So I have my MsII v3 all working and running the car now. I am going to drive it around some but wanted to get some tuning opinions.

Here are the relevant mods I have:

FMIC
3'' exhaust
Stock turbo, ported waste gate
Electronic boost controller
Walpro fuel pump
Professionally cleaned and matched stock injectors
Fresh rebuild

I am using Aaron Cake's A/F, VE, and ignition tables. My question is, how ""safe" is it to tune it myself under stock boost myself. I am learning and have never tuned a car before. I have a wideband and understand most of the concepts but I am just curious if I am better off staying out of boost completely for now?

I plan on getting some upgraded injectors and a BNR setup. I just want to drive it around and get the engine good and broke in and enjoy the car some. I will most likely take it and have it dyno tuned for the BNR. My thoughts are that under stock boost conditions or close I am less likely to screw up as long as I datalog and monitor my wideband. I am not reckless and want to learn but would hate to pop my engine right out the gate.

I really appreciate all the help on the forum. Thanks

 

So I read some more online and found this book. I think I am going to go through that and get some ideas.

 

That is a wonderful book and will give you the basics. It won't go into great detail on any one subject through, so just be aware that it's more like a thorough introduction. It does have some informative chapters on the methodology of tuning.

As for the original question, it is fairly safe if you have some common sense. That means not making wild changes without knowing the consequence, approaching boost carefully (don't just go WOT), working rich to lean and carefully reviewing datalogs.

Boost tuning is actually the easiest part because you're just tuning to an AFR ratio. As a rotary under boost, we have a narrow range of acceptable AFRs for reliability so it's just a matter of adjusting the VE table to produce those. Unlike tuning the rest of the map which is as much about feel as it is about AFRs and timing numbers.

I assume you've see my very basic tuning guide?
How To Megasquirt Your 2nd Gen RX-7: Basic Tuning

 

Thanks Aaron. I have you entire writeup printed and in the car . I think once I drive it around some I will get a better idea what its all about. I certainly wont be going WOT out of the gate. Just wondering if you get into boost a little and go lean for a sec and POP or if it's more like you go crazy and push through a lean spot and then POP. If that makes sense... I will take it slow and read up.

I have found that when I am worried about doing something myself the most and pay to get it done I am most disappointed in myself for not trying. But would hate to pop my motor too. Thanks again!

 

Noch get a friend, easiest thing I ever did was have a friend run the comp and even out my fuel map making a ton of highway pulls. then we drove around simulating stop and go driving in traffic. its amazing what someone else can do because they can have all their attention on the afr and fuel map. we redone my entire table and creeped into boost slowly getting everything smoothed out from vacuum to boost. Just remember cover as much as the map as possible, we did part throttle cruising at all different rpm ranges to get everything cover as be we could. It is a night and day difference when you can have someone with you can knows exactly where the table needs adjusted while it was bucking trying to cruise through town and you can focus on the road.

 

I'd be comfortable in saying that with Autotune turned on, one person can make a drivable VE table quite easily by just driving through traffic and varying conditions over a period of about 2 - 3 hours. Then it takes a bit of time tuning the transitions (decel, accel, etc.) which can be done by one person. Faster with two, but no required.

Boost on the other hand I would suggest be a two person affair. It's far less annoying to have someone else making corrections real time than datalogging and making the corrections yourself. And FAR safer than looking at a wideband/computer while trying to drive! Unless you're on a dyno.

Now as for your question regarding a lean spot in boost. The simple answer is don't create a lean spot in boost. Start rich to the point where the car won't even run in boost and then gradually pull fuel. An experienced tuner can start this way and make major changes to the map knowing what the effect will be and the result is tuning a car very quickly in boost. For a first timer, moving down a few VE percent with every run while still in the crazy rich phase is the safest method.

Autotune in boost...I see no reason why it wouldn't work (don't use it to tune around the injector stage point...exclude those bins and do it manually) but make sure to set a conservative target AFR (say, 10.8:1) and the adjustments to be non-aggressive. Then once you have a smooth boost VE, manually go in and lean it out a few % to your target (say, 11.5).

 

Thanks for the help guys! So like Aaron said, after a few hours of driving around in traffic my heat map on Tuner Studio was pretty much all green and it drove much better. Today I set it to not update the controller and modified the TS A/F reference map to target 10:9:1 starting at 115kpa. I crept into boost and it runs good and rich. I kept doing that and would look at the changes TS suggested and apply them, rinse and repeat. I finally got it to just under 5PSI and it goes from mid 11s to mid 10s A/F in that range. It hits a rich spot and stutters when the secondaries kick in but I guess that takes some work. Does the reference table I am using look ok? It seems to be working well and is close to Aaaron's down low. This is pretty fun. I mean even if I blew the engine it would be worth it just to learn all that I am learning. Oh and I found another good book I am enjoying. Its more technical than the first one I read and covers a lot of details.


Thanks again! This is really fun!

 

Your AFR table looks workable, but there is some oddness.

Overall in the NA area it's very rich. In the 80-99 area just before boost, you'll typically find more power in the 13.8 range.

In your cruise range (middle of the map typically 2500 - 4000 @ 50 - 80Kpa) you can be much leaner. I typically aim around 15 and then lean it out further once in closed loop. You can be leaner than 16 if your EGTs agree. If you don't monitor EGT, around 15.5 is typically OK.

The bottom most line from 3000 RPM up can be 16.0. At that point you're probably in decal cut anyway and leaning that out will avoid that bucking as you decal, eliminate the popping from the exhaust, and make the transition on and off overrun cut smoother.

Anywhere else in the map can be 14.7 except the area just above idle (low RPM low vacuum) which responds better around 13.8 - 14.0. And the area 6000 - redline between 70 - 100 Kpa which will need to be richer due to the load on the engine.