Marquis de Sad - 1997 Mercury Grand Marquis

[dbh97]

I have acquired a 1997 Mercury Grand Marquis for a transmission test subject. It's got a 4R70W, which ought to be pretty easy to control.

I bought this thing from a kid in Oklahoma City on January 20. I failed to sufficiently "buyer beware" and only gave the title a passing glance. As it turns out, it was not only not notarized (Oklahoma is one of 8 states that requires it), but even worse was signed by someone other than who I was buying it from. I just glanced at the signature and saw it started with the right letter. Then followed a long goose chase in which the kid I bought it from and his dad were quite uncooperative, and my local DMV here in Kansas were even less cooperative. Luckily for me, I found a receipt in the car with the phone number of the guy who signed the title. I ended up hitting the road at 3 in the morning on March 23 to drive 4.5 hours to OKC to meet up with him at a tag agency. Everything went smoothly for once, and I walked out with an Oklahoma license plate, and should be getting a title in my name in a week or two, fingers crossed.

In the intervening month, I did some work on it to get it to a relatively usable state. The driver door hinge was so worn that the top of the door was hitting the rear door. Both rear window regulators were broken, and the driver's side one was failing to keep the window up, so I replaced it so I wouldn't need to keep the thing inside all the time. It also looked like it had backed into something at some point. I pulled the sheet metal (relatively) straight and replaced the left tail light and heckblende.

Now I need to replace most of the stuff in the front suspension. I waited until I had a tag to dig into that just in case things really turned south and I couldn't even keep the thing. I replaced the tie rod ends the other day, and it already drives a lot nicer. Today FedEx dropped off a set of eBay control arms with ball joints, so one of these days I'll replace those.

Today I got my Proteus plugged into it for the first time, with the stock PCM handling the engine, and everything transmission-related wired to the Proteus. Looks like the stock PCM and Proteus can share the same crank signal just fine, so RPM input is a go. The vehicle speed sensor input, however, has a lot of noise for some reason. It's reading anywhere from 7 to 25 MPH sitting still. I seem to recall something about putting a resistor in series with VR+, so maybe I'll try that next.

[AndreyB]

Exciting news and let von Sacher-Masoch be with you on this journey!

[dbh97]

His spirit marches on.

The 10K resistor has been quite successful. There's no noise when parked. When you start moving there's some noisy nonsense but it settles out quickly and behaves as it should.

[dbh97]

I need help understanding electronics again. The pressure control solenoid seems to have PWM control targeting some current, but the duty cycle doesn't change significantly, only the frequency. This goes against my understanding. Does varying the frequency to a solenoid change its output force?
KOEO

KOEO-1ms.png (52.51 KiB) Viewed 4779 times

Parked

parked-1ms.png (53.42 KiB) Viewed 4779 times

Driving

driving-1ms.png (65.11 KiB) Viewed 4779 times

[Dron_Gus]

What is timescale? 1mS?
So frequency is about 5..8 KHz? This seems to much. Looks like you are looking at switching regulator trying to keep constant current through solenoid.
Switch to 100mS scale. As far as I know transmission solenoids modulated at frequencies about 10Hz.

[dbh97]

If that's the case it's slower than 10hz; at 100ms it looks the same:

100ms-2.png (115.91 KiB) Viewed 4705 times

100ms is the highest my cheap USB scope will do.

[Dron_Gus]

If that's the case it's slower than 10hz; at 100ms it looks the same:
100ms-2.png
100ms is the highest my cheap USB scope will do.

Hm... Do you know how output is implemented in stock TCU?
Add RC filter and connect oscilloscope after it to measure effective voltage.

[NormanAlphaspeed]

I need help understanding electronics again. The pressure control solenoid seems to have PWM control targeting some current, but the duty cycle doesn't change significantly, only the frequency. This goes against my understanding. Does varying the frequency to a solenoid change its output force?
KOEO
KOEO-1ms.png
Parked
parked-1ms.png
Driving
driving-1ms.png

AS FAR AS I UNDERSTAND, yes it does.
From working with things that deal with air (boost solenoids and idle valves), lower frequencies flow more air at the same duty, something with the air's motion being disturbed by the valve's movement. I wouldn't doubt it's the same deal with fluids (since air is technically a fluid)

[dbh97]

A multimeter in DC mode, which I assume does basically the same thing as a RC circuit would, shows 9.8-11.2 volts. It doesn't seem to vary in a way that makes sense to me, it seems pretty random.

I feel like ignoring for now, controlling it with ordinary PWM seems to work fairly well. I just thought if someone happened to know exactly what was going on it would be helpful.

[dbh97]

I woke up this morning with the goal of making the transmission shift automatically. I didn't reach that goal, but I'm really close.
Remaining problems:
1. I forgot to reconfigure my shift solenoids after my configuration got wiped. (I think this was due to changing FLASH_DATA_VERSION, but IDK how that works.)
2. VSS going crazy at first is no bueno as it usually tries to make the transmission shift into its highest gear right off the bat.

Honestly I could probably ignore #2, go out and reach my goal tonight, but I'm tired.

[dbh97]

I got 34 automatically-shifting miles in today. The VSS is a problem, but otherwise it's drama-free. I reckon maybe the issue I am seeing with the VSS is probably the same as Andrey was having with ISS. The next step is to throw a scope on it to see if I'm getting a signal that ought to be usable.

[AndreyB]

Wow!!! I might end up with a crown vic one day?

[dbh97]

Some VSS scope captures at low speed for reference. There's a little EMI noise, not sure if that's what's causing the issues or not.

vss.png (36.28 KiB) Viewed 3421 times

vss4.png (32.57 KiB) Viewed 3421 times

vss5.png (31.41 KiB) Viewed 3421 times

vss8.png (34.01 KiB) Viewed 3421 times

vss9.png (35.07 KiB) Viewed 3421 times

[dbh97]

Here's what the frequency looks like when you get rolling, pre-filter:

Code: Select all

0
347
48
336
49
41667
2
71
4
347
183
57
5
535
15
111111
8
6
591
7
7
7
8
8
7
8
8
8
8
8
8

So yeah, it's a noisy mess, and I don't know what to do about it.
The filter doesn't help much, it comes out looking something like this:

Code: Select all

0
142
228
183
194
17101
24991
1995
-3605
1885
-267
261
12
212
331
45488
66677
5240
-9486
4991
-1418
246
29
-29
25
2
9
8
8
9
8

Garbage in, garbage out.

[mck1117]

Looks like you are looking at switching regulator trying to keep constant current through solenoid.

it's a degenerate case of a current mode switching regulator - it's just freewheeled PWM through the solenoid (solenoid itself is the inductor in the buck)

[dbh97]

Matthew figured out why the VSS wasn't working at low speeds - The MAX9924 goes into a more sensitive mode if there has been more than 85ms since the last output, which in my case works out to about 3.4 MPH.
https://github.com/rusefi/rusefi/issues/4117#issuecomment-2050869491

There is another VR decoding option, however - rusEFI's own discrete VR implementation. Andrey sent me a uaEFI, and it seems to work quite well. It also works with Ford's one-wire VR sensors.

I'm not sure what the path forward is for this vehicle - I'd like to make Hellen-EEC-V, but that might be a D is for Distraction. I'll think about it some more.

[AndreyB]

So next milestone repeating same on official master build? Maybe even with some default calibration hard-coded into https://github.com/rusefi/rusefi/commit/cea92b0f8293bba0abdedc349e6797e67a20a5d6?