Tuning larger LT-5 cams

[XfireZ51]

Thought I would share one of those tuning "mystery" stories. Sometimes you've got to play detective. I have been busy tuning my LT-5 for the last 2 months. Over the winter I added a set of ported cylinder heads (AFR or Trick Flow don't make DOHC 32V high flow heads) and decided to take advantage of the additional airflow by installing larger single pattern intake cams. This is all on a stock block 5.7L LT-5 motor w 1 7/8" Watson headers and 3" Magnaflow exhaust. These babies LOVE to breathe. Very much a top end motor. Not much tops an LT-5 at full song around 7000rpm IMO.
Anyway, have been playing with the tune for a couple of months when I noticed the BLMs are not updating. The LEARN flag is OFF although motor was going into C/L. I thought possibly there was a problem with my new copy of TPRT 5.0. I also "noticed" that the bin where all this started had a Checksum that reset, IOW it went beyond the 65xxx. I do multiple changes to a bin but none were of the kind that should affect LEARN control. Or so I thought. It took me a couple of days of eliminating the parameters that had changes between the bin that DID work from the bin that DID not. It turned out to be coincidence that the Checksum reset at the same bin change but had nothing to do with the LEARN staying off. Using Craig's Ostrich 2.0 and Mark's TPRT 5.0 really made the sleuthing a much more effcient process. Still took me most of the morning today BUT I finally got it. With the larger intake cams, you invariably get the rich smell at idle and I had lowered the O/L change v CTS table to take some fuel out. Apparently the code doesn't like too much fuel pulled out because it appears to prevent LEARN from turning on. Essentially you are running O/L although the ALDL says you are in C/L.
Made the change to the bin, download and bingo LEARN ON. I re-input the stock values but for grins I would like to find out how much I can decrease fuel before re-creating this issue again. Maybe one of the hack gurus can tell us what the logic is behind this outcome. After going thru this, I thought I would have LOVED to have an ECM bench. :-x

[HAWAIIZR-1]

Thought I would share one of those tuning "mystery" stories. Sometimes you've got to play detective. I have been busy tuning my LT-5 for the last 2 months. Over the winter I added a set of ported cylinder heads (AFR or Trick Flow don't make DOHC 32V high flow heads) and decided to take advantage of the additional airflow by installing larger single pattern intake cams. This is all on a stock block 5.7L LT-5 motor w 1 7/8" Watson headers and 3" Magnaflow exhaust. These babies LOVE to breathe. Very much a top end motor. Not much tops an LT-5 at full song around 7000rpm IMO.
Anyway, have been playing with the tune for a couple of months when I noticed the BLMs are not updating. The LEARN flag is OFF although motor was going into C/L. I thought possibly there was a problem with my new copy of TPRT 5.0. I also "noticed" that the bin where all this started had a Checksum that reset, IOW it went beyond the 65xxx. I do multiple changes to a bin but none were of the kind that should affect LEARN control. Or so I thought. It took me a couple of days of eliminating the parameters that had changes between the bin that DID work from the bin that DID not. It turned out to be coincidence that the Checksum reset at the same bin change but had nothing to do with the LEARN staying off. Using Craig's Ostrich 2.0 and Mark's TPRT 5.0 really made the sleuthing a much more effcient process. Still took me most of the morning today BUT I finally got it. With the larger intake cams, you invariably get the rich smell at idle and I had lowered the O/L change v CTS table to take some fuel out. Apparently the code doesn't like too much fuel pulled out because it appears to prevent LEARN from turning on. Essentially you are running O/L although the ALDL says you are in C/L.
Made the change to the bin, download and bingo LEARN ON. I re-input the stock values but for grins I would like to find out how much I can decrease fuel before re-creating this issue again. Maybe one of the hack gurus can tell us what the logic is behind this outcome. After going thru this, I thought I would have LOVED to have an ECM bench. :-x

This is like speaking Greek or Japanese to me. Having the SGC Stage 1s on my 350, one day I hope to understand this stuff and get mine tuned right. :confused:

[XfireZ51]

This is like speaking Greek or Japanese to me. Having the SGC Stage 1s on my 350, one day I hope to understand this stuff and get mine tuned right. :confused:

Well thanks for taking the time to read and comment on this anyway.
Just a small caveat. Once you go down the tuning road, it's addictive because there is ALWAYS something else you'll want to tweak. ;)

[XfireZ51]

Dom...I'm intrigued! Congratz on the perseverance and the stick to itiveness, and not giving up (and all that sort of rot!):-D! Sounds like a thorny one to figure out - another FBI triumph, I recon!;)

:thumbsup:

P.

Paul,

I could have tuned this thing in Open Loop, but decided I wanted to take advantage of some of the controls available in C/L. A bit more of a challenge but I'd done something similar when I modded my old Xfire that ran low 13's on street tires. Actually beat a stock ZR-1 at Byron once. But he was coming up fast!

[mike100]

I read your post last night, but didn't reply...Thanks for putting up that detail. These older controls do have range limits on a lot of things and get wacky when you exceed them and never find equilibrium. Obviously lots and lots of things going on with the strategy of operations that are not apparent.

[XfireZ51]

I've been reviewing the def file for my 92 ZR ($D0A) and I noticed there is a constant for O/L Change Bias v CTS of -13.67%. Coincidently?, the table values in the O/L Change Bias v CTS do not go below -13.67% beginning at 80C on up.
I had set the O/L Change to -11.67% from 80C on up in an attempt to lean out O/L idle. I have a suspicion that anything less or should I say leaner than the Change Bias number prevents the LEARN flag from flipping to ON. At 80C and above with a Change Bias of -13.67, the ECM won't modify the AFR produced by using the appropriate VE table value (RPM x MAP). Makes me wonder if there's a way to run O/L idle. Perhaps setting the O2 idle voltages to the point where the O2 sensor doesn't swing thru the O2 window at idle. So O/L idle and C/L cruise. Hmmm?:huh:

[HAWAIIZR-1]

Well thanks for taking the time to read and comment on this anyway.
Just a small caveat. Once you go down the tuning road, it's addictive because there is ALWAYS something else you'll want to tweak. ;)

Yes, I have a friend with an LT1 Vette that does his own tuning and keeps telling me how easy it is the Moates Ostrich and some tools and software that he has. He'll show me the next time I go back home to Hawaii on vacation so I'm excited to learn. All the mail order tuning is good, but I know only so much can be done without having the car and dyno too. First I want to at least get smart with the Datamaster and understand all that it provides. I admire all you smart guys with this technical stuff. I forget the guys name or the exact program but I remember on a TV program some guy had a C4 that had extracted good power gains just from proper tuning. I understand that you can bolt on all you want, but if you can't get it tuned properly you're wasting a lot of power and money.:cheers:

[XfireZ51]

That's what got me started on this stuff about 10 years ago. I decided I wanted more power from my Xfire so I started scoping out heads and cam. Then somebody said well you'll need a different tune for that. And I said how do you do that? Connected with some guys on the Crossfire Forum, and then I heard about a guy who had modded a Xfire to run 13's.
He was Bruce Plecan otherwise known as Grumpy on 3rd Gen. Pretty much the father of tuning as we know it now. Then read some tuning articles from Bruce and Robert Rauscher (owner of dynamicefi.com). Back then, no Ostrich and using a slow TBI truck ECM, 7747, datalogged at 1 frame/1.2 sec. I had to erase and burn chips for each cal change. ;)

[HAWAIIZR-1]

Thanks for the info and motivation. Marc H has mail order tuned a few chips for my application and one especially to help me out with the emissions testing that I will encounter soon. The thing is if I still have problems or to get maximum benefits from the heads and cams I need to do as you said and get smart with this stuff. My friend also mentioned something about Tuner Cat and have not checked it out in detail yet.

[XfireZ51]

I prefer using TunerproRT. Started tuning using TC.

[XfireZ51]

You know you have a good tune when:

1. If you have a SM FW, there is little or no clatter from ZF-6 at idle.

2. When cruising down the road, you only hear the exhaust note and no motor noise.

3. At steady cruise you hear a steady exhaust note, no oscillation.

[HAWAIIZR-1]

Thanks for the info and I'll shoot for that good tune. When Marc H sent me this last tune a few weeks ago for the Stage 1 cams, it did make a night a day difference versus his standard 500HP package tune. He upped the idle a bit too so that is probably why I don't have the Fidanza aluminum SM rattle now; I have not confirmed the exact idle speed, but analog tach shows a little under 1K range. Not as lopey sounding, but much better than the rattle.

[XfireZ51]

I have the motor idling between 775 and 825 based on
my scans.

[XfireZ51]

Pretty much putting a fine point on the calibration. I've been playing with AE(Acceleration Enrichment) for throttle response. Nice at this point. You can feel a direct connection to the pedal effort and the response. Also, adjusted Min Air for getting the IAC counts to mid teens. I played with RPM Deadband at Idle and went from +/- 50 to +/- 25. Seemed to like that also. Quiets the SM flywheel a bit more. Overall Left BLMs are higher than Right but that difference becomes minimal at cruise. Its exaggerated more at idle and when Coolant Temps go up.
But Overall Left Avg. BLM is 132, Right Avg. 125. Close enough, IMO.
Motor is quiet at cruise with a lope at idle. All you hear is the exhaust note and its a mellow purr. Not harsh or loud. No drone in the cabin even at 1600rpm or so. Tuning is soooo much easier using the Ostrich and =Jeff='s VeTuner. You can have a new set of VE tables calc'd in about 3 min and then ready to download.
Next is installing the WB O2.

[Paul Workman]

Pretty much putting a fine point on the calibration. I've been playing with AE(Acceleration Enrichment) for throttle response. Nice at this point. You can feel a direct connection to the pedal effort and the response. Also, adjusted Min Air for getting the IAC counts to mid teens. I played with RPM Deadband at Idle and went from +/- 50 to +/- 25. Seemed to like that also. Quiets the SM flywheel a bit more. Overall Left BLMs are higher than Right but that difference becomes minimal at cruise. Its exaggerated more at idle and when Coolant Temps go up.
But Overall Left Avg. BLM is 132, Right Avg. 125. Close enough, IMO.
Motor is quiet at cruise with a lope at idle. All you hear is the exhaust note and its a mellow purr. Not harsh or loud. No drone in the cabin even at 1600rpm or so. Tuning is soooo much easier using the Ostrich and =Jeff='s VeTuner. You can have a new set of VE tables calc'd in about 3 min and then ready to download.
Next is installing the WB O2.

Like a moth to a flame. Fascinating.

Maybe you should do a demonstration/presentation at BG next spring, Dom! Think about it...:cheers:

P.

[XfireZ51]

Paul,

Glad someone finds this useful. I'm no tuning guru but I could probably discuss it from the perspective of someone who wants to get involved in their own tuning. The evolution of tools for tuning has been pretty rapid in the last 10 years even for OBD1 stuff thanks to guys like Craig Moates, Mark Mansur, Rob Rauscher and Grumpy. They started out hacking GM stuff and have moved on to Ford, Honda etc.
As a point of clarification, the tuning I have done is on a
stock block LT-5, Fidanza wheel, ported top end and GVD heads w 236d/.425" lift single pattern intake cams & stock exhaust cams. 63mm TB, 1 7/8" Watson headers. Now that Part Throttle is pretty well dialed in, I'm hoping to get to dyno for work on WOT. Results so far show little to no knock retard which tells me top end fueling and timing isn't too far off.

[HAWAIIZR-1]

Dom,

I'm all ears and want to learn this stuff. With the exception of the difference in cams and header tube size having .430 lift with 230 deg @ .050 and 2" primary tubes, I have almost the identical set up. Thanks for sharing all the technical data and I'll try to be a sponge and retain.:cheers:

[mike100]

...
But Overall Left Avg. BLM is 132, Right Avg. 125. Close enough, IMO.
Motor is quiet at cruise with a lope at idle. All you hear is the exhaust note and its a mellow purr. Not harsh or loud. No drone in the cabin even at 1600rpm or so. Tuning is soooo much easier using the Ostrich and =Jeff='s VeTuner. You can have a new set of VE tables calc'd in about 3 min and then ready to download.
Next is installing the WB O2.

Tell me about the VE tuner function...does it make a base map off of STFT values or does it use a strategy to tune each cell based on a target air/fuel ratio using a wideband or even the O2 sensor?

[XfireZ51]

Tell me about the VE tuner function...does it make a base map off of STFT values or does it use a strategy to tune each cell based on a target air/fuel ratio using a wideband or even the O2 sensor?

=Jeff= built it and I did some testing for him. It's pretty flexible. Can use either WB O2 scan or BLMs for Open or Closed Loop tuning. You can set the "windows" for the data you want to use. For example, I use data with Learn ON, C/L, +/- 2.5kPa, +/- 50rpm. You can do same for using AFR instead.
Also has provision for datalogger being used and whether you're in
Port Throttle Open or Closed mode. you can also set target BLM or AFR for the calc. Neat if you want to run a bit rich or lean. Be cool if that could be done by RPM range so cruise could be on the lean side, while upper RPM richer.
Basically it takes average of L/R BLM and compares to target BLM.
Calcs % adjustment and applies it to current VE tables, then creates new bin file. You can also apply "smoothing".
Something you want to do with tuning us turn OFF
DFCO, CCP, and EGR so you're not chasing your tail initially. Once you have tune set then you can turn them
back on and tweak a bit. Also spend some time on SA tables to optimize along with ancillary parameters.

[tomtom72]

Dom, I would like to add my Thank You also. No, I don't understand much of this. I haven't yet to plow thru the corvette FI book by Mr. Probst. I got side tracked with night courses for my job.

I am going to ask what could be a really novice Q. This fine tuning that you are doing would only benefit an LT5 that has it's cams timed correctly, right?

TIA
:cheers:
Tom

[XfireZ51]

Dom, I would like to add my Thank You also. No, I don't understand much of this. I haven't yet to plow thru the corvette FI book by Mr. Probst. I got side tracked with night courses for my job.

I am going to ask what could be a really novice Q. This fine tuning that you are doing would only benefit an LT5 that has it's cams timed correctly, right?

TIA
:cheers:
Tom

Tom,

Probst's FI book is a good place to start, but frankly it was too general for me. To really learn about tuning, I would visit thirdgen.org and their
DIY Prom forum. Many valuable articles and stickies available like
Tuning 101. Also, many knowledgeable posters and moderators on there sharing lots of good information.
As to you question, there's no doubt that you want to base a tune on mechanicals that are correct. The objective of a tune is actually to have the ECM intervene as little as possible. IOW, VE and SA tables that are close to optimal as possible w the ECM making "minor" changes or adjustments as dictated by operating conditions, ie driving through the mountains or varying elevations. However, every motor is different even tho they are the same. The right tune for one stock LT-5 is not necessarily optimal for another. Close but not necessarily optimal. I retuned my motor after adding just the Fidanza as an example.
When we pulled the motor out of #474, Pete checked the cam timing. I don't recall the exact #s but the intakes were something like 109/120.
However, I had tuned that motor just a few weeks before to produce ~400rwhp on a ported top end w headers/MF exhaust. So you can attempt to optimize the motor performance with the conditions you have.
But the performance you achieve will be limited by how optimal the mechanical condition of the motor is.

[XfireZ51]

This past weekend gave me the opportunity to migrate the tune for my motor over to the Blue Turtle. Essentially, Dave's motor is a copy of mine with the ported heads, top end, intake cams, and headers. Some differences are in the details. My heads were done by GVD, and I did my own top end porting 2 years ago. The headers are the Watson 1 7/8" with a MagnaFlow system behind them. With Pete chasing down the mechanical issues, we used my VE and SA tables for Dave's car so Pete could start with a tune that was pretty close to what was needed and save time. One main difference between the tune on Dave's motor and mine is that I am running Closed Loop while Dave's is Open Loop. However, the base VE tables are very similar although I haven't spoken with Pete on the tweaks he did afterwards. Not sure if Pete made any changes to the SA tables I had. However, Pete burned a chip with my VE and SA tables onto the Haibeck calibration, installed it, and the car idled pretty well right off the bat, albeit without the IAC issue resolved (which Pete fixed later). AFR was at about 14.3, the Stoich ratio I have targeted for a 10% ethanol fuel. I'll be interested in seeing where and how much my base and Dave's final calibrations differ.

P.S. Just spoke with Pete. As a point of clarification, Pete tuned the motor in Open Loop but then finalized the calibration by re-enabling Closed Loop. I originally tuned the motor using the BLMs in Closed Loop

[rkreigh]

I'm facing VA emissions with the big 234 cams (not sure what LPE timed them at). I called Graham for some advice and help. for an emissions profile, he recommended going back to an open loop chip and pulling fuel out to clean up the idle. I have an old LPE closed loop chip, but it was before I had Marc pull the secondaries out which does nothing to help the emissions either :neutral: I can get the car down to 130 or so HC, but the new standard is 48

soooo........ I'm going to try fresh oil, plugs, cats, and getting an emission chip burned.

I'll need someone in VA that has an exhaust gas analyzer who is willing to work with Marc to do a mail order tune.

any suggestions?? I need to get this done NLT end of July so I need to move out.

HELP!!!!

sorry for the hijack, but it's relavent, and I'll start another thread too.

[HAWAIIZR-1]

I'm facing VA emissions with the big 234 cams (not sure what LPE timed them at). I called Graham for some advice and help. for an emissions profile, he recommended going back to an open loop chip and pulling fuel out to clean up the idle. I have an old LPE closed loop chip, but it was before I had Marc pull the secondaries out which does nothing to help the emissions either :neutral: I can get the car down to 130 or so HC, but the new standard is 48

soooo........ I'm going to try fresh oil, plugs, cats, and getting an emission chip burned.

I'll need someone in VA that has an exhaust gas analyzer who is willing to work with Marc to do a mail order tune.

any suggestions?? I need to get this done NLT end of July so I need to move out.

HELP!!!!

sorry for the hijack, but it's relavent, and I'll start another thread too.

Ron,

Thanks for posting the question. I only have a 350 with SGC Stage I int/exh cams and not sure how strict the standards are here in Japan. I am getting ready for my first test so I'm all ears to know what helps to pass. I have my still have my stock secondaries and based on Marc's advice about emissions he also burned a chip for me. Thanks for the idea and I'll change my oil and get some new plugs too.

[XfireZ51]

Ron,
Is there any chance you could do a run thru the emissions test while datalogging the run with a scantool? Just making some "uneducated" guesses based on my experience with my modded Xfire, I would try:

1. Hotter spark plug
2. Activate Decel Fuel Cut-Off
3. Raise the TPS% for secondaries so you are running only
primary injectors for the emissions cycle.
4. Bump timing
5. Lean out Acceleration Enrichment pump shot
6. Increase the AE Coefficient slowing down pump shot
response to throttle changes.

You'll need to make certain you don't
go into Lean Misfire. My initial thought is that the HC spikes during acceleration/decel which makes up a significant portion if the test. Not to mention the "tech" driving the car.

[Paul Workman]

Couple thoughts...


Something we discussed at one of our FBI bull sessions** was pulling the plenum and blocking off the secondary ports and shutting off the "Full Power" switch. This essentially reverts the mods to stock and keeps the secondaries from being activated, depending on the chip calibration. (Depending on the circumstances of the mods and calibration, a special calibration (primaries only) might be one way to assure the car is compliant.)

Also, mixing fuel for a 15% alcohol ratio has helped some of the cammed motors; one LT5 and a few pushrod motors too that I've read about recently.



**(Next BS session is tonight 6/24 at Home Run Pizza, if anyone is interested (see East Central Region page - look for Bloomington Gold threads)



P.

[rkreigh]

anyone do any open loop tuning to fiddle around with the calibrations? with the big cams I've heard the 02 sensors can "detect a false lean condition" and add fuel when in fact the car is already running rich

the lack of vacuum signal and high overlap of the cams contribute somehow to this.

I bit the bullet and ordereded some big manaflow universal 3" cats and although it pains me, they were only 75 each and getting them installed although it will violate my nice b&b exhaust, the fresh cats, alchy, fresh oil, and running a tank with seafoam throught the car is the route I will take.

I'm not overly optimistic but I gotta try something and before the end of july!!:proud:

[XfireZ51]

Ron,

Running O/L forces the fueling to be based strictly on the VE tables. O2 sensors feedback to the ECM for pulsewidth mod for the Integrator and BLM calcs. There are some threads on ThirdGen.org that discuss Closed Loop tuning for larger cams. The greater overlap does cause fresh air to be detected in the exhaust by the O2. Consequently the ECM interprets that as a lean condition and adds fuel. That's why you see the BLMs drop to minimum 115 that is in the calibration. In fact, the INT goes lower than that. What most people don't realize is that a 128 BLM DOES NOT necessarily correspond to 14.7:1 AFR. When running C/L, you'll see the AFR toggling rich/lean in order to not oversaturate the cats. Probably a reason why yours may very well be shot.
The magic 128 BLM for C/L indicates where the O2 swing points are. The voltages can be manipulated based on airflow. It means you can modify the calibration to tell the ECM that what appears to be lean actually is not. And it can be done
in such a way to affect principally only the idle. Being able to use C/L with the larger cams also allows use of additional parameters such as proportional gains which make a difference in managing surging for example.
At Bowling Green, Graham said something very interesting, if I recall correctly, in that the LT-5 wants to stall. Increasing the overlap exacerbates the oscillation bringing the LT-5 into areas where it will stall. One reason why people raise the idle when going to larger cams. So being able to control idle more tightly becomes even more important when using larger cams. C/L presents finer control of the motor which is why I believe Graham suggested C/L for your emissions calibration.

[C4Fanatic]

Suddenly wishing I had taken Dom for a ride in the Skunk while I was at BG this weekend!

[-=Jeff=-]

Suddenly wishing I had taken Dom for a ride in the Skunk while I was at BG this weekend!

now another reason to come back

you can stop at Portillo's at that time too

[C4Fanatic]

You just had to go and use the "P" word didn't you!?!?!?!?!?

[XfireZ51]

Here's a very interesting set of graphs that describe idle activity and how each condition can be addressed through tuning. There are 9 graphs. If you mouse over the graph it will present tuning suggestions for what are classified as
PID controls (Prop Gains, Integrator, Decel).

http://www.online-courses.vissim.us/Strathclyde/controlmap.htm

Thanks to Saar on ThirdGen.org for finding this little gem.

[rkreigh]

Ron,

Running O/L forces the fueling to be based strictly on the VE tables. O2 sensors feedback to the ECM for pulsewidth mod for the Integrator and BLM calcs. There are some threads on ThirdGen.org that discuss Closed Loop tuning for larger cams. The greater overlap does cause fresh air to be detected in the exhaust by the O2. Consequently the ECM interprets that as a lean condition and adds fuel. That's why you see the BLMs drop to minimum 115 that is in the calibration. In fact, the INT goes lower than that. What most people don't realize is that a 128 BLM DOES NOT necessarily correspond to 14.7:1 AFR. When running C/L, you'll see the AFR toggling rich/lean in order to not oversaturate the cats. Probably a reason why yours may very well be shot.
The magic 128 BLM for C/L indicates where the O2 swing points are. The voltages can be manipulated based on airflow. It means you can modify the calibration to tell the ECM that what appears to be lean actually is not. And it can be done
in such a way to affect principally only the idle. Being able to use C/L with the larger cams also allows use of additional parameters such as proportional gains which make a difference in managing surging for example.
At Bowling Green, Graham said something very interesting, if I recall correctly, in that the LT-5 wants to stall. Increasing the overlap exacerbates the oscillation bringing the LT-5 into areas where it will stall. One reason why people raise the idle when going to larger cams. So being able to control idle more tightly becomes even more important when using larger cams. C/L presents finer control of the motor which is why I believe Graham suggested C/L for your emissions calibration.

this explains it very well really need someone who can tune the car with the exh gas analyzer going

I've got a wazoo guy graciously stepped up to loan me some nice cats and hopefully I can get this stroker to blow clean

I believe 48 HC is going to be a BIG challenge as even the stockers are failing at this level

it's ridiculous that VA cut the standard from 98 to 48. cars are getting any cleaner as they get older [-X

[Kevin]

it's ridiculous that VA cut the standard from 98 to 48. [-X

that's ********

[XfireZ51]

Driving the car back from BG was a low point for me. The car felt like it was running like Sh*t. MPG was not very good IMO. There is a rhythm to a well tuned motor and the trip back from BG, it sounded like a out of control orchestra. Just didn't have that harmony. One of the things that has really
made this package sing is playing w the SA tables. More timing
has brought it together. Adjusting the Accelerator Enrichment also helps with giving you that sense of being directly connected to the motor. You tune it to eliminate that count to 1 before you actually feel the response from
the go pedal. At cruise now you get just a steady purr of the exhaust with no motor sound coming from the front end. Happy noise!
So now the tuning is focused on things like getting rid of the annoying surging on decel for example. Little nit picks but since I don't need to live with it, I choose not to. ;)
With Part Throttle pretty well locked in, I'm looking forward to optimizing WOT.
The cool thing about ECMs and tuning the ZR-1 is how you can create a Jekyll and Hyde car. A motor perfectly fine idling at 775-800rpm with little to indicate that there's a motor under there producing 500+ hp and 1/4 mile speeds of 120+. As the Octane Magazine describes it, the perfect Q ship.
I love sleepers.

[XfireZ51]

Here's a bit of the "proof of the pudding". A vid of idle after my last calibration change. Very nice.
http://i187.photobucket.com/albums/x198/Z51Xfire/th_RozaNeroIdle2vid.jpg (http://s187.photobucket.com/albums/x198/Z51Xfire/?action=view&current=RozaNeroIdle2vid.mp4)

[ZZZZZR1]

Dom,

Unreal tuning!

I want a dyno and 1/4 mile run ASAP!!!!

:cheers:

David

[XfireZ51]

Dave,

Here's one with camera resting on plenum.

http://i187.photobucket.com/albums/x198/Z51Xfire/th_RozaNeroIdlevid.jpg (http://s187.photobucket.com/albums/x198/Z51Xfire/?action=view&current=RozaNeroIdlevid.mp4)

[Paul Workman]

So now the tuning is focused on things like getting rid of the annoying surging on decel for example.

Yeah, baby! I'm all over that one! Apparently the surging is "one of those things" to be addressed when bumping the GO peddle output to some point over 500 ponies. Adjusting the idle screw helped a little. My IAC counts are a bit erratic tho.... Marc has a cal tweak for the surging, and I'll R&R the IAC motor this week sometime.

Anywayz, Dom, I really eat this tuning stuff up. (Comes from decades of tuning rifles for competition, I guess.) Ya gotz me on the edge of my chair, buddy! :thumbsup:

P.

[tomtom72]

Jez Dom...the camera isn't even moving:jawdrop:



Way to tune Dude!