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...

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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.

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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.

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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

Thought I'd provide an update of my efforts the last few weeks. Got to say I really enjoy this Autoprom. I have it installed in the glovebox. It is so easy to access with the laptop when I want to tune, or disconnect and close the glovebox for daily driver operation.

I'm on the third tank of 92 octane fuel now. Also pulled some timing (0.5-1 degree) in the 95 and 100KPA area of the spark map. The knock sensor is still pulling timing in the upper rev ranges at WOT; around 4 degrees above 2,800 rpm. Seems it only wants to tolerate 10-11 degrees of WOT ignition lead. I posted earlier that this was only occurring in second gear. However, in recent WOT runs I've seen KR in 1st gear too. It's interesting that KR is about the same with 92 octane as it was with 87. The 92 has eliminated the part throttle KR though. I suppose next step is to pull that 4 degrees out of the high kpa areas of the spark map and see if I can eliminate knock sensor activity in entirety.

I made another almost 400 mile loop over three mountain passes, datalogging, and massaging the VE tables. I had them in pretty good shape already, so adjustments were pretty minor. After I've been on the highway for a while and the engine is fully warmed, BLM's are consistently in the 125-129 range, and mostly 127-128. It feels very smooth. I did notice something interesting driving back worth mentioning. I was coming down the east slope of Stevens Pass, spending a lot of time decelerating. Outside temp was 20F or so. As I continued to down the hill the BLM's on decel rose to the mid 140's. Coolant temp was down to 177 from 183 where it normally cruises. Once the pass flattened out some and I got some heat back in the engine, BLM's returned to 127-128.

I've also fiddled some with the open loop AFR table to help with warm-up. In the stock bin, the engine enters closed loop at -1.8C and starts block learning at 20C. At colder temps, some of the BLM's would get into the low 100's. As the motor warmed up and I accelerated through these cells the INT could not move the BLM's fast enough to prevent some minor lean surge. I'd have to drive around for 1/2 hour before the BLM's would return to normal. I enabled use of the open loop AFR table in closed loop. To my surprise, the stock table with target AFR's of 16:1 in many of the cells was reasonably close. The engine goes into closed loop and the INT makes minor adjustments as needed to target the switching point of the O2 sensor. BLM adjustments are not made unless the values in the open loop table are equal to the Stoich AFR. I set all values in the table 80C and above to 14.7, which is what I have Stoich AFR set to. I later reduced the Maximum Temp for AFR lookup in Closed Loop to 80C to achieve the same outcome. I could have obtained a similar result by simply running open loop until 80C. I personally like running closed loop during warm-up because the engine will tolerate it, and uses less fuel in the process.

I'll admit tuning is addicting. As we move into spring though I'll need to burn a chip and remove the Autoprom to temporarily eliminate the temptation. It'll be time to move on to other things till winter.

Tuning can be addictive!:rockon:

dave w

Sounds to me like your knock issues are mechanical rather than in the tune. L05's are infamous for false knock. You should be easily be able to run at least 25 deg. total advance at WOT with 92 octane and real knock counts diminish with the benefits of gearing, i.e they will increase as you go from 1st to 2nd and 2nd to 3rd as the load on the engine increases.

Several things can cause false knock. Valve train noise, especially from flat tappet cams can do it. Timing chain slap is a big cause. Lastly but least likely in your case is in my view bad valve stem seals. Oil entering the combustion process can cause knock.

Try running some straight 30W oil on your next change and test the chain by loosening all the rocker arms relieving spring tension. Remove the cap and try to move the distributor shaft. If it moves back and forth excessively, the chain is loose. There are ways to de-sensitize the knock sensor but I would only recommend that if you had a lot of tuning experience and eliminated all the mechanical issues. Hope this helps.

climbing BLM's on decell is normal and actually desirable for fuel economy.

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Good points Billy. I have taken pretty good care of the truck, and addressed most of what you posted above. I verified the balancer with a piston stop last month. I replaced intake, TBI and EGR gaskets a few years ago. Copper terminal cap, rotor and wires are fairly new (good 8mm silicone wires). Motor bay is kept clean and doesn't leak a drop of oil. A few weeks ago I decarbed the top end using seafoam followed by a shock treatment of ringfree in the fuel tank. O2 is newer heated Delphi and switches very well in the datalog.

Although it runs well for a 1995 truck, I have to accept this is the stock 160K motor and trans and very well could have some mechanical problems. Oil consumption has increased over the last few years. It doesn't smoke, but I am adding a quart between changes. It's also consuming some coolant, and not from on external leak.

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Originally Posted by billygraves

Next time you change our Oil and filter, I would add the pre-filled filter and the rest of the 5 or 6 quarts. Start it up and run for a min. Shut off. Then check the oil level. I have seen a number of dipsticks that are 1/2 inch long. I use a small tubing cutter and cut off the amount. Now the level is true and you won't be adding another quart.
Maybe the seafoam is better now but a few years ago the only way to de-carbon the chambers, pistons tops, and intake valves was to use the GM stuff. We tried a number of these at the GM Tech Center using a bore scope to check before and after. That is why I suggest you let it sit OVER night and not the hour. If you get the engine as hot as possible, pour the TOP ENg Clnr in and stall the engine the last 1/3 can it really works the best. If ya run Valvoline I have had the engine consume a quart every 500 miles. To fix it, change to Castrol if your using conventional oil. With 3 yrs on the intake and TB gaskets, check them again. Don't run the dexcool either.

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I've run Chevron conventional 10W/30 oil for 100,000 miles. I've owned the truck since about 50,000. When newer it would use less than 1/2 qt in 3,000 miles. Now it's a quart every 1,200 or so. 4-3/4 quarts with a filter puts the oil level at the full mark on the dipstick after its been run. I run Chevron 5W/30 oil in our '06 Yukon and it doesn't use a drop in 6,000 mile oil change intervals.

No dexcool here. And it's used coolant for a long time; even before the intake gasket change. I've kinda been looking for a reason to overhaul it, port the heads, install a bigger cam...

Can I talk someone into looking at the WOT runs in the attached datalog and tell me if you see anything out of the ordinary? Is the noise in the 02 trace normal? WOT runs start at about 13:30. Thanks.

It's not noise, it's cross counts you see moving O2 signal above and below Stoich.

Right at you WOT you can see it go flat. This is because the PCM goes into Open Loop during PE. See your O2 numbers around .930v? This is a very rich reading and good to see at WOT.

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Originally Posted by billygraves

If you LEAN the calibration out @ WOT, just keep in mind that in SOME engine combos it is FAT because of Mal-distribution problems that lie within the intake/TBI. Some cyls run Lean at certain RPM and are on the opposite side of the O2 measuring. So a A/F Ratio meter (on the other side) would be a good check. (And not to miss this point, some fuel is FAT to actually COOL the top and ring pack IF pulling a load up a long hill ect ect ect......)
(I was coached on a 5.7L TBI and with the intake sometimes cyl 5 runs lean and 7 runs FAT. This is because of the fuel is being robbed from one and pulled into the other. This was the intake release person I had discussions with in the early 90's about intake gasket leaks and how to help seal them.)
The TBI steers the fuel toward the rear of the engine where it is a bit rich or Fat. TBI was used by the companies because PFI was 900 additional an engine. This was back in the early 90's.

For those of you who are considering TBI use in High RPM ranges, I would you look at some other approach and go PFI. If you look @ the Holley 4 BBL TBI you will see them use a small tab that rests against the injectors. It is for this reason.
As the fuel is blown into the air stream at hi rates the fuel stream is moved toward the center of the air stream and this ends up with the outer 4 cyl very lean and the inner 4 very rich. Another way to see this is hold a hose with a stream of water up in the air and as the wind picks up it moves the liquid or bends it. The same thing occurs at 5,500 to 6,000 RPM or at an air flow rate, inside the engine. Just be careful.
The reason I know this is I ran one of Holley's first 4bbl TBI on my 9 second Vega. With 2 fuel pumps and about 6 passes with a best time at 10.80 from 9.40 with a 1050 dominator, I pulled it and reinstalled the dominator. The engine headers were coated and had turned blue from being so lean.

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On a factory TBI setup there is no possible way for 5 and 7 to draw from each other. They get fuel from opposite sides of the intake.

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Originally Posted by Fast355

On a factory TBI setup there is no possible way for 5 and 7 to draw from each other. They get fuel from opposite sides of the intake.

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He might have meant 5 and 8. I've been told more than once 8 will run rich and 5 lean on a SBC running a dual plane intake. These cylinders share the same runner out of the plenum (passenger side rear). When I recently changed the plugs on my LO5 they all looked good except 8 which was noticeably rich. 5 had slightly less color (lean) then the others.

5 and 7 are the two that get cross fire in ignition in a little tidbit billygraves gave us a few days ago. So he probably switched them up.

Took the truck on a one-day business trip and decided to check fuel economy. I topped off at the Chevron station in Quincy, WA and drove I-90 to Spokane and back. The tunerpro display bounced around 16-17 mpg with the cruise control set at 75 mph. Coming back I got into an awful headwind; one of the worst I've experienced on this stretch of highway. MAP spent a lot of time in the 80-90 kpa range with PE active The display bounced around 10-11 mpg. At one point on just a slight grade the trans actually downshifted. Anyway gassed up at the same Chevron station in Quincy and averaged 13.0 for the trip. Worst highway mileage ever for this truck.

I also noticed it bouncing in and out of DFCO. When it left DFCO at 1,200 rpm the added fuel would increase rpm to around 1450 and after the delay it would reenter DFCO. I was on a pretty long grade and it did this several times. I can't think of anything in the tune I would have changed to cause this, or perhaps I just never noticed it. There is a DFCO rpm hysteresis set to 200 rpm in the stock tune. I might try increasing it to 300-350 and see if makes a difference. It will probably be a while before I can repeat those conditions though.

Quote:

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Originally Posted by Roadknee

Took the truck on a one-day business trip and decided to check fuel economy. I topped off at the Chevron station in Quincy, WA and drove I-90 to Spokane and back. The tunerpro display bounced around 16-17 mpg with the cruise control set at 75 mph. Coming back I got into an awful headwind; one of the worst I've experienced on this stretch of highway. MAP spent a lot of time in the 80-90 kpa range with PE active The display bounced around 10-11 mpg. At one point on just a slight grade the trans actually downshifted. Anyway gassed up at the same Chevron station in Quincy and averaged 13.0 for the trip. Worst highway mileage ever for this truck.

I also noticed it bouncing in and out of DFCO. When it left DFCO at 1,200 rpm the added fuel would increase rpm to around 1450 and after the delay it would reenter DFCO. I was on a pretty long grade and it did this several times. I can't think of anything in the tune I would have changed to cause this, or perhaps I just never noticed it. There is a DFCO rpm hysteresis set to 200 rpm in the stock tune. I might try increasing it to 300-350 and see if makes a difference. It will probably be a while before I can repeat those conditions though.

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I have hit those kind of headwinds before and for future reference you would have done better in 3rd gear with the engine rpm higher and out of PE.

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.

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?

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

Code:

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      ;------------------------
        ; 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
        ;------------------------

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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

Quote:

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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

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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.