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my 350 TPI 89 firebird has 24lb high impedance injectors installed on a totally stock engine. are these any good? will the PROM work well with them? the plugs all looked a bit rich when i replaced them. im wondering if there is another better set of injectors, or to run the ac delco stock ones? opinions? thanks
Stock is 22lbs/hr, so you are effectively richening the entire fuel map by 10% everywhere, which is why your plugs are rich. Stock tune needs stock injectors, you can either change the tune or change the injectors to fix it.
I'm thinking the Corvette L98 did have 24# injectors due to the better exhaust and maybe some tuning differences? Any mods to your engine at all? I put 23 # Accel injectors on mine and they've worked good with good mileage. The original Multec injectors did have problems which is why I replaced mine.
I think 85 c4 was the only with 24#hr and lt1 but rest of tpi l98 was 22#hr.
agree two choices replace or tune
agreed. im leaning on going back to the 22#hr stock ones, which injectors would you recommend? i have heard about issues with multec injectors. had an issue with those on my 91 sunbird 3.1. thanks
I'm thinking the Corvette L98 did have 24# injectors due to the better exhaust and maybe some tuning differences? Any mods to your engine at all? I put 23 # Accel injectors on mine and they've worked good with good mileage. The original Multec injectors did have problems which is why I replaced mine.
no, no mods to motor at all. all there including cat. converter. 94k miles. had issues with cold engine starting and stalling, but new fuel pump fixed those issues. yes, i do not like to be running rich. ill post a pic of the plugs in a day or 2.
If you consider the ethanol content of today's fuel, you will need about 5% enrichment to compensate for the ethanol, so the BLM will be elevated somewhat (by maybe 6-7 counts) with respect to nominal.
Since 24 lb injectors are roughly 9% larger than 22s (by mass flow rate), there will only be about 4% excess for the fuel trims to deal with after compensating for the ethanol. As result, the BLM will run a bit lower (by maybe 5-6 counts) with respect to nominal. This amount of correction is rather trivial unless already running at or near the lower limit of 108.
Last edited by tequilaboy; Oct 22, 2022 at 08:09 AM.
If you consider the ethanol content of today's fuel, you will need about 5% enrichment to compensate for the ethanol, so the BLM will be elevated somewhat (by maybe 6-7 counts) with respect to nominal.
Since 24 lb injectors are roughly 9% larger than 22s (by mass flow rate), there will only be about 4% excess for the fuel trims to deal with after compensating for the ethanol. As result, the BLM will run a bit lower (by maybe 5-6 counts) with respect to nominal. This amount of correction is rather trivial unless already running at or near the lower limit of 108.
i hear ya on that, however, my spark plugs are jet black and i havent looked at the 02 sensor yet. im assuming im running quite rich. im hoping the correct 22lb injectors will get me back on a good fuel ratio. im planning on only running pure gas (no ethanol) which is available easily where i live, as i know that these cars were designed at a time when 10% or more ethanol fuel was nonexistent.
I purchased a set of these delphi's from southbay a few years back and can not be happier with the choice. Have not had one issue with them and the car runs as smooth as it would have when new. I also use non-ethonal fuel, not just for the fuel map, but we still have rubber fuel lines and rubber o-rings and such that ethonal tends to destroy.
Yeah get Delphis. They may be a little more expensive from what I understand, but if you're intent is to avoid tuning, they're the closest to factory (vs the Bosch III style).
If that was a carbed engine I'd say the choke is stuck on. What's the plug number? To keep other things as is I'd try a hotter plug for sure.
plug is R45TS. stock plug..lol..and no, its not a carbed engine. its obvious that the car is running very rich. im going to check the PROM and see if there was a tune or not.
Have you actually scanned the ECM ? I wonder if maybe the coolant sensor for the computer (not for the gauge) is reading correctly? A low temp reading could make for a rich mixture. The 45 plugs should be good for that motor.
i just replaced that coolant temp sensor for the ecm. the one under the throttle body when i did the tune up. i dont see any black soot in the tail pipes, and it doesnt smell rich. im going to scan the ecm and check the prom for any mods when i get a chance. and im changing the injectors back to the 22lb hr ones.
