24lb high impedance injector question
#1
Junior Member
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24lb high impedance injector question
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
#2
Supreme Member
Re: 24lb high impedance injector question
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.
#3
Supreme Member
Re: 24lb high impedance injector question
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.
#5
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Thread Starter
Re: 24lb high impedance injector question
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
#6
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Thread Starter
Re: 24lb high impedance injector question
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.
#7
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Re: 24lb high impedance injector question
The 22's are the way to go. Yes tuned performance the 85 C4 used 24lb injectors. Multecs are crap. Very prone to coil failure
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#8
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#10
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Re: 24lb high impedance injector question
#11
Re: 24lb high impedance injector question
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.
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; 10-22-2022 at 08:09 AM.
#13
Junior Member
Thread Starter
Re: 24lb high impedance injector question
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.
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.
#14
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Join Date: May 2015
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Car: 1991 Z28
Engine: 305 TPI
Transmission: 700R4
Axle/Gears: 3:42 Auburn
Re: 24lb high impedance injector question
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.
#15
Re: 24lb high impedance injector question
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).
#16
Junior Member
Thread Starter
Re: 24lb high impedance injector question
thanks guys. yeah im going with the delphis. have to check the PROM first to see if stock. heres a pic of the recent plugs
#17
Junior Member
Thread Starter
Re: 24lb high impedance injector question
what do you think of the condition of thses plugs? these are with the 24lb hr injectors, as how i bought the car.
#18
Supreme Member
Re: 24lb high impedance injector question
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.
#19
Junior Member
Thread Starter
Re: 24lb high impedance injector question
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.
#20
Supreme Member
Re: 24lb high impedance injector question
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.
#21
Junior Member
Thread Starter
Re: 24lb high impedance injector question
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.
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