Swapping TBI to TPI

[Txwildman]

Hi guys I am dong a TBI to TPI swap in my 90 chevy truck I will be having a lot of question on wiring heard a lot about this forum all good all good so hope to read some great info here!! Yes the computer and harness came with the engine it's a L98 5.7 from a Firebird Formula here's a pic of it I had it creamic coated and polished I'm just wondering how the intergration of the harness's are going to go from TBI to TPI any help here would be gladly appreciated Pic of the engine and truck it's going in thanks again

1990 chevy truck


TPI 91 L98

[dave w]

Having the correct wiring schematics for the TBI to TPI swap is essential!
Here is a link to the TPI wiring information: http://www.gearhead-efi.com/Fuel-Inj...CM-information
Here is a link to the TBI wiring information: http://www.gearhead-efi.com/Fuel-Inj...Information-42

I can't tell from the posted TPI picture, is the TPI system speed density (MAP)?

It's possible to make an adapter plug, TBI computer to TPI computer.

dave w

[Txwildman]

Thanks dave w for the links. The TPI is speed density, and are you talking about an adapter as to where you can hook up direct to the TBI ecu from TPI ecu? Pic is from the 91 Formula harness with ecu

[dave w]

Thanks dave w for the links. The TPI is speed density, and are you talking about an adapter as to where you can hook up direct to the TBI ecu from TPI ecu? Pic is from the 91 Formula harness with ecu

The attached pictures are from a TBI computer upgrade (1227747 to 16197427) adapter I did. The same concept could be used to adapt a TBI computer to a TPI computer.

dave w

[Txwildman]

So you're saying (sorry i'm a below novice for wiring) I have to make an adapter that can go from the TBI (1227747 to 1227730) TPI and make the adapter part from the TBI ecu by taking it apart? Sorry if I sound stupid LOL!!

[dave w]

So you're saying (sorry i'm a below novice for wiring) I have to make an adapter that can go from the TBI (1227747 to 1227730) TPI and make the adapter part from the TBI ecu by taking it apart? Sorry if I sound stupid LOL!!

You can either re-pin the TBI connectors into the TPI connectors, or make and adapter. No need to do both. The adapter is virtually "Plug-N-Play" conversion.

Basically, the old TBI harness can be re-configured / re-purposed for TPI service. No need to pull the TBI harness and install the TPI harness.

dave w

[Txwildman]

You can either re-pin the TBI connectors into the TPI connectors, or make and adapter. No need to do both. The adapter is virtually "Plug-N-Play" conversion.

Basically, the old TBI harness can be re-configured / re-purposed for TPI service. No need to pull the TBI harness and install the TPI harness.

dave w

[Fast355]

Your truck looks very familiar. You are not from the Hurst Euless Bedford area are you?

As for your 7730 ECM on the 7747 harness you can repin the TBI harness to connect to the TPI ECM. I did the same thing with my TPI G20. Also recently did the same thing to run the Australian $12P code in a 165' TPI ECM.

[dave w]

Yes.
There are many details to work through!
http://www.eficonnection.com/eficonn...spx?ItemId=309
http://www.eficonnection.com/eficonn...spx?ItemId=307
http://www.eficonnection.com/eficonn...spx?ItemId=308

dave w

[Txwildman]

Thanks Fast355 and dave w

[Txwildman]

Okay finally put the TPI in the truck wiring all done but now the FPR (Holley adjustable) touches the bottom of the upper plenum intake can I just grind down the part of the plenum that touches the dial to give it room so I can turn that dial on the FPR to adjust my flow of fuel? Thanks in advance

[bybyc5]

You are going to love the TPI in your truck.
I did a similar project not to long ago, and I couldn't be happier with the results. Mine is a 93 Silverado K1500. Your motor looks great all chromed and polished up!

I still have my notes if you think you need them, albeit we are using different PCM's.
http://www.gearhead-efi.com/Fuel-Inj...68625+16197427

And yes, I had to modify my intake (stock tpi) to accommodate the adjustable fp regulator as well. But your likely past this by now.

Keith

[Txwildman]

You are going to love the TPI in your truck.
I did a similar project not to long ago, and I couldn't be happier with the results. Mine is a 93 Silverado K1500. Your motor looks great all chromed and polished up!

I still have my notes if you think you need them, albeit we are using different PCM's.
http://www.gearhead-efi.com/Fuel-Inj...68625+16197427

And yes, I had to modify my intake (stock tpi) to accommodate the adjustable fp regulator as well. But your likely past this by now.

Keith

Thanks bybyc5 I really appreciate it I'm running into a problem on the installation of the efans I am using the dual fans from a 05 silverado (cause it's a perfect fit to my radiator but I'm stumped on the connecting to the ECM I have all the relays hooked up I just want the ecm to control when they come off and on also when using the a/c any help would be appreciated thanks

[Txwildman]

Here are the fans I'm using the harness has been built but according the diagram I can hook these up to the ECM? But just wondering if I can splice them into the temp sensor that's on the passenger side head and the a/c switch that's on the dryer? Or will that not cause the fans to turn on? I don't want to run a separate switch I want the ECM to operate them any help is appreciated thanks

[Fast355]

Here are the fans I'm using the harness has been built but according the diagram I can hook these up to the ECM? But just wondering if I can splice them into the temp sensor that's on the passenger side head and the a/c switch that's on the dryer? Or will that not cause the fans to turn on? I don't want to run a separate switch I want the ECM to operate them any help is appreciated thanks

If you are using the 7730 ECM it has ability to control two fans. The 2nd fan output is on the same connector directly opposite the 1st output. The PCM has parameters to adjust for both low and high speed fans and can also control the fans with the A/C and turn on and off at a programmed vehicle speed. I used primary fan control to ebergize the low speed and the secondary output for high speed.