stcctln

Hello.
I plan to turbocharged my DOHC sierra using the 5th injector like TT kits use.i have built the exhaust manifold, downpipe, inlet elbow and mounted the intercooler.

I plan to keep the stock ECU and use a microcotroller to control the 5th injector.

So the problem.What to do with the MAP sensor?

I`ve tried to use a microcontroller (Arduino) to filter the frequency.Now i`m getting 37 code (Map sensor voltage low).
I have also tried low pass filter (speaker type) and an one way valve inline with the sensor.No result.


I`m all out of Ideas.
Stand allone ECU are out of the question as they are very expensive in my country.

Tnx in advance.

Dan_RS500

If I remember right, TT used to get the frequency controllers made by an outside company and some where on here there is a thread with contact details for that company (I think it was basically a one-man operation), maybe a nice email to them/him might get you some info.

AiToR51

Did you've analyzed the signal to extract it properties and make a table?

I've a dohc turbo but im using a megasquirt... But.. I've a few friends who want to turbo it low cost. I'm going to use also an arduino with new map sensor.
I didnt tried yet with stock map to study how it works.
But arduinos like DUE have onboard analog outputs(not just PWM). You can build a signal generator and simulate stock map..send it to ecu and remove the stock car map

Then with the arduino you can make tables rpm vs map and adjust the 5th injector. Also you can connect low octane wires over some map value to make the std ecu retard ignition

JFB Tech

I bought the last frequency limiter off the original manufacturer through Turbo Technics. Stupidly, I potted it into it's case before noting the component values and PCB layout. Wish I had now. If I remember correctly there were only a few components on the board. I do have all the details for the DCU which controlled the 5th injector as I made my own when the original fried itself. I also changed the original additional MAP sensor which Turbo Technics used for the DCU from GM/Motorola to a standard 2 bar one as used on the Cossies (Weber Marelli) as the GM ones suffer from water ingress which stops them working. They use the same 5V supply and output an identical voltage relative to boost.

Originally, Turbo Technics used a couple of valves to make sure the stock MAP sensor didn't see boost. I think they went electronic as the mechanical system responded too slowly. I originally fitted a solenoid valve into the boost/vac line to the MAP sensor which was switched by a vacuum switch. It did work after a fashion but was too slow, it would drop into LOS if it boosted quickly. That's when I got in touch with Turbo Technics and got the frequency limiter.

Regarding the octane adjust to retard the ignition, Turbo Technics simply grounded all three wires in the adjust plug, including the idle speed raising one. After experimenting, I found that you could short out the octane adjust "on the fly" while the engine was running so I fitted a pressure switch to only switch the octane adjust when on boost. It made a hell of a difference to the performance off boost.

stcctln

The sensor is still on the car and send`s signal into the arduino,then the arduino output the signal into the ECU.The stock map is diferent from other brands.It`s output is in frequency and not in voltage.
The car still gives code 37 code in ignition on-engine on, but in ignition on-engine off its ok.getting 11 codes.

How do i know when the car goes in LOS?

for the 5th injector i will use tables,and use an output thru a relay to retard ignition on the fly.

Ill use an arduino to control as it is more simple to read the second map sensor and when it reaches 2.4 volts(for a2bar map)to control the 5 injector and ground the timing wires.


This is the code for arduino:
#include <FreqMeasure.h>
#include <Tone.h>
Tone tone1;
void setup() {
Serial.begin(57600);
FreqMeasure.begin();
tone1.begin(9);
pinMode(13 , OUTPUT);
}
double sum=0;
int count=0;
void loop() {
if (FreqMeasure.available()) {

sum = sum + FreqMeasure.read();
count = count + 1;
if (count > 1) {
float frequency = FreqMeasure.countToFrequency(sum / count);
Serial.println(frequency);
if (frequency <155) { tone1.play(frequency); }//frequency output off boost
else { tone1.play(154); }//frequency output on boost
sum = 0;
count = 0;
}
}
}
//it reads the frequency and if it`s below 155 output is 155 and if its more then 155 output it`s 155Hz

JFB Tech

You'll feel when it goes into LOS, poor throttle response and very down on power. If it drops into LOS when you're on boost then you will suffer from severe detonation, you'll be able to hear it from in the car. If the ECU detects a malfunction of a major sensor, e.g. MAP or TPS then it fixes the ignition timing and injector pulse time. This suits a warm engine and medium load but in pretty much every other condition it will run very rich. Fuel economy will become dire. Other sensor failure results in a substitution figure being used and no LOS.

I'm not sure what voltage the output from the stock MAP sensor is or what frequency range it generates. It might be that the Arduino is outputting too low a voltage on the frequency signal to the ECU.

It would be so much simpler if Ford had used the more common 0-5 V output MAP sensor. As I said, using a vacuum switch and valve to stop the boost signal getting to the stock MAP sensor is theoretically simple but getting a quick enough response would be the challenge. I did try changing the switching value of the vacuum switch but it didn't help.

stcctln

I will try with a 3way valve that i got from an old vw and use arduino to analyze the signal and switch the valve on and off using a mosfet transistor.I hope will be fast enough since the only moving part will be the valve itself.

By the way what boost should i look for? I was going on 5psi for the start until working right and then going up to 7psi.Is that ok i`m off.
Hope till friday i can mount the turbo again and test the valve.Still have to write the code for the injector and buy a 2bar map.

JFB Tech

The Turbo Technics spec is 0.42 bar/6.1 psi. I wouldn't want to go any higher than that really as the engine is 10.3:1 compression ratio and only has cast pistons. I always ran mine on super unleaded as a precaution.

AiToR51

the biggest problem I found with my dohc turbo were the conrods. I broke 3 engines with the same failure (1st cyl conrod),one was with c20xe forged pistons and 8:1 CR.
Pistons were right for me running around 11-11.5:1 of AFR on high boost and good ignition without knocking (up to 1,1 bar in high revs, limited to 0,7 below 4500 to avoid high torque, and ford MLS head gasket and a set of camshafts for na engines with more overlapping than std ones)

If you are with std head gasket don't go above 0,6bar.



But today you can get forged conrods and with c20xe forged cheap pistons you can make a good combo. I'm building an engine with this pieces.

http://www.maxspeedingrods.co.uk/hig...lts-x4pcs.html

mickycc83@outlook.com

I was told that a superchipped ecu would do the same thing as a frequency limiter as in hide the boost and stop the fuel cut does anyone know how true this is?

stcctln

Succes.
I`m not using the stock sensor any more.
I`ve got my hands on a 2bar map sensor And using the arduino to generate frequency based on the output of the sensor.Its workin.No LOS.]
I can post the code if someone is interested.

JFB Tech

Don't try and run a turbo with a Superchip, it advances the ignition too much and it dets like hell. I know, I tried it. Took the Superchip off and it was fine.

I like the sound of using an arduino to generate the frequency signal to simulate a standard MAP sensor.

mickycc83@outlook.com

Im new to all this
I've managed to find a dohc turbo technics kit minus the frequency limiter
Are there any other ways around it?and what is an arduino?

stcctln

Google it.It`s a cheap microcontroller.