Qzilla, this message is for you (or anyone who's done this mod?):

I just installed the Commander and am quite pleased with most of the results. The pyro's working perfectly and the coolant temp works right, after the coolant actually warms up. Before that, it's all over the place but I haven't actually checked yet to ensure coolant is completely full. I know trapped air can make the sensor read funny.

Anyway, the problem I'm having is that I spliced what I'm fairly sure is the MAP sensor, it's definitely on the bottom of the three wires like the instructions say, but my cold readings this morning were "40 psi," and, by the time I made it to work, were down to "2-3psi." Boost reading was not affected at all by throttle input, only drive time, like the sensor I spliced into is reading changes based on engine temperature. Exept it's reading backwards. Did I find the oil temp sensor and accidentally splice that? It's behind the fuel filter housing near the top of the block just about underneath the 2nd-to-last injector. It's round and appears to be cut for a larger-diameter wrench/socket. (18 mm, maybe? - I didn't try removing it). So, maybe it's not the MAP sensor but the electrical socket looked identical to the one in the Commander instructions.

So, the question I've got is, I think I'd trust a boost bolt and boost tubing more than a MAP sensor, especially as it appears that the older 24-valve trucks don't always have the most reliable MAP sensors. Will the Commander accept input from a mechanical boost pressure setup? Does it need some type of mechanical to electrical signal converter? I believe I read a comment posted by someone vaguely hinting at the Commander being able to accept such an input. If so, where would I go about collecting the parts I need?

 

I would venture to say you are hooked to some sort of temperature sensor. I am not exactly sure what is right there near the MAP sensor as our test truck is a 2002.

I know that the correct MAP signal should read somewhere are ound .5v-.6v at idle. To show 40psi you would need to be over 4v and maybe even 5v.

Most temperature sensors start at a high voltage and then slowsly fall in voltage as the sensor warms up. So I think you are right there.

We need to find you the correct wire and I think all will be good.

We do have a mechanical to digital converter but, not in production yet. This is mainly meant for people wanting to make more boost than the factory MAP sensor will read.

Also I want to make sure that you went into >menu>setup>vehicle selection and then selected the proper vehicle. This may help with your coolant issue if you have not done that.

Also a tip with the wire taps is to make sure that you do not spin them after you conenct them. Sometimes if you spin them or move them around a bunch they loose some of their connection. So if the vehicle selection is not the culprit just make sure you have a solid connection at the temp sensor.

I will see if I can find a nice diagram for a 98-00 truck to help you get the right MAP wire.


Quad

 

Quad, thanks for your quick reply. I was under the hood again yesterday trying to figure out where the MAP sensor really is. The only other connector near the sensor I tapped is a two-wire connector leading from the top of the fuel filter canister and getting lost in the wiring harness after that. I'm beginning to wonder if someone took off the MAP sensor for "more smoke." To be honest, though, my truck only ever puts out a light gray haze at high throttle inputs, then clears right up. Maybe Dodge just mounted the MAP sensor in a totally different location in my '99? If I have time today, I might also try going to the steelrship and asking one of the techs where it's supposed to be located.

On the splices, I filled each splice with dielectric grease before clamping them to the wires and tried to clamp them tight around the wire. I don't think I moved it too much. I still didn't check my coolant level. I can just expect the Commander to tell me my coolant is ~196 degrees first thing in the morning and will start reading accurately once the temp needle in the dash starts to climb past 140. It'll go all the way back up to 190 + when I'm idling but once I start moving, it'll drop back to where it's supposed to be and by the time the truck has reached normal operating temperature, the reading has pretty much normalized and matches the temp gauge reading.

Oh, and I did go through the vehicle setup menu - twice. Just to be sure I'd selected 98.5-2002 Dodges.

And one other thing: the frickin' menu button has to be pressed to within an inch of its life to get any response. I know I bought my Commander used so I can't expect perfection but is there any remedy to this? The other three buttons work fine, no drama.

 

Holy crap, in one day I went from page one to page 3. I guess this is a "bump."