I've been attempting to remote tune a highly modified MSM and am coming across something I don't think I've encountered before, and am wondering if anyone else has. It's warming up nicely but we're still working on warm restarts, as rpm is currently fluctuating like crazy.

My main concern is that it's idling at 60kpa. I've looked over a number of my datalogs from other vehicles and usually see low 30s. Idle valve is in a normal range of ~30%, and the car refuses to idle leaner than ~13.0, which was apparently similar with his Hydra. Am I missing the reason for this?

Yes I have CL idle, idle VE, and a number of other features disabled as we try to work on just warming up and restarting.

.msq and log attached.

Shoot log is too big, I'll get a shorter one soon

 

Sounds like a vacuum leak? The other time I recently dealt with a high kpa idling car the intake came was off a tooth.

60kpa of vacuum at idle is way too high, something is wrong.

 

Can't open map at work, but definitely should not idle at 60 unless itb's or big cams. leak(s)?

 

It does supposedly have big cams. Adjustable exhaust cam was 6* advanced, I had the owner return to zero advance with no change in idle load. I'll have him double check for any vacuum leaks.

 

When my VVT was fuckity I also had huge MAP values at idle. Looking at the VVT map, you have 8.4 degrees at 60% fuel load. Might want to set all values to -1 until 2000 rpm.

 

Msm doesn’t have vvt unless its got a head swap

 

If it still has the MSM head then there is no VVT.

 

He did say highly modified... Looking at the tune, someone has definitely been playing around with VVT settings.

 

Sorry, wrote the original post too early. It's an 01

 

Here's the engine bay, I'm trying to find the description he sent me of the specs, but it's a built engine with a 3071 or something close to that.

 

which injectors

 

1000s, I'm assuming IDs.

02 with a 1952cc McCulley engine in it Skunk2 intake, GT3170R FM turbo kit

 

02 Miata with a McCulley 1.8 (Bored to 2.0) Manley rods, Skunk2 Intake,
Skunk2 throttle body, Garrett GT3170R turbo with a 3” exhaust out the back. Wideband
sensor and 1000cc injectors

 

which 1000cc injectors

 

Large cam muscle cars don't even make enough vacuum to make good use of the power brake booster. It's not unheard-of.

 

Leaking junk2 intake?

 

He said he sprayed carb cleaner everywhere without an increase in RPM, I'd be doing a smoke test, but that's out of the typical home mechanic's abilities.

 

What is the idle RPM? Do throttle changes result in reasonable MAP/RPM changes? Is MAP stable? Unless the ignition timing, cam timing, or something else is totally fubar, I would expect the torque to prevent it from getting down to anything a normal person would call idle.

 

Continued...

I would start by targeting a stable afr of like 12.5. If the CAM profile really is that aggressive, you are probably getting all sorts of sporatic combustion behavior at 13 or higher. Once you get the AFR/rpm stabilized, you can try leaning it out.

 

Again...

drop idle timing to 14. This also gives idle advance much more to play with moving forward.