Joined: Fri Jan 15 2010, 08:36PM
Location: Indiana
Posts: 142
We went down to The Goodguy’s show in Indy last weekend at the Indianapolis Motor Speedway. One of the really cool things about it was we got to take a lap around the track in the car. My grandpa was a huge Indy 500 fan so I’m sure he would of enjoyed it.
Thought I would report in that I have been driving the car quite a bit this summer, about 3,000 miles. Only one problem. Twice it has died stopping from highway speed. 70-75mph, off ramp and dies while costing to the stop light at the bottom. Still working on what causes that and it has only done it twice. Longest road trip yet was to the Columbus Ohio Goodguys, about 4 hour drive. I also just finished the new hitch and brake controller install. Today is the first test tow with it.
Wish I had seen your car. I was at the Columbus Good Guys show and I took a ton of photos, but I don't remember seeing your green Plymouth wagon. I certainly would have remembered that if I had as there can't be too many 1972 Plymmies running a modern hemi.
Joined: Wed Dec 21 2005, 07:34AM
Location: indiana
Posts: 791
john66ny wrote ...
fuselage wrote ...
Twice it has died stopping from highway speed. 70-75mph, off ramp and dies while costing to the stop light at the bottom.
Torque converter not unlocking?
I’m not up on the latest OEM EFI strategies in the ECUs, but I’ve got some familiarity with the EEC-IV Ford stuff of the mid-late 80s. If the vehicle speed sensor (VSS) signal isn’t correct in an old-car retrofit setup it can lead to engine shutoff when coasting, stopped, etc.
That family of ECUs has a fuel shut-off strategy when it sees coasting (0% throttle, engine RPM above 1500, and sufficient vehicle speed). It uses these 3 inputs to determine when to cut fuel back in, so if the VSS is off it might think you’re still moving along when you’re almost stopped and pow – still no fuel, and no more backdriving of engine, so now the engine is truly off. When OD kicks out automatically at reduced vehicle speed the engine RPM pops up, extending the no-fuel coast if the VSS is still good. (VSS is most critical for putting fuel back in in a seamless manner). On a particular combination of coast and grade and hitting a red light -- it might be a corner-of-the-box scenario that you’ve only hit a 2 times this summer. Again – I’m not saying the Hemi ECU has this strategy, but it’s food for thought, and I’m sure it’s doing something for fuel savings.
I’d discount the TC not unlocking with the brake pedal (but verify it). If that was the problem, you’d be having trouble much more frequently in other driving situations too. But if it’s a VSS issue, though, that could affect TC unlock strategies and give low-speed trouble.
There are aftermarket VSS sensors with different signal rates, so you can research that if you find that’s your problem.
Side note - Once I learned how the fueling thing worked I consciously tried to take advantage of it, and the inst-MPG display numbers would tell when it ramped in. My 88 Lincoln Mark7 would average 22-23 mpg for mixed driving (not bad for a 4000+ lb car that would give my Cs a strong run for the money), and on long grades on the highway it was pretty common to see the MPG readout go to 75+ mpg. It would read triple digits, too – I did see ~150 on a few long 75mph coasts sometimes.
Joined: Tue Oct 11 2005, 01:33AM
Location: Calgary, Alberta
Posts: 5893
Joe, congrats on a great job!
For some reason I've managed to miss most of your build thread, but this morning I started at the beginning and read the whole story. An amazing job, my hat is off!
Joined: Fri Jan 15 2010, 08:36PM
Location: Indiana
Posts: 142
1975 Chrysler, We got to the Goodguys show late and parked way out behind one of the buildings. We sent the day there and I know we didn't see everything. Fury Fan, That is food for thought. I think it has something to do with the street and performance system eliminating the wheel speed sensors. I'm planning to call them and see what we can figure out. Thanks Bill, As soon as I'm caught up at work I plan to do some more to it this winter.
