New LT1 tuning tool

IF you do your own tuning...

IF you haven't heard (I copied and pasted what I wrote on ISSF a bit ago)...

There is a new open-source LT1 tuning tool that's being developed by some truly gifted individuals.  I had the privilege of beta-testing that tool over Christmas, and it is by far the best OBD1 LT1 logging/flashing tool in existence.

Among the dozens of cool features in that tool are real-time spark timing adjustment, idle speed adjustment, AFR adjustment, and tune uploads up to twice as fast as Winflash. No those aren't typos. It literally reduces LT1 drivability tuning from days to a few hours. Several folks on that forum have made tremendous progress cracking the LT1 code, which you can read about here. I think a custom LT1 OS is not far off.

That said...
Tuning done right takes a lot of understanding of combustion dynamics, sensors, fuel injector nonlinearities and characterization, O2 integrator gains and delays, and computer hardware and software, and if you don't have the time/energy to learn that stuff, it's far better to pay someone who does to tune your car for you. And DON'T go on there asking for a free tune. That's rude and ignorant.  Proper tuning is well worth paying for.  I have over 100 hours invested in tuning my STOCK '94 Roadmaster wagon, but it runs and shifts PERFECT at 190k miles.

FYI - Greg Banish's books are a great starting point and massively helped me get going.

[You must be registered and logged in to see this link.] - download site

[You must be registered and logged in to see this link.] - discussion site.

Finally, a few of you probably saw me adjusting someone's PCM at Wagonfest 2013 with a hacky little setup... I bought that for $10 off ebay and have tuned multiple cars flawlessly with it. I discovered it on the gearhead-efi.com website as well.

Are you doing custom tuning for hire?

Cool. Thanks for the info.

Up to this point I've only tuned cars in person.  These cars are so old that there are too many maintenance variables for me to simply email out a tune.  Before I'll even tune a car, I check the following things:

0. Ignition system (ICM, coil, optispark, coil wire, plug wires, plugs) in good working condition, plugs are correct heat range for the motor.
1. Injectors in good working order.
2. Fuel pump operating at spec pressures across the load spectrum.
3. MAF is clean, screened, and reading properly.
4. Intake tract is in its final state and not about to be changed (makes a HUGE difference in part-throttle and idle tuning.
5. All exhaust manifold bolts intact, no broken bolts or gasket leaks.
6. O2 sensors working properly.
7. Knock sensors working properly.
8. Cooling system functioning properly.
9. Other sensors (TPS, coolant, MAP) functioning properly.
10. Powertrain is not hitting the suspension or frame (this often causes false knock).
11. Exhaust in final form and not about to be modified.
12. PCV system operating properly.
13. EGR operating properly (ideal) or properly blocked off.
14. Transmission mechanical health ok (above 175psi at top of 1st gear at WOT).
15. Consistent quality fuel available.  I've seen tunes vary 10% from tank of gas to tank of gas due to ethanol content fluctuations (there's a reason they say "UP TO 10% ethanol").

If you can demonstrate to me that ALL of these parameters are addressed, then we can talk.  Otherwise, just buy a mail-order tune and be done with it.

Thanks for the directness,and honesty. In short supply these days.

Just wanted to add an update. EEHack version 4.6 is out, and boy is it sweet. The data analysis tools match nearly all of the homebrew analysis software I created and used in the past. I'll never flash any other way ever again. They're looking for B-body testers too.

Combine this with the latest binfile definitions in TunerPro and you can pretty much fix anything in the tune the right way (provided you know what you're doing).

sherlock9c1 wrote:

(provided you know what you're doing).

sure gets interesting when you 'think' you are improving things,.and then you drive it and then you find out that its 'not' improved,. aaaargh.

Would be really great to get a tutorial explaining how to set certain things,.and what the outcome will be if you go too far,. or not far enough etc,.

Plus a nice explanation of the gobbledy gook way that GM labels certain functions ,. enable,. disable,. which are all over ridden by something else anyway,.and which go completely against a logical way of thinking,.

GRRRRRRR,... lt1's can be exceptionally frustrating for a 'simple' minded guy like me,.

First, THANK YOU for working with steveO on that. That's huge.

For me, honestly I've always ended up using EEhack via my benchtop programming harness so I don't have module cross-talk problems.

I posted up on gearhead EFI that I tried reflashing a PCM I had flashed using EEhack 4.0 and I couldn't reflash it using 4.6; I was constantly getting Mode13 (Security) failures. I switched from B-body mode to F-body mode and was able to successfully flash.

Nick, I hear ya. There's a lot of adders and adjusters out there for sure. I've done a LOT of reading, and a LOT of trial and error and looking at data logs. There is a large amount of good information out there, just takes time to find it all and digest it.

The other thing to do is do as much figurin' and trial and error as you can, then join a group and start interacting with and trying to improve the community. I made a lot of good friendships that way; the tuning community quickly gets frustrated with folks getting on and their first post is "hey I need a free tune for a 383 with 42lb injectors, headers, hot cam, 4.10s blah blah blah." But they are GLAD to know someone who's genuinely looking to improve the art.

Just to give a reference point for any newb reading this, the last tune I made for a highly modified car, I spent literally 30 minutes walking the car owner through all of the changes I made (from a stock tune) and we STILL were using generic timing tables. There are literally hundreds of parameters and they all need to be in the ballpark for the car to run decently. And there are some areas that don't matter much and some areas that are critical.

The EE hack works great with my caddy,. i use it to log,. and play with the afr,.
but i use tuner cat to load a new file,.

I just need something to adjust the speedometer in my 9C1, was set for 275/40/17, need it back to stock size. Last time I tried Tunercats and couldn't get it to connect to the PCM, maybe I'll try this later.

It's been awhile, and I know TorqHead is getting a lot of press right now (rightfully so), but eehack 4.7 has a [You must be registered and logged in to see this link.] (modified PCM operating system) that puts the Mass Airflow Sensor (MAF) and Volumetric Efficiency (VE) tables in RAM which means you can edit them in real time, and then recover the modified tables after you're done tweaking.  This is a quantum leap in '94-95 OBD1 LT1 tuning, particularly if you're operating in speed density mode (MAF disabled) or you've modified your air intake AT ALL.  You could theoretically be done tuning your MAF tables in an hour or two, rather than a day or two.  

And just to reiterate, if you have changed your intake piping AT ALL, the stock MAF tables won't be accurate anymore.  That means if you've removed any of the resonators ("first base" and "homeplate"), "upgraded" your system with pipe from a hardware store, etc.  I've seen it every time.  The factory ECM will compensate to an extent but the car won't run as well as it did before until the MAF tables are recalibrated.

For those of you with severely modified setups, eehack also has integrated wideband datalogging capability with the stock PCM. Unscrew the stock O2 sensors, screw in a wideband, connect them to specific pins in the PCM, and now you have synchronized datalogging.

Awesome stuff, even though I have absolutely no clue what to do with any of it.

Just wanted to update this again - the latest from the OBD1 LT1 crowd at eehack/tunerpro is the ability to alter fuel injector timing.  It probably doesn't apply to this crowd, but if you are running a cam with a lot of overlap, getting closed loop fueling at idle to be stable was nearly impossible.  It ended up that delaying the injector timing until AFTER the exhaust valve closed eliminated this problem and also eliminated what a lot of people called "cam surge" at low rpms.  

I do believe TunerCat has incorporated this, though I haven't verified.

Freebie:  the parameter "max line pressure" is not the maximum line pressure; it's actually the value at which the force motor current reaches zero (the force motor (or electronic pressure control solenoid) works opposite; more current = less line pressure).  So the common mod of raising the stock value of "90 psi" to "120 psi" actually LOWERED commanded line pressure unless you completely reworked the rest of the tables to add 30 to them.... which gets you right back where you started.

Figures this gets posted the day after I order the TunerCats kit.

Sherlock - is there a forum where people are sharing tuning tips specific to the wagon and the like? (should we do that here somewhere?) I got the CATS kit mainly for "safe" changes like fan temp settings and VATS disable, (figure I may as well do that myself rather than sending the PCM out) - but I'd be interested in seeing how actual engine tuning is done.

Try this place. [You must be registered and logged in to see this link.]

Lamune, the best I can suggest is to get any of [You must be registered and logged in to see this link.].  I bought his "Engine Management: Advanced Tuning" and "Designing and Tuning High-Performance Fuel Injection Systems" and they were very helpful.

GM loaded a very conservative engine tune in the B-bodies to account for manufacturing variability and reliability / longevity.  There's plenty of room to optimize (particularly in MAF, VE and spark tables) but the car needs to be in good order before you do this (as I detailed in a post above).  Step one is to take off the stock exhaust manifolds, have them planed flat, and reinstalled with new gaskets and bolts. Stock LT1 fuel injectors are not doing you any favors either at this age; several of us have stated avenues for using newer GM or Ford injectors to get ethanol resistance and improved spray patterns.  On a stock motor you won't see big horsepower gains just from a tune but you can get better drivability and gas mileage.

I'd also say there's a lot of drivability improvement to be had optimizing TRANSMISSION tuning - the shift MPH tables for your particular driving style and commute.  

It's worth stating that as far as TunerCat vs. anything else, it's fine to use, but eehack's uploader is far more rugged and error-proof.

Any issues with win10?

I just saw this thread for the first time. I'm still using a demo mode of Datamaster on a winXP laptop for monitoring....

Thanks Sherlock, I have some reading to do.

I'm building a 355 for it now so it'll be basically new. I have replacement injectors in there... The stock tune seems to run on the lean side assuming it wasn't due to some fault so I wouldn't mind tweaking that a tad to keep the valves from getting burnt. But I think we're digressing a bit.

eehack's uploader can be used with any eprom image, I would assume, but I haven't gotten that far yet.

No issues with Windows 10 and eehack. I do strongly suggest buying a USB to TTL cable and hard-wiring it to the back of your ALDL port if you're doing any uploading of tunes to the PCM. I and others have bricked PCMs because of those loose ALDL connector pins. Those cables are very inexpensive on Ebay. You can read more about the specs [You must be registered and logged in to see this link.]

Remember that the PCM is able to adjust for roughly +/- 10% fueling variation without issue so just because it's showing that it's adding fuel doesn't necessarily mean the motor's actually running lean.

As far as your stock tune being on the lean side, how are you coming to that conclusion? Start another thread and we can talk about it.