$EE / LT1 Injector Swap Running Rich

[Terminal_Crazy]

Do you mean the 'Injector Offset Adder' table (tunerpro)?

Yes.

The voltage offsets I have are slightly higher than the stock figures at around 13V but I don't think they affect much if the motor is running well (and electrics are stable). (same sort of curve).


If your injector constant is upto 46 on 36lb injectors they should be running _very_ lean.
I'm now down to 38.5 on the Injector Flow Rate on the 42lb to keep the VE table within range.

Running CL here even with a crappy VE table, the car would tune itself back happily enough.

I hope the new injectors will cure your issue.

Mitch

[spfautsch]

If your injector constant is upto 46 on 36lb injectors they should be running _very_ lean.

You would think. The MostPlus injectors came out and stockers back in. Model # MO2A36 - if anyone is considering them save yourself the headaches and buy something reputable.

I'm now down to 38.5 on the Injector Flow Rate on the 42lb to keep the VE table within range.

I need to do this myself as I'm out of headroom in the bottom left corner of VE. I might try scaling with the factory injectors to see what happens. I'd hope a complete remap of VE would not be necessary. This is the primary reason I chose to wait to install the bigger injectors - I know the constants for the factory Rochester / Multecs are right, and if nothing else has changed but the injectors logic dictates you should be able to get back to where you were by simply tweaking the IFC and offset vs voltage table.

[spfautsch]

Remanned 42lb injectors showed up yesterday. Lacking any flow bench data (what happened there FIC?) I punched in 43.0 for IFC and used an offsets table I found for the injector part #s (12561462 - LS1/LS3 injectors). Initial start was ok, but it was quite a bit rich so instead of increasing IFC I took 5% off my VE table except for the 10 cells that were maxed out at 99.6. Now it's flooding when started cold (I have to pedal it to clear the flood), and sputters some when restarting hot. A short drive shows my trims are pretty close with these changes (I've been targeting 3% rich).

Anyone have any ideas on how to prevent the cold start flooding? I haven't messed with any of the tables named "* prime pulse width vs coolant temp" since they didn't seem to have any impact on initial start pulsewidth previously.

[Terminal_Crazy]

As I've said I'm not using any offsets.
If they aren't right, the fuel curve will be off anyway and you'll be retuning anyway to correct it.

I've only bothered to lean out the Open Loop AFR table to lean out during startup & the Initial AFR Enrichments vs Coolant.
I don't expect the other tables will make any huge difference to the startup.

At idle you will be running around 2ms any small adjustment will be a relatively large jump percentage wise.
Log and adjust VE tables or just lower the corner of the VE table from just above idle (rpm & map) ( or drop the whole table 3% first ).

Mitch

[spfautsch]

I think you're confusing the offset vs voltage table with low pulsewidth adder. The tune you shared with me had a populated offset table. I've zeroed the low pulsewidth adder table which is what I think you're talking about.

It's idling fairly well, not exactly like it was last month when my "long way to work" road was horribly mutilated by the Missouri Department of Transportation (we rednecks refer to it as chip-n-dip). But it's also 100F ambient and 50% relative humidity here so I haven't run it in this type of weather much to have a "baseline". Driveability is good. The seat of pants dyno says mid-range power isn't great, but again the weather may be a variable. I won't be able to collect much data to verify for quite some time, but my worst trim cell after a 10 minute drive was 5% rich so I'm not thinking a big VE remap will be in order.

I'll experiment some and report back. I'm beginning to think there are some IPW calculations happening during cranking that don't reference the VE table or the injector flow constant.

[spfautsch]

Well color me stupid. No sooner than I clicked "post" it occurred to me there's a "Crank Volumetric Efficiency Vs. %TPS Vs. RPM" table that I hadn't adjusted to match the main VE tables.

I'll have to test more after she cools down but it sprang to life almost as quickly as it used to (feels like within the first 180 degrees of rotation).

[Terminal_Crazy]

I think you're confusing the offset vs voltage table with low pulsewidth adder. The tune you shared with me had a populated offset table. I've zeroed the low pulsewidth adder table which is what I think you're talking about.

It's idling fairly well, not exactly like it was last month when my "long way to work" road was horribly mutilated by the Missouri Department of Transportation (we rednecks refer to it as chip-n-dip). But it's also 100F ambient and 50% relative humidity here so I haven't run it in this type of weather much to have a "baseline". Driveability is good. The seat of pants dyno says mid-range power isn't great, but again the weather may be a variable. I won't be able to collect much data to verify for quite some time, but my worst trim cell after a 10 minute drive was 5% rich so I'm not thinking a big VE remap will be in order.

I'll experiment some and report back. I'm beginning to think there are some IPW calculations happening during cranking that don't reference the VE table or the injector flow constant.

I did say to get your data first!

Nope, no confusion there. I've got the Voltage offsets set, I have since zero'd out the low pulsewidth adder.
As I don't know that they are correct, close or way out, I've removed them from any interference in the data logging.

This motor will start at 7.5:1 or less and 22.4:1 or more without any issue.

If you do adjust your VE table i'd only adjust it fractionally from what you are calculating so it doesn't shift too far from where you are now.

Mitch

[spfautsch]

This motor will start at 7.5:1 or less and 22.4:1 or more without any issue.

You also have another 30 cubic inches of displacement, which is not insignificant.

If you do adjust your VE table i'd only adjust it fractionally from what you are calculating so it doesn't shift too far from where you are now.

I had the opportunity to do some more logging this afternoon and found the trims aren't very far from what they were with the factory injectors. I feel confident I'll be able to tweak the offsets and injector constant to "a happy place" without significant remapping of VE.

The Crank Volumetric Efficiency Vs. TPS Vs. RPM table looks to have the biggest influence on my starting flood problems. Extremely rich pulsewidths on a 24 lb injector are a completely different animal with a ~43.5 lb injector setup. In addition, this cam is right on the edge of ridiculous in my book - the idle cells are around -30% from the factory tune. So far I've tried three different scalings on this table, all with extremely noticeable and some very promising results.

I'll be happy to spend whatever time it takes to get this one just right because it's hard to describe how satisfying the sound is when the engine breathes to life within 500 milliseconds of crank start.