Timing marks blurred + question on user outputs.

Quagmire · Post by **Quagmire** » Thu Sep 24, 2009 2:55 pm

Right, so my Defender (running a 3.5 Rover engine) is finally running on Megajolt! Everything appears to be running smoothly and it starts much better, runs more smoothly (it didnt feel rough before, so this was quite a surprise) and pulls better, first tank was 1.5mpg better on consumption too

However, on checking my trigger wheel- vr sensor alignment i found that it is running at about 6deg BTDC on EDIS alone, rather than 10deg. This is not a problem as i will adjust the position later but have compensated in MJ for now.

The thing that i wanted to ask about was this- my timing marks show up as a blurred line, rather than a single white stripe. Instead of seeing a nice 1.5mm line, i am getting a blurred stripe about 4-5mm thick- is this down to my timing light, or could i have a problem with EDIS somewhere? This makes timing things a bit of a guess which i don't like.

Next question is this.

I run the vehicle on LPG 99% of the time, only using petrol when I am out of gas. The LPG is a single point, closed loop system whereby the liquid fuel is vaporised and then fed into the carbs as a gas via mixer rings. A lambda sensor reads the EGO and controls a stepper motor to control the flow of gas and achieve the correct mixture. This is all fine, however at idle I can get some hunting as the system plays about with the mixture (RV8's apparently like a richer mixture at idle...)

The system has connections to take a reading from a throttle position sensor, the idea being that at idle the system goes "open loop" to prevent hunting. However, being a carbed system, running MAP sensing I have no TPS.

Could I use the Megajolt outputs in some way to fool the LPG control box into thinking that it is seeing a TPS in the closed/idle position? I was thinking i could take an output triggered at say <800rpm (750rpm is the Land-rover specified idle speed)...

Thanks

NITROPIXIE · Post by **NITROPIXIE** » Thu Sep 24, 2009 7:51 pm

The thing that i wanted to ask about was this- my timing marks show up as a blurred line, rather than a single white stripe. Instead of seeing a nice 1.5mm line, i am getting a blurred stripe about 4-5mm thick- is this down to my timing light, or could i have a problem with EDIS somewhere? This makes timing things a bit of a guess which i don't like.

Is your trigger wheel on a damper pulley?? It could be the rubber in this has deteriorated and is causing some vibration

I run the vehicle on LPG 99% of the time, only using petrol when I am out of gas. The LPG is a single point, closed loop system whereby the liquid fuel is vaporised and then fed into the carbs as a gas via mixer rings. A lambda sensor reads the EGO and controls a stepper motor to control the flow of gas and achieve the correct mixture. This is all fine, however at idle I can get some hunting as the system plays about with the mixture (RV8's apparently like a richer mixture at idle...)

The system has connections to take a reading from a throttle position sensor, the idea being that at idle the system goes "open loop" to prevent hunting. However, being a carbed system, running MAP sensing I have no TPS.

Could I use the Megajolt outputs in some way to fool the LPG control box into thinking that it is seeing a TPS in the closed/idle position? I was thinking i could take an output triggered at say <800rpm (750rpm is the Land-rover specified idle speed)...

I don't see why you can't use the map sensor output as an indication but without the instruction manual in front of me obviously i can't say for sure. The outputs of megajolt are digital, on or off, so could switch at a differing map pressure if programmed to do so.

Hope this gives you some ideas. If you can find an electronic manual somewhere ic an try to help you work it out.

Ryan

Quagmire · Post by **Quagmire** » Thu Sep 24, 2009 10:46 pm

Good point about the trigger wheel and the pulley damper- could be the reason for the bluriness i guess.

As for the question on tricking the LPG into thinking its seeing a closed TPS, i guess the first question would be seen from a TPS in this condition? Are they just some kind of variable resistor? Usually three wires though... i believe one is a reference voltage of some kind. Other than that i have no ideas about their operation whatsoever...

NITROPIXIE · Post by **NITROPIXIE** » Fri Sep 25, 2009 6:11 am

Correct a tps is just a potentiomoeter. It has 3 connections going to it which are usually a very steady 5v, 0v and output which can vary between 0 and 5v obviously.

Your Map sensor in megajolt works on a similar basis and has 3 connections, altough there are 5 pins on it only 3 are used with megajolt and its senses vacuum in the manifold.

I'm only guessing when i say this but you may be able to setup a threshold voltage on your lpg ecu, at which point it will go into idle mode.

If you can follow this, the megajolt units outputs only ground when they are activated or float (not connected to anything) and don't produce an output voltage. If you add a pull up resistor then you can add +v and 0v. When you program megajolt on the configuration page, select options, then on one of the outputs select the load option, then input a load value at idle. I'm not sure if you want normal or invert output mode. Then you should be able to control the idle on your lpg through megajolt.

If you need more help and a circuit diagram then i'm pretty sure i can help you out. But i do need to see your lpg instruction so i can get a better idea but i believe something is very possible here.

Quagmire · Post by **Quagmire** » Sat Oct 03, 2009 2:13 pm

Thanks Mr Pixie,

The TPS threshold is adjustable on the Lambda box, so does this mean that i can just set the MJ to output in a specific scenario and then adjust the box to suit?

So if i understand correctly, i connect the MJ to the lambda box TPS input, and the Tee off of that to +12V with a resistor inline? I'm afraid my last qualification in electronics was a GCSE over 10 years ago...

Thanks for the assistance

NITROPIXIE · Post by **NITROPIXIE** » Sat Oct 03, 2009 6:58 pm

Hey Quagmire

Did you manage to source the problem with your trigger wheel yet??

From your description it sounds like you have hit it on the nose. Below should be a diagram of how to wire it up. You should be fine using the 5v reference from the Megajolt as +v. Around a 1 KOhm resistor should be adequate and fairly easy to get hold of. I think most TPS's are around 2 KOhm so what ever you can find bewteen these should be ideal but isn't that important. So long as it isn't Mega Ohms

As to whether you want normal or inverted outputs, the normal load output is activated (grounded) when it goes above the set threshold. We want it to activate below a set load threshold so that it is grounded. Vacuum is around 102KPa at wide open throttle and around 35KPa at idle. We want it to activate say below 37KPa so we will need to invert the outputs in the software.

For information, the TPS sensor normally has 5v from an ecu as a reference and the output voltage increases as the throttle opens more on most cars.

You just need to set the Lambda Box to switch at anywhere between 0.1v and 4.9v, as Megajolt is now going to control the switching of the idle. To get the right point of switching for you will be a matter of trial and error but i suggest a value just above your normal idle value to start with.

Hope this helps

Ryan

Quagmire · Post by **Quagmire** » Fri Oct 30, 2009 8:59 pm

Sorry, just realised i hadnt posted back here with results- the open loop trigger is working, currently set to go open loop at <900rpm. It idles at 850rpm...

May try switching this to a MAP based reading as that would reflect a more true TPS situation, i.e. you can have your foot completely off the loud pedal but still be doing a fair few rpm, but on the other hand it works brilliantly the way it is so may just leave it.

Have been tweaking my map which was orginally based on Mr Two Sheds LPG map. I have altered it a few times now to better suit my engine (mine is only a 3.5- not a 3.9) and am now getting 16-17mpg on Autogas- previously i was getting 15.5 tops...

Car is much more responsive and i have been concentrating on the cruise area (i do a lot of motorway driving). The Defender now needs noticeably less throttle under acceleration and in cruise.

Am now moving onto the water temp sender calibration with a view to using MJ to switch my electric fan and get rid of the horrible Kenlowe controller that give me endless water leaks...

In the words of a certain fast food purveyor "I'm loving it.."

Now to get the rest of my family to MJ their V8's too

Thanks to Brent for such an awesome piece of kit! And to Nitropixie for his help thus far. Much appreciated.

Will post in the "powered by" section once i have some HT leads that won't be laughed at!

NITROPIXIE · Post by **NITROPIXIE** » Fri Oct 30, 2009 11:28 pm

diggity diggity diggity!!

its good to hear you are having fun with it at the moment and doing it successfully. Keep up the good work and let us know what changes you make and how successful they were.