NEED HELP TBI TO TPI CONVERSION TUNE ON 1227747

[cor242487]

Hey everyone so my friend decided he was going to take is 89 chev k1500 with 5.0 tbi and install a tpi intake a mild cam and gear to gear timing on this engine. Now he's wired the injectors up to the existing tbi wiring to amazingly it will run on a stock tune but its really hard on fuel and also doesnt run the best. So he bought from moats the autoprom kit that had everything for tuning to data logging. I have been on this forum reading up on tuning but from what im understanding is that im not just tweeking for a little more hp im looking to remap the whole deal get this 5.0 tpi with map to run like it was stock then tweek it for the bigger cam and to open up some potential from the motor. So here's where im at i have messed around with the ve 1 and 2 tables and adjusted the bpw i got the truck to run some what decent but then it will start to surge and lose in the higher rpms. I really need some help i think im going about this all wrong and a little professional help to guide me to where i need to be would be awesome. Im having alot of fun tuning being its my first time but this one is an advanced tune and maybe a little outta my league at this state but i wont give up i just need some help. So anyone who may have done this type of conversion and tuned it to a 747 ecm that can help would be super awesome or any help would be just perfect. Any questions or requests for the bin file i have saved just ask i will answer all questions thanks.

Corey R

[Six_Shooter]

Honestly your best bet is to swap to a 1227730 ECM, it will make your life MUCH easier.

Part of the problem in the injector firing strategy. The TBI injectors fire every revolution, and even though they alternate from one side to the other (or however your friend wired them up), this will cause fuel to puddle behind the valve that will cause surging, rough idle, hard to tune driveability, and just give you headaches.

In a TPI application the injectors fire every other revolution, and while a little bit of fuel may accumulate behind the valve, it is usually kept in suspension, due to the fuel hitting the heated valve, and works well with a fuel delivery where it is an injector placed in each intake runner.

Now, I've been told that the injector firing scheme can be changed in the '7747, but IIRC it's a hardware (ECM) modification.

I say this with experience attempting something very similar to what you are attempting, only the actual engine itself was different, using a custom MPFI intake on a 348 (Baby 409). We started with a '7747, because I was more familiar with them at the time than the '7730, but in the end swapped in a '7730 and may leaps and bounds progress in minutes/hours, over what took months with the '7747.

[cor242487]

ok thanks im going to get my hands on a 7730 ecm, your statement about the fuel puddling up on the valves makes sense, when the truck is off and you open the throttle you can hear the fuel sizzling inside the intake which you just explained that. So once i have the 7730 ecm what bin file should be used in particular or just a general bin file that close suits the manual tranny and size of motor? Im not as worried about the gear to gear timing i just want to get a base tune working then worry about those details afterwards. Thanks for the info this really does help me to head in the right direction

[EagleMark]

But you were told the Gear Drive timing set is going to cause problems with knock sensor. So why aren't you worried about it?

Maybe explaining it another way will help? The gear drive timing makes so much noise that the knock sensor picks it up and constantly reduces timing... up to 10*.

[cor242487]

Oh yes that makes more sense i didnt realize thats what it happens so should i just advance the timing 10 degrees advance to compensate for it or will the ecm constantly fight with me thinking the knock count is to high and keep retarding the timing?

[EagleMark]

Well optimal would be don't use gear drive... but instead disable the knock sensor, I hate to ever say that!

Usually the MAF guys convert to 7730 and use S/D as well...

[cor242487]

so i was talking with my friend and he has a complete wiring harness for a 5.0 tpi with maf and the matching computer thats for 5spd transmission. He has the maf sensor so were going to go ahead and just change the whole harness with computer and make it into a mf setup. Now just a question that i have i know now we will have to get a different chip adapter for the new ecm but what i was wondering is what kind of tuning can i do to that setup apposed to running the 7730 map setup. Will i be able to make adjustments for the cam and timing. Also he's adding headers to the setup and increasing exhaust to 2.5" with a flow master dual setup, and later on possibly swapping out injectors and possibly doing some internal mods. So with this maf setup will i be able to compensate the upgrades with a tune?

[jim_in_dorris]

Hey everyone so my friend decided he was going to take is 89 chev k1500 with 5.0 tbi and install a tpi intake a mild cam and gear to gear timing on this engine.
Corey R

Good Luck with that.... Timing gear drive really messes with the knock sensor. You are going to be fighting it the entire tune if you can make it work. All the rest of the parts aren't hard to tune, just that. Six shooter is correct, 747 is not the best ECM for TPI.