Transient Fuel & LS9 Injector Data

[Aaron407]

I've been struggling with transient fuel in my car, a G8 GT with TVS 1900 supercharger, LS9 injectors, long tubes, and intake. I have lean tip-in and rich tip-out, especially when the engine isn't up to temperature.

The MAF table is tuned well. I thought that it was an issue with VE, so I VE tuned it under 3000 RPM, but it made absolutely no difference for the lean tip-in and rich tip-out conditions. I have modified the transient fuel tables, but they have acted somewhat unpredictably.

Then I read that about half of all transient fuel issues are related to the injector data. Comparing my injector data with that of a CTS-V with the same injectors, I have noticed that there is a difference in the injection timing boundary table, Normal RPM injection timing table, and makeup pulse minimum table. Can anyone confirm whether or not I should be incorporating these? I believe that the injection boundary and normal RPM timing tables are related more to the cam and wouldn't need to be changed, but I'm not sure about the makeup pulse min table.

Anyone?

[supergt99]

some people on this forum were having this problem not that long ago. they got the best results by increasing the manifold volume setting. its under the transients tab. if you dont see it there you may need to contact hp tuners so they can add it.

[Aaron407]

Thanks for the suggestion, and I indeed don't have access to this table. I'll email support, and hopefully they'll provide some info on how to adjust it.

[GHuggins]

Use the zl1 manifold volume and transient tables. This should fix the large majority of your problems.

[Aaron407]

Thanks. I've put in a request for table/cell access, and I'll give the ZL1 transients a try after they (hopefully) get back to me.

[Jabbott]

Have you changed anything in the wall wetting settings. I think the Maggie fuel injection hole is dead center of the intake. The LS9/LSA injector has a 20 degree offset in the spray pattern so if you put the injector in the middle it sprays against intake port wall.

[Aaron407]

Have you changed anything in the wall wetting settings. I think the Maggie fuel injection hole is dead center of the intake. The LS9/LSA injector has a 20 degree offset in the spray pattern so if you put the injector in the middle it sprays against intake port wall.

Please correct me if I'm wrong, but isn't that effectively what the impact factor is? i.e. what impacts the walls and back of the valve and doesn't make it into the cylinder. As of today, I have actually made significant strides in adjusting it to fix many of my transient issues with an excel worksheet I built to analyze each MAP setpoint relative to each other point for a given IVT, and relative effects when changing each point. I found that looking at each lean tip-in and seeing the previous and final MAP values that caused the lean condition gives a good indication of the relative areas that need to be changed. I'll still be trying out the ZL1 settings once I have the intake manifold volume setting available, but things are indeed starting to shape up regardless.

I'm still wide open to thoughts and comments, though.

[Jabbott]

Yes it is, which effects tip in throttle and really all throttle including transient.

[Jabbott]

I don't think it is a good injector to use period because of this. Same with using the ford 47's with split spray. You would be better off using a set of deka 60's. You will have some wall wetting (impact factor) but it will be minimal.

[Aaron407]

I don't think it is a good injector to use period because of this. Same with using the ford 47's with split spray. You would be better off using a set of deka 60's. You will have some wall wetting (impact factor) but it will be minimal.

Thanks for the feedback. I'm basically at the limit of my LS9 injectors, and will eventually be replacing them when a cam and better fuel system come into play. That could be awhile, though, so I'm hoping to dial this in as well as I can for the time being.

[Jabbott]

I understand but you end up spending a ton of time working on something that will never really be right. We all do it and end up working allot of hours before just putting the right part in. Save yourself the time and get the Deka's. The ones you would be using would actually be 76's so they would have some room for you.

[Aaron407]

I understand but you end up spending a ton of time working on something that will never really be right. We all do it and end up working allot of hours before just putting the right part in. Save yourself the time and get the Deka's. The ones you would be using would actually be 76's so they would have some room for you.

Oh I hear ya. If I had worked at my day job for the hours I've spent tuning for transients, I could have bought many sets of new injectors. At this point it's more of an "I will not be defeated" approach. I'm too stubborn