MX5 Owners in here....bring your curling tongs

adam cool dude · 24 Nov 2015 at 14:04

Frozennova said:
I want more power in my mx5 hence going turbo, I could have swapped in a different engine nut ultimately would say an SR20DET give me anything doing a turbo swap would, probably not. But if I wanted a 200+bhp rev monster would I build a Mx5 engine for that, no I'd swap in an F20C like somebody else has done

Swapping a f20c seems even more pointless. Just buy an s2000 in the first place!

mark66 · 24 Nov 2015 at 14:16

wesimmo said:
Went to pick the car up from BBR today, bolting on the supercharger got it to 183bhp, mapping it took it to 219bhp.

Just need to learn how to drive a stage 3 clutch equipped car without launching it every time I pull away or kangarooing and stalling...

Sounds good - tell us more!

Watched this video the other day featuring a 270bhp BBR Turbo - yes please!

wesimmo · 24 Nov 2015 at 20:00

mark66 said:
Sounds good - tell us more!

Watched this video the other day featuring a 270bhp BBR Turbo - yes please!

Well the idea was born over a year ago....

http://forums.overclockers.co.uk/showthread.php?t=18620213&page=1

But it's been a constant pain in the rear and I've often thought of calling it quits.

Sent it to BBR in the end to sort out various issues, which they've done to some degree, but the advice i received to install an MS3 wasn't great IMO....

However they did get cold start infinitely better, it was horrible before, raised the coilovers to "get the wishbones at the right angles" and aligned it, and then obviously they've done the power mapping.

I went supercharged for the straight line power delivery, so it felt more like it was just a bigger engine than a turbo would, and i felt 190ish at the wheels as the kit promised would be about right for my talent and the car..

BBR pretty much delivered with this graph!

Frozennova · 24 Nov 2015 at 20:11

Cold start takes a good chunk of time to perfect on a Megasquirt, mines almost spot on now. Just need some more mornings with temperatures in the minuses

wesimmo · 24 Nov 2015 at 20:19

Yeah that's the feedback I've had elsewhere, BBR said I could take it back and leave it for a week to try and tweak it further but there's only so much they can do each day. It is Much better but I get idle droop when coasting to a stop in neutral.

I'm getting used to the clutch too which is reassuring as I thought it'd ruined it as anything but a track and fun drive car.

Frozennova · 24 Nov 2015 at 20:35

It's a right pain, you get 1 maybe 2 chances a day to tweak and test before having to wait another 12-24 hours again, fortunately I've got a company van so the engine is back to being stone cold by the time I get home in the evening

I assume you've got a laptop with a copy of tunerstudio?

If it takes forever to turn over then it's likely you'll need to remove some fuel for that temperature in The Cranking Pulsewidth table. Once it fires if it only runs for a second or two before stalling then you need to increase the After Start percentage for that temperature.

As for the idle droop that will be down to closed loop idle settings, which will more than likely be the Closed Loop initial table.

wesimmo · 24 Nov 2015 at 21:07

Frozennova said:
It's a right pain, you get 1 maybe 2 chances a day to tweak and test before having to wait another 12-24 hours again, fortunately I've got a company van so the engine is back to being stone cold by the time I get home in the evening

I assume you've got a laptop with a copy of tunerstudio?

If it takes forever to turn over then it's likely you'll need to remove some fuel for that temperature in The Cranking Pulsewidth table. Once it fires if it only runs for a second or two before stalling then you need to increase the After Start percentage for that temperature.

As for the idle droop that will be down to closed loop idle settings, which will more than likely be the Closed Loop initial table.

I have a laptop and Tunerstudio, but TBH the rest lost me!

It pretty much fires up now and then stays alive, this morning it died first time round after a second or 2, but it was the first morning of frozen windscreen days so i guess that's to be expected if BBR never had a chance to tweak it down to that temp.

It used to over rev and surge then die unless i blipped the throttle 2 or 3 times to catch it, it would then over rev until the temp gauge started to move. So, much better now!

I'm just dying to drive it in anger now, i did a track day at Teeside autodrome when it wasn't tuned, there's another open pit lane 10-4 day for £55 on the 14th so will be interesting to see what my speed is at the end of the straight there. I should be getting better speed out the corner due to the geometry tweaks and the obvious more power down the straight itself.

Just need to get the time off work....

Frozennova · 24 Nov 2015 at 21:27

wesimmo said:
I have a laptop and Tunerstudio, but TBH the rest lost me!

It pretty much fires up now and then stays alive, this morning it died first time round after a second or 2, but it was the first morning of frozen windscreen days so i guess that's to be expected if BBR never had a chance to tweak it down to that temp.

It used to over rev and surge then die unless i blipped the throttle 2 or 3 times to catch it, it would then over rev until the temp gauge started to move. So, much better now!

I'm just dying to drive it in anger now, i did a track day at Teeside autodrome when it wasn't tuned, there's another open pit lane 10-4 day for £55 on the 14th so will be interesting to see what my speed is at the end of the straight there. I should be getting better speed out the corner due to the geometry tweaks and the obvious more power down the straight itself.

Just need to get the time off work....

When I get home from work tomorrow, I'll get some screenshots from Megasquirt on mine to show you which tables need editing a write a little guide for you.

When you say over rev, how much?

wesimmo · 24 Nov 2015 at 21:57

That'd be amazing mate.

The over rev was probably 1.5-2k depending on where it settled after the blip.

There's no lambda, but a wideband obviously, which BBR didn't remark on.

Frozennova · 24 Nov 2015 at 22:01

It should be idling around 1500rpm from cold settling to ~900rpm

All the symptoms you've described sound like not enough fuel during the Afterstart Enrichment

wesimmo · 24 Nov 2015 at 22:21

TBH the start is ok now, like i say, the really cold day caught it out a bit but now i can even try the auto tune function i guess based on a pretty decent base rather than the dogs dinner it was before!

It's more the idle droop i want sorting now. That's intermittent too, so another annoying one to diagnose for a mechanic/tuner who only drives it a little.

Frozennova · 25 Nov 2015 at 21:29

wesimmo said:
TBH the start is ok now, like i say, the really cold day caught it out a bit but now i can even try the auto tune function i guess based on a pretty decent base rather than the dogs dinner it was before!

It's more the idle droop i want sorting now. That's intermittent too, so another annoying one to diagnose for a mechanic/tuner who only drives it a little.

Just remembered I said I'd post these tables for you.

Assuming the MS3 is the same as the MS2 then the table on the right is the one which will need adjusting to cure the idle droop when pulling up to lights, the easiest way to tune this roughly is by changing one of the gauges on the dash board to display Idle PWM% and opening the table so you can see both.

At this stage start the car (from cold) and you'll see a little blue dot in one of the cells on the right which indicates which cell it is currently using, change this value to 3% higher than the Idle PWM% displays on the dashboard as the blue trace moves into each cell.

To sort the issue of it cutting after start you want to adjust the table on the left, with the ignition on you will see one row highlighted green which is the current row being used, in steps of 3-5 at a time increase the value and try a cold start (My values *might* work well for you but every car/setup will react differently)

Rainagul · 26 Nov 2015 at 01:38

I just installed TD04 - 13T turbo kit to one of my friends 1.8 MK1 MX5's over the weekend.

Currently have it running on the stock injectors and ecu just so she could continue using the car to and from work this week. It dosen't really boost at the moment, as either bogs down if you go WOT, or if you ease into the boost then the engine starts running lean (as expected) so as a safety measure I've told her not to go over 3.5k revs.

We have a set of RX8 440 injectors, and a second hand 'ME221 MX5 MK1 Engine Management' standalone ecu that has already been mapped conservatively to use the same 440 injectors , which we will install this weekend which should get us boosting properly.

I have been reading that the 1.6 engine comes with a throttle switch rather than a variable TPS. Does anyone know if the 1.8 is the same? Also, for any MX5 owners here who have turbo'd using standalone management, would you recommend upgrading to a variable TPS (assuming neither the 1.6/8 come with it) or is the stock throttle switch fine?

nicRob · 26 Nov 2015 at 07:47

From memory there's a bmw tps which is a straight swap..

Frozennova · 26 Nov 2015 at 08:10

1.8s all have a VTPS

Sonea Fifer · 26 Nov 2015 at 15:40

Recently I had a strange whirring noise I could hear over the exhaust in my MX5. :confused:

Turns out it was the differential - new one ordered, delivered and it's being fitted right now . . . . .

Diddums · 26 Nov 2015 at 15:43

Saw a new MX5 yesterday. When I saw the pics I thought it looked a bit crap but in the metal it's actually a very nice looking car.

Frozennova · 26 Nov 2015 at 15:57

Sonea Fifer said:
Recently I had a strange whirring noise I could hear over the exhaust in my MX5.

Turns out it was the differential - new one ordered, delivered and it's being fitted right now . . . . .

Mk2.5? If so the Super Tochigi Fuji diffs are known to be a weak point. I need to decide what route to take, either a second hand Torsen or a Kazz/Quaife /ATB in my casing

GreenMint · 26 Nov 2015 at 16:06

Sonea Fifer said:
Recently I had a strange whirring noise I could hear over the exhaust in my MX5.

Turns out it was the differential - new one ordered, delivered and it's being fitted right now . . . . .

Mine does the same between 2.5-3k revs, is this really a problem, annoyance, or a way to make you think you have a supercharger!

Sonea Fifer · 26 Nov 2015 at 17:23

Frozennova said:
Mk2.5? If so the Super Tochigi Fuji diffs are known to be a weak point. I need to decide what route to take, either a second hand Torsen or a Kazz/Quaife /ATB in my casing

Mine is the Mk2.5 Sport (6 speed Box) which I understand comes standard with a Torsen LSD (3.9 ratio) I'm aware they're a weak point and I consider myself fortunate I've had no issues in over two years of ownership. Given the amount of money I've put into my car over the past year (Respray, Chassis rails wax oiled, arches fixed, alloys refurbished, upgraded braking) I decided another diff made sense in order to allow me to keep this car for at least the next few years. I couldn't get one of those standard diffs so I bought a Quaife with a 4.1 ratio. I'm aware it'll throw my speedometer out slightly (about 7MPH) and affect the revs (by about 500RPM) but I can live with that.

TimBrad said:
Mine does the same between 2.5-3k revs, is this really a problem, annoyance, or a way to make you think you have a supercharger!

If yours is doing this already Tim I seriously suggest you keep an eye on it. Mine was throughout the rev range but was most prominent at 30MPH in 4th.