kenai Posted January 26, 2007 Share Posted January 26, 2007 I have posted about this a month or so ago and have put the engine back together. Anyways, i am back at square one. I swapped in a 94 LT1 and 4l60e from a vette and used the stock wiring/pcm. I spent many hours on the harness and used tuner cat to reprogram. My problem is that the engine runs for 5 seconds then dies. It will restart fine, but again will only run for 5 seconds. If i start it and give it gas, the engine will rev just fine but again, will only last for 5 seconds. I have deducted that there is not a fuel pressure or volume problem. It has to be the PCM killing the engine....via injector pulse? i don't know. I dissable the VATS with tuner cat. I even reneabled the VATS to see if it would act different.....no difference. Is it possible to have a bad PCM? Its the weekend and getting this baby running would be awesome! Can anyone think of anything that would make the engine die after 5 seconds? thank you! Quote Link to comment Share on other sites More sharing options...
deja Posted January 27, 2007 Share Posted January 27, 2007 I am no expert one this but am about to do the exact same swap. From what I have read and have been told by people who know this engine, removing the VATS from the computer does NOT always work, neither does the resistor "fix". I've head good things about the GM VATS or PASSkey II Bypass Module available on EBay for around $25. My plan is to leave the computer VATS setting alone, use the Bypass Module installing it with a connector to make it easy to remove which will reactivate VATS when I want it to work as a theft deterrent. I certainly don't know if this is your problem but it sure sounds like it. Good luck. I have posted about this a month or so ago and have put the engine back together. Anyways, i am back at square one. I swapped in a 94 LT1 and 4l60e from a vette and used the stock wiring/pcm. I spent many hours on the harness and used tuner cat to reprogram. My problem is that the engine runs for 5 seconds then dies. It will restart fine, but again will only run for 5 seconds. If i start it and give it gas, the engine will rev just fine but again, will only last for 5 seconds. I have deducted that there is not a fuel pressure or volume problem. It has to be the PCM killing the engine....via injector pulse? i don't know. I dissable the VATS with tuner cat. I even reneabled the VATS to see if it would act different.....no difference. Is it possible to have a bad PCM? Its the weekend and getting this baby running would be awesome! Can anyone think of anything that would make the engine die after 5 seconds? thank you! Quote Link to comment Share on other sites More sharing options...
wheelman Posted January 27, 2007 Share Posted January 27, 2007 If the VATS has been programmed out then thats probably not the problem. You might have a problem with the fuel pump not running once the engine starts. The PCM will run it for about 2 seconds when the key is turned on and then shut it off. After the engine starts and the oil pressure comes up the oil pressure switch will keep the fuel pump relay energized, thats assuming you wired in an oil pressure switch with the fuel pump relay. I used an LT1 from a caprice so the wiring harness is a little different, it has an under hood fuse/relay box with the fan, fuel pump and injector fuses and relays. This is where the oil pressure switch was connected to the fuel pump relay on mine, not sure how a corvette system is set up so you'll have to trace it out but I'd start with that. If thats wired fine then I'd check the VATS again but I've never heard of problems with programming it out, maybe the Corvette PCM is different from the F-Body and B-Body PCMs. Wheelman Quote Link to comment Share on other sites More sharing options...
kenai Posted January 27, 2007 Author Share Posted January 27, 2007 thanks for the help. I the fuel pump continues to run. I even hot wired it to double check and i had the same result. I ordered one of those VATS bypass modules for $25 dollars on EBAY i figured it was worth the shot. Quote Link to comment Share on other sites More sharing options...
hanomon Posted January 30, 2007 Share Posted January 30, 2007 I have a 94' too, Got the vats programed out with the Tuner-cat software, even picked up one of those vats by-pass modules. Mine did the same thing died after a few seconds. Turned out to be the throtle position interface module. Quote Link to comment Share on other sites More sharing options...
Bartman Posted January 30, 2007 Share Posted January 30, 2007 Here's a couple of links that may help: http://www.mainstreamtopics.com/forums/index.php?showtopic=78 http://shbox.com/1/4th_gen_tech2.html#opti_test Is the engine throwing a code? Is it always five seconds exactly? Quote Link to comment Share on other sites More sharing options...
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