Tuning Injectors without any or little data... methods? tips? tricks?

I have to tune a set on injectors (in my case jumping from 30lb to 42lb) and i have no solid data on them (yes, i have Gregs dvd and xls sheet and they are not mentioned) what is good method to start with?

reading this post http://www.hptuners.com/forum/showth...l=1#post234377

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Originally Posted by MNR-0

Yes, you are correct

High impedence injectors usually go down to 1.6ms. Low impedence around 0.9-1ms. Again, it depends on the quality of injector, but that is a rule of thumb I have observed over the many years

If you do not have any injector calibration data then you *always* start with your stock calibration (adjusted for flow rate of course) and tune from there to reach your desired results

For example,

I recently fitted 60lbs injectors to a factory stock car (exhaust and intake only) with an outcome of reducing the idle pulsewidth from 2.8ms (factory) to 1.6ms (60lbs). I would not think a factory car could handle anything bigger

I had no injector data short of the flow rate

With factory calibration, it would flatline at 1.8ms. Idle AFR was 11:1 and if left alone would foul the plugs and wash bores

I reduced the minimum IPW to 1, zeroed out the short pulse adder. That got me to 1.7ms - still too rich. I then re-scaled the offset table 20% lower at a time until I reached 1.6ms. At this AFR I now had bi-directional control around the stoich point (richen it up it would go richer and lean it off it would go leaner) and that was my goal. Now I had fuel control back, I tuned the VE map from there

The car now idles at 14.5AFR when warm and does everything it is supposed to when cold (starts nice) with a startup AFR of 11:1 (what I want) and leaning off from there

This was done with a wideband before the CAT

You can tune any injector (within reason) on an LSx without injector data

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left me with the questions: is it a good idea to keep min pw set to 1? left the short pulse adder on zero and just re scale the offset/volt table?

what are your methods or can you share any advice on this procedure ? i have access to install these set of injectors an a stock car (same 98 ls1) to set VE as close as factory just moving injector data but what should i move first?


thanks

You will need the correct specs on the 42 lb injectors to put in your tune. Are your injectors bosch 42lb/hr @3 bar green tops? One of gregs dvds has the injector info on it in excel format for that injector. If you cant get the correct specs for those injectors then get others with the correct specs.

Quote:

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Originally Posted by Force

You will need the correct specs on the 42 lb injectors to put in your tune. Are your injectors bosch 42lb/hr @3 bar green tops? One of gregs dvds has the injector info on it in excel format for that injector. If you cant get the correct specs for those injectors then get others with the correct specs.

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thats the purpose of this thread, theres got to be a way to calibrate injectors without having data, like frost post in a comment theres was injector tuning before greg published his dvd... green tops are on the xls but not the green giants for example. will not throw a set of injectors to the thrash , i want to set them the best as possible or at least give it a try.

Send them in to get them cleaned/flowed at the pressure you intend to use them at. Problem solved.

not a chance in my country marcin.

anyone with a hptuners way to do it?

Not really. the normal tuning process asserts that IFR is known and good, and attributes all fueling errors to VE (or MAF, whatever you're tuning). If your IFR is unknown, then you end up with one equation, and two unknowns, which by definition has infinite amount of answers.

i have the flow rate, but the rest of the data like min pw , short pulse adder and offset is only a guesstimate

You have a _nominal_ flow rate, at some rated flow. That's nice to have, but there's multiple problems:
1. you want effective flow rate, which is a result of:
2. fuel system imprecisions (manufacturing errors, wear'n'tear)
3. battery voltage
4. fuel pump flow (which in itself is HIGHLY nonlinear, especially at high flow it can display all the shortcomings of the fuel system)

Between these, I would barely agree calling it an approximation of effective flow.