Cannons

iTrader: (2)

I am having a 93 Z28 Dyno'd tomorrow and Im wondering if It will be driveable with 36 lb injectors vs. the 24's that its programmed for? The dyno shop is 20-30 minutes from me and I can go slow on back roads if I have to. I just dont feel like getting my trailer and going all over town just to tow this thing.

96capricemgr

iTrader: (1)

I would swap the injectors at the shop, simple enough project.
You are talking going half again the programmed size that will massively overfuel likely to the point of detonation and definetely to the point of washing the oil off the bores and contaminating the oil not what you need just before wailing on it on the dyno.

infinitebird

iTrader: (11)

I agree I would not drive it at all like that. If you were just swapping to 28 lb or a relatively minor upgrade it wouldn't be horrible just for a short time but your motor is going to be seriously not running right with that much of a difference.

TAQuickness

iTrader: (28)

I drove mine untuned for ~35-40 miles to the tuner. You should be fine as long as you don't get a heavy foot

93BlackZ

a 93 is programmed for 22#'s, since thats what they are, unless you have had it tuned for 24's and now your tuning it again for 36's, just a lil FYI

96capricemgr

iTrader: (1)

Untuned for an exact combo is one thing this is VERY different from that, the info you are giving him WOULD result in engine damage. We are not talking stock timing curves on a cammed motor or something that will just make for poor performance. We are talking about the engine getting 150% of the fuel it needs and the pcm can adjust maybe 10%. 40% too much fuel would do damage.

RamAirRocket

iTrader: (1)

Honestly, going from smaller to larger injectors, no problem, it will just run rich in open loop. In closed loop it will be fine, but the fuel trims will be down around 80-90. Won't be a problem. Don't just let it idle to get into closed loop, as it will be dumping fuel no knowing and will wash the cyl walls down. Change the oil afterwards.

Think of it this way, your injector constant stock, is around 24-25. The PCM is calculating fuel for your engine expecting xx cc of fuel out per pulse. Now, you put in larger injectors, for each pulse they are putting out xx+y cc of fuel. That is roughly 50% more fuel. So at cold start you are running 12:1 AFR, you would be running like 7-8:1.

Wanna bandaid trick? Put a resistor in the CTS that is around 80C temp instead of what it is now out (assuming you live where I do and it is cool out). Then it will lean it out accordingly. As soon as it gets into closed loop, around 90-180 seconds later, remove the resistor and plug it back in to the sensor. Yes, it is impractical, I know. Just a way to fool it while in open loop.

Just drive it and get into closed loop ASAP.

Cannons

iTrader: (2)

Swapped out the injectors when we got there. Got 390 RWHP and 400 RWTQ only ran it up to 5600 rpm

96capricemgr

iTrader: (1)

The pcm can not compensate for 50% too large an injector, as others and myself already said going from 24 to 28 is one thing this was another. At least the guy with the question was smart enough to filter out the intelligent answers and follow them.

Cannons

iTrader: (2)

And I thank you, it was soo simple. even the tuners said it was the way to do it. They said If I drove it I might have made it difficult to tune.