JTEC 5.2 Turbo 2 bar MAP questions

[Ralphie361]

Good evening, new to HP tuners, but the jtec support inspired my latest project, an ?84 Dodge Diplomat with a 5.2 magnum and a gt45 turbo. Starting the tune and it seems like there isn?t a way to get rid of the map sensor reading baro on startup. Also I?m not sure what units the scaling on the map sensor data is in, so I?m not sure what (if anything) to change when using a gm 2 bar. It seems that there is no way to change the map reading scale in the tables, so I was thinking that 105kpa = 200kpa(actual) in the tune and ?trick? the pcm that way? If there is an easier way or a way to add cells for boost I haven?t found it yet. Any help would be awesome, I want to hear this thing rip! 🤘🤘🤘

[jmardlin]

I just scaled the injector pulse width to accommodate having a 2 bar map instead of a 1 bar. My 2001 Cherokee with a 2 bar sensor and a turbo works quite well.
Essentially you double the values for pulse width then multiply by the percent change to adjust for different injectors. I know there is a different way to accommodate different injector sizes but I did it like I did because you can add or subtract fuel in specific areas as needed.

[spoolboy]

You need to make the altitude correction table all 1s or when you go into boost it may update atmospheric conditions and adjust fueling. Not something you want to happen. You will lose atmospheric compensation, so keep an eye on the wideband.

If you want some help, send me a PM and I'll try to help. There isn't much info for the JTECs when using HPT. Also, post your stock tune file here.

[jmardlin]

You need to make the altitude correction table all 1s or when you go into boost it may update atmospheric conditions and adjust fueling. Not something you want to happen. You will lose atmospheric compensation, so keep an eye on the wideband.

I don't see altitude correction tables on a JTEC+. Does the earlier JTEC ecm have them? I haven't looked that close at a JTEC tune file.

[xlr8n]

I don't see altitude correction tables on a JTEC+. Does the earlier JTEC ecm have them? I haven't looked that close at a JTEC tune file.

Yes, the earlier JTEC has "34042 - Altitude Fuel Compensation". As Spoolboy mentioned, folks using the earlier JTEC with boost are setting that table to all 1.0.

Not sure about the JTEC+, sorry.

[Ralphie361]

Thanks guys, I actually have it running and driving around now, and I did set the altitude correction to 1. Waiting for spring to fine tune it, but it?s definitely fun 👍

[spoolboy]

I don't see altitude correction tables on a JTEC+. Does the earlier JTEC ecm have them? I haven't looked that close at a JTEC tune file.

Post your JTEC+ file. All PCMs have some way of adjusting for altitude compensation, but some aren't mapped by HPT. And some don't cause this problem, depending on how they work.

[Tobbe1]

read this from an old 2bar map tune 42lbs injektors . mabey it can get you in the right direction.

dakota rt blower race 2bar sensor.hpt

[Xjturbo]

i have mine running really good as well. But it will throw a cel for tps doesnt agree with map sensor. have you had this issue?

[jmardlin]

Post your JTEC+ file. All PCMs have some way of adjusting for altitude compensation, but some aren't mapped by HPT. And some don't cause this problem, depending on how they work.

There is I found it in the power enrichment sub tab in the fuel tab.