I just installed a tpi 350 in my 1981 elky. The other day I tried starting the engine up but it died after about 2 seconds. Sounded great while it lasted! All the tpi stuff was from a 91 camaro. I'm pretty sure its a computer issue. I've heard how the anti-theft sys could be interfering. Does anybody know which wires are which on the wire bundle that connects between the engine wiring harness and the printed circuit board in the guage cluster for an 81 elky? I think some of them may be mismatched with the engine harness. I don't even think the ecm is getting power. Has anybody out there installed tpi before and know there way around all the computer related hassles?

scott

Well, on a Camaro, the VATS (Vehicle Anti Theft System) box is located under the dash, about where the passengers shins would be. The VATS unit is black and about 4" wide x6" long x2" thick. It's kinda got it's own bundle of wires from the main computer unit. Hope that kind helps to narrow down where to look on your harness. I do think there is a way to bypass the VATS unit, try a forum search on www.thirdgen.org , I know theres been plenty posted there on this topic. The stock VATS keys wore out quite often giving people fits rtying to start thier cars. Also, did you replace the entire fuel line with larger dia. fuel line? The stock fuel line can't supply the fuel injection with enough flow/volume.

I just had this same VATS (Vehicle Anti-Theft System) problem with my LT-1. "Painless Wiring Harnesses" knows how to bypass the VATS, but I sent my computer chip to "Street & Performance."
http://www.hotrodlane.cc/
They "burnt out" the VATS circuit(s) and tuned the chip for another 17hp.

It was fairly expensive to do it this way, $175, plus my old chip for a "core" exchange.

It cranked up and stayed running on the first turn after installing the new chip.

Here's one bypass I found on the internet: http://www.drdetailshop.com/gmpellet.htm

I doubt your trouble is with VATS or your fuel line sizes... VATS wouldn't even let the starter engage if that was the problem and the fuel line issue would only affect power under heavy/full throttle acceleration.. Sounds like you may have some wires crossed somewhere that you only have power to the ECU during cranking which would explain why it shuts off after a couple seconds?? Good luck..

Here is some very helpful info that I used to make a generator to create the signal the ecm is looking for from the vats module.

http://home.houston.rr.com/lisfamily/passkey/

Here is the link that take you directly to the page with the info.

http://home.houston.rr.com/lisfamily/passkey/Passkey%20bypass%20-%20FieroAddiction_com.htm

Thanks for helping out everyone. Turns out it was a whole bunch of problems. First the new ecm wasn't getting power or the right signals because some wires were either in the wrong places or not connected at all. Plus the vehicle anti-theft system (VATS) had to be fooled into thinking it was receiving the right signal. A VATS modulator was installed along with a special resistor to fool it.

I had a certified master auto mechanic do all of this stuff since its way over my head. My advice to anyone else out there considering a fuel injection conversion project like this is don't do it unless you know what you're doing and have a lot of extra money, time, and patience. Most important is a complete donor car. Mine was mostly from a single car.

The car sounds great now with the new exhaust system. It consists of long tube headers with air tubes that connect to a Y pipe, goes through a catalytic converter, then branches out at another Y pipe that has two mufflers.

Tomorrow I'm taking it out on the road for the first time. It has a remanufactured 350 transmission. I'm wondering how the old stock driveshaft and axle handle all this torque. My friends keep asking me if I'm going to change them out.

Does anybody happen to know the normal idle rpm for a tpi 350 engine? This was idling between 1000 and 1100 rpm.

When I get some good pics I'll attach them to this tread.

If your engine has one your problem might be the Idle Air Contril valve. My Lincoln had exactly the same problem, I had to keep it running with the gas pedal until it got warm enough, othherwise it would stall a few seconmds after starting or pulling up to a light. I replaced the IAC valve and the problem went away.

Does anybody happen to know the normal idle rpm for a tpi 350 engine? This was idling between 1000 and 1100 rpm.

Normal idle speed fully warmed up in park should be around 600 to 700 depending on the chip used. I am attaching a few pics of factory idle speeds and adders(a/c and in gear).

Sounds like the IAC is sticking or there is a moderate vacuum leak.

http://home.houston.rr.com/lisfamily/idlespeeds.jpg

I had the same type of problem when I installed an '88 350 tpi in my 82 El. The problem turned out to be a wiring connector that was loose enough to vibrate and loose the connection upon starting. Luckily I discovered it late one evening and saw the sparks flying from the connector while the car was being started. This was a connector that was an original that was mounted on the firewall. Like your problem, the car would start and run for a few seconds and die. Good luck.