TCC output blinking when I mess with certain thinks like Hiway cruise

Hey guys, I have a 1990 chevy c1500 with a 1227747 and 305 that I rebuilt about 30k miles ago. I have been modifying my proms for about 6 years now.

I found an issue recently while trying to get the hiway lean cruise mode to work where something that I am changing makes my TCC output like blink quickly rather than coming on. I have an LED wired to the TCC pin on the ALDL connector (had this since before I was modifying stuff, works great). The output blinks when you'd expect the TCC to come on but it never goes solid. I worry that this may be screwing up the transmission so I pull over and load an older BIN into it and everything is fine. My thinking is that there is some kind of address problem on one of the parameters and something I am changing is overwriting some other value in the PROM.


Vehicle info:

305 with flat top pistons (9.5-10:1?), swirl port TBI heads, L03 cam, short stock fit headers, 3" straight exhaust, 700R4, 3.08 gears, 31" tires. No EGR, I am planning on making an EGR cooler type thing to work with the stock style valve but keep the nasty crusty stuff out of my intake

Background info:

I use the Ostrich 2.0 and tunerpro RT to make my adjustments. I started out erasing and burning proms the old way since I had the equipment at work.
I am an electrical engineer that writes code for embedded micros sometimes so I sorta know how these computers work.

What I'm trying to accomplish with this tune:

The truck had an ASDU labeled prom in it when I got it. Ran pretty OK. After the rebuild I wanted to fine tune the VE table and add a little timing to take advantage of the compression and make it idle better in open loop. I read the chip into tunerpro and all of my early tuning was based on that. Weird thing is my BIN does not match the ASDU bin that I've found online. Anyhow, more recently I decided to try something completely different. I downloaded the AJUK bin which is supposed to be for a truck like mine with the 305, 700R4 and 2.73 or 3.08 gears. It ran pretty good unmodified. I downloaded a BIN for the L03 on a different ECM, opened it with the right XDF, copied the timing table into excel, loaded my BIN back up with it's XDF and pasted that timing table in. That ran great! the BLMs were pretty dang good for stock. I added back in my A/C idle speed increase and tweaked the TCC rpms and speeds along with a few other things and it ran excellent. THEN I decided to give the hiway lean cruise mode a try since I drive about 25 miles of 60mph country roads to work every day. As soon as I enable everything for that I get this TCC output problem.

Try looking at the parameter- Hiway-Min Coolant under Highway Lean Cruise. When that gets changed there will be a few negative things happen. Two in particular is no TCC lockup. The other it will mess with your idle speeds.

Awesome I will give that a try. Thanks!

I noticed something else weird, the Hiway AFR tables for my stock BINs look like some address is wrong because they are sort of random values. My bin that's giving issues has proper looking values in there, there must be something wrong with my XDF. Maybe putting values that agree with my XDF is trashing some area of the PROM that's supposed to have something else in there. I'm using the $42 V5.9.3 Is there a newer version?

Also the max MAP for Hiway mode is only 37.29, I tend to be in the 50's going 60MPH in overdrive at 1250ish RPM. is raising this value known to mess up other functions?

I have not yet attempted highway lean cruise. I just looked and I also have what looks like bad AFR values in the table and max MAP is 37.29. I am using $42-1227747-V5.9.3.xdf. Something may be corrupt in that xdf. It took me a while to figure out what patch/file was causing my issues. My motor is similar to yours in build only a 350. 9.4-1, swirl port heads, mild melling mtd-1 cam, shorty headers, 2 1/2" duals, modded the TBI. I would be curious to see your fuel and timing. I am pretty new at all this. I hope that I have helped.

Wow, good to know that I'm not the only one with the weird AFR table. It must be pointing at the wrong area of memory. Yeah you've definitely been helpful! At first I thought I might be crazy since so many people use this XDF.

Got to test on the way home from work, Turns out I hadn't messed with the Min CTS but changing my hiway AFR table back to the bogus numbers fixed my TCC problem. I guess I will have to check out some other XDFs for what addresses they use for that table

I didn't see it ever go into open loop signifying the lean cruise mode. Weird, more digging to do.

Side note, I did find something else in this XDF, the TCC table notes are worded kind of weird. I was never able to change the values to accomplish what I wanted until earlier today I read a post on here that explained the way the tables work

I had run a crudely modified timing table based on the PROM that was in the truck (labled ASDU but not?) I was pretty happy with that. I did a lot of BLM tuning and I had got to the point where I was getting the power I wanted but the mileage was not super. I could get 16-17 going mostly 60. I have an 84 firebird that I put a little diesel engine in that I drive most of the time so I didn't care too much and used the truck a couple times a month when I needed to carry stuff in the bed or tow, otherwise I drive the car that gets 60mpg as much as I can to save money on fuel. My car was out of commission for a while recently when I was waiting to find enough time to replace the clutch cylinder so I found myself daily driving the truck and got interested in tuning again to get a bit more mileage out of it. I really need to get my EGR put together but that's another story.

This time around so far I'm running a stock L03 FBody timing table and a stock AJUK fuel table and my BLMs are pretty darn close and the performance is great. I'm trying to sort out all the extra features like the lean cruise, DFCO and also get my TCC settings dialed in so it's not so aggressive before I do the BLM fine tuning again. I use the excel spreadsheet I found on here but I added more stuff to it to make it fancier.

One thing about the compression bump and good exhaust is I had to pop out the TBI idle screw cap and open it up a tiny bit to get my IAC in the ideal position at idle in order to get it to idle smooth.

Glad you are making progress.

Your firebird sounds interesting. What diesel engine?

I also had some difficulty with the TCC controls. Between the conflicting theories of operation around and that temp setting in my .bin it took me a bit to get a grip on it as well. Also I did not want lockup in third gear. Some time in the near future I will be looking at the lean cruise. If you find that a different XDF file is needed or something other than that I would appreciate a heads up. Thanks

The firebird has a yanmar diesel from a john deere tractor. The model is 4TN82, meaning 4 cylinder 82mm bore. Comes out to 1.8L. 33HP stock, I've got a turbo on it and I think it's somewhere around 100 now. I've got an NV1500 5 speed behind it and it's not particularly fast but the diesel instant throttle response and turbo make it sound and feel fast haha. mileage is the name of the game.

https://78.media.tumblr.com/tumblr_l...w4no1_1280.jpg
https://78.media.tumblr.com/tumblr_l...w4no1_1280.jpg
https://78.media.tumblr.com/tumblr_l...w4no1_1280.jpg

I looked at like 4 XDFs last night with no luck. I'm going to look through some bins and see what the heck is the deal with these bogus numbers. Every XDF I found has the address down as 0xB2B. I assume this is the starting address and the only thing that signifies the length is how much stuff is in the table. When I look for 0xB2B in the disassembly pages that some of the old school guys have made there's nothing listed as far as I can tell, however it seems like there are other unrelated bytes pretty soon after that address where I don't think an entire table would fit in there. I wonder if it's possible that some bins or ecus or something only have one AFR byte for the whole function rather than a table, but why would all the XDFs have a table for the 1227747. I'm super confused. My brother does some intense assembly programming on hacking the old nintendo 64 game console, I'll try to see if I can get him to look at it with me. It's hard to get him to look at anything other than the nintendo 64 but I think he would get excited about enabling a feature that the EPA blocked. He has an 89 camaro with the 2.8L and gets close to 30mpg stock.

Interesting on the Firebird!!

You are in the ecm's farther than I understand. I believe the 7747's had lean cruise. I don't think it was hacked later. Not for sure.

I was able to rope my brother the assembly code expert into this and we are finding some really weird discrepancies in the BINs. I don't know if I should keep this thread going or start a new one with a more fitting title.

If anyone comes across this thread for the original question, it ended up being some issue with the Hiway AFR table. Still working on exactly why