Mike33Stig Posted October 22, 2021 Share Posted October 22, 2021 (edited) 1978 280z L28. Full emissions delete. So she was running great and strong. Drove the car all day. On my way home, I had a little fun. Opened her up a little. She pulled nicely. Then I turned a corner and the car got rough and I had to shut it down. I had to tighten up the AFM quite a bit to the lean side to get her to run again. So my assumption is a vacuum leak. The problem is that I can not find it. I have all new vacuum lines and all extra ports are capped off. I inspected all lines and caps in good shape. I then went with a can of carb cleaner around the intake to try and get a rise, with no effect. Also checked timing again. Solid @ 11 degrees. Fuel pressure around 36-38psi. All symptoms point to a vacuum leak but for the life of me I just can't find the source. She was running great. And then not. No immediate signs of the problem. Just the symptoms. The only vacuum lines I have are brake booster, dist vac advice, charcoal canister, FPR and pcv valve if you want to call that a vacuum. All thoughts and suggestions are welcome as always. And thank you in advance. Edited October 22, 2021 by Mike33Stig Quote Link to comment Share on other sites More sharing options...
NewZed Posted October 22, 2021 Share Posted October 22, 2021 1 hour ago, Mike33Stig said: car got rough and I had to shut it down. 1 hour ago, Mike33Stig said: All symptoms point to a vacuum leak Not so sure that your symptoms point to a vacuum leak. How about fuel supply? Did you measure fuel pressure? Quote Link to comment Share on other sites More sharing options...
NewZed Posted October 22, 2021 Share Posted October 22, 2021 1 hour ago, Mike33Stig said: had to tighten up the AFM quite a bit to the lean side to get her to run again. Also, if you "tighten up" the AFM you're actually reducing fuel. Implying the opposite of a vacuum leak. Maybe a blown FPR diaphragm? Quote Link to comment Share on other sites More sharing options...
Mike33Stig Posted October 23, 2021 Author Share Posted October 23, 2021 So I found the problem while going over the vacuumal lines again. It was a bad connection to the temperature sensor causing the motor to run very rich. Cleaned and tightened up the connection and all is well again. @NewZed Thank you once again. It was just luck i found this bad connection when i bumped the harness in the area. 1 Quote Link to comment Share on other sites More sharing options...
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