ECU change in a 98 have questions - The 1947 - Present Chevrolet & GMC Truck Message Board Network

speedygonzales · 03-31-2013, 08:22 AM

The vehicle is a 99 but it's the same as a 98. I refer to it as 98 since 99 had both 5.7L and 5.3L engines in 2 different body styles. This is the Vortec 350.

We all know the crappy intake gaskets and CSFI

I want to change to either a complete RamJet 350 engine or change the intake to the Ramjet and use the Fast EZ-EFI.

My question is this. What have others done with the old ECU? For example, the speedo is driven by a modulated signal from the ECU.

I would like the gauges to work as they should with no noticeable difference and no "check gauges" light on.

I understand the SES light will be inoperative maybe.

Then of course there is the whole transmission deal which would have to switch to it's own controller. Ugh. There must be a better way.

Is the answer to use both the old and new ECU? New one for controlling engine functions and the old one for gauges and transmission control??????

panhandler62 · 04-02-2013, 09:03 AM

Can anyone address this question?

**VetteVet** · 04-02-2013, 12:14 PM

Search results I found .
The first thread might give some answers.

........ http://www.google.com/custom?domains...D%3A1%3B&hl=en

03-31-2013, 08:22 AM	#1
speedygonzales Registered User Join Date: Jan 2006 Location: Smithfield, VA Posts: 1,501	ECU change in a 98 have questions The vehicle is a 99 but it's the same as a 98. I refer to it as 98 since 99 had both 5.7L and 5.3L engines in 2 different body styles. This is the Vortec 350. We all know the crappy intake gaskets and CSFI I want to change to either a complete RamJet 350 engine or change the intake to the Ramjet and use the Fast EZ-EFI. My question is this. What have others done with the old ECU? For example, the speedo is driven by a modulated signal from the ECU. I would like the gauges to work as they should with no noticeable difference and no "check gauges" light on. I understand the SES light will be inoperative maybe. Then of course there is the whole transmission deal which would have to switch to it's own controller. Ugh. There must be a better way. Is the answer to use both the old and new ECU? New one for controlling engine functions and the old one for gauges and transmission control?????? __________________ 99 Z71 (98 body style) Pride and joy

04-02-2013, 09:03 AM	#2
panhandler62 Java Mechanic Join Date: Jun 2005 Location: Martinsburg, WV Posts: 6,764	Re: ECU change in a 98 have questions Can anyone address this question? __________________ Keith 11 Lincoln MKT -- Momma's wagon 13 G37xS -- middle age crazy car 68 C20 Fleetside -- RIP Decorating the whole town up at a cost of $27 ....

04-02-2013, 12:14 PM	#3
VetteVet Msgt USAF Ret Join Date: Jan 2005 Location: Kalamazoo, Michigan Posts: 8,703	Re: ECU change in a 98 have questions Search results I found . The first thread might give some answers. ........ http://www.google.com/custom?domains...D%3A1%3B&hl=en __________________ VetteVet metallic green 67 stepside 74 corvette convertible 1965 Harley sportster 1995 Harley wide glide Growing old is hell, but it beats the alternative.



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