Help, guidance and advice please (2.3 engine swap mx5)

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Mx5 mps
Posts: 3
Joined: March 30th, 2024, 2:23 am

Help, guidance and advice please (2.3 engine swap mx5)

Post by Mx5 mps »

Hi all, new here and completely new to tuning, many noob questions may be asked and many silly statements may be made, but bare with me, learning all the time.

I have swapped a 2.3 disi from a 2007 CX7 into a MX5 Mk3/NC the swap is near enough complete, the car is running and slowly working through issues here and there - latest being a faulty EGR valve with a replacement on its way.

So, with the above said here is a list of modifications
Cone filter
shorter run from intake to turbo
FMIC which I think is a little bigger than stock
Longer run from turbo to TB and not as straight as I would like due to space and a longitudinal engine position.
mx5 kraken top mounted turbo exhaust manifold
Custom downpipe - no pre-warm cat - not ideal flow, again down to position and space
second O2 sensor now mounted after main cat under the car
Aircon delete
balance shaft delete
obviously no longer 4WD and just RWD

The rest of the engine is stock as it came out from the CX7 - ECU, dash, electronics, ABS - all from the donor car.

I have done all this myself to keep the costs down as much as possible

With the above said, I am now looking to get everything working better, up until now I have been using forscan to data log everything (didn't know there was a free versatune logging option) as I have said above I am working through small issues to get things up and running as expected.

List of currently known issues
EGR CEL - tried cleaning this but still throwing an error, got a new one on its way
LTFT is + 25%
ABS pump - stability control keeps kicking in on corners
4WD module light error (to be expected!)
twice now where I have had a very sudden loss of power jerking the car when doing a slightly hard pull (avoiding hard WOT until I have got things running better)
possible exhaust leak (sounds a bit louder than when I first put the exhaust in so one of the welds may of cracked - will be testing this soon)

it passed its MOT here in the uk and have probably done a couple 100 miles so far in total over the last few months.

All I can say at this point though - MUCH faster than the stock 2.0 that came in the MX5! :D

I was hoping I wouldn't need to get a tune, money being the limiting factor as dyno and expert costs are rather high, but this is my first time actually working on a car, I learned everything I needed so far, so I am not above learning how to tune.

So before I go put down a wad of cash on versatune I have a few questions
1. My main concern at the moment is that LTFT, the AFR is coming back as expected - with the modified intake would this be a possible cause for the high LTFT? the MAF sensor is the original and has been cleaned - found a boost leak and fixed that but didn't change the trims

2a. Using the versatuna full do you have access to the ABS pump data - can this be modified?
My current issue is depending on the steering angle and the speed the stability control keeps kicking in, only has happened at lower speed and tighter corners (kicks in around 20 mph) I am trying to work through this issue and I know after taking it for a 30+ mile drive that after a while the ABS unit throws an error and disables the stability control until error codes are reset. I have the original MX5 ABS too but when fitting this a VIN mismatch error occurred (was expecting something like this) but my plan is to read and compare between the 2 and modify it as such

2b. The CX7's ABS pump also has a TSC disable switch - this I was disappointed with as I assumed this would be the same as the MX5's DCS disable switch - it is not! the TSC seems to re-enable after you go above a certain speed :banghead is this something that can also be changed in versatune?

3. I am not really after anything more at this point from the engine (maybe in the future but from what I am told the limiting factor on these engines is the fuel delivery (HPFP & injectors, if is the case the HPFP may be an issue anyway due to once again, space, it's all super tight fitting back there) apart from fuel economy though, running at +25% fuel trim with this reduce the lifespan of the engine? and thus will it be worth spending all this time needed to learn to tune - everywhere I read they say leave to an expert - how hard is it?

4. If I am to learn (and may help go to answer the above question), where to start? Is there any good initial information on tuning and using versatune? from my understanding tuning can be a complex things that mix together to get a complete package and know if you push too far things can go terribly wrong!

5. EGR delete, this is where more of the thought of late for tuning has come in, near enough everywhere I have read the only thing for the EGR delete is the CEL comes on, however I did read that there might be a EGR table that the ECU mixes to adjust for an open/closed EGR valve, is this the case for this platform or is it just throwing the CEL only?

6. I know this is a long shot at this point without any log data but has anyone got an initial thought on the sudeen loss of power - this concerns me a fair bit as its not just like it stops accelerating but feels like its actualy slowing the car downa and jurking it a fair bit, I have at this point been unable to log this issue (and not sure what causes it I am unsure on everything I need to log to identify it), left this question to last as its a shot in the dark and still slowly working through all the other issues in case they are the root cause.

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mituc
VersaTuner guru
Posts: 1329
Joined: December 17th, 2011, 2:47 pm
Location: Iasi/Romania

Re: Help, guidance and advice please (2.3 engine swap mx5)

Post by mituc »

LTFT 25+% - assuming there's no obvious leak I'd say that intake needs a calibration.
Versatuner will only give you access to the ECU, no other modules. I guess you can access the other modules with forscan or a similar tool and see what can be done from there.
The TSC switch on the CX7 will only disable traction control and only up to 30 or 50kmph (I don't remember exactly).
EGR Delete - can be handled by Versatuner no problem.
2008 Cosmic Blue Mazda 3MPS
Built engine + WMI + GTX3071 gen2, ~509BHP @34PSI
2008 Icy Blue Mazda CX7
Stock engine and exhaust (YES!!), JBR3" + GTX2867 gen2 + Autotech HPFP, self-tuned to 330-ish BHP
CrazyCanadian
Posts: 23
Joined: July 4th, 2021, 8:32 pm

Re: Help, guidance and advice please (2.3 engine swap mx5)

Post by CrazyCanadian »

You've gone a really difficult route in order to turbo your MX5.. Changing the gear ratio's in the ECU programming to match the transmission and rear diff in the MX5 could help your issue... Both Versa Tuner and Cobb can do that... Outside of that, there isn't any programmable solutions as far as I know.. It might be possible to vin match your stock ABS pump using ForScan and as built data programming... You'll need a program like ForScan in order to scan and watch the traction control/abs data to see if there's a possible sensor problem, or if you are hitting a programming issue.. Versatuner can reduce how aggressive TC works with a 1 button blanket modification... Where as Cobb has a more customizable option, but you can't access the self tuning software from Cobb anymore.. so you'll be stuck with a remote tuner..

As far as the engine stuff goes.. Versatuner can handle the engine tuning issues you are having... As mentioned you need to make sure you've got no vacuum leaks going on causing the high fuel trims before you go tuning to fix that.. the EGR valve can be deleted..
Mx5 mps
Posts: 3
Joined: March 30th, 2024, 2:23 am

Re: Help, guidance and advice please (2.3 engine swap mx5)

Post by Mx5 mps »

Thanks guys, I know it was harder, I broke the old engine, so was more about replacing the engine anyway.

I'm looking into forscan for the abs, having slight issues with accessing abs via windows app whilst working with android app... I'm surprised I'm not able to modify that stuff with versatune.

I hadn't really considered ECU stuff for the gearing tbh, though it would make sense.

I have started to read the sticky posts here on the methods of how to tune bits here and there, still is there any resources to recommend for understanding the fundamentals of tuning, as in what tables are and how they work together, what's the ideal rates depending on usage, how to recognise safe limits etc?
mituc
VersaTuner guru
Posts: 1329
Joined: December 17th, 2011, 2:47 pm
Location: Iasi/Romania

Re: Help, guidance and advice please (2.3 engine swap mx5)

Post by mituc »

Mx5 mps wrote: March 31st, 2024, 1:13 pm as in what tables are and how they work together, what's the ideal rates depending on usage, how to recognise safe limits etc?
The factory turbo can barely push the engine towards the "safe limits" if the boost control system is in factory configuration.

I could try to help you with the tuning side of this project if you want.
2008 Cosmic Blue Mazda 3MPS
Built engine + WMI + GTX3071 gen2, ~509BHP @34PSI
2008 Icy Blue Mazda CX7
Stock engine and exhaust (YES!!), JBR3" + GTX2867 gen2 + Autotech HPFP, self-tuned to 330-ish BHP
Mx5 mps
Posts: 3
Joined: March 30th, 2024, 2:23 am

Re: Help, guidance and advice please (2.3 engine swap mx5)

Post by Mx5 mps »

Thanks for the offer, might take you up on that, won't be for a while I don't think as I got some other expenses to pay out on the car, had it welded and need to get a proper paint job/wrap also need to swap out the rear diff for an LSD.

Paint first to stop it rusting again along with full underseal, then I'm not sure about the LSD or tuning, I wouldn't thought it would make much of a difference for tuning but I would summise the rear diff will have a slightly different gear ratio.

All that and the replacement EGR valve has took nearly 4 weeks to come and still not here.
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