patsmx5

iTrader: (16)

Got a lot done today, not ready to start up to test wiring/auto but close. Should test tomorrow.

sixshooter

iTrader: (12)

Automatic transmissions use hydraulic pressure created by the pump to press the clutch discs together inside the clutch packs. If it slips, it can be remedied by raising the pressure of the system sometimes. Most transmission builders could help with that simple part of the process. What you really need to be concerned about his actual breakage of components when things don't slip.

patsmx5

iTrader: (16)

Yeah I guess I'll be finding all the weak links soon enough. I did note the output shaft of the auto is bigger than the 6 speed, had to buy a new driveshaft for that. And the box as a whole is a lot bigger/heavier. But who knows how strong it is, pretty sure nobody has ever pushed this auto very hard.

mx5psi

there was someone on here or mx5nutz forum that had a turbo auto NB running 15 psi no issues breakages so far was and old post they did have an issue with increasing revs and the shift points i will try and find it again i ran into it when i was doing all my research

patsmx5

iTrader: (16)

IT RUNS AND IT SHIFTS!!!!!!!!!!!!!!!!!!!!!!!!!!!

Tested on jackstands it seems to shift fine. Kind of hard to tell if it shifts from 1-2 on jack stands, but going into 1 or 2 shows it to absolutely works then. Will know for sure once I drive but probably fine.

Have two electrical problems to fix. First, fuel pump for whatever reason just turns on when you key-off. Before the key-off event it works as normal, controlled by MS. No idea on this, but it's simple enough so can't be too hard to fix.

Second I forgot to put some freewheel diodes on the fans, opps. Gotta add those. Fans went bananas when they powered on without them likely due to all the noise going into the electrical system from PWMing those fans without freewheel diodes.

BUT YES IT RUNS AND SHIFTS AND OMG FINALLY! Will fix electrical stuff tomorrow and try to get it put together enough to test drive it.

mx5psi- if you can find a link I would very much appreciate it! Would love to see what others are doing and getting out of these autos.

mx5psi

iam still looking stumbled across this in the states Custom Mazda Upgrades | Mazda Transmission | Mazda Torque Converter | Mazda Valve Body

stefanst

iTrader: (1)

Congrats!

patsmx5

iTrader: (16)

Drove it. Shifts and drives fine for regular driving. Apparently "wastegate" is 20 PSI on this setup, so that's as low as I could go. Wasn't sure as I never run wastegate.

It hates the 1-2 gear change at WOT, like hang the tach till I lift bad. Also the 1-2 gear change isn't happening until about 8,000 or so. Not sure if torque converter or clutch pack at this point, probably clutch is my guess*.

The 2-3 gear change is completed in 0.25-0.30 seconds every time, no problems there. If you manually put it in 1st, 2nd, or 3rd it will hold and not slip.

Possibly related, I have a problem with my VVT cam going so retarded at high RPM that the stock ECU looses sync with the cam/crank wheel (MS3 is fine though). Since the ECU transmits RPM to the TCU, this could be the reason for the 1-2 problem. Going to retard the VVT less at high RPM and see if that has any affect on the 1-2 shift.

Based on the fact that 1st, 2nd, and 3rd can hold 20 lbs once it's done with a gear change, it looks like I'm going to put some torque management hardware/software into it to pull timing on gear changes. Most autos do that for anyway, I have no idea if mazda did it or not, probably not given the lack of torque a stock miata has.

2nd and into 3rd at 20 pounds felt pretty nice though.

* Oldly enough, it did once shift into 2nd firmly under power at about 7K, and it spun second it hit so hard. So that is odd, may point to it not being a clutch but maybe sucking air or revving too high and cavitating the pump. Only did that once but it surprised me.

More in the coming few days as I figure out what's actually going on.

EDIT: Also going to build an indicator to show what gear the transmission is commanding to see when it commands a shift vs when it happens.

Leafy

iTrader: (1)

Pat, on the vvt thing. I bet your reluctor wheel on the back of the cam slipped. All us auto-x guys reving the **** out of these motors have done it. I just tack weld the wheel to the cam and then re-adjust the trigger points to wherever the wheel slipped. Just make sure you put the ground clamp directly on the cam shaft and that its not touching the head, and dont accidentally start an arc on the head, dont want to get any micro welding on the cam journals.

patsmx5

iTrader: (16)

I bet you're right on the money, I didn't even think of that. I got two vids I'm about to upload that show the tach dropping out under load, but it's fine for regular driving. Do these symptoms match a slipped cam wheel?

patsmx5

iTrader: (16)

2nd to 3rd is great, 1st to 2nd is sad. This was shifting at about 6K in 1st, but you can hear from the vid it didn't shfit till another 1,000-1,500 RPM after I told it to. I pedaled it in 2nd trying to get it to stop slipping.

I'm starting to think the converter is just way too loose and that's why the revs aren't dropping on the 1-2 change but it's perfect on a 2-3 change. I think the converter is unlocked on the 1-2 and locked on the 2-3.

Any ideas on WTF my tach is doing would be greatly appreciated. There are no codes so it may not be the cam sensor, maybe the tach itself? It cuts out under load for whatever reason, I know I've seen other people's miatas do this before.

aidandj

iTrader: (5)

Are you controlling the tach with the stock ecu or the megasquirt

patsmx5

iTrader: (16)

Stock ecu running the tach.

sixshooter

iTrader: (12)

Torque converter should never be locked up under any shift conditions. So I don't buy that theory. I also don't buy that the torque converter is selectively slipping. It is a mechanical device once it reaches its flash stall speed. If it gives you good hard acceleration up through the mid-range of any gear then it is not slipping internally. What you are likely experiencing is a computer control problem regarding shifting. Usually throttle position is used to determine the load to effect shift RPMs. In the old days this was monitored physically by downshift cable or a TV cable in conjunction with a vacuum modulator and a governor managed by swinging weights. I'm sure this is all done by computer now. It will be necessary to determine what sensors are entering into this decision making process.

mx5psi

1st to 2nd looks like it is slipping when 2nd gear finally grabs it spins tyres you can have stronger bands or clutches in different gear changes 2nd to 3rd is probably a stronger band or more line pressure someone will have to know how to up line pressures in the a44de gearbox

there are a few cars here in where the australia that are controlled by the main ecu and you can put in resistors inline in the wiring to up line pressure

patsmx5

iTrader: (16)

I went digging through the 99 factory service manual and found the shift diagram.

Above 62mph, it will lock the converter in 3rd at all throttle openings. Above ~96 it will lock the converter at all throttle openings in 4th. Thus at WOT, the 2-3 shift would happen with the converter locked, but it looks like the 3-4 shift it would unlock for that shift, then relock about 3mph later.

The trans does have a kickdown cable on the transmission connected to the throttle body. The TCU has serial comms with the ECU, and it has TPS going to the TCU and a few other sensors as well.

Since I can't easily turn the boost down, I went and pulled 15* of timing in all the boosted cells and drove it. It STILL slipped on the 1-2 change, and this was driving with probably 100-130whp. I tried pulling 20* instead of 15 and it wouldn't go over 6K at WOT.

2-3 gear change, 20 PSI, no slip, gear change completed in 0.25 seconds.

1-2 gear change, minus 15* timing (about 120whp) second pic, slipped, gear change completed in 0.97 seconds.

3rd pic is shift diagram for this trans

The fact that it slips like crazy at stock power tells me the trans is damaged. Trying to find out now if I can run the 03-05 newer model auto trans (is it 100% backwards compatible with my 99?) as they are much more common and easier to find with low miles.

99' auto is a 30-70LE, SB011
01 auto is a 30-70LE, SB101
03-05 auto is a 30-70LE, SB131

Mazda's auto repair manual that has every spec and clearance for how to rebuild an auto covers the 01-05's. I suspect the newer ones will swap right in and work, gotta do more research though.

patsmx5

iTrader: (16)

Thanks. Yeah I think 2nd gear clutch is toast or the hydraulics that control it are leaking. It can't even hold stock power on a 1-2 gear change. I think I'm going to buy a low mileage newer auto and swap that in, and see how much a stock box in good health can take and go from there.

sixshooter

iTrader: (12)

Wow, I never knew they were keeping converters locked during shifts on modern cars. Mind blown. Better for economy but harder on the clutches and bands.

18psi

iTrader: (76)

Lots of newer auto's do that, but I didn't know the miata did that so long ago. that's the surprising part

patsmx5

iTrader: (16)

Yeah I wasn't sure till you mentioned it not locking and I went and found that diagram. Looks like mazda does both depending on the gear.

So I did some more testing and research. This trans slips on the 1-2 gear change at stock power, yet 2nd can hold 20 PSI boost if you just put it in 2nd and floor it. So it seems the 2nd gear clutch can hold the power, but the trans isn't applying that clutch quickly. This suggest a hydraulic problem (1-2 shift accumulator or 2nd gear servo), specifically a hydraulic leak resulting in slow and lower pressure on this hydraulic circuit.

I ordered a line pressure gauge so I can measure line pressure in every gear to compare against factory specs.

Since I thought it might be a hydraulic leak I put a bottle of Lucas magic-in-a-bottle trans slip fix stuff in there. It's really thick and helps get leaking seals to leak less. If it's a hydraulic problem that should help. Well, it did help some. It still slips in 2nd, but now it slips about 1/2 a second before it starts spinning 2nd till 60 mph. Not fixed but wayyyy better.

Line pressure gauge arrives tomorrow, will test and have data on that tomorrow.

For now I'm going to build a torque management system and tie it into my electronic boost controller and the MS3 PRO so I can pull timing on gear changes as needed (torque management sends signal to MS3 PRO), and run as much boost as each gear will hold with boost by gear (boost controller). The boost controller already works, just needs some updating for boost by gear functionality. The torque management is just an idea at this point, going to start on that next.