New to forum with fresh tbi install.

[EagleMark]

Your right! I just looked at ACJH because we have it and sure enough Initial Timing is 9.84.

[damanx]

Strangely, I have the timing set at 10 right now and the pinging seems worse than before.

Going to recheck the timing again and see if it drifted. Maybe set it back to 6 degrees and see what happens.

[EagleMark]

Looking at that bin it also adds 2.9x degrees when EGR is on, fueling changes with EGR on as well......

[damanx]

So I just added a banana jack to the est wire inside the cab. Much easier to disconnect there.

Anyways, checked base timing again and it was at 20 degrees, which would explain the previous pinging.

Going to run it again and see what happens.

Maybe ESC module issue...

is there a definition that reads the actual spark timing?

[EagleMark]

is there a definition that reads the actual spark timing?

Yup, I added it to $42...

[damanx]

Ok, insured the timing was set at 10 degrees and still had pinging. I then dropped the timing to 8 degrees and that reduced the knock counts significantly. Will record the drive in to work tonight and share that result.

[Fast355]

2.8 based TBI setups are weird breeds. Take my advice here. The 2.8/3.1 and 3.4 engines are VERY EGR SENSITIVE on STOCK tunes. The EGR passageways clogged up completely on my 87 2.8 GMC Jimmy and it would knock count practically any point from off-idle until it hit power enrichment. When I swapped the 3.4 into it, I used 4.3 injectors and the stock 2.8 prom chip for a time. Then swapped a 4L60E into it using a 94 4.3 TBI Astro van chip. The 4.3 tune required many hours of rework to run the truck properly.

[damanx]

2.8 based TBI setups are weird breeds. Take my advice here. The 2.8/3.1 and 3.4 engines are VERY EGR SENSITIVE on STOCK tunes. The EGR passageways clogged up completely on my 87 2.8 GMC Jimmy and it would knock count practically any point from off-idle until it hit power enrichment. When I swapped the 3.4 into it, I used 4.3 injectors and the stock 2.8 prom chip for a time. Then swapped a 4L60E into it using a 94 4.3 TBI Astro van chip. The 4.3 tune required many hours of rework to run the truck properly.

THANKS for posting that.

Once I get the prom reader in hand, I'll be able to focus on that stuff more. I am considering the swap to a 7747 ecm, but I really need to get the basics down first before I brick anything.

[EagleMark]

You can't brick these ECMs, that's a term used for a bad flash on OBDII stuff. Worst that can happen when you burn 27Fs512 chips is you click erase and try again...

I was looking through this XDF and Fast is correct about EGR fueling. It has a table for EGR BPW changes that are pretty drastic.

[damanx]

Okie dokie.

I am hitting the scrapyard tomorrow and have about $90 credit for a few parts that I could/decided not to use, so I'll grab a 7747 ecm from a 4.3l

Definitely want to use something more open to "hacking" per se.

[Fast355]

I have some IIRC 3F calibration information like a XDF and .BIN file for an 87 2.8 TBI that you might find helpful. The stock spark map is like nothing you will find in a 4.3. Also worth mentioning the V6s do not run well at all outside of complete asynch operation.

[EagleMark]

Also worth mentioning the V6s do not run well at all outside of complete asynch operation.

Do you know why? Man that's been bugging me but I've never had one to play with. I've fixed a lot of I6 conversions that had Async V6 chips with a built Sync chip and ran much better. There's one guy here that fixed a ASync V6 to run Sync and have not seen issues... yet...

[fasteddi]

Id say 2k pulse per mile for the vss. Is your datalog mph off compared to the speedo?

[damanx]

It's off by about 2-3 mph, but that I think is tire size.

Also, if I pick up a 7747 ecm tomorrow, can I plug it in and start the truck just to test it before i leave the scrap yard in case it's bad? I understand it probably won't run very well, I just want to not have to drive 30 miles round trip to return a bad ecm.

[EagleMark]

Sure. I've never done this one so it's not proven. But the 16146299 is again similar and plug and play. I also use a 1228746 ECM from Camaro and Caprice to plug into my 90 Suburban 1227747 and works fine.

Need a V6 though for the netres chip.