1998 Vortec 5.7

[HartRod]

1998 Chevrolet Tahoe stock 5.7 Vortec other than a Magnaflow muffler. 135K miles, new plugs, rotors, cap and wires. Stock tune, but getting some knock I can't figure out. Tune and log attached. TIA

[SiriusC1024]

It's usually best to get fueling correct before messing with spark to address KR. Do VE and MAF. If you need help lmk.

[HartRod]

It's usually best to get fueling correct before messing with spark to address KR. Do VE and MAF. If you need help lmk.

Any help would be greatly appreciated. I've been around HPT for a while now, but I'm not a tuner. So far I've concentrated on doing the engine swaps including wiring. I would like to learn some basics so that I can get these swaps drivable enough to take to a tuner. This truck isn't a swapped vehicle, but should be a good one to learn the basics on. Here's another log I did this morning after doing the plugs, wires and cap. Thanks in advance for your help.

[SiriusC1024]

See if this helps. After loading the tune go into VCM Scanner>Vehicle Controls & Special Functions then clear fuel trims and LTFT's.

[HartRod]

See if this helps. After loading the tune go into VCM Scanner>Vehicle Controls & Special Functions then clear fuel trims and LTFT's.

Thanks! I'll get that flashed tonight and do a new log.

[Fast4.7]

These all spark knock on 87. Best to run 91 and give it the timing it wants to run well.

[HartRod]

No log today, hopefully tomorrow.

These all spark knock on 87. Best to run 91 and give it the timing it wants to run well.

No 91 around here, 87, 89 and 93.

[bk2life]

No 91 around here, 87, 89 and 93.

then fill'er up with the 93 juice

[HartRod]

then fill'er up with the 93 juice

LOL, will do!

See if this helps. After loading the tune go into VCM Scanner>Vehicle Controls & Special Functions then clear fuel trims and LTFT's.

My apologies for being slow on this, the wife and I have been sick for the last week and a half. Here's the latest log with the MAF adjustments. Do you have a good cfg file for Vortecs? Thanks again for all your help.

Rob

[abc]

Looks like it is just octane limited. As suggested, test with higher octane fuel. If the KR goes away with the additional octane then you have your answer. If it is still present and you want to dig in heavy, use a secondary method of knock detection, such as knock ears, to verify if it is actually knock. If you don't hear it with the secondary detection, you can then adjust the sensitivity of the knock sensors to get your ignition advance back.

[HartRod]

Looks like it is just octane limited. As suggested, test with higher octane fuel. If the KR goes away with the additional octane then you have your answer. If it is still present and you want to dig in heavy, use a secondary method of knock detection, such as knock ears, to verify if it is actually knock. If you don't hear it with the secondary detection, you can then adjust the sensitivity of the knock sensors to get your ignition advance back.

Log with 93 Octane.

[Pitbull]

Thats not bad at all as far as knock goes. Is the truck high geared? Looks like it just lugs out of the bottom a little. What does it look like at WOT?

[HartRod]

Thats not bad at all as far as knock goes. Is the truck high geared? Looks like it just lugs out of the bottom a little. What does it look like at WOT?

It's got 3.42s with 33" tall tires, so yea, 4.11s would be better.

[SiriusC1024]

It's still knocking with fueling corrected and higher octane. You can either desensitize the knock sensors or remap spark. Any chance the knock is related to the ignition components you recently installed?

[HartRod]

It's still knocking with fueling corrected and higher octane. You can either desensitize the knock sensors or remap spark. Any chance the knock is related to the ignition components you recently installed?

I don't think so, the log was similar prior to changing any components.

[SiriusC1024]

There's always Seafoam.

[HartRod]

There's always Seafoam.

I use Marvel Mystery oil.