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Discussion Starter · #1 ·
Okay, I put a TPI on my 55 a couple years ago. I used the 730 ECM and wiring from a 92 Camaro w/5.7L. This thing runs like it's on fire. No problem whatsoever 'except'.........it isn't seeing deceleration. The idle stays a little high thru the downshifts and for just a second or two at a stop. I deleted the speed sensor (or had it deleted) when I had the PROM burnt. I also had the PROM switched to manual transmission. I thought with a manual setting the ECM would be fooled into thinking it was a stick and idle down like one. But it's not. I don't mean a big difference, but I'm guessing 4 to 500 too many RPM slowing down. You can feel the down shifts.
I know there will be questions about how everything is setup, so I thought it better for the questions to be asked than for me to try to list everything.
 

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Have you tried dialing in the TPS sensor, and resetting the IAC?

I know those tps sensors like .54 volts with the throttle closed, and should go to at least 4 volts at wot.
 

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Discussion Starter · #3 ·
Yup, been there done that several times. I replaced every sensor when I put it together. However the IAC turned out to be bad from the box when I got it. Thing is I bought the sensors and was two years getting it to the point of firing it up. By that time all warranty was long gone.
 

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Discussion Starter · #4 ·
In case anyone is watching to see the outcome here, I figured I would post what I think it is. When I did the harness I deleted the VSS (vehicle speed sensor). Now the ECM doesn't know the car is slowing down. Problem is, I may have removed the VSS in the EPROM when I had it burned. No biggy, but since I never bothered to get the equipment for burning EPROMS, I have to send it out. Oh, and pick up a VSS. Couple hundred bucks should do it.
 

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Discussion Starter · #5 ·
19_Chevelle_69...... aka Don, got any of these laying around in your tool box or junk boxes? It's a VSS for a 91 Caprice with 5.7L MPFI. The Delco part number is 213202. It's the one with both the cable drive and plug for the ECM.

 

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Discussion Starter · #9 ·
Okay Don, thanks for trying. I have a fellow at a local boneyard looking as well. These things sold for less than 50 bucks from GM, but they quit making them. The hot rod guys bought up everyone they could find and are now asking double retail. I just have a problem with that.
 

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Discussion Starter · #11 ·
I picked up a harness from a local boneyard out of a 92 Z-28 and then removed everything that wasn't TPI. It took a little time to trace each wire from the pinout of the ECM, but I got it done. I removed that harness from the boneyard myself. The guys at those yards don't know whats important and whats not. I was upgrading a 87 Vette tunedport to speed density from MAF. So I had to do a little research. I found a couple good books available. The best I found was "CHEVY TPI Fuel Injection Swappers Guide" by John Baechtel. I has the GM flow charts etc.. Makes things easier to check out.
 

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Discussion Starter · #13 ·
Well, the VSS came in and I installed it tonight. I drove the car around the neighborhood and it seems better, but not perfect. I will put a scanner on it sometime soon and see what the ECM is seeing from the VSS.
 

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Mike, I meant to get back to you a few weeks ago on this item. We can't seem to locate one either. Sorry
 

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Discussion Starter · #15 ·
No problem Bruce. They are as scarce as hens teeth. GM quit making them and most of the aftermarket ones I found were priced based on that fact. I finally found a supplier that sold them for 1/3 of what everyone else asked. $29.00 including shipping. Can't go to too much trouble for those dollars anyway.
Trust me, I know you would have helped if you could have.
 

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Discussion Starter · #16 ·
Update. The scanner did not see the VSS. I expected as much since when I first had the chip burned, I had the VSS disabled :eek: . Anyway, I pulled the chip and sent it out to be changed. With USPS I will hopefully have it back in a week or so. I will update again then.
 
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