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Does the computer need time to learn new injectors? If so, how long generally?
If you way oversized it, never. I have 22pph, I put in 30pph, it will never learn it. 22 to 24, it probably won't make a difference enough to take more than a drive. What are you replacing from what?
I have these set of 24s I installed a few years ago but got a long start problem. I reinstalled my stock ones and no problem. Well, now I think the opti went out, again. I looked over a few things and noticed the 22s all read 13 except for #3. I remember someone saying the computer needs to learn new injectors so I'm wondering how long, I think I ran the 24s for about a week or so and still had a long start. Just at that point where Im tired of messing with it. I have weatherstripping, suspension kit and other stuff to install and want to get it all taken care. I want to install the torqhead system but not available yet for the 93-92 Ybody yet, go figure. Died on me Saturday haven't had time to really check things out, starts occasionally. When it WAS running I connected to datalog it wouldn't start then after it sat for awhile it started. I DID have a code 43 that I grabbed before I tried data logging but has since disappeared. I don't see how a knock sensor could do this though.
I have these set of 24s I installed a few years ago but got a long start problem. I reinstalled my stock ones and no problem. Well, now I think the opti went out, again. I looked over a few things and noticed the 22s all read 13 except for #3. I remember someone saying the computer needs to learn new injectors so I'm wondering how long, I think I ran the 24s for about a week or so and still had a long start. Just at that point where Im tired of messing with it. I have weatherstripping, suspension kit and other stuff to install and want to get it all taken care. I want to install the torqhead system but not available yet for the 93-92 Ybody yet, go figure. Died on me Saturday haven't had time to really check things out, starts occasionally. When it WAS running I connected to datalog it wouldn't start then after it sat for awhile it started. I DID have a code 43 that I grabbed before I tried data logging but has since disappeared. I don't see how a knock sensor could do this though.
IF it hasn't learned by now, it probably never will so I'm going to guess it has adapted. Now if you have other issues, that is a different story. Have you checked fuel pressure? How are the wires? Do you get a blue flame? Any modifications? I think the KS can retard timing but enough to kill the motor? I don't think so.
If I could make it financially feasible for the amount of driving I do, I'd wait a bit and get a C6.
I think I would miss the flipup headlights. lol
I know I kinda rambled all that. Just to be clear though. I first installed 22lb injectors, they sent me the wrong ones and had a slow start condition. I was told I needed to 24s so I returned the 22s and they sent me the 24s. Still had a slow start condition. I reinstalled my factory 22s and have never had a slow start condition running them so I stuck with them. But I have a slight miss on that bank. #3 reads at 10ohm, the rest read at 13ohm. I did disconnect #3 harness and the idle really didn't change so I guess that probably not the miss issue.
I guess I'm just wondering if I gave the replacement injectors enough time to be learned by the computer. If thats the case then I will reinstall the 24s when I do the rest of the work.
I will be replacing the weatherstripping soon along with the suspension bushings, the radiator, thermostat, the AC compressor, maybe the opti(crossing fingers) and going with a tune. I think thats it anyways.
Between the Multecs and the Bosch, there may be no difference in the ultimate volume but maybe the way it delivers the fuel might be different, hence the longer start.
I look at it this way. I can give you $10 on different denominations. You still get $10 but how it fits into your wallet might be different.
I just installed 24lb Bosch III injectors in my 85. I also replaced the fuel pressure regulator diaphragm. The first few start ups seemed a bit sluggish. And the idle was a little off. Up and down. Now it's running beautifully with a very quick ignition and my gas mileage has gone up by at least 4-5 mpg average so far. The quicker response of the accelerator pedal is much better also. I don't know for sure, but I feel the computer may have re-adjusted or relearned itself as everything corrected itself to a perfect idle and response of fuel delivery.
I just installed 24lb Bosch III injectors in my 85. I also replaced the fuel pressure regulator diaphragm. The first few start ups seemed a bit sluggish. And the idle was a little off. Up and down. Now it's running beautifully with a very quick ignition and my gas mileage has gone up by at least 4-5 mpg average so far. The quicker response of the accelerator pedal is much better also. I don't know for sure, but I feel the computer may have re-adjusted or relearned itself as everything corrected itself to a perfect idle and response of fuel delivery.
How long was it before the 24s seem to start running correctly?
Between the Multecs and the Bosch, there may be no difference in the ultimate volume but maybe the way it delivers the fuel might be different, hence the longer start.
I look at it this way. I can give you $10 on different denominations. You still get $10 but how it fits into your wallet might be different.
Absolutely but I have a feeling that you are going to need some fine tuning to get rid of that problem. That or go back to 22pph multecs which is the thing the program is geared for.
How long was it before the 24s seem to start running correctly?
It only took about 2-3 starts to adjust to a smooth idle. I did nothing additional. It seemed as if the system adjusted it self. As far as your long starts, I have to ask how old and in what condition is your battery and charging system. The reason I ask is I had a hard start situation a few years ago. It would mildly crank for what seemed like 15-20 seconds before it would start. I replaced my battery with a stronger one and it then started with just one crank. Call me crazy...but it worked!
It only took about 2-3 starts to adjust to a smooth idle. I did nothing additional. It seemed as if the system adjusted it self. As far as your long starts, I have to ask how old and in what condition is your battery and charging system. The reason I ask is I had a hard start situation a few years ago. It would mildly crank for what seemed like 15-20 seconds before it would start. I replaced my battery with a stronger one and it then started with just one crank. Call me crazy...but it worked!
Good point I'd also check the starter Maybe bring it to the rebuild shop for an internal look see.
As you are probably aware, there is a table that controls the settings for the flow rate. This is a snapshot of the table from my stock '96. I don't have a copy of an earlier LT1 to look at, maybe one of the forum members does.
But as far as "learning" the flow rate, seeing as how it is set in the programming, that might be a longshot.
I looked and the 92/93's use 22 lb injectors, so 24's have exceeded what is programmed into the ECM.
As you are probably aware, there is a table that controls the settings for the flow rate. This is a snapshot of the table from my stock '96. I don't have a copy of an earlier LT1 to look at, maybe one of the forum members does.
But as far as "learning" the flow rate, seeing as how it is set in the programming, that might be a longshot.
Someone brought up an idea that while you have say 5 brands that flow at similar rates, that number is for peak flow and how they ramp up might be different Would that affect anything? IDK
I'm kind of confused with this. Does the flow characteristics matter? I don't honestly know Part of me thinks it might but the other part thinks that since the ignition sequence is so fast, it might not matter
Someone brought up an idea that while you have say 5 brands that flow at similar rates, that number is for peak flow and how they ramp up might be different Would that affect anything? IDK
I'm kind of confused with this. Does the flow characteristics matter? I don't honestly know Part of me thinks it might but the other part thinks that since the ignition sequence is so fast, it might not matter
IDK either. I looked at a stock table for a '96 LT4 and it says 27lbs/hr for that engine.
I looked on the web and found this: (still looking to clarify. this is good research for me as I accumulate the parts for the upcoming mods to the engine)
IDK either. I looked at a stock table for a '96 LT4 and it says 27lbs/hr for that engine.
I looked on the web and found this: (still looking to clarify. this is good research for me as I accumulate the parts for the upcoming mods to the engine)
so if this holds true, the from an above post:
is why they smoothed out, that is what the engine is programmed for, not that it adjusted itself.
I guess you're correct. My 85 was already programmed for 24 lb. injectors. The first few mildly rough starts must have just been just the system "feeling out" the newer Bosch III's spray pattern improvement over the 33 year old original injectors. I don't know what else to say. The car runs like new now.
I guess you're correct. My 85 was already programmed for 24 lb. injectors. The first few mildly rough starts must have just been just the system "feeling out" the newer Bosch III's spray pattern improvement over the 33 year old original injectors. I don't know what else to say. The car runs like new now.
But don't cold start situations come back to the open loop program? Are there adjustments done for open loop situations?
But don't cold start situations come back to the open loop program? Are there adjustments done for open loop situations?
My 9th injector, or cold start injector was removed, cleaned and new O-rings were installed. I never had any cold start issues with the old injectors and I noticed no problems with the cold start injector upon first start with the Bosch III's. It fired right up. It just had a few slight rpm spikes and almost stalled at idle from a rev on the pedal. It then all just leveled out normally with no attention from me.
