505 ZDJL - is megasquirt worth it?

odddit

odddit

Member
Fellow Frogger
Tadpole
Joined
May 11, 2019
Messages
153
Location
Brisbane
I've taken most of the intake and exhaust apart on my 505 wagon due to persistent idle issues and to replace the timing belt, found a huge intake leak that's the likely culprit, wondering whether to rebuild it as is, or switch to megasquirt fuel injection and get rid of some of the vacuum piping all over the place. does anyone have experience with aftermarket ecu's on these engines? is it worth it? engine is at ~350,000 k'd so don't really want to put too much money into it, but I do so enjoy driving it, and maybe the extra reliability is worth it?
 
I fitted megasquirt 1 fuel only ECU to a couple of these engines and they went really well. One of them actually revved to over 7000!
 
It depends on what you're after. I had been looking at Megasquirt on and off for a few years and, when the AFM started acting up on my car, rather than replace it, I went the MS route -- specifically Megsquirt 2.

It was quite a lot of work, but a great way to get more up to date on EFI. My 505 GTI with 310k km on the clock now performs better than it ever did in the 28 years I've owned it and, since fitting a taller diff (3.7:1 rather than 4.11:1) now gets around 7.5L/100km (37mpg) every fill compared with the 10L/100km I got on a good day with the standard EFI. MS was getting around 8L/100km with the standard diff.

Along the way I've made plenty of mistakes. Recommend you decide your end point up front. Don't try to start with fuel only, then bring in ignition (or, even worse, go the other way). Fuel only is a good deal easier but leaves you with the vagaries of the standard mechanical dizzy. If you do ignition, don't try to use a standard distributor trigger. You could fit a small toothed wheel inside the dizzy or go with the chunky one on the front pulley as I did. Or you could go deluxe and have a toothed arrangement on the flywheel.

I'd also recommend you include a wideband oxygen sensor since this helps with tuning and allows for feedback to keep the mixture optimal when cruising.

Finally, I have posted other articles here about Megasquirting my 505 and 604 which give a few more details and, if you go ahead with it I'll be happy to answer questions, offer advice, etc. But maybe you'd like the adventure of working it all out for yourself. I enjoyed it.

Have fun,

Rob.
 
Cheers rob, and thanks for the advice. I think i'll go through with a proper megasquirt 2 build, probably with a toothed wheel inside the dizzy. My old O2 sensor was buggered anyway, so i'll definitely go for a wideband. Did you use the standard throttlebody? I was thinking to maybe swap to something with electronic idle control, and a better throttle position sensor. Also, coil on plug ignition? standard 505 MAF sensor, or MAP sensor conversion? I guess I've got some research to do, and some parts to buy
 
I've found MS3 to be a lot better than MS2. Would either go MS1, trigger off the coil, or MS3.
 
Graham, what were your problems with MS2? I'm on a bit of a budget so tossing up between MS2 & MS3, would you say the extra $100 is worth it?
 
odddit said:
Cheers rob, and thanks for the advice. I think i'll go through with a proper megasquirt 2 build, probably with a toothed wheel inside the dizzy. My old O2 sensor was buggered anyway, so i'll definitely go for a wideband. Did you use the standard throttlebody? I was thinking to maybe swap to something with electronic idle control, and a better throttle position sensor. Also, coil on plug ignition? standard 505 MAF sensor, or MAP sensor conversion? I guess I've got some research to do, and some parts to buy
Click to expand...

Yeah, wheel inside dizzy is good for stealth. Good idea to include a PWM idle air valve (I'm fitting one to the 604 which has a pretty lumpy idle when cold, but the 505 muddles on with the Bosch stuff).

I'm running the standard throttle body with a Hyundai TPS which was easy to adapt. The standard throttle switch isn't up to the job. MS2 can do coil on plug and sequential injection. I didn't try and I think Graham's advice to go MS3 is good if you want to get fancy. MS2 and MS3 share a lot of code, but the MS3 processor is twice as fast and, more importantly, has an interrupt handling coprocessor on board which looks after a lot of time-critical stuff which is some of the messiest code in MS2.

MS2 doesn't support drive by wire -- but I have a feeling neither does MS3. The hardware could easily do it, but I think they're worried that someone might sue them after rear-ending someone (or whatever).

MS2 includes a 2.5 Bar MAP sensor; MAF is treated as a poor cousin by the firmware. Not sure MS2 or MS3 would support the Bosch AFM. Before you decide to keep the AFM, look at its outlet. Not much point in a new throttle body if you keep that!

Have fun,

Rob.
 
If it's only $100 extra for MS3, I'd go for it. MS2 firmware is no longer being upgraded and pretty well all the flash and all the RAM is spoken for. The MS3 has quite a lot of headroom -- although a lot of its extra features require you to buy extra boards for extra $$.

Have fun,

Rob.
 
speaksgeek said:
I would switch to MAP, it's easy to get a reliable sensor. For coils, I don't know if you'd be able to make a bracket easily to use coil on plug, but using 4x LS or IGN1A coils would get you a very good sequential spark with some custom ignition leads. IGN1A is probably total overkill.
I'd personally go for a replacement Bosch DBW throttle body, but that also requires a new throttle pedal and an ECU that supports DBW.
https://www.efihardware.com/products/c562/drive-by-wire-throttle-bodies
Click to expand...

Hadn't thought of just having four coils with leads, thanks for the tips. Is the extra spark from an LS coil necessary on one of these engines, or would a yaris / camry coil do? Most likley going to go for a GM MAP sensor, and i'll try to find a wrecker's camry throttle body to keep cable throttle but get the better tps and IAC, as drive by wire is probably out of my scope / ability at this time. it sure would be nice to have cruise control though... maybe in future.
 
odddit said:
Graham, what were your problems with MS2? I'm on a bit of a budget so tossing up between MS2 & MS3, would you say the extra $100 is worth it?
Click to expand...

Seems a bit unstable, a few things happening at times.. Also the system of keeping track of firmware updates and files is horrific. This could be just Megatune, maybe Tuner Studio on MS 2 would be OK. FOR $100 extra it is a no brainer though, go MS3. I've found MS1 to be trouble free.
 
odddit said:
Hadn't thought of just having four coils with leads, thanks for the tips. Is the extra spark from an LS coil necessary on one of these engines, or would a yaris / camry coil do? Most likley going to go for a GM MAP sensor, and i'll try to find a wrecker's camry throttle body to keep cable throttle but get the better tps and IAC, as drive by wire is probably out of my scope / ability at this time. it sure would be nice to have cruise control though... maybe in future.
Click to expand...

MAP sensor comes with the Megasquirt, mounted on the board.
 
GRAHAM WALLIS said:
Seems a bit unstable, a few things happening at times.. Also the system of keeping track of firmware updates and files is horrific. This could be just Megatune, maybe Tuner Studio on MS 2 would be OK. FOR $100 extra it is a no brainer though, go MS3. I've found MS1 to be trouble free.
Click to expand...

My tuner also has a dislike with MS2, no problem for him with MS3.
 
GRAHAM WALLIS said:
Seems a bit unstable, a few things happening at times.. Also the system of keeping track of firmware updates and files is horrific. This could be just Megatune, maybe Tuner Studio on MS 2 would be OK. FOR $100 extra it is a no brainer though, go MS3. I've found MS1 to be trouble free.
Click to expand...

If you've been using Megatune I think you must have been using the old Bowling and Grippo firmware. The MS3 code is based on the MS2/Extra code developed by Ken Culver and James Murray. It's been stable for me but, as I said, it uses up pretty well all resources of the CPU. AFAIK, it *only* supports TunerStudio.

If you ever have to use an MS2 again, here is where you should go to get MS2 (and MS3) firmware udates. And definitely get rid of Megatune!
 
That EFI Hardware setup looks to be very similar to the one used on 205 Si and S2 405 SRi, in my opinion the best setup ever, totally reliable and fuss free. I hated the LS1 setup, too many wires, too bulky and I had two coil unit failures.
 
Thinking about wasted spark because on motorbikes this has caused them to catch fire on more than one occasion.
Anyone had any problems that way? I'd be very worried about it.
 
I'll ask the folk who know about this. It has happened specifically on Moto Guzzi, but BMW uses the wasted spark with no issues and yes I know what you are saying so it obviously isn't an issue with 505. That's good, because I'm seriously considering the Multi Squirt system but I may need to ask you a few questions if you don't mind.
 
Here's an explanation which is probably only relevant to motorbikes, however I suppose any engine could do it.
If, during starting, you have a spark at the top(ish) of the exhaust stroke, when the inlet valve is already open and charge is forcing its way in, you can get a backfire which, if you are lucky, will only blow your carbs off. As happened many times on my V50II. This is merely a royal pain the the behind. If you are unlucky, as my mate Bill discovered with his Maglita-ignitioned Rudge, instant conflagration is the consequence.

Inlet valves usually open before the exhaust is closed, since the early 1920s. More so on performance engines unless they have VVT. It's called overlap and can easily be heard in the exhaust notes of vehicles that use it.

The Maglite was an evil device that tried to use the maneto windings to power the (4V...) lighting system. To do so, it had to rotate at engine speed, not half speed, and so had a wasted spark.

It's one of those things that is really quite unlikely to happen.
Click to expand...
 
You must log in or register to reply here.
Top