busterbrown

Hey all,
I have a 92 formula that had a 305 TBI, I just build and installed a 355 TPI. However when I tried to crank it nothing happened. All other electronics worked fine and there was fuel pressure on the fuel rail. I hooked a manual starting switch to the starter and tried it that way. The engine would crank but wouldn't start. I pulled and varified that I had fire to each plug, they all checked out ok. So I had fuel and fire and it still didn't start, any clues as to why?

KNBlazer

spray some fluid into the intake and see if it fires up... you most likely either have a blown fuse or your distributor is faulty.... you need to check for pulse at the injectors... make sure your distributor and internal components are wired correctly...

busterbrown

I sprayed started fluid in the intake and it fired up. I varified that all plugs were firing by hooking up an inline spark identifier. Someone just mentioned that where i replaced the computers from a TBI to TPI that the VATS key wouldnt match up. I wasnt sure if the VATS system just disabled the starter, or if it disabled the injectors as well. Like i posted before I have fuel pressure at the fuel rails, and maybe the injectors arn't injecting any fuel. Any idea how the VATS system works or what it disables?

KNBlazer

hmm... then it sounds like a VATS... I believe the injectors don't get juice when Vats is activated... The injectors are controlled by a driver inside the computer... so you will have to do a search here on TGO about how to bypass the VATS system.. I'm not sure if it's the prom that has the VATS or the actual Computer... I'm not familiar with VATS as my 3rd gen doesn't have VATS... ....

busterbrown

Just got off the phone with Jim at TPIS, he said that they could upgrade my chip and remove the vats system from it. He didnt say if the vats would keep the injectors for operation though.

KNBlazer

http://forums.corvetteforum.com/c4-t...or-bypass.html

travis401

iTrader: (1)

The way the VATS works is, your key has a small "chip" in it. That chip is a carbon pellet resistor. When you insert the key in the column, it completes an electrical circuit with the VATS module. The VATS module then determines if the correct key is inserted in the column by measuring the resistance of the "chip" in the key. If it reads the correct resistance, it grounds the start enable relay, allowing it to function and send voltage to the starter when the key is turned. It also send an "enable" signal to the ECM to allow the injectors to fire and the distributor to fire the spark plugs.

If your have the stock distributor, it wouldnt get spark without the VATS working.

EDIT:
If you pull the driver side kick panel, youll see a square of black goo, under that goo is the start enable relay. Take the black wire on the relay, snip it up the wire loom some to give you enough wire attached to the relay, then ground it on the body. I grounded mine to a screw right were the relay was. If after that you can turn it over with the key, you may have a VATS issue.

game1939

vats problems suck dont they?

travis401

iTrader: (1)

Im glad I got rid of it when I ditched the computer

busterbrown

Ok, I had spark but when i measured the pulse width on the injectors i got nothing. I did have spark, but I have an aftermarket distributor and coil. I am doubting that they would prevent my system from firing seeing how they are connected to the original wiring harness. I wont able to work on my car till this following weekend, but I did send the chip off to have it reprogrammed at TPIS. The man there said he would remove the vats system from this chip and that should fix my problem. But if there is a starter relay that is not tied to the ECM I am going to assure that removing the VATS from the ECM isnt going to remedy that problem will it?

travis401

iTrader: (1)

The VATS module grounds that relay when the key is inserted, so having the VATS programmed out of the ECM wont effect the relay function. Youll need to ground the relay yourself to get it to work, which Ive already posted the steps on how to do it.

busterbrown

I tracking. I really appreciate the help. I'll work on it this weekend and see if a cant get that grounded. this VATS crap is starting to wear thin on my patience. If i hadnt already spent so much on the system i would chuck it and buy a carb setup!