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Discussion Starter #1
I am helping a buddy finish his 87 Chevy with a new crate engine install and it wont idle. We did the cam break in and it will stay running as long as he revs it but will die the second he let's off the gas. It is TBI and I'm close on the timing but it just wont idle. The one thing I am concerned about is the factory engine was a 305 and after we got this engine in there he tells me it's a 350. My fault for not asking I guess. Is the computer the issue with the extra cubes? Timing still off? It fires instantly when we hit the key. It was also running open manifolds with no exhaust so a O2/backpressure issue? We took it to get exhaust today so will get it back in a day or two. Any ideas? Thanks
 

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The distributor in those years caused so many problems. Is it on the stock 305 tune and is the cam any different? That year has major issues when you change anything with the things motor. Between the crank trigger, distributor, and fuel pump settings when you upgrade anything the computer just can’t adjust.

I would think you need the full exhaust installed with O2 sensors as well.
 

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Discussion Starter #5
It has the O2s in the manifold and everything is hooked up. It just didnt have any exhaust after the manifold collector. I basically only did the cam break-in procedure and all went well so we decided to load it up and take it to the exhaust shop. To set base on that is there anything special I need to do/unplug like needed on a carbed H.E.I ignition? We are now trying to locate a ECU from a 350 since it still has the 305 ecu.
 

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There should be a brown wire connector up by the wiper motor that you need to disconnect to set the base timing . It may be in the wiring harness . Set the timing with it disconnected and then clear the code .
 

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No I did not. I hate this electrical crap. Lol. I will Google how to do that and make sure I try that when it gets back. Thank you
DO you have a scan tool? should be OBD 1 if it's a TBI system. Idle counts should be around 13 at idle. If the PCM commands it and the engine does not respond then you may have a bad IAC. When you put a new one in don's pull or push it, that will damage it.
 

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Discussion Starter #10
Thanks guys I appreciate the help. I hate this tbi system crap. It's been a real pain in the ass. Lol. I will check those things mentioned. Thanks!
 

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Discussion Starter #12
I tried to get him to do that but he is bound and determined to keep the tbi. It has been a cluster of issues so far. Will be glad when it's done and I wont be messing with that tbi system again
 

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Without a scan tool to see what's going on, your operating blind. Basically, no idea what ignition and fuel is doing. TBI is capable of 300+whp. I kept the 5.7 TBI on my 383 tow vehicle. Air horn mods, different injectors, and fuel pressure adjustments are all possible, They use TBI on 454. Just a matter of what you want to achieve and ability to achieve it.
 

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I've done that swap and didn't have to mess with the computer. I was able to get the timing in range with a conventional timing light. Once it was close the computer took over. Will it idle with an artificial choke like partially covering the TBI. I never did an IAC relearn or disconnected the the wire to set the timing. The only problems I really had was the coolant temp sensor in the intake read cold all the time. Once I figured that out it ran fine.
 
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