OK, I've got a stock LG4 with TPI on top, TH350, in an 83 4x4 s-10 blazer . I've got it running pretty well at the moment using a bin file from a 91 305 auto. Its running rich enough to cause backfiring after hard acceleration. I assume this is because the VE on my lg4 is lower then on the 91 tpi 305 engine. Should I start tuning this one down or is there a bin that would be better to start with? Also, is there an input to the ecm from the gearshift to tell it its in gear vs in neutral?

Thanks

 

If you are using the SD TPI, then you should get the prom burning equipment and use the $8D TDF (that is the one used for SD cars).

Is your truck a manual? And was your 305 memcal a manual? A number of guys that convert to a standard that start with an auto BIN notice this.

I have an auto, but my ECM DOES detect Park/Neutral, Gear and O/D. I think the logic for the $8D also does this for the Manual except with a few twists. I haven't really dug into that part of the logic as I have had no need with my automatic car.

 

Thanks for the reply. I'm already set up for prom burning and I've got moates' software working for a scanner. Truck is an auto, TH-350. I'm actually using a modded memcal but I downloaded and burnt a chip for a 91 GTA 305 auto, unmodified except for turning off VATS. I got it from the diy-efi.org ftp, was listed under 8D so I'm assuming this is the right code. There are a number of other bins there with the 4 letter code I've seen, what are those? Also, does the ecm detect neutral/drive/overdrive logically or does it get inputs from the shifter/tranny?

When running the truck, I'm observiing what i think is strange behavior. The blm cell number will be a 00 when cranking but then as soon as it fires up it goes to 04 and wont change agian, even with varying loads and throttle while driving. I found a few other posts about this but couldnt really find an answer. When I'm driving BLM counts range in the 116-120 range usually. I assume this is because the cam in the lg4 sucks (I wish i'd not been so cheap and changed it, but for now i gotta live with it) so I'm going to need to adjust the VE tables. But I dont want to start playing with it until i get the BLM cell number un frozen.

 

Well I found part of the problem, what i though was a 305 bin was actually a 350. Did a little searching in the gmecm archives and found that AXXF should work for me. Just got back from a drive and it seems to be working much better. Its still exhibiting the same behavior with the BLM cell number. Is this just because it hasnt learned the engine yet?

 

What size injectors did you put on w/ the TPI? I installed TPI on my LG4 and used the stock SD 305 auto calibration. I had to do some tweaking however, since I am using 22# injectors. You may want to try increasing your injector flow rate constant.

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1987 Trans Am 305
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I'm using 19 lb injectors, at least i'm pretty sure they're 19lb. The truck was running better with the AXXF in there, but I didnt get a chance to do much testing because of a bad connection in the modded memcal, but that's easy enough to fix. With the 305 chip the What I'm really interested in now is why the BLM cell number doesn't ever move from 4 no matter what load and rpms. I dont want to start tuning it until that is working properly.

 

Also, can someone clear up whether I need to wire up a switch that tells the ecm the tranny is in gear or not? When I put it in gear the target idle speed doesnt change and it just uses the IAC to try to bring it back up.