Re: Confused
Mx6Man said:
Isn't is possible to get a KLZE PROM to replace the one in the KL03? Would you please explain the PROM and VRIS points to me. Is the prom just the chip that needs new commands burned into it? I am very impressed with response I got back from Mike. I like reading the messages you give back to other peoples questions. You actually give information as opposed to saying what you think looks good or sounds good.
The PROM is memory in the PCM that contains the program the PCM's microcontroller runs and it also contains calibration data the program uses to calculate things like spark timing, fuel delivery, VRIS operation etc. All told, something just over half of the PROM (about 17K bytes) are devoted to calibration data, the rest to the program with unused bits here and there.
The KLZE and KL03 PROMs are remarkably similar to each other, with the biggest differences in occuring in the VRIS points & strategy, the main spark timing table and the VAF linearization table. To visualise the spark timing tables for instance, go to my web site and look under the PCME page. Near the bottom I show graphically the two spark timing tables. They are quite different.
"VRIS points" refers to the RPM at which the PCM switches the VRIS plates to a new configuration. In the KL03 for instance (assuming more than 2.75V of throttle), the PCM sets both VRIS plates to the closed position from 500 to 3250 RPM. When the RPM hits the 3250 "point", the PCM opens the #1 VRIS plate. Similarly, at the 4250 point, it opens the #2 plate and at 6250, it shuts them both again.
The "points" at which the plates are switched is programmed into the PROM and are determined from the design characteristics of the intake manifold. That is, in certain RPM ranges, the intake pulses from each of the cylinders resonates with the natural frequency of the volume inside the manifold. At this point, there's a small (but noticeable) "supercharging" effect as pressure pulses, enhanced by constructive interference due to the resonance, pushes air into a given runner. The strategy of VRIS is to try to make the manifold have several of these resonance ranges, thus maximizing torque, by varying the effective lengths (and thus volume) of the runners and plenum. This is primarily the function of the VRIS #2 plates. The VRIS #1 plate opens or closes the passage through the small "loop" on the passenger side of the intake (near cylinder #1) that connects the two plenums (cylinders 1, 3 and 5 share one plenum, 2, 4 and 6 share the other). By doing this, the pulses from cylinders 1, 3 and 5 can help cylinders 2, 4 and 6 and vise versa...but only in certain RPM ranges. In the case of the KL03, it's in the 3250 to 6250 range. Outside this range, not only is there no benefit but it might be detrimental to have the plenums connected; it may
lessen output due to destructive interference.
Just by looking at the two types of manifold (KL03 and KLZE), it's clear they are physically quite different, with different internal volumes, runner sizes, shapes etc. As a result, the KLZE manifold has different resonance points than the KL03 manifold.
If the VRIS points are wrong, the torque curve will have drop-outs in it as the engine passes out of a resonance range and the plates don't change properly. For example, way back when when I was first playing with the VRIS points on my PGT, I lowered them a few hundred RPM. Compare
http://home.golden.net/~trinity/dyno/run3.jpg
with
http://home.golden.net/~trinity/dyno/Run5.gif
in which the points were returned to near-normal. Look at the torque curve for run3 at 2900 and 3750...look at the sudden drops in torque. In run5, things are much smoother. Even though the dip at the 4250 isn't tiny, clearly the engine has a much easier time pulling itself back up again, compared to run3.
This is why I say that, to get the most from a KLZE conversion, the PCM must be re-programmed with at the very least, the KLZE VRIS points, if not the KLZE spark as well.
A KLZE PROM cannot be used directly in the KL03 for several reasons. Primarily, the VAF used on KLZE cars was different than that on the KL03 so the PCM wouldn't be getting the correct airflow data. As well, the KLZE PCM doesn't have a baro sensor so the fuel calculations might be incorrect and it also doesn't have any EGR actuation hardware. One can, however, given the tools and knowledge, copy the VRIS activation points & strategy from the ZE to the 03 PROM (ensuring you get the addresses right
