1983 Toyota Cressida - 18 MPG to 27+, but running out of ideas...

[JRMichler]

Originally Posted by gizzardgulpe

Automatic. It sits at 2200 RPM at 60 mph, in fourth with the torque converter lock engaged. I have wonderful power at this speed, and I can easily accelerate uphill without downshifting. In fact, the only way to make it downshift at that speed is to press the accelerator all the way down and trip the computer's shift trigger. It has very nice power in that band.

This car is begging for a gear ratio change to get that RPM below 2000. You will lose the "wonderful power", but won't need that power once you get good at DWL.

As for ignition timing, look for a Haynes or Chilton repair manual. You can lose several MPG if the timing is off by only a few degrees.

Cam timing is not intended to be adjustable. It changes when timing chains wear.

Does it have a carburetor or fuel injection?

[gizzardgulpe]

Originally Posted by JRMichler

This car is begging for a gear ratio change to get that RPM below 2000. You will lose the "wonderful power", but won't need that power once you get good at DWL.

The gear ratio on the transmission is the same as my wife's Grand Prix, but the difference is in the differential, according to the research I did. The one I probably have is a 4.1:1 and they made a few 3.7:1 differentials. The trick is finding one that is in good working condition. And having the money to pay for it as well.

Originally Posted by JRMichler

As for ignition timing, look for a Haynes or Chilton repair manual. You can lose several MPG if the timing is off by only a few degrees.

I used the instructions in the Chilton manual that resulted in such poor timing that I couldn't accelerate into traffic safely. I cannot seem to log in to the state library website to get back to the manual to double-check what I learned, so that'll have to wait for a day or two, but I seem to remember it saying to set the timing to ten degrees at ~600 RPM, and that was just obscene. The car barely ran.

Originally Posted by JRMichler

Cam timing is not intended to be adjustable. It changes when timing chains wear.

Does it have a carburetor or fuel injection?

The timing belt is only about 5 or 6 thousand miles old. It is fuel injected.

Originally Posted by Cobb

Plan b, instead of lowering, add an air dam, lawn edge strip bottom of bumper.

The bumper sits about a foot off the ground and I haven't quite figured out how to extend that downward enough to put a wind dam on short of building some kind of framework and manufacturing a new bumper. Any suggestions?

[gizzardgulpe]

https://www.dropbox.com/s/uk5gtrssgk...65217.jpg?dl=0

Here's a profile shot of the bumper situation. It has two recessed turn signals underneath the bumper.

[nemo]

Originally Posted by gizzardgulpe

I used the instructions in the Chilton manual that resulted in such poor timing that I couldn't accelerate into traffic safely. I cannot seem to log in to the state library website to get back to the manual to double-check what I learned, so that'll have to wait for a day or two, but I seem to remember it saying to set the timing to ten degrees at ~600 RPM, and that was just obscene. The car barely ran.

This sounds about right to me, in the static position without advance.


Important steps in the process.

Short the terminals of the check engine connector to check the timing-1983-84 Cressida

Allow the engine to run at the specified idle speed with the gearshift in Neutral with manual transmission and Drive (D) with automatic transmission.

Procedure
| Repair Guides | Firing Orders | Ignition Timing | AutoZone.com

[gizzardgulpe]

I just got back from a quick trip having just adjusted the timing. I've lost a considerable amount of power. Not as bad as before, when I set it to 10 degrees at 600 RPM; now it's at 10 degrees at 800 RPM. It's very sluggish and the engine vibrates a bit more.

Something just doesn't seem right.

Also, I just found out how to test the EGR, so that's going on the to-do list.

[nemo]

With the jumper wire removed from the engine check connector, the ignition timing advance will be between 9-11° BTDC.

Does this happen?

[redneck]

.

It seems that you're right on the revised EPA average.

1983 Toyota Cressida Fuel Economy Ratings



Does you car have this button...???

Also new, and going well with the power boost on the straight-six, was the world’s first electronically controlled automatic transmission to offer drivers the choice between power, normal driving, and economy with the push of a button; it also had four speeds, still very unusual at the time.

Toyota Cressida - Mark II history and information




You need a mpguino.


>

[NateHale88]

Yes! You definitely need a MPGuino! It will help you exponentially!

I may have an extra I could sell you. Just let me know. :-)

[gizzardgulpe]

Originally Posted by nemo

Does this happen?

Yes. The engine slows by about 100 RPM when I short the connector, then jumps up when I remove the wire. The timing changes by a degree or so as well.

@ redneck:

Yes, it has the selector and it works. It basically sets the RPM/Load ratio to shift at lower RPM in economy mode, so with gentle acceleration, it won't get over 2000 RPM before it hits overdrive.

It bothers me that I'm barely getting the EPA estimate after all the work I've put into this car.

@NateHale88:

I can't afford much, but PM me a price and we'll talk. ^_^

[gizzardgulpe]

Took my usual trip today. Checked the brakes twice for signs of heating and they were all uniformly cool. Shifting into neutral allows me to coast for much longer than coasting while in drive, so the engine definitely slows the car.

Other than the questionable idling and losing some power in lower RPM ranges, the car ran fine with the new timing adjustment.