So I bought a car. A 95 1.8 with a BEGI S1 gt2554 and MS2 pnp built by Braineack. I am having issues with the tune right off the bat, and I feel a bit lost. I am familiar with tuning GM cars with HPtuners, but this is a bit more.... complicated.

The Idle is awful, most of the time it idles at 1500-2100 even though it is commanding ~900 rpm, it pings EXTREMELY badly under boost, but only when ~60-100% throttle. Under part throttle in boost it is fine. Watching the AFR under WOT, it seems to stick pretty well around 11.5:1 and the timing table looks prety conservative, so I am unsure as to what the heck...

Attached is the msq file.

 

If it's pinging that bad, might be a better idea to play around with the tune with no boost.

 

First thing you should do is verify that the MS is timed to the engine. I'd proceed as follows:

1. Make sure that your crank pulley is aligned with your crankshaft. Believer or not, there have been instances where the stock pully disintegrates and slips rendering the timing marks misleading. Best way to do this is to stick your dipstick into spark plug hole #1, bring it to TDC and make sure the mark on the pulley is lined up.

2. Assuming we're OK above, align the MS with the engine using a timing light. With an MS1, this is under Spark=>Spark Settings. There's an option to set the MS to a fixed angle and then you can either turn the CAS or adjust a software Trigger Angle setting so that your pulley indicates the angle that the MS is set to. Hopefully someone will pipe up with where this is found on MS2 (probably similar).

Do that and let's go from there. Don't forget to look through the MS stickies. I find tuning MS (at least the fuel tuning) to be really easy because of Phil Tobin's work with VE Analyzer and VE Analyzer Live. Awesome tool.

 

Can I use a regular timing light on the trigger wire for the COP to check the base timing? I am using Toyota COP's, and the tune is configured for waste spark, so I am assuming that is how it is wired as well.

The other problem is, how the hell do I get it to idle at 850 rpm to check the base timing if it won't idle as 850 rpm?

 

Yes, you can use a regular timing light. I run Toyota COP's too.

If you set the MS to generate a constant trigger angle, it doesn't matter what your RPM is or whether it's stable. This is like the first thing you need to do when installing an MS. Idle is usually not smooth upon a first start.

 

Bad ping + conservative timing = slipped pulley/slipped timing belt

 

Stupid question, I obviously haven't tuned MS before. Do I need to burn the tune settings while running, or not running? Remove the coil harnesses when burning the tune? The stuff I used to play with flashed it key on, engine off.

 

I did just change the battery as it was starting hard when I got the car. Could that affect it? I didn't hear any ping on the 300 mile drive home and I was in boost several times.

 

You can change settings while running the engine, although given your current state of tune, I wouldn't do that now. You don't need to remove coil harnesses when burning a tune . . . BUT . . . IMPORTANT:

If you ever find you need to burn new SOFTWARE (not just a tune), you will want to unplug the coils for that.

Seriously though, you are WAY out of time. Check that crank pulley. It's likely you'll need to make some mechanical repairs.

 

Checked base time. The CAS was a little off, so I adjusted the offset from 10* to 8.5* and it is now at 10* on the timing mark with the timing fixed in TS.

The idle problem now has a probable lead, it doesn't go into closed loop when it displays the high idle symptom. I could blip the throttle and sometimes it would go back into cl but most of the time it would just hang at 1500 rpm and not go back to CL.


Anyone have any ideas based on my .msq file?

 

Did you verify that your crank pulley indicates correctly? It's important -- has bitten a few people.

Make sure you have no vacuum leaks. There are ports in hidden places on the IM that are plugged by rubber caps that deteriorate. Fuel injector seals are another common leak source.

See here for a primer on setting up idle (starting at post 11). Written for MS1, but MS2 will be similar:

https://www.miataturbo.net/megasquir...me-help-57133/

 

I figured out the ping, I filled up with a bad tank of gas. Poured some NOS octane booster in and it is completely gone.

Idle, is worse now with headlights on. I'll read your link. It is strange, if it is idling at ~1500 and you drag the clutch to bring the rpm down, it will go into closed loop after you release the clutch pedal...

 

Suspect you are idling so high that you exceed the "Idle Activation Adder" RPM (i.e., so high that you are not engaging the idle control algorithm). Bottom line, you've got a lot of air getting into the intake manifold and it's probably not coming through your IACV.

Better read that link. Please read to the end . . . lots of good info. Be aware that there are differences in the minimum and closed DCs for the different year Miatas because the design of the throttle body and IACV changed over the years.

 

The first thing I did was eliminate any vacuum leaks as a cause to the high idle. There is nothing leaking into the intake manifold, I am sure of it. When I unplug the IAC, it idles down immediately to around 600 rpm and stays there. I have a 99 intake and should have a 99 IAC. Should I change the min and max DC on the IAC controls? When I start it, it revs up to 2100-2300 rpm right away and stays there for 3-4 seconds before idling down to either 900 or 1500 rpm.

Still reading the linked thread.

 

I'd put the IACV into a manual mode (called "Warmup Only" on MS1, something similar on MS2) and then start cutting back on the DC to see what RPM you get. When the RPM no longer changes, you've found your "Closed DC" for the IACV. "Minimum DC" will be 1 or 2 points above this. IIRC, on a '99 you'll be in single digits.

Learning curve is a bit steep, but finite.

 

I did the idle test to figure out the proper duty cycles. I got everything plugged in, but I have an uncontrollable low amplitude oscillation now. I think it may be the frequency of the valve is not what I set it to. I set it to 15 which is what I read to do with a 99 IAC. I am wondering if the resolution is too low and I need to lower the frequency number?

Maybe I don't have a 99 IAC since the min dc was 20-21% and the frequency is set way too high?

 

Hmmmm . . . .

One thing you could do is go over to the MSPNP site and check out some of their canned tunes. Pretty sure they have one for the '99. See where they've set the frequency and min/closed DCs. There are now MSPNPs that are MS2 based (mine is an original that is MS1 based).

 

I wouldn't do that.

 

BTW, are you oscillating in manual mode or only when you switch to closed loop?

 

Manual is peachy and smooth. CL is the problem.