89 Iroc Z

I am running a 730 with the Super AUJP code. I have a ZZ4 and I am getting a ton of knock counts has anyone else experience this? I am going to pull timing out but didn’t think the super AUJP had too much timing.

Also here is a really stupid question but what do knocks sounds like. At WOT I hear like a clicking coming from the engine bay / trans area, almost sounds like a exhaust rattle. Just wondering if anyone could explain what a knock sounds like.

Z69

What's your static timing set to?
Might try changing it to see if the noise goes away.
Might be slightly faster than a chip burn....
The knock sound can vary.
Also depends on how hard it is.
I notice my hyperuetectic's sound a little different than forged pistons do too. Or could just be the acoustics of a newer design head and stroke crank combo.
Best I can do is it sounds like a spray paint can being shaken but has a higher pitch usually.

3.8TransAM

Any rattling sounds from the engine can be picked up by the knock sensor. Exhaust leaks from header collecotrs seem to be a real popular one as well. Specially us folks with SLP headers lol

Misadjusted valve train or springs suffering from coil bind can trigger it as well, as could bad accesories or belt tensioner.

I dont like the Super AUJP, IMHO it has wayyyyyyyyyyyy too much part throttle timing and the wot is more than I run...(yes i know u ahve aluminum l98 heads)

Have a stock GTA(inj and catback only) using a anjf as a base .bin putting 225hp and 315 ft lbs at the wheels on a dyno and 14.40's at 97mph with 2.3 60's at the track :-)

I use a lot less cruise timing(usally 2 deg less than aujp or anjf) and around 27-28 deg tops at wot. (may even be as low as 26.x have to verify on bin)

Less timing and = to or greater than performance works for me :-)

later
Jeremy

JP86SS

iTrader: (1)

I've been running the S_AUJP and have not had any issues with the timing or knock counts.
I get good midrange and real nice drivability from just tweaking the VE tables.
There must be something causing the false readings.
My motor is pretty stock (i think its an 86-88 T/A motor, will find out this winter).
Don't have anything else to add.
JP

clippjr8

I just fixed a problem like this last week. The distributor set a 6* would cause a ton of knock using the S-AUJP bin and i could not fix it by just lowering the spark tables so we had to back the distributor down to 2* base timing and all the knock is gone along with the sound of the valves when there is too much advance.

nape

iTrader: (1)

I blew out a couple rings running Super AUJP and that was even after cutting out a bunch of timing, I was on 87 octane though. I'm sure that had something to do with it, it ran a lot better with 93.

89 Iroc Z

Well I ran a new engine about 500 miles on the super AUJP until I got around to scanning it and it would go to 255 knock counts then reset a few times over the coarse of a 15 minute drive. I just hope it didn't do any damage!

I just copied the stock corvette tables over and the problem is fixed.

JP86SS

iTrader: (1)

I'm only running 93 octane with about 4* BTDC and haven't had any issues. At 6* I did get some constant knocks but just 2* removed it completly. Only get an occasional 4-6 counts when tromping on it.
I'm beginning to wonder why if alot of others are saying there is too much timing.
My knock circuit is working well, etc.

89 Iroc Z

Is there any way to tell if you blow a set of rings other then to do a leak down test? I did a leak down test and the numbers were pretty bad. Can you measure the blow by via the PCV port or something?

Black 91 Z28

I'm running it and am not have in a lot of knocks. I get a couple on cranking and shutting down and 1 or 2 during WOT driving. Other than that it runs fine in closed loop mode. When I start it up in the morning after leaving it off for a while it kinda chugs some..but once it goes to closed loop it's fine.

Grumpy

A borescope. The prices have come way down, for under $200 you can get a 1/2 decent one. There's been a bunch on eBay lately.