What are the differences between 89 Mark VII pcm , 89 Mustang HO PCM vs 91 LOPO PCM?

[stinkydogfilms]

Are the shift points different in each, if so what rpm are they at? Any other differences in the block,rods,crank and pistons? I know the heads and the cam are different.

Any major difference in the AOD transmissions in the following motors/car combos?

The LOPO would be in the 91 GM.
The HO in the 89 Mark 7.
The HO of course would be in the 89 Mustang GT.

Thank you

[sly]

none of them control shift points (mechanical trans). Mark VII and Mustang have HO firing order. Lopo has ... lopo/truck firing order. Different cam is the main difference (for the firing order). HO intake manifold is a bit better too. No major difference in the AODs... though 89+ are better as a base. The HO cars do have the high rev governor in the trans that sets the shift points higher though. The mustang doesn't have cruise in the ECM, but the other two will.

[jaywish]

Also the Lincoln transmissions have the longer tailshaft.

[gadget73]

lopo pistons are different. cast dished piston vs a forged piston with valve reliefs in the HO engine. The remainder of the bottom end is the same. Heads, cam, and intake are different but identical between the Mark VII and Mustang. Lincoln engines are usually a bit less beat on since they cost about twice as much when new.

The governer in the AOD for HO cars does a WOT shift around 4800 RPM, the governer in the non-HO cars shifts about 4200 RPM. Lincoln tailshaft is longer as mentioned. Column shift vs floor shift cars have a different linkage on the side of the trans, but its not a big process to change the parts out. Basically a roll pin and a nut and a few minutes paying attention to what you're doing and its done. AODs are purely mechanical and shift scheduling is done with a combination of TV pressure and valve body springs and flow ports. its a pretty damn complex valve body.

Another difference besides the firing order and cruise is the fact the 89 Mustang ECM uses a completely different fuel mapping system. The Grand Marq and Mark VII ECM use whats called speed density. It relies on engine speed, air density as determined from some temperature sensors, engine load from the MAP sensor, and throttle position to determine how much fuel to give based on known engine parameters that are coded in the ECM. The Mustang ECM is mass air, which means it directly senses how much air is being sucked in via a MAF, or mass airflow sensor. It has the temperature and throttle position sensors as well but it figures its fuel based more on direct data. It still has it's limits but generally you can change more on a mass air motor before it runs stupidly and forces you to have it re-tuned than you can on a speed-density engine. On the other hand, it also means you need to do a little presto-chango wiring magic to accomodate the extra sensor. Its minor and has been documented fairly well but its something to be aware of. The Mark VII ECM you simply plug in and run once you change the engine.