Fabrik8

Yeah, if you blow up engines with turbos that small something is definitely wrong somewhere, and like everyone else I'm assuming it's a tuning problem.

And yes, stay away from the FMU and that "MAP management unit".. Those are both cheap Band-Aid solutions to tuning that can have very expensive results.

Joepiper151

yea on my last engines i was running a greddy emanage ultimate. I just got completely dicked by the mechanic. He talked about how good he was at tuning boosted motors, turns out he wasnt. i had a 9.1 compression lsvtec with a built head last 8 days with a greddy turbo kit pushing only 10psi. so i'm going into this next build very defensive. i dont want to waste my money like that again, it was a horrible feeling. i think i'm just going to save and get a hondata s300.

atmdc

so whats better? Getting an after market map sensor or getting a missing link?

I Love (.)(.)

after market map sensor imo, like a gm, depend how much boost you are running, mine had a fuel cut at like almost 11lbs, I just stayed with a stock map and tuned with crome, never had a single problem. but hondata is a great stand alone system. there is a wide variety of ems you can use, you just need to find the right tuner, shad, ccc, etc...

Fabrik8

An aftermarket MAP sensor. And you'll still need tuning. The pressure range of a MAP sensor is scaled over a range of 0-5V. So the low end of the range will be at 0, and the high end of the pressure range at 5V. If you get a MAP sensor with a higher pressure range, that higher pressure range is scaled over 0 to 5V also, so you can see why something like 2 psi from one MAP sensor isn't the same voltage output as 2 psi on a different model of MAP sensor. That's why you need to get tuned; the different pressure range needs to be changed in the ECU tuning.

Missing Links just clamp the pressure reading at a certain point. So the pressure can go up and up, and the ECU doesn't see it changing at all, and thinks that the pressure is still in a nice, acceptable range that it expects. No matter how far you go above that point the sensor output is the same. So if you're at 12 psi (for example) and the Missing Link has clamped at that point, the ECU is seeing 12 psi. Now you go to 20 psi, and the ECU still thinks you're at 12 psi. That's a horrible tuning solution.

atmdc

Oh god lol that is crap. thanks for clearing that up, was the only part of the turbo system i didnt understand

+rep

Fabrik8

Yeah, it's just a band-aid to use the stock MAP sensor instead of doing it the right way with proper parts and proper tuning. All you need to know is to stay away from MAP clamps like Missing Link.

I've actually oversimplified how it works by the way, but the rest of the details aren't important.


Edit: To correct myself, I think the Missing Link keeps the MAP sensor from seeing boost at all. I was thinking of a MAP clamp, which works differently (it clamps the sensor's output signal to a certain voltage) but ultimately serves pretty much the same purpose as far as band-aid solutions go. The Missing Link works on pressure, not the MAP sensor signal. All of those types of devices are meant to fool the ECU so it doesn't know what's going on with boost, but there are different ways to go about that.

thermal

yes.... basically, a "missing link" is a check valve(s) that relieves pressure in line of the map sensor. The check valve releases pressure away from the map sensor or releases the pressure before the map sensor reads the signal. Partial flow is directed towards the sensor. At vacuum state, the check valve is closed. At boost state, the check valve is open or partially open as it partially sends signal to the map sensor. It works the same way as this:
http://www.geocities.com/thermalfid16/check_valve.html

radiaki11

good old map sensor clamping , solderng in a zen diode to trick the ecu , ii had to do this in MY POS golf 1.8t i owned to get the car from hitting boost cut , i hate that engine design , mechanically and electrically . 1 and only VW ive ever owned and never will again .