Tuning a crate 350 H.O.

[rokcrawlin85]

I'm currently working on tuning my 85 K5 Blazer using a retro fit TBI off a 91 Suburban with 350/th400 setup for my 350 H.O. I am using the 1228747 (HD truck) ECM using $4F and tunerpro rt for tuning. I'm having issues keeping it from stalling out when going from park to gear. i would love some help with some things to look at in the bin other areas. I would also like to add a A/C idle raise somehow to the bin to raise my idle while using a winch or the on board air, but i have no idea how to add definitions. Help with this would be awesome too. Is it possible to use the $42 mask since its used for the 7747, which, as far as i can tell from reading, are very close to the same?

[EagleMark]

There's a guy here doing a 1227747 conversion to his 1228747 system but not sure what he did or is doing to control the Turbo 400 kickdown. Naybe he has updated the details? The ECM plugged in. The $42 XDF and ADX files are more detailed because of all the work into them. May be able to find some more paremeters from $4F hac to add to XDF?

Stalling from Park to Drive? Conversion system... did you hook up Park. Neutral wire and VSS? These are 2 things that work the IAC logic to make that a smooth transition. Mine never even has a hint of a hiccup there...

Since you have a 350 HO motor getting a good solid idle would be first. I'm guessing you can tune/burn a chip? With that motor adding 100 RPM to Idle, may be 2 spots for Opena and closed loop would help. Adding a few degrees at distributor timing with wire disconected would help but must take that extra and add it to Intail Timing setting which is usually 0 on these trucks, so if distributor set to 2 or 4, set Intail timing to 2 or 4. This takes it off top so you don't end up with to much timing!

Then doing the Min Air Setting because of the change in engine at link below is a real help for stable idle.
http://www.gearhead-efi.com/Fuel-Inj...-Fuel-Pressure

[rokcrawlin85]

i know i'm fighting some issues with tuning at low RPM's. i do not have VVS since i am running the 700R4 from the 85 K5 (no electronics). as far as i remember i have raised my target idle to around the 750 mark to keep it from trying to hop around at idle. I was debating on starting fresh again with one of the stock bins from the 1228747 forum for a 7.4 since my motor obviously needs more fuel than a stock 350 would. bad idea? It's nice to have choices. i haven't found that many stock bins for this ecm before!!

I would love to have more peremeters to change like you can do with the 7747 mask. can you post up a link to that thread about converting to the 7747? How do you use the hac info for the $4F to change what the ecm reads? i haven't a clue about that... too deep to explain?

[EagleMark]

Here's the link to guy doing the swap already.
http://www.gearhead-efi.com/Fuel-Inj...o-1227477-swap

You can add a VSS to speedometer cable with aftermarket from Jaqs that run, or in your case a speedometer cluster from newer 1987 truck or 1987 to 1991 Blzer or four door dually, Suburban as they has a VSS in speedometer, to DRAC, to ECM and ABS, cruise control.

Starting with 7.4L bin just to add fuel is not going to add fuel, just change VE table closer to 7.4L VE.

Problem with adding fuel to 1227747 and I'd need to look at 8747 is there are VE1 and VE 2 adder tables. If you add the 2 together your already over 100% and it is supposed to truntacate back to 100 so GM made a mistake from factory. Tuners don't like to go over 95 as a rule as injectors can go static (never close, flicker, spase out) Really only way to get more fuel for more HP engine is adjustable regulater and rasie pressure. Only way to get it right for your motor is do data log and tune your VE tables.

Hacs and adding things to XDF is not something I am that knowledgable of, others guys here are and we will see what they say. I have not even opened the $4F hac to see what it has to say, maybe take a look and see what you can find?

[rokcrawlin85]

In the $4F mask it only has one VE table. Probably due to the fact most of the trucks using these ECM's aren't going to be pushing higher RPM's, since there mainly used for towing and what not. I have been playing with logging and changing VE stats. I'll jsut keep playin and seeing what works for the better and post up with what i find or with questions.

[EagleMark]

I've only been answering your questions, but someone is going to come along and suggest you do a ECM swap to 16197427 since it is about a bizillion times faster and has a bizillion times more paremeters and hac options $OD is best supported... electric fan options, MPFI options...
http://www.gearhead-efi.com/Fuel-Inj...out-Directions

Repin your wires to 16197427 PCM
Remove ESC and run knock sensor wire to PCM
Have to have VSS, actually VSS is a good thing on all EFI systems whether you can remove them and run or not. You can fool even a fool! But why take out something that works?

I think Greg has a couple for sale with plugs and pin tails in for sale section if you don't have a Pull and Save JY nearby...

G1 Adpater and 27S512 chip from Moates with a burner, TunerPro and all other files needed are here!

[gregs78cam]

Does anyone know how closely the '7747 and the '8747 are built to each other? I mean do they have the same MCU I/O ports. My bottom line thought is, would it be possible to run $42.bin in this ecm, and tweak it with $42.xdf and log it with $42.adx? You know just like we can run $0D, $0E, $85, $E6 interchangeably in '7060, '8625, '6395, and '7427.

[JeepsAndGuns]

Yep, I'll be the one to suggest the 7427 swap.

I would love to have more peremeters to change

I have the answer for you. Its called the 16197427 PCM. Simply change the wires from your old connectors, and put them in the connectors for it (using a wiring diagram of corse), and have a computer thats 100 times better. Learing curve is a little steeper, but if I can do it, anyone can. I have loved this computer ever since I have swapped it in.