IVT Terms

[GXPLS4]

Ive noticed this new addition to the software for IVT AFR weighing coefficient. Does anybody know the impact of these tables

[DSteck]

It's to help with scaling when cheating the stoich afr table. I've been begging for a while... And HPT delivered.

[GXPLS4]

It's to help with scaling when cheating the stoich afr table. I've been begging for a while... And HPT delivered.

I figured that have somethimg to do with it lol. Now gonna have to find a way to figure it out if needs messing with

[HartsG8GT]

It's to help with scaling when cheating the stoich afr table. I've been begging for a while... And HPT delivered.

Can you elaborate on this at all. I have cheated my stoic afr table, so what should I do with this table now? Any info on this would be greatly appreciated.

[CatnipG5Bandit]

Can you elaborate on this at all. I have cheated my stoic afr table, so what should I do with this table now? Any info on this would be greatly appreciated.

I'm also interested for the same reasons.

[DSteck]

Cut the IVT term in half when you double the stoich.

[realcanuk]

Cut the IVT term in half when you double the stoich.

Dave,
Can you elaborate a little bit ? What is this table doing exactly. For example.... If I have my car tuned to perfection (in my eyes. LOL), and I cut this IVT in half, what could improve and more importantly, are there other things I would have to retune?

Thanks.

[DSteck]

IVT affects open loop fueling and transients. When you scale with the stoich method, IVT becomes artificially high. Cutting this value back down fixes the IVT model.

IVT is a calculated value based on multiple things. The value added is the coefficient for the commanded AFR term. If commanded AFR is double what it actually is, then the coefficient should be half.

[realcanuk]

IVT affects open loop fueling and transients. When you scale with the stoich method, IVT becomes artificially high. Cutting this value back down fixes the IVT model.

IVT is a calculated value based on multiple things. The value added is the coefficient for the commanded AFR term. If commanded AFR is double what it actually is, then the coefficient should be half.

Thank you for the explanation.... Do you think if I change this, I will have to redo the maf and/or VE ?

[DSteck]

No.

[realcanuk]

Just to update.... I cut the IVT terms in half as Dave suggests. Nothing else changed in the tune. Although my car was running great before, it seems to be just a touch better mostly during the first few minutes of a cold start. Could be placebo effect but I am happy with it.

Thanks for the info Dave

[HartsG8GT]

Also made the changes and definitely notice a difference. Mainly when taking off from a complete stop, just feels smoother.

[ajayniceg8]

where is the Ivt tab in the software?

[realcanuk]

where is the Ivt tab in the software?

Engine... fuel.... general..... IVT terms

[kllrvet]

I found IVT terms, but there is two tabs under it. AFR term
Has to do with alcohol percentage. I am in the process of running e85, but I'm unsure how this tab helps with scaling larger injectors....the mention of cutting this table in half has never said anything about alcohol percentage

[schpenxel]

Just cut it in half if you've doubled the stoich AFR / cut IFR in half. It's not absolutely required, but does help with intake valve temp calculations which otherwise go overly high with the higher stoich / lower IFR combinations for whatever reason.

[sssnake]

Should the IVT terms be changed when scaling a tune manually (using a factor on all air and fuel values)? I have manually scaled all of the air and fuel values in my tune and things work pretty well with the exception of transient fueling (which I know is hard in and of itself). However, I noticed that all of the transient fueling table include IVT terms. My IVT averages about 115-125C (pretty stable as well) while cruising so am I in the right ballpark or should I be adjusting the IVT terms?

[GHuggins]

Should the IVT terms be changed when scaling a tune manually (using a factor on all air and fuel values)? I have manually scaled all of the air and fuel values in my tune and things work pretty well with the exception of transient fueling (which I know is hard in and of itself). However, I noticed that all of the transient fueling table include IVT terms. My IVT averages about 115-125C (pretty stable as well) while cruising so am I in the right ballpark or should I be adjusting the IVT terms?

Corrected my statement

[dankmac]

How is that calculated? Mine have been logged consistently in the 330 F range - 165 C.

Edit - did some searching and many people are reporting normal IVT to be in the ~300's F range.

[GHuggins]

Nope - having a senior brainfart moment Was thinking of injector tip temp... Will clear my last post