Help with a 5-speed swapped 93' S10 8625 $E6 Vin "Z" TBI 4.3

That's a very valid point LOL, I didn't look at the 92 ECM that hard, and I've been running on about 5 hours of sleep since Saturday. I think I posted a pic of my memcal on the previous page, but I bought some 3M ZIF sockets off of Amazon, and modified one of them to fit the memcal in my 8625. I should've paid more attention to the action of the sockets when I got them because on the ones I bought, there is no spring that holds them closed like on the AutoProm. I have to make extra sure that the lever is pushed all the way down and doesn't try to come back up, but once you get it all the way into the latched position, it does alright. I had to trim the cover a bit, but with some rubber edge-moulding around the hole, everything fits rather nicely, and the board is still protected. I put a little corrosion-x on the chip, and it's good to go. I guess I'll keep what I've got since it's a 28 pin socket, and it works!
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Attachment 13874

Welp. . . Took her out tonight with the $0D tune in her, and she idles down and shifts like a DREAM under 2000 RPM, but there is a terrible jerking studder if I hold her around 2000, and she is still slow to decel above 2K. It almost feels like the IAC is doing a funky dance but when I get it above or below the studder, it seems to really smooth out. I am not sure if there is a "learning" process, but if not, it's worse.

I'm at a loss atm, and I think I'm gonna get some rest and look at it with fresh eyes and mind tomorrow. I'm hesitant to make runs around the neighborhood at night with the glasspack muffler and my laptop in the passenger seat. Hopefully tomorrow I can get some datalogging in, and maybe start looking around for what's going on. I'm hoping that with the datalogger hooked up, I'll find something blatantly obvious :confused: but I'm skeptical.

The damn thing ran too well before to have any major issues. . . Just seems like this trans swap thing is like organ rejection for the old red turd. :mad1: I'm sure I'll eventually figure out what she's mad about and fix it, but for now, she's really not happy with me dinking around with her brainbox. Thanks everyone! I'll keep yall informed if I come up with a smoking gun, and as always, if anyone has any bright ideas I'm always willing to try em out!

~Phil

IAC tends to react slowly compared to changes in spark timing or fuel. It can help to remember this while chasing problems.

Does your engine have EGR? Is it operational? If the ecm is advancing timing because it expects the EGR to be operational or to allow more exhaust gas into the intake when commanded then you can get surging. Hmmm... Comparing C/K truck file to the one from yours it looks like the C/K needs to have "EGR Off in Open Loop" set and "Backpressure EGR" cleared.

1Project2Many, you were spot-on with your EGR suggestions. I fixed those two (which were both wrong) and the surging/jerking stopped right away, which left me with the same ol' issue. I bought myself a little power inverter today, so I could plug in my laptop in the truck, and set off early this afternoon logging data with the computer connected. It dodn't take me too long to notice something that didn't make sense to me. I noticed that the spark advance was staying up around 28-35* even when I let my foot off the accelerator, and didn't settle down until I came almost completely to a stop.

I opened up the search in TunerPro, and searced "speed", "idle", and "spark" just to have a look around. Long story short, I found that the spark advance table was releasing the spark advance back to 12* anywhere below 1200 or 1600 RPM while the truck was running, so I set the entire closed throttle table to 12. This made a good bit of difference! I also set the maximum speed for idle from 3 to 60 MPH, and changed some of the percentages of TPS to spark advance. PRESTO!!! I can shift with much quicker decel time between shifts, and she's even gurgling on engine braking like I was wanting. I've finally got her drivable again!!!

I think I can tune and tweak settings from here, but I wanted to let you know that between the EGR settings, and the timing map on closed throttle, I made some GREAT headway today! Thanks to everyone for all the help, and a special thanks to 1Project2Many for the patience and willingness to nudge me in the right direction throughout these issues. I can't tell you enough how appreciative I am. Truly a gentleman and a scholar! Thank you!

~Phil

Excellent news.

For about five years I worked in an area where trucks were popular. The C/K trucks with 4.3 and manual tranmissions always seemed to "hang" when shifting gears. I've never checked to see if the issue was the IAC / throttle follower, spark, or another value. It soulds like you're on the track to solving it.

I recently located a file which has all of the calibrations which were on the old gmecm website. I'm in the process of organizing them now. If I locate any interesting and relevant files I'll add them.

1Project, I was kinda wondering if that "hang" as you called it, was a "normal" side-effect of the ECM and TBI setups. I might not be doing things "correctly" as a professional tuner would, but I was so sick of the idle not going down, I broad-stroked the entire closed throttle spark advance map down to 12, and somehow, the program read in the negatives when I checked it on my other computer (rather than the laptop in the truck). I just thought, there's no real need to have the timing advanced at all when you're off the accelerator. I thought back to the good ol' carbie days with vacuum advance timing, and as soon as you got off the accelerator, the timing would immideately drop back to whatever you had the base timing set to.

Like I said, I'm probably going about this in a way that'd make real pros cringe, but it seems to be working out for me. I have been building small engines since I was 8, and I tend to think of their operation as a good foundation for what I'm programming here. I hope that by having the spark advance drop to nothing on 0 TPS input, I don't cause problems somewhere else, but in the little piddling around with it I did yesterday, I don't see any major issues I can't "tune and tweak" around. I just love the gargling engine braking, and the responsiveness improvement. It's not perfectly where I want it yet, but I'm really happy that I"m not slipping the clutch between shifts anymore.

Is there any validity to me thinking that the ECM is making it's own little adjustments to my base tune and timing "suggestions" or am I just imagining that my values are changing? Thanks again!

~Phil

The hang is caused by throttle follower. Look at the parameters for that. If you lug these engines down in higher gears, you will also get a hang that is related to stall saver and it will not go away until you come back below max mph for idle. Try lowering the value for Time for limiting throttle follower to about 0.1 second and test the effect. I also bumped the max MPH for IDLE VE and Max MPH for idle spark to something like 30 MPH. This forced the IAC back to idle from stall saver mode once it gets below 30 MPH. I also played with the RPM settings for stall saver. Use the parameter finder in tunerpro to search for throttle follower etc. These PCM's are highly configurable but that makes them more tedious to calibrate.

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Originally Posted by Philalbar1

I just thought, there's no real need to have the timing advanced at all when you're off the accelerator. I thought back to the good ol' carbie days with vacuum advance timing, and as soon as you got off the accelerator, the timing would immideately drop back to whatever you had the base timing set to.

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I'm wondering when were the good ole days for you. From your comments, it appears to be the early 1980's. Prior to the early 1980's and the OEM's dealing with emissions, engines used manifold vacuum to control vacuum advance. When you let off the throttle or at idle for example, full vacuum was applied and timing advanced accordingly. A lean fuel mixture called for more ignition advance and the engines ran smoothly. When the OEM's began developing strategies to deal with emissions, ported vacuum came into play. When you let off the throttle with ported vacuum, vacuum was cut off to the distributor and the ignition timing returned to base timing. Engines didn't idle very smoothly and other strategies were employed.

I'm glad to see you are gaining on the problem. I personally believe you raising the MPH for idle had the greatest effect but don't quote me on that. :)

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Is there any validity to me thinking that the ECM is making it's own little adjustments to my base tune and timing "suggestions" or am I just imagining that my values are changing? Thanks again!

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Well, the ecm programming doesn't support that theory. The ecm is able to learn some fuel corrections but it must do it each time the vehicle is driven.

If you watch your MAP sensor it can tell you whether or not the throttle or IAC is staying open during deceleration. If you'd like to turn the timing down then be my guest. But it's possible the MAP doesn't trigger deceleration enleanment which, with hot exhaust and low spark advance, could lead to a backfire. With IAC closed during decel, MAP could drop to 20 kPa or less. If MAP is higher you may want to follow up on the tip from sturgillbd.

Quote:

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Originally Posted by Philalbar1

1Project2Many, you were spot-on with your EGR suggestions. I fixed those two (which were both wrong) and the surging/jerking stopped right away, which left me with the same ol' issue. I bought myself a little power inverter today, so I could plug in my laptop in the truck, and set off early this afternoon logging data with the computer connected. It dodn't take me too long to notice something that didn't make sense to me. I noticed that the spark advance was staying up around 28-35* even when I let my foot off the accelerator, and didn't settle down until I came almost completely to a stop.

I opened up the search in TunerPro, and searced "speed", "idle", and "spark" just to have a look around. Long story short, I found that the spark advance table was releasing the spark advance back to 12* anywhere below 1200 or 1600 RPM while the truck was running, so I set the entire closed throttle table to 12. This made a good bit of difference! I also set the maximum speed for idle from 3 to 60 MPH, and changed some of the percentages of TPS to spark advance. PRESTO!!! I can shift with much quicker decel time between shifts, and she's even gurgling on engine braking like I was wanting. I've finally got her drivable again!!!

I think I can tune and tweak settings from here, but I wanted to let you know that between the EGR settings, and the timing map on closed throttle, I made some GREAT headway today! Thanks to everyone for all the help, and a special thanks to 1Project2Many for the patience and willingness to nudge me in the right direction throughout these issues. I can't tell you enough how appreciative I am. Truly a gentleman and a scholar! Thank you!

~Phil

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Thanks for detailing your progress with this Phil. I will be building this exact combo this year (93 TBI with T-5) to replace a tired 2.8L and want to use the 16168625 for a few reasons. I had yet to find an OEM .bin for this combo besides the aforementioned "California" .bin already on the forum.

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Originally Posted by Eds

I'm wondering when were the good ole days for you. From your comments, it appears to be the early 1980's..............................
I'm glad to see you are gaining on the problem. I personally believe you raising the MPH for idle had the greatest effect but don't quote me on that. :)

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EDS, yea man, my first "real" tuning experiences with cars was on my 1980 El Camino. I fought with that ol' PITA for MONTHS trying to get the carb to act right at idle and WOT. Lots of metering rod adjustments, jets, a FPR, several spark plug and oil changes later, I got her to run pretty decent without dumping gallons of raw fuel right out the tailpipes. I was 16 then and that old gal was my absolute favorite cruck in the world!
Attachment 13918
I thought that finding the MPH for idle was going to be my ticket too, but even after raising that to 60 (I think), I still had issues with the engine returning to idle, and I noticed on TP that the timing was directly related. I think I have a post about what I was seeing there previously when 1Project2Many was helping me with my amature-hour ignorance. I can assure you, the closed-throttle timing reduction was the money-maker in my case. Thanks though, and I'm definitely gonna keep this thread bookmarked to go back and tinker with it some more. I just got in a couple more chips, so I can easilty transfer between one tune and the other.

Quote:

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Originally Posted by 1project2many

Well, the ecm programming doesn't support that theory. The ecm is able to learn some fuel corrections but it must do it each time the vehicle is driven.

If you watch your MAP sensor it can tell you whether or not the throttle or IAC is staying open during deceleration. If you'd like to turn the timing down then be my guest. But it's possible the MAP doesn't trigger deceleration enleanment which, with hot exhaust and low spark advance, could lead to a backfire. With IAC closed during decel, MAP could drop to 20 kPa or less. If MAP is higher you may want to follow up on the tip from sturgillbd.

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1Project, when it comes to backfire I have had her to full operating temps and used engine braking down the hill in my neighborhood, and I didn't get any backfiring at all. She did make some really nice gargling noises that really made my heart happy. Through the shortened exhaust and the glasspack, it reminded me of my Meano. I appreciate the input, as always, and I will definitely be looking into Sturgillbd's "throttle follower" and "stall saver" references, and see what I can find in my tune on that. I initially thought I was having issues with the IAC not coming back down, but watching the live TP data while test-driving, I saw the IAC was acting just fine (I just completely rebuilt the throttle-body as well, and paid special attention to that bugger) as I wanted to elimiate that as a potential problem. I was thinking the same with the ECM "tuning itself" and it may have just been a bad copy from my laptop to my desktop. I'll go back this next week and check it out in real-time with the laptop in the truck. I might have to pick your brain yet again if it's setting all my timing values in the negatives for closed throttle timing.

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Originally Posted by UglyBoost91

Thanks for detailing your progress with this Phil. I will be building this exact combo this year (93 TBI with T-5) to replace a tired 2.8L and want to use the 16168625 for a few reasons. I had yet to find an OEM .bin for this combo besides the aforementioned "California" .bin already on the forum.

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Yea UglyBoost, I've gotten loads of help from 1Project2Many, and he turned me on to the fact that I could load other bins to my 8625. I don't know why I didn't think about that before, but as I've said, I'm pretty new to this "Old-school tuning method" which happens to be pretty "new-school" for me. I can understand about half of what I'm reading in the bins now, but I'm not solid enough on it yet to be someone to come to. If you want to help each other out, I'd love to swap tunes with you when you get your project done. I will be the first one to admit I'm no "tuning pro", but I (after some time and a LOT of pounding my head on the desk:mad1:, as well as the occasional coulorful word) have managed to get my ugly ducking to run pretty decent. I haven't put any real road miles on her yet, but I'm hopeful! I'd love to find someone with the same setup and put our minds together to see if we could iron this whole thing out. I've at least got a good drivable starting point for ya when you are ready! Let me know bud!

Thanks a million guys, I really do appreciate all of your help on this goofball project of mine. I'm in finals week of school now, and I'll have next week to tinker more with it, but I've been spending about 16-18 hours per day getting my classes for this term buttoned up. Everyone needs 3 engineering degrees and 2 specializations right? :laugh:

~Phil

Here's an update

https://drive.google.com/file/d/12hO...ew?usp=sharing
https://drive.google.com/file/d/1gfw...ew?usp=sharing
https://drive.google.com/file/d/1pPI...ew?usp=sharing
https://drive.google.com/file/d/1dZt...ew?usp=sharing
https://drive.google.com/file/d/1d43...ew?usp=sharing
https://drive.google.com/file/d/1srx...ew?usp=sharing
https://drive.google.com/file/d/1S8L...ew?usp=sharing
https://drive.google.com/file/d/1iOJ...ew?usp=sharing
https://drive.google.com/file/d/1u94...ew?usp=sharing
https://drive.google.com/file/d/1P1w...ew?usp=sharing
https://drive.google.com/file/d/1qh6...ew?usp=sharing
https://drive.google.com/file/d/1ZsX...ew?usp=sharing
https://drive.google.com/file/d/1mAn...ew?usp=sharing
https://drive.google.com/file/d/1SGE...ew?usp=sharing
https://drive.google.com/file/d/1dRd...ew?usp=sharing
https://drive.google.com/file/d/1zBx...ew?usp=sharing
https://drive.google.com/file/d/1N9m...ew?usp=sharing
https://drive.google.com/file/d/1ntk...ew?usp=sharing
https://drive.google.com/file/d/1wFb...ew?usp=sharing
https://drive.google.com/file/d/1pHT...ew?usp=sharing

I've had some ups and downs, but the new problem is the timing advance. . . Truck is running pretty decent, and I've read all the timing advance posts, but the problem came after eliminating the EGR and redoing the grounds for the ECM. I'm exhausted and will throw some more info in tomorrow, but let me know if anyone has any ideas on the tune