My 1989 Iroc Z, 305TPI, 5 speed, (205,000 miles) has the original fuel injectors. At idle when hot, it has an intermittent misfire. I've checked and/or replaced everything to eliminate any possibility of an electrical/electronic issue. In checking the resistance of the fuel injectors, all were between 17 and 17.2 ohms, except for one that was 9.5 ohms. I'm assuming this one needs to be replaced since the factory shop manual says any injector under 10 ohms needs to be replaced. At this point, I'm thinking of just replacing all of them since they are all probably dirty and since all have the same amount of miles on them, they may all start failing one by one. Do you think its wise to replace all of them at this point? Would you suggest stock replacements or SVO's? Will the 24# SVO's that I hear about being used on the 350 engines also be OK for the 305? Who's got the best prices, for either stock or SVO injectors? Do new O rings come with the injectors?

 

In 89 the stock fuel injectors were the grey multecs, if this is the case with your car they should all be replaced. They are a poor design fuel injector. If your engine is mostly stock, or even slightly modded, the stock 19lb injectors would be plenty for a 305. If anything get an AFPR if you want a little more fuel.

The 24 lb injectors would be too big, plus the computer's injector constant would be set at 19lbs @43.5 psi, so going to big might cause problems there. I would recommend going on ebay and getting some replacement 19lb bosch style fuel injectors.

 

Thanks for the reply Pellmanm.

In looking around for injectors, I noticed on fiveopeformance's website that the 19# Bosch injectors they specify are for '85 to '88 305 TPI eingines and for '89 to '92 305 TPI engines, they specify the 22# injectors.

Does anyone know if the factory changed the stock injector specification from 19# to 22# between 1988 and 1989 for the 305 TPI engine?

Also, fiveoperformance says to eliminate the stock clips that holds in the fuel injector when using the Bosch injector. If you eliminate the stock clip, what holds it in?

Anyone have any experience in dealing with fiveoperformance or any other recommendations for injector suppliers? I didn't find any on ebay.

 

Check out this link:

http://members.shaw.ca/s15/Fuel%20Injector%20List.htm

Scroll down to the bottom of the page and you will see that even in 89, they used diferent injectors in the 305s than in the 350's.

The Lucus replacements have one part number for both of the 89 350's (22lb) and a different part number for the 305's, so i am guessing that they are 19 lb. To me, because the replacement part mumbers are different that means the injector has a different flow rating, otherwise they would just list one replacment part number for both the 305's and 350's because all the list fuel injectors would fit in the same fuel rail.