1995 K1500 LO5 tuning- Autoprom

**Roadknee** · 03-24-2014

I think I verified the knock retard is mechanical. I was looking at my tune and I had the spark advance down to about 14 degrees WOT at 4,000 rpm and was still getting KR. I bumped it up to 20 and get the same KR. However, now it runs around 18 degrees according to the datalog instead of 12. Pulls a heck of a lot better too. A post above suggested a loose timing chain as a probable cause. I must admit I haven't seen many (any) 160K mile SBC timing chains that didn't need replaced.

**Roadknee** · 03-25-2014

I was at my dads place today and he had a handheld vacuum pump laying around. I thought to test the EGR valve and it would not hold any vacuum. It was just like pumping through an open hose. Shouldn't this have thrown an EGR Fail code?

**EagleMark** · 03-25-2014

You'd figure that would make the test fail. Here's what it has to do?

Code:

       ;------------------------
        ; ERR 32    
        ; EGR Diag & Errrr calib
        ;------------------------
L4E42   FCB 30      ; 30 SEC DIAG CYCLE TIME
L4E43   FCB 64      ; 60 Kpa Low Load disable
L4E44   FCB 208     ; 15 Kpa Hi load disable
L4E45   FCB 15      ; 6% Low TPS Disable
L4E46   FCB 77      ; 30%  Hi TPS Disable
L4E47   FCB 243     ; 95% Desired required for Err test
L4E48   FCB 30      ; 3 SEC'S Err delay timer
L4E49   FCB 3       ; 3 Fail counter min
L4E4A   FCB 10      ; 4% diff TPS to escape test
L4E4B   FCB 25      ; 2.5 Sec's integrator test time
L4E4C   FCB 4       ; 4 integrator count max for err
L4E4D   FCB 45      ; 45 MPH min for test
L4E4E   FCB 12      ; 300 Msec Integrator delay if EGR
        ;------------------------

**Roadknee** · 08-13-2014

In April I burned a chip and took a break from tuning to concentrate on some other things. I've been pleased with how it runs with the custom tune. Recently I've noticed what sounds like pinging so I pulled out the Autoprom and went for a spin, with my son driving and me handling the laptop. Knock counts increase a lot, but not always enough to trigger KR. I could hear the "pinging" even with no KR. Question: is it possible to hear ping with no KR, or is it more likely something else I'm hearing that sounds like ping? I've attached the datalog for anyone with time to look. Thanks

**Fast355** · 08-13-2014

Originally Posted by Roadknee

In April I burned a chip and took a break from tuning to concentrate on some other things. I've been pleased with how it runs with the custom tune. Recently I've noticed what sounds like pinging so I pulled out the Autoprom and went for a spin, with my son driving and me handling the laptop. Knock counts increase a lot, but not always enough to trigger KR. I could hear the "pinging" even with no KR. Question: is it possible to hear ping with no KR, or is it more likely something else I'm hearing that sounds like ping? I've attached the datalog for anyone with time to look. Thanks

More than likely you are hearing something that sounds like a ping. Either an exhaust leak or if you are running headers they tend to ring like a bell under load and sound a lot like knock. The thinner the primary tube the worse the bell effect.