Map Sensor?
 

Do microtech's have the map sensor in them, or is it separate? If it is separate, where is it? Also, if anyone has any pictures or diagrams of their install and all the vaccuum lines and wiring, that would be a huge help! thanks.

The 2 bar map sensor is internal, but there is an optional 3 bar sensor that is external if purchased. The wiring is very easy, if you can follow diagrams and solder, then you can do it. I'll get pics up of my install some time tonight.

ok great! i figured the map sensor was internal because of the vaccuum line into it....thanks

How much is the 3D map sensor extra if purchased at the same time as the unit itself?

The ECU has to be configured for the 3 bar which runs $55, and the sensor itself is $125.

The 3D is alot better, right? I've always heard that most EMS's run them.

Most ECU's have otions for 3 bar sensors, but I don't really see the point unless your vehicle has the abilty to surpass 20 PSI.

Well I plan to run a pretty large T04S, and to its peak. Might be up to 20psi or so.

i see some GM 3 bar map sensor around $60

My LT8 with internal sensor reads 5hg of vacuum even when the car is turned off. It reads 20hg when the car is idling, it's a 13b turbo with large streetport so that number is WAY off. I'm in the proccess of sorting out what to do with the thing.

Where do you have your vac source for the ECU?

It has a devoted source on the upper intake manifold, past the throttle plates by a great deal.

do you mean 3 bar? The Microtech is in 3D with the 2 bar or 3 bar, the 3 bar just lets you run over 20 PSI.

Well, Calgary is 3556 ft above sea level, so I'm guessing that will mess with your vac reading pretty good.

Yes, I meant 3 bar. Not sure about everyone else, but thats what I meant. My mistake.

The vacuum line, running from the ECU to the Engine Bay, should have an uninterrupted source at the bottom (of the 3 nipples), front Upper Intake Manifold.

That was my assumption as well. However I have friends with Wolf and Haltech who do not have this issue. Their units seem to calibrate themselves.

It's not the end of the world I will just have to tune it knowing it's a bit off, kind of annoying.

Can the source come from the back of the UIM by the firewall?

That source will work fine, but the front-bottom is the best. That source comes right from the back of the throttle plates, and will result in the best response, as well as minimise erratic readings from intake manifold pressure waves.

Brandon
BR7 Racing

Hey Brandon, If my suggested source Is "better", than why wouldn't Jimmyv13's be more superior? Considering you would avoid a nasty 180 degree of the vacuum line which may result In a kink?

Okay, whats the difference b'n the front and rear of the TB nipple?

The reason I like the front-bottom is that the black TB spacer directs the airflow to a little hole that's just behind the primary throttle plate on the engine side. This means that its readings are the best-damped, since they have the benefit of using the entire surge plenum to dissipate spikes. Jimmy's will work just fine; its reading is taken from the side of the plenum. It's really just a matter of preference. The only thing that I will discourage is readings taken from sources within the runners, e.g. the nipple right above the ACV. These readings tend to be quite erratic.

Brandon
BR7 Racing

Something I found helpful was placing a little "pill" thingy in the line. The thing I am talking about is found the in the vacuume line that goes from the side of the manifolds to the Atmosphere Pressure sensor. The little black box on the PS strut tower. I cut it out and placed it inline with the map sensor. It seemed to really help the erractic readings esp since my car is N/A.

The MT must show density altitude instead of above ground level altitude. Density altitude is calibrated to sea level, and will be correct for measuring the actual amount of air going in your engine.

Try this cheaper alternative if you're handy with a soldering iron and drill.

That is 0 volts at closed throttle and 5 volts at full throttle. It varies linearly in between those points. So all you need is a pressure sensor that reads 0 volts at the lowest pressure you'll see and 5 volts at a pressure a little above your maximum boost pressure. It needs to vary linearly in between those two points. The sensor must be able to survive in the harsh environment of an engine bay [high temperatures and dirty air]. Finding a sensor with all of these qualities is not easy, especially for a novice like me. After much searching, I did find the proper sensor. Its a Motorola MPX 4250 AP. It reads from 2.9 to 36.3 psia and gives a 0.2 to 4.9 volt output. It is actually designed to be used in turbocharged automotive MFI applications. You can get it from Newark Electronics for about $22. You'll need an enclosure to protect it. A little black box, 1551GBK, works nicely. You need several feet of high temperature 24 AWG wire. Three different colors is the best way to do it. That way, you know what wire is what. Tap-in connectors will also be needed. Radio Shack sells some with built in bullet connectors [for quick disconnects]. The part number is 64-3089. A crimp tool, zip ties, bullet connectors, soldering iron, solder, flux, drill, quick-cure plastic epoxy, and double sided foam tape will also be needed.



Building and installing


This is the easy part. Before anything else, get familiar with the sensor characteristics. Read through the specifications in this PDF file: MPX4250A.PDF. Be careful with the sensor. Don't touch the leads with your fingers. The sensor is labeled "static sensitive", so don't take chances. Now drill a 3/16" hole in the side of the box for the sensor port to stick out of. Drill the hole so that the sensor can sit against the bottom of the box. See picture below.






Solder a 1 foot length of wire to pins 2 and 3. Pin one is denoted by the notch in the lead. Solder a length of wire to pin 1 that is long enough to go from the sensor to your S-AFC wiring harness. Drill a 3/16" hole in the other side of the box for the wires to pass through. Drill a tiny hole in the top for an air vent. Thread the wires through the 3/16" wire hole in the box. Spread some plastic epoxy in the bottom of the box and lay the sensor in it. Make sure the vent hole in the sensor is up [you don't want to epoxy it shut]. Push the port of the sensor though the port hole as far as it will go. Use some more epoxy around the port hole. You need to hold the sensor in place while the epoxy cures. If you shopped wisely, it'll only take 5 minutes. Once the sensor is secured, you can screw the top on. You can use the foam tape to attach the sensor to something in the engine bay [preferably something cool]. Mine is on my cruise control box. Use the tap-in connectors to tap into the 5 volt power and ground for the stock MAP sensor. It is very important that you use these two connections from the stock wiring. The voltage is very stable here. Sensor output is related to its power source.

Her's the link http://www.2gnt.com/www/corbin/foolafc.html

My setup Is no different...when the car Is off and Ign Is ON, my LT8 reads 5 Hg too. Is this something to concern myself with - a side from my Inability to adjusting my Timing?