8 degrees retard on stock timing table.

[EagleMark]

2* is not bad and it's just one area. Is it real knock though? If you pull say 3* from that cell and surrounding cells does it go away?

There always the chance your enablngn PE at that point and that can add spark just before you get the AFR change! Sometimes I leave a onen second delay in PE and this never happens.

[Scrufdog]

I'll pull some timing from that area and see what happens. I'll look into PE time too.

[Scrufdog]

I took out 3 degrees at 1600/70 and 1.5 degrees onthe surrounding 8 blocks. I also dropped the KR attack rate from 0.5 to 0.4 and doubled the recovery rate. Should help narrow down exactly where I need to soften my timing, while I figure out why its knocking only right there.

[billygraves]

...............

[Fast355]

You are missing some real basics here. I've seen a oil dipstick rattling induce knock, the heat shields around the spark plugs, and the Heat pipe for the air cleaner rattle induce knock. Even worn out starters that the bendix just hitting the flywheel will set it off on one. Missing bolts on the stamped converter cover or dust shield on a stick shift. Does anyone ever check this type of thing first?
The spark plug wires NOT separated on cyl's 5 and 7 and on the other side 4 and 8. GM had a Service Bulletin on this on this around 88 or 89. 82-87 ESC Trucks with 5.0L were real bad for this with a carb because the spark advance was aggressive. We had a meter we put in line with the 5.0L ESC Truck Controller to actually see the retard and when knock was actively occurring. It was an extra from GM Engineering staff we used in the Buy-Back garage.
These carbon cleaners. We ran tests on GM Top Engine Cleaner vs the Walnut blasting of the back of the intake valves around 87 or 88. Different chemicals as well. The way it functions the BEST and MOST EFFECTIVE is when the engine is VERY HOT. PLUS Allowing the engine to SOAK OVERNIGHT COVERED UP WITH BLANKETS to hold in the heat. We used bore scope before they were ava to the automotive industry and were actually from the medical manufacture to insoect before and after combustion chamber and the intake runner/ and back of the intake valve where carbon collects. (The Top Engine cleaner will foul spark plugs and contaminate the engine oil. We tried to burn it off, it didn't work and we replaced plugs and oil/filter each time)
GM Top Engine Cleaner may not be ava but a Delco distributor should have it in the Delco can. SHAKE the can up before use PLUS it DOES have a shelf life so don't buy a case and save it.
There is one more trick to detect knock. All of the Engine calibration vehicles had Stereos with Equalizers and cassette tape decks in them. The Lab took CD converter (the tape with the wire on it for the CD player.) and they used the Tape Adapter plugged into the deck. The Lab wired the center wire to the Knock Sensor Blue wire and grounded the outside wire. The calibrators would slew in about 10 degrees spark, tune IN the sounds of the spark knock, then they could hear the knock. (Slew in 10 degrees spark? This is the instrumentation stack and you could slew in neg or pos timing or fuel or EGR ect..) With the engine under a slight load in spark knock, they "TUNED" the EQ to HEAR the knock on the stereo. They would HEAR this while setting the tables. Just a tid bit to help.

I had one of those 5.0 ESC Vans that had a standard M4ME Q-Jet on it. Later in its life it got an intermitent no start when the ESC control module died. Dropped a conventional HEI that had been recurved for heavy towing/rv application into it and it ran so much better.

[Scrufdog]

I really wouldnt be surprised if it were something rattling around, if it weren't for the fact that 93 took the knock down from 8 to 2 degrees. It's just really odd to me it only happens in that one specific spot and nowhere else. I got some more cleaner stuff today and will proceed from there. Any more ideas are always handy.

[Scrufdog]

Disabled the TCC lockup today. Couldnt get it to knock. Bumped the timing tables back up to stock, no knock. Advanced entire table 4 degrees, got 3 degrees of knock in the same general area. Tweaked the tune again, bumped the timing back to stock, left the TCC disabled; will upload in the next day or 2 and see if I can get it to knock. If need be I'll avoid advance in that area and give a gradual bump up from stock over 2000 RPM.

[steveo]

at least you've determined it isnt false.

be careful with substantial changes in timing too, remember that modifications in timing move you across the map axis of the timing table (lower map for more timing usually). if you add more than a couple degrees timing to a cell, sometimes that'll shove you right into an adjacent cell, and if the curvature of your timing map isnt quite right, you could be chasing ghosts.

[Fast355]

Disabled the TCC lockup today. Couldnt get it to knock. Bumped the timing tables back up to stock, no knock. Advanced entire table 4 degrees, got 3 degrees of knock in the same general area. Tweaked the tune again, bumped the timing back to stock, left the TCC disabled; will upload in the next day or 2 and see if I can get it to knock. If need be I'll avoid advance in that area and give a gradual bump up from stock over 2000 RPM.

With stockish TCC settings my Express Vans 5.7 Vortec would knock in about the same place with the stock timing map.

I use BC Transmission software to adjust my shift points and TCC lockup tables. I set the minimum RPM for TCC lockup to 1,800-2,000 rpm depending on the vehicle and delay the part-throttle upshifts slightly. The result is a much nicer driving vehicle that isn't as lugged down and sluggish. Anywhere it is 65-70+ KPA and under 2,500 rpm at part-throttle it should really have the converter unlocked or the transmission downshifted. Too much lugging is abusive on the rod bearings.

[alkatyler]

at that kind of mileage on the tickomoter, how is the timing chain set looking.
take off the cap and turn the crank back and forth. The rotor should turn immediately and not have any hesitation.

just a thought, how is the compression on the cylinder with the white plug?

[Scrufdog]

yeah, i was thinking about that. Problem is my bin seems to rely only on MPH for shifting, not RPM. All the shift points vs RPM are 0. I'll tweak around and see what I can do.

[Scrufdog]

at that kind of mileage on the tickomoter, how is the timing chain set looking.
take off the cap and turn the crank back and forth. The rotor should turn immediately and not have any hesitation.

just a thought, how is the compression on the cylinder with the white plug?

When I change the cap/rotor/wires I will check all that.

[Fast355]

yeah, i was thinking about that. Problem is my bin seems to rely only on MPH for shifting, not RPM. All the shift points vs RPM are 0. I'll tweak around and see what I can do.

Thats why I use the BC software. The RPM is handled by the software. It uses alot of different logic to calculate the shift points and lockup parameters.

[Fast355]

GM transmission tables mostly carry over so it should not be hard to use this program even with a TBI.

http://www.hptuners.com/forum/showthread.php?44953-Bluecat-Transmission-Table-Software

You can see the end result is very nice. LT1 cammed L31 suburban with a S10 converter that flash stalls about 2,800 rpm, and 3.73s out back. Driving it around town it is as driveable as the stock engine and stock programming.

http://www.youtube.com/watch?v=3RAqXKq1e9Y

[Scrufdog]

Thats why I use the BC software. The RPM is handled by the software. It uses alot of different logic to calculate the shift points and lockup parameters.

BC software? Please expand on what you mean?