Assuming the stock system is working AS INTENDED all of the above EXCEPT performance.

I don't know....you'd probably be able to improve performance also. The stock system doesn't allow you the ability to dial in/fine tune things like a modern system.

Edited January 8, 201213 yr by sblake01

By taking control of the timing curves, you can gain performance. However, ALL of the above can also be made WORSE. It all depends on the tuner's and installer's expertise.

Performance will increase if the spark and fuel maps are done adequately. Removing the restriction of the AFM (not needed with MAP based EFI, aka "speed-density") gives you inherent gains in performance. All aspects of engine performance will be better, again, if done correctly.

HP is a product of airflow-not fuel delivery method.

  Z train said:

HP is a product of airflow-not fuel delivery method.

Right. I'll quote myself, with some emphasis added this time:

  LeonV said:

Performance will increase if the spark and fuel maps are done adequately. Removing the restriction of the AFM (not needed with MAP based EFI, aka "speed-density") gives you inherent gains in performance. All aspects of engine performance will be better, again, if done correctly.

Also, MS can be (and often is) used to go to distributor-less ignition. A completely tunable timing curve will give you more power compared to using a distributor, because of total spark map control and essentially zero spark scatter.

  Z train said:

HP is a product of airflow-not fuel delivery method.

BTW, power is very much a product of fuel delivery method as well, since different fuel delivery methods have their own inherent pros and cons.

Carburetors use venturis, this is an inherent pressure drop caused by the fuel delivery method of any carb'd engine. Equally sized ITBs will make more power.

Port fuel injection injects fuel essentially at the valve, thus there is much less opportunity for the injected fuel to homogeneously mix with the air. Less homogeneous mix equals a less efficient burn which equals less power. Not as big of a deal as a venturi, but it's still there. This is why high-performance (read: race, "not for highway use") engines inject before the throttle body, not at the valve.

These things all have to do with how fuel is introduced into the intake/engine, thus fuel delivery very much affects HP. In the case of carburetors, the fuel delivery method directly affects airflow. In the case of port injection, the fuel delivery method affects the way the mixture is burned. The causality is the same for direct or TB injection.

This can go on for any system, so making a generalization such as HP not being a product of fuel delivery is incorrect and at best a gross oversimplification.

Only one way to put this-Leon,go back to school.You haven't a clue.

  Z train said:

HP is a product of airflow-not fuel delivery method.

Since proper vaporization of fuel and precise metering IS important to power, along with a dozen other factors, what's your point?

Steve

  Z train said:

Only one way to put this-Leon,go back to school.You haven't a clue.

Seems like you're then one without a clue...

Let's keep things civil, guys. This looks like a problem that several hundred thousand engines may have, and if we can come up with a good solution, bring some new life into all these older engines.

I keep wondering... Could we come up with a (new) system to do what the old ECU did, including attach to the factory EFI harness? Even with all those aging wires and connectors? The stock ECU costs almost as much as a rebuilt engine longblock! There ought to be a way to take in the factory sensor signals, and run the injectors just like the factory ECU, but with certain adjustments

Aaaanyway. The stock EFI system is a good system. It was leading edge, reliable(most are still working fine). It got you through extreme cold and hot, and it met emissions criteria...even in Cali. It was pretty easy to fix if you had the FSM, and had some basic electrical skills. It drove great, without hiccups and misfires. All in all, I would say even an excellent system.

There are DOZENS of options for upgrading/replacing/updating the JECS system. There is no magic bullet. Bottom line, is that in 99% of the cases, I venture to say, the problems are due to age, wear, and corrosion. Not problems due to not having a "good" system in the first place.

Edited January 9, 201213 yr by cygnusx1