what would be the right injector for 89 5.7 liter iroc [Archive] - Team Camaro Tech

: what would be the right injector for 89 5.7 liter iroc

Apr 7th, 08, 06:05 PM
i was wondering if any one could tell me the right injector lb s,
for a 89 iroc 5.7 liter.
and is there a way to measure this ,

Apr 7th, 08, 07:32 PM
I believe it is 21lbs. Many run a 24lb injector since it's a common after market size. I think you need a special device to measure the output. A couple place will refurbish your originals as well. Check thirdgen.org


Apr 7th, 08, 08:29 PM
They are 22lbs.I just replaced mine in my 88 5.7.I used bosch design III.But if you get those you have to grind down the intake manifold where the fuel rail bolts to.Check out fuelinjectorconnection.com They had the best prices on injectors.

Apr 8th, 08, 05:21 AM
I used Accel's 24 lbs injector from Summit Racing for, at the time, $249/set and worked fine with OE ECM and was a direct replacement.

Apr 8th, 08, 09:23 AM
Are the Irocs mass air or speed density controlled? If Mass air you will need a meter thats calibrated to the injectors you have, if other than factory. Something to consider.

Apr 8th, 08, 01:47 PM
what meter ,mine is mass air .

Apr 8th, 08, 03:29 PM
what meter ,mine is mass air .

Mass air meter. I have never worked on an Iroc, but my Mustang is mass air and the mass air "meter" has to be calibrated to injector size, I don't think it's just a Ford thing either, it's how the info is sent to the computer.The mass air meter reads air volume and adjust fuel accordingly, if it thinks its compensating for 19# injectors but there are 24# injectors installed it will run poorly, make sense?

Apr 8th, 08, 07:05 PM
so i would i have to have the prom re-flashed with new higher # injectors ,
there is only one type of maf sensor for my stock car ,i dont think taking the screens out or even getting an airfoil would have any effect on controlling the amount of air
that is needed ,so ya re-flash the prom ,right?

Apr 8th, 08, 07:45 PM
You won't have any problem running the 24lb injectors with a stock TPI setup. It may not have the best tune, but with the small increase and that being the only change, it won't be noticeable. I would not mess with the screens or the airfoil - neither are worth much (if any) power - lots of debate on both. The screen removal also makes the MAF unusable as a core should it fail - they have about a $200 core:(

If you increase airflow (headers/TB) and the injector size, then a change to the code will be needed.

You will find that once you start changing airflow, injectors, programming; it will snowball with little things happening as a result of the previous change. OK if you want to max out performance, but not good if you just want to drive it.


Apr 8th, 08, 11:20 PM
It's the opposite for my Mustang at least, Mass air makes it's own adjustments after the changes made increasing flow and tune is not affected at all, thats why it's better than speed density for modifications. Speed density has a set calibration and big changes on the intake or exhaust side makes the tune go south. Where mass air doesn't care about anything other than how much air flows through it and adjusts fuel signal accordingly. The problem arises when it's adjusting fuel signal for larger injectors than it's calibrated for. I've seen 5 liters running 10's with a stock type Mass air system and a meter calibrated to bigger injectors, no computer changes.
The only thing holding back a Mass air system is the injectors it's calibrated for. Thats another thing, with mass air (at least on my Mustang) you change the mass air meter calibration, not the computer.
Now I can't imagine they are much different, mass air from Ford to Chevy, but maybe, I know for sure thats how the Ford with the EEC IV computers work, like the 5 liter Mustangs. :confused:

South Side Goons & Hitmen
Apr 9th, 08, 10:00 PM
There is a 1989 5.7L IROC-Z for sale not that far from me. The IROC has been for sale for a while. The car has had extensive intake manifold work done, cam headers and rund 30 lb injectors.


1) What type of modification's would this car have needed to run 30 lb injectors?
2) Any issues w/ 30 lb injectors?

Apr 13th, 08, 12:16 PM
the mass air sensor is only telling the computer how much air is coming into the engine...not how much fuel to funnel into the injectors...the combination of the afm, coolant temp sensor, o2 sensor and so on adjust the injector pulse...if you have 24 lb injectors in place of 21 lb injectors, the o2 sensor will compensate for the larger injector, and shorten the injector pulse...this is true only to an extent,though...the fuel map in the ecm will only go so far...when changing a cam, compression, and soforth, you can easily go past the ecm`s capability to compensate for the increase in fuel and timing reqirements...it would have to be a really snotty rig to require 30 lb inj`s ssgh...those inj`s would prolly support 500 or so hp, i believe...(i think even more, but dont really want to call out numbers cus i`d prolly be wrong...lol)thats a pretty tough number to get with a stock tpi setup imo...