Ok so my ECU is still pulling timing and I know I don't have knock but maybe I do.
I have 2 options now.
Strap the knock sensor to the chassis and hope it doesn't pick up even more vibrations. OR
Knock is related due to MAP overload.
Is the second option even possible?? I don't know how many people are running 16-17 psi and I don't know who is using a check valve or whatnot.
So I am gonna try using a check valve to back out some pressure of the MAP sensor.

Well before I had a chance to do this, I get this info saying well how bout you put a 1 BAR, in reality 2 Bar if you include vacuum, Cobalt SS MAP sensor and see what the ECU does, and I did.
Well this is what happened and I am still riding with it.

S-AFC if anyone realized and I know people have reads about -590-600mmHg, on idle, after you do the resistor deal to get rid of the CEL it drops to -490-520mmHg.

Well when I put the 2 Bar MAP I acctually was reading -630 with the resistor, the car idled for a little and stalled. If you try to rev it up it breaks up really bad before it picks up higher than 4000 rpm.
I changed it on the AFC from 760mmHg to 1Kg/Cm2, and started playing with pressure sensors in and out, and got the pressure to stay at about -460 on idle and it doesn't break up any more.

On thing it DOES do is under hard deceleration the RPM's get looooooooow, and sometimes stall so I was messing with Dec-Air as well, and I might have gotten it to stay a little even tho that is a option for hot-wire set up and not pressure.

The car seems to run sooooo damn rich on just regular driving, it is crazy.
Now, the way 1 Bar MAP works is sends the most fuel at 5V, right??? and also 0 psi.
2 Bar should give me less and a little in boost, no??
I am gonna try it tomorrow and see what is going on.

It is picking up positive psi because when I go in boost the pressure goes positive 1.25 maxes out there, whereas my vacuum MAP would only go up to 0.25 and stop.

Any input apreciated.




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"Growing old is mandatory. Growing up? Definitely optional."

i dont think the cobalt map is 2 bar , i think its more i know they will read close to 20 psi on the stock boost gauge , and the gauge is feed info from the pcm , which gets its reading from the T-map


in order for the t-map to work correctly you need the reflash for the s/c to go with it , with out the reflash the t-map is useless


no one with a eco i know of is running a check valve , because the map is directly in the intake manifold


as far as i know hahn hasnt had any problems with high boost and the map either


http://www.j-body.org/forums/read.php?f=40&i=105994&t=105994 , this is the post justin made with some parts needed , and how to have it hooked into the stock wiring , and as i said you gotta have the reflash for it to work

oh and the t-map reads the iat temp , and is part of the reason for a issue with the stock eco plastic intake


the saab intake can be made to work with the t-map

I dont think the plastic mani is a big problem. It can be done



"Growing old is mandatory. Growing up? Definitely optional."

I do not see this map working without a computer set-up to read it. Just because it is a 2bar map does not make it work like a 2 bar. The ECU is not going to know what to do with the extra readings it is getting. Now are you running the map right into the AFC, or the ECU? Also I know of a Ecotec 2002 that had to have check valves to run correctly. I do not know most others have not.



FU Tuning

I dont know if it would help, but i read an article in super chevy where they turboed an 04 cav with the hahn kit. They put a 100 ohm resistor in place of the knock sensor, because the car had solid motor mounts + the turbo the knock sensor was going off when it wasnt supose too... you could try that if you wanted too... 30 cent fix

basicly this is what you did SunCavi....

The 2 bar map takes 1 bar readings, and cuts the voltage in half......... BUT the computer is still reading it as a 1 bar.

Stock MAP reads 20-102 kPa (2.9-14.79psi)
2 bar MAP reads 40-333 kPa (5.8-48.29psi)

kPa/PSI-------------1bar--------------2bar
20/2.9------------.193-.419v------.195-.405v
40/5.8-----------1.321-1.451v-----.740-.860v
94/13.6----------4.238-4.368v----------?
102/14.8---------4.816-4.977v----------?
160/23.2-------------OL------------3.74-3.86v
200/29---------------OL------------4.72-4.88v

(these readings have atmospheric pressure added)

You understand what I'm getting at right? The stock sensor reads from vac - atmospheric pressure...... and breaks it down in a 5v scale. The 2 bar reads from vac - twice atmospheric pressure...... and breaks it down in a 5v scale. 14.7 psi on a 2 bar is half the voltage of 14.7 on a 1 bar........ understand? Your computer still is looking for 1 bar readings, so all your really doing is confusing the computer, it thinks your getting half the air it really is.

NOW IF you go into the computer, and change that scale (or do the Eco S/C reflash) your computer will be able to understand that the sensor is reading 2 bar.

Also..... as far as I've been able to tell, running higher boost then what the sensor reads shouldnt hurt things, unless you put enough pressure into it to physicaly damage it.

A normal MAP sensor has a MAX of 300kPa (43.5 psi - atmosphere)

A 2 bar (2.4 Gm S/C) MAP has a MAX of 700kPa (101.5 - atmosphere)

Some how I dont see you pushing enough boost to damage the MAP sensor.

schools out




SPD RCR Z - '02 Z24 420whp
SLO GOAT - '04 GTO 305whp
W41 BOI - '78 Buick Opel Isuzu W41 Swap

Surprised I missed this.

SpeedracerZ's got some of it. The 1 BAR sensor is good for reading 100 - 110 kPa (0 - 1 psi boost) only. The 2 BAR sensor is good to 200-210 kPa (about 15 psi boost) only. There is a 3 BAR sensor which is good to about 300 kPa but we won't even get into that one. As mentioned the 2 BAR sensor represents a different pressure at the same voltage as the 1 BAR sensor. There's some serious problems with just bolting on the 2 BAR sensor.

Look at the voltages above. The scale isn't the same between the sensors. See how the voltage for the 2 BAR and the 1 BAR are about the same at 20 kPa? Then it starts to change as pressure gets higher? It's definitely not a 50 / 50 split. The difference between readings gets greater as the pressure gets higher. This means the error gets worse as boost rises.

What happens is that the pcm sees a voltage and looks up a spark and fuel value based on only that voltage. It doesn't know or care what the pressure is... it _only_ knows the voltage. So think about this. When you start making boost, ideally you want more fuel and less spark. You want the ecm to add fuel above what it's doing at 100kPa, atmospheric pressure. And you want it to drop spark advance, even less than what it's delivering at 100 kPa. So let's say you've got the 2 BAR sensor on and you're at 7 psi boost. The voltage from the MAP sensor is around 3.8V. The pcm looks at that 3.8V and looks up spark and fuel... but it gets the spark and fuel values for the 60 kPa entries... that's about 8-10" vacuum. And what happens with less than full throttle? The pcm increases spark advance and decreases fuel. This is just the opposite of what you want to happen!! It's even worse if the pcm thinks you're not at wide open throttle because it tries to stay in closed loop. You can play around and try to cover the fuel, but you've still got too much spark advance.


The best way to stop this is don't run the 2 BAR MAP on a 1 BAR pcm if you can't change the PCM calibration.

As far as the knock goes, you can try a few things. If you're fairly sure you're not getting knock, remove the sensor from the block. and wrap the threads in teflon tape. You can also install the sensor in brass or even plastic fittings to dampen the noises it's hearing. You'll need to attach a ground wire to the sensor if you use plastic fittings or the pcm will flag a bad sensor right away. Problem with doing anything to dampen the knock signal is part of the test for a bad knock sensor is to run timing up to till the pcm hears knock. If it doesn't hear knock, you get a KS code and default timing. Maybe that's not a bad idea... you don't need as much spark advance anyway when boosted.

How about an MSD or other device that retards timing based on boost? Even one of the nitrous controllers that retards timing a fixed amount... put it on a switch that closes when intake pressure gets above a couple of psi? I dunno what works best for ya. But if you do remove the sensor, check for dark fly turd looking spots (detonation) on the plugs enough to decide whether or not you were seeing false knock.

-->Slow

sorry to thread jack, but using that principle is the same as tuning your own PCM for boost with a tuner..... is it not?


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Quote:

as far as i know hahn hasnt had any problems with high boost and the map either

the hahn portfueler has its own 3 bar map sensor