 Corvette and I have lived through the replacement of the Multec injectors used in years 89 thru 91. The symptoms of my car were a very bad idle and loss of power....especially after the ECM was in a closed loop operation.

The problem with the injectors is easy to diagnose and shorted injector coils will not set a code in the ECM. Measure the resistance of each injector when the engine is cold and hot. The specification of the resistance is 16.5 +/- .3 ohms. All eight injectors should be very close to the same reading. If you find injectors that are below the spec, the coils are starting to short out. I have heard of some readings around 4 to 5 ohms. My lowest reading was about 9-10 ohms. Injectors with low reading will not supply the correct fuel to that cylinder and the engine will run like crap

Once you find you have this problem, your next problem is what to do about it. I priced new GM injectors and the list price each was $198. My neighbor is a GM parts manager and he could get them for me for only $142 each

I went to Rich Jensen at Cruzinperformance and he was a big help to me. Here is a note from Rich on Multec injectors:


Hi Bob,

The problem you currently have is that from 1989 through 1991 on the L98 engines GM installed Multec injectors. These injectors have one of the highest failure rates of any injector ever installed. It's not a matter of "if" they are going to fail, it's simply a matter of "when" they will fail. That is why some of your injectors look differently than the others. Some of them have obviously already failed and were replaced. Because of their design they cannot be repaired so the only solution is to replace them.

You can try to find some of the same injectors to use as replacements however they will likely eventually fail also so a better alternative is to replace them with an aftermarket set of replacement injectors or find some of the earlier Rochester injectors that were used from 1986 though 1988 on the L98's. These were a Bosch design injector and they don't have the problems that the Multecs do.

I don't sell any injectors so I can't help with supplying replacements but if you do find a set of the earlier design injectors I can service those and they have a very good track record of long life and serviceability. The part numbers you would be looking for are: 1986 = 5235211, 1987 and 1988 = 5235302. These are the part numbers that are on the injectors themselves. They are not the part numbers that would be listed in a GM parts catalog.

Sorry to be the bearer of bad news but that's just the way the Multec injectors are.

Hope this helps. Let me know if you need more info or have additional questions.

Rich Jensen


Here is a copy of a GM service bulletin on shorted coils on Multec injectors:



I personally believe that the addition of injector cleaners (I was heavily using Chevron Techtron Injector cleaned to improve my idle) accelerated the degrading of insulating enamel on the injector coils. The Multec injector is cooled by passage of fuel over the turns of wire in the injector coil. This sounds like a cost reduction program that was a good idea for the short term. It sucks for long term or product relialibility

I solved my problem by finding a used set of Lucas injectors from a 88 model and sent them to Rich. The total cost of buying the used parts and having them serviced was less than $200......and I did the labor to replace the injectors. If you decide to replace them yourself, I have a procedure that will allow you to replace the injectors without pulling the runners.

Hope this is helpful!

 

"FWIW/food-for-thought Dept"

My past run problem:
Rough idle and run. White "smoke" with very rich gas smell. Raw gas in cylinder and engine block. REASON: Injector stuck open. Replaced injectors.

Past stall problem:
Starts fine, runs fine cold, rough warmed up. Eventually stalled and died on way home. REASON: Alternator winding shorted out. Rebuilt alternator.

NOW: No problem.


Mike
'90 'vert