ECU or MAP sensor?? '98 Jeep 4.0 Turbo

[Mr4btTahoe]

Hey alls...

I'm having an issue. Just got back on tweaking the cheap after a break from it. It's been parked.

I was having an issue before that every time I changed the tune, I would have to unhook the battery and hook it back up otherwise, the map reading would go haywire.

Now it does it every time I cycle the key. I load up a tune... unhook the battery.. hook it up.. runs great.. drives great. Shut it off and next restart, the map reading will be WAY off which throws the tune for a loop as it thinks its under load. Unhook the battery.. hook it back up and it goes to 0 again KOEO... starts and does fine until the key is cycled off and back on which then that number jumps to mid 40s up to mid 80s instead of 0 where it should be.

WTH is going on?? You can see it jumps to a completely different part of the map. Unhook the battery and it goes back to normal... then after a key cycle, same issue.

Ive attached a couple log files.

[Mr4btTahoe]

Update... ok.. I was able to get it to let me start the jeep a few times before acting up... but this time when it acted up, it threw a code. P1296 (5v to map sensor).

I'm digging into this a bit but I'm thinking its freaking out because with KOEO, the map sensor is showing ~2.5v (2bar) instead of the ~5v(1bar) its supposed to see. Looking to see if there is anything I can do about that.

[FstdodgeKY]

cheapest and easiest fix would be be try new map sensor.

[Mr4btTahoe]

I think I'm onto something unless it's a fluke. I dropped the MAP Low Count quite a bit and the code went away. So far, no more issue. I've restarted it a dozen times.. drove into town and back. I guess the ecu expects to see 5v at KOEO from the map and it didn't like seeing 2.5v so it was going into some form of "limp" mode.

Right now, its doing great. We'll see if it lasts.

[spoolboy]

Did HPT ever add the altitude compensation table for you?

[Mr4btTahoe]

Did HPT ever add the altitude compensation table for you?

That's a big negative. Cant even get someone to email me back. I've e-mailed them a half dozen times or so. Pretty well have given up on them at the moment. I tried asking on here and got a "they'll get to it when they get to it" response and then the thread was deleted. That was a few months ago.

[spoolboy]

That table is defined in a 1997 4.0 file I have. You could try flashing that in.

[Omunoz]

i have mine, min count to 50 and thats been working fine so far