waxen

The adjustment line of thought makes sense now that I think about it......It does seem that the valve is not capable of withstanding the full vacuum signal, it is after all there as an air adder to increase the idle not decrease it...........'tis clearer now after discussion:rolleyes: Thanks

Well it's been a long time since I've been playing with my Megasquirt setup. I have had the Bosch idle valve disconnected because I cannot get it to work properly, so after a few months or so of fiddling and resorting to Niges original settings I tried today to get it working on warmup............Success well for a short time, it all went pear shaped after I tried to adjust the air bleed screw on the valve to trim the idle down about 50 or so RPM. As the screw was adjusted the idle jumped up to 13-14 hundred RPM, the same result I had been getting all along. So... what I think I have discovered is that the valve is unable or not strong enough to stay closed against the engines vacuum demand. A few things that might be at play here, i suspect are: Faulty valve? A need to readjust the throttle body or something screwy going on at the electronics end. I have tried various pulse widths with the valve in my hand and watched the idle dc gauge in Megatune and it has remained stable. Does anyone have any ideas or similar experiences?

Hi Richard, I set up the active high input version of the switchable maps, Works well. The reason I chose it over the simpler one is that it offers a bit more circuit protection. IIRC the Magna injectors fit into the rover manifold.............regarding differences between the 3.5 and 3.9 I think they are pretty much the same, I thought they were different but it is the injector mount plates and fuel rail that are different. Try RS components or Jaycar for the Diodes

This might help Mega Index

Sounds like a Manifold leak, Your idle MAP should be somewhere between 30-40kpa. A kpa of 80 or so is like a wide open throttle. An easy way to test it is to disconnect the vacuum line to Megasquirt and see if it is running the same or similar.

I mounted the Coil packs behind the Plenum on the Firewall with the connectors facing down. The idea was to reduce the possibility of water getting in. This turned out to be a not so bright idea as the leads now dont have enough room to interlock with each other. Here a couple of early in progress shots, mines a Range Rover but the Discoverys have more room behing the engine for the Coil packs

Thanks, Nige & Fridge, When I get Megatune running on this computer I'll work out how to do a screen dump and post. The issue is not that big a deal as it works fine after about 10 -20 seconds. The whole PWM thing has been a bit of a nightmare because I built my own board, I followed the directions (or so I thought) in the MSextra manual for the flyback diode. 3 TIP 122's and 2 Diodes later it works. The pictures in the manual show the diode connected to S12 NOT S12C as it is written. that little issue had all sorts of ramifications. In the end the Flyback diode is now at the valve, works heaps better.

Bobtail84, I will be interested to hear if the change of transister makes the PWM valve behave any differently. Whether it is coincidence or not........I had to change my settings a fair bit to get the valve to behave the same way, and while I was playing discovered the flyback diode was faulty as well. This brings me to a new query, it doesn't seem to matter what PWM idle settings I dial in I can't seem to get it to hold the idle immediately after a cold start unless the throttle is coaxed initially. I was wondering if it was because the warm up enrichment isn't rich enough to begin with. Mind I have been using some of the settings found on this thread, which would appear to be suited to a colder climate from where I am. Cheers Wayne

Sounds like the Flyback Diode or Tip 122 is faulty, I had a similar problem and it was the Tip122

Richard I would think that the Megasquirt would have to be built with fueling in mind to get it to work properly. That being said I run my setup with dual fuel, the Megasquirt controls EDIS via dual mapping and an empty fuel table. I simply have the power feed to the injectors interrupted by a relay when on LPG. You would need to hook up a MAP sensor regardless and the O2 sensor is handy for tuning. Cheers Wayne

Yes you are absolutely right there. Om a bright note my box of goodies arrived from DIY yesterday............my first reaction was OMG what have I got myself into , now that everything is here. Question, the ms squirt n spark extra manual often suggests different circuits for the same modification i:e Fan control, what are the pro's and cons of these? As I understand it the mods I need are PWM driver, dual tables? and fan control. Does that sound about right?

Hi all, First post. First off compliments to you HFH on a first class thread, have read and reread it and I still haven't absorbed it all. After a couple of years procrastinating about Megasquirt, finally I bit the bullet and have bought it , the decision was helped along by my engines death and this thread. The project begins with a 3.9 Serpentine, EDIS8 system from the US and MS1, the idea is to go with the recommendations found here. So first question (I've searched with no success)is there a wiring schematic for grafting the Hotwire loom onto Megasquirt? Or am I better off adapting a Flapper loom? Bear in mind that this is going into a 1976 2 door. Second question, Has anybody got an idea of spark maps for LPG as this project is dual fueled? So far the project has been about procurement and modifying some engine ancillaries to fit on the serpentine motor. Then it will be fuel tank and lines from a Disco (gives me a great reason for a body lift, they are a swine to remove and refit) and when the goodies arrive set to a bit of electronic assembly. Any tips? Hopefully this is in the right area and I will update as progress is made. Cheers Wayne