1995 K1500 LO5 tuning- Autoprom

I finally purchased an Autoprom and all the accessories to tune the L05 in my truck. The motor is stock with the exception of a K&N air filter, 3" performance cat and cat-back exhaust and a 180 degree thermostat. I had a bit of a learning curve, but successfully read my stock chip and am datalogging and emulating the $0D mask with Windows 8. So far the stock fueling tables don't seem too bad. I set stock AFR to 14.3. BLM's are mostly in the low 120's. The lowest I've seen is 117.

I've owned this truck since 1999 and I've always had to run the ignition timing about 4° retarded to keep it from pinging on 87 octane. I noticed some timing retard (mostly less than one degree) in TunerproRT during light acceleration. At WOT it's pulling out up to 4 degrees. The stock timing map provides 16 degrees (accounting for the 10 degrees bias) at 4,000 rpm. Thus, at WOT this motor can only tolerate about 8 degrees total timing at 4,000 rpm and 0 degrees at 2,000 rpm.

I have disabled the WOT delay and set PE AFR to 12.5. I also set all the PE added spark to zero. It goes into PE right away and the narrow band 02 reads about 880 mv. I think it's plenty rich.

For a sanity check, I reduced the bias to 6 degrees, which increased the timing map 4 degrees across the board. The knock sensor began pulling timing everywhere, even under light acceleration.

I've read various reports online that these TBI motors with swirlport heads will tolerate 25 to 30 degrees of WOT ignition advance. The motor has 160k miles and seems to run reasonably well. It will get about 17 mpg unloaded on the highway. Any idea what's going on here?

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Originally Posted by Roadknee

I finally purchased an Autoprom and all the accessories to tune the L05 in my truck. The motor is stock with the exception of a K&N air filter, 3" performance cat and cat-back exhaust and a 180 degree thermostat. I had a bit of a learning curve, but successfully read my stock chip and am datalogging and emulating the $0D mask with Windows 8. So far the stock fueling tables don't seem too bad. I set stock AFR to 14.3. BLM's are mostly in the low 120's. The lowest I've seen is 117.

I've owned this truck since 1999 and I've always had to run the ignition timing about 4° retarded to keep it from pinging on 87 octane. I noticed some timing retard (mostly less than one degree) in TunerproRT during light acceleration. At WOT it's pulling out up to 4 degrees. The stock timing map provides 16 degrees (accounting for the 10 degrees bias) at 4,000 rpm. Thus, at WOT this motor can only tolerate about 8 degrees total timing at 4,000 rpm and 0 degrees at 2,000 rpm.

I have disabled the WOT delay and set PE AFR to 12.5. I also set all the PE added spark to zero. It goes into PE right away and the narrow band 02 reads about 880 mv. I think it's plenty rich.

For a sanity check, I reduced the bias to 6 degrees, which increased the timing map 4 degrees across the board. The knock sensor began pulling timing everywhere, even under light acceleration.

I've read various reports online that these TBI motors with swirlport heads will tolerate 25 to 30 degrees of WOT ignition advance. The motor has 160k miles and seems to run reasonably well. It will get about 17 mpg unloaded on the highway. Any idea what's going on here?

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Can you post the original stock .bin file?

dave w

here you go.

Last summer I actually found a bad BJYL memcal. Yours seems just fine.

As an experiment, maybe disabling the EGR might help understand the source of the spark knock.

dave w

Or the balencer has slipped and the timing marks are not accurate...

Quote:

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Originally Posted by Roadknee

I finally purchased an Autoprom and all the accessories to tune the L05 in my truck. The motor is stock with the exception of a K&N air filter, 3" performance cat and cat-back exhaust and a 180 degree thermostat. I had a bit of a learning curve, but successfully read my stock chip and am datalogging and emulating the $0D mask with Windows 8. So far the stock fueling tables don't seem too bad. I set stock AFR to 14.3. BLM's are mostly in the low 120's. The lowest I've seen is 117.

I've owned this truck since 1999 and I've always had to run the ignition timing about 4° retarded to keep it from pinging on 87 octane. I noticed some timing retard (mostly less than one degree) in TunerproRT during light acceleration. At WOT it's pulling out up to 4 degrees. The stock timing map provides 16 degrees (accounting for the 10 degrees bias) at 4,000 rpm. Thus, at WOT this motor can only tolerate about 8 degrees total timing at 4,000 rpm and 0 degrees at 2,000 rpm.

I have disabled the WOT delay and set PE AFR to 12.5. I also set all the PE added spark to zero. It goes into PE right away and the narrow band 02 reads about 880 mv. I think it's plenty rich.

For a sanity check, I reduced the bias to 6 degrees, which increased the timing map 4 degrees across the board. The knock sensor began pulling timing everywhere, even under light acceleration.

I've read various reports online that these TBI motors with swirlport heads will tolerate 25 to 30 degrees of WOT ignition advance. The motor has 160k miles and seems to run reasonably well. It will get about 17 mpg unloaded on the highway. Any idea what's going on here?

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Are you accounting for the PE spark advance of up to 4* @ 4,400 rpm??

I always run 24-29* total timing on these heads on 93 octane gasoline and reduce the spark advance as the coolant rises above 180*F.

I always run CR42TS plugs in these engines as well. Too hot a plug can give you fits with detonation.

I did try a datalog with the EGR off. Didn't notice any difference as far as spark knock. The numbers I posted are with the PE spark advance zero'd out. I was going to change the plugs and check the position of the timing mark on the balancer. I'll pick up some CR42's to try.

I've been making some minor tweaks to the 4L60E code to address shift points and firmness. I'm surprised how well it responds.

I ran a 300 mile loop over two mountain passes and datalogged both ways. I was able to run cruise control at 1,600, 1,800, 2,000, 2,400, 2,800 and 3,200 rpm to get some really good blm data. Fuel map is looking pretty good. On the way home I was running blm's in the 125-130 range. Stopped for gas and when I got going again blms were mid to high 130's. They settled back down after about 5 minutes on the highway. I noticed something similar in stop and go traffic where blms will increase to mid 130's. I suspect it has something to do with heat soak, but don't understand why it would need to be richer. Is this common?

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Originally Posted by Roadknee

I ran a 300 mile loop over two mountain passes and datalogged both ways. I was able to run cruise control at 1,600, 1,800, 2,000, 2,400, 2,800 and 3,200 rpm to get some really good blm data. Fuel map is looking pretty good. On the way home I was running blm's in the 125-130 range. Stopped for gas and when I got going again blms were mid to high 130's. They settled back down after about 5 minutes on the highway. I noticed something similar in stop and go traffic where blms will increase to mid 130's. I suspect it has something to do with heat soak, but don't understand why it would need to be richer. Is this common?

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Yes.

I verified the timing marks were accurate, took a compression test and swapped in new plugs. Compression was 160-170 psi across all cylinders. The local parts store didn't have the colder AC Delco plugs so I purchased some Autolite 24s. These are one heat range colder than stock plugs for this truck. The CR43TS plugs I removed were pretty tired, but overall the motor seems to be in decent shape for 160k miles. I got if fired up and verified timing. I thought I'd been running it retarded, but the timing was set to the 0° spec. I took it for a quick highway drive the knock sensor is about as active as it was before the plug change. During WOT acceleration its removing 3-4 degrees of timing throughout the rev range at 95 kpa. I have WOT AFR set to 12.5 and the 02 was showing about 920 mv.

The old plugs have some deposits on them so it's very possible some carbon in the chambers is contributing to the spark knock. I'll give it a seafoam treatment and run some ringfree through it. I might just end up tuning this thing for premium fuel though.

Can anyone offer some guidance how much more WOT timing the LO5 can use when changing from 87 octane fuel to 92?

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Originally Posted by Roadknee

Can anyone offer some guidance how much more WOT timing the LO5 can use when changing from 87 octane fuel to 92?

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Timing changes are trial and error. Usually 3 degrees to 5 degrees is safe with 92 Octane in the 80 Kpa and 90 Kpa above 1600 RPM. Usually 2 degree to 4 degrees for 100 Kpa above 1600 RPM.

dave w

I ran the tank of 87 octane very low and topped it off with Chevron 92. I don't have any WOT knock retard in first or third gears now, but still have up to 5 degrees in second gear. I've read where a worn tranny can cause this. I'm running the original 4L60E with 160K. Here's a datalog if anyone cares to look.

Quote:

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Originally Posted by Roadknee

I ran the tank of 87 octane very low and topped it off with Chevron 92. I don't have any WOT knock retard in first or third gears now, but still have up to 5 degrees in second gear. I've read where a worn tranny can cause this. I'm running the original 4L60E with 160K. Here's a datalog if anyone cares to look.

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I had a 4L60E that was causing false knock retard only in 2nd gear. It would show up to 8° of retard in 2nd gear that would instantly vanish under heavier load in 3rd gear.

Quote:

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Originally Posted by Roadknee

I ran the tank of 87 octane very low and topped it off with Chevron 92. I don't have any WOT knock retard in first or third gears now, but still have up to 5 degrees in second gear. I've read where a worn tranny can cause this. I'm running the original 4L60E with 160K. Here's a datalog if anyone cares to look.

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I looked at the data log for knock retard, nothing alarming. A few cells above 80 Kpa had an average knock retard of about 2 degrees. I can often eliminate knock by retarding spark advance by 0.50 degree increments in the cells that have knock.

dave w