AC and timing...

[marc_w]

Why is it that timing gets pulled when the AC compressor cycles on?

Most of the time it's pretty transparant when driving... but others, like when driving at low speeds, the cycling interferes and make throttle control a little difficult.

Any way to disable or modify this?

[Screamn03]

That's weird, all the ideas I came up with got shot down when I looked at your screenshot. At first I thought there might be a MAP change but that's not the case. Then I thought a RPM change, nope. Then I thought maybe the A/C clutch was triggering the knock sensor, no KR detected. WTF?

[Screamn03]

BTW:This thread is almost a month old, did you ever figure it out?

[LBSBLOWN]

Why is it that timing gets pulled when the AC compressor cycles on?

Most of the time it's pretty transparant when driving... but others, like when driving at low speeds, the cycling interferes and make throttle control a little difficult.

Any way to disable or modify this?

On my 2001 Suburban 5.3 4x4:
After my magnacharger Install I noticed this Timing being pulled issue also
and with the supercharger it was much more noticeable,
It took 4 months working with Magnacharger and superchips that dose the programer for Magnacharger to find and fix the problem .
I was told that there is a timing table for the A/C compressor and that the removed some of the timing being pulled.
Anyways they fixed it and I'm happy.

[Bill@HPTuners]

On my 2001 Suburban 5.3 4x4:
After my magnacharger Install I noticed this Timing being pulled issue also
and with the supercharger it was much more noticeable,
It took 4 months working with Magnacharger and superchips that dose the programer for Magnacharger to find and fix the problem .
I was told that there is a timing table for the A/C compressor and that the removed some of the timing being pulled.
Anyways they fixed it and I'm happy.

a blower and a/c are very different...theres the iat vs timing table as well you have to keep in mind where if the intake temps hit a certain degree it will pull loads of timing i know on trucks they pull even more i believe up to 11 degrees with the stock table...there may be a separate table as you say for a/c but the iat vs. timing table is probably what they "fixed" on your truck more then likely.

[LBSBLOWN]

a blower and a/c are very different...theres the iat vs timing table as well you have to keep in mind where if the intake temps hit a certain degree it will pull loads of timing i know on trucks they pull even more i believe up to 11 degrees with the stock table...there may be a separate table as you say for a/c but the iat vs. timing table is probably what they "fixed" on your truck more then likely.

No,
What was going on is at steady cruise, steady TPS, flat road I would see
the Ignition Timing adv. at 40deg and then for no reason dip to 18deg and
them jump back to 40deg.
This only happens when the Air Conditioning was on, the compressor cycles
and the timing dips.

I complained to Magnacharger about this because you could really feel it
when driving at light cruise.
They reproduced the problem on there dyno and modified the Timing table for the Air Conditioning compressor, I was told.
anyways they fixed the problem.

[Bill@HPTuners]

No,
What was going on is at steady cruise, steady TPS, flat road I would see
the Ignition Timing adv. at 40deg and then for no reason dip to 18deg and
them jump back to 40deg.
This only happens when the Air Conditioning was on, the compressor cycles
and the timing dips.

I complained to Magnacharger about this because you could really feel it
when driving at light cruise.
They reproduced the problem on there dyno and modified the Timing table for the Air Conditioning compressor, I was told.
anyways they fixed the problem.

huh well at least you got it fixed...i thought before you had the blower you were getting say 40 degrees but then after the blower all of a sudden you were getting 30 degrees but your intake temps wouldve been say 60 degrees warmer so it wouldve been pulling...but if its sparadic when the a/c is on thats something different.

[Chris@HPTuners]

yes there is a timing retard when AC cycles on. I have added this table to 1.6

Chris...