Finished cam in sig swap last night and car idles fine but is running very rich. Closed loop tune so o2's have nothing to do with it. Let it warm up and try to give it gas and it falls flat on it's face and wants to die and runs even more rich. It also starts right up but only runs at 500 rpm for the first minute or two til it warms up.

I did not change anything else. It seems like not getting enough spark so am going to check opti and coil when I get home. Why I am asking for other thoughts is previously when I was stock the car would not even run when opti went out, but this one idles good once warmed up. Sounds just like all the other 847's I have heard.

Also fuel pressure regulator was replaced before swap with and adj, but was not changed for this set up. Going to check the settings tonight also but would think a larger cam would like more fuel so it should not run rich with pressure set for old cam ?

Thought or advise? Also valve lash was check twice to see if I had an intake valve to tight or something, as well as made sure timing marks ligned up on the cam.That is not the issue.

 

Set valves again on a whim and found another burnt wire. Car runs fine now but I discovered the scrader valve leaking gas, and a lot of it. Have to fix that tonight. Other than that I would call this done and now it's suspension time.

 

You were able to have the stock cam reground to GM847 specs?

 

Yep. Guy here local in Dallas. All they do is cam grinds. I took them an 847 that some cam bearings took out and they used it as a template and cut a stock cam to the same specs. Stock pushrods work good too. I know a lot of people say the metal is too soft to do regrind put these guys do regrinds and fresh grinds and said they have never had anything happen.

 

Tune was problem. Got HPP to fix me up with a quick tune so I could drive it and they are going to dyno tune on monday. Runs a lot better already but still way too rich. They'll fix me up.

 

I was just going to ask if you had it tuned, but I see you just did .

 

Yeah, just never had a cam swap make a car run that bad, but I forgot about the open loop factor. I just bought a new o2 to replace the one that was bad and going back to dyno for fine tuning tomorrow. Then I can go back to closed loop tuning.

 

Chances are if its fuel injection, any major mod will need a tune, sometimes it will run without a new tune, but your engine will hate you.