Socnarftrucks Posted December 4, 2022 Share Posted December 4, 2022 When the truck is idling at a stop light it feels a little rough and shaky, when in park the shaking is less and there’s a cyclic variation between 750 rpm’s and 1000 rpm’s. New spark plugs, wires, TPS, and IACV. Any help is appreciated. Link to comment Share on other sites More sharing options...
Gary Lewis Posted December 4, 2022 Share Posted December 4, 2022 Sounds like it is lean. Have you checked all the hoses to see if something might be off or cracked? Link to comment Share on other sites More sharing options...
Socnarftrucks Posted December 4, 2022 Author Share Posted December 4, 2022 Sounds like it is lean. Have you checked all the hoses to see if something might be off or cracked? I have. Tried finding vacuum leaks with the non flammable break cleaner approach. Also tried a power balance disconnecting the driver side injectors. Link to comment Share on other sites More sharing options...
LastDeadLast Posted December 4, 2022 Share Posted December 4, 2022 I have. Tried finding vacuum leaks with the non flammable break cleaner approach. Also tried a power balance disconnecting the driver side injectors. Any codes? -Shannon Link to comment Share on other sites More sharing options...
Socnarftrucks Posted December 5, 2022 Author Share Posted December 5, 2022 Any codes? -Shannon No, sir. Occasionally the Emissions light will flicker for a few seconds especially during a cold start. Link to comment Share on other sites More sharing options...
mat in tn Posted December 5, 2022 Share Posted December 5, 2022 No, sir. Occasionally the Emissions light will flicker for a few seconds especially during a cold start. nonflammable will not burn! in or out of the cylinders. therefore, it will not find a vacuum leak. you need a fuel in order to get a combustion response. Link to comment Share on other sites More sharing options...
Socnarftrucks Posted December 5, 2022 Author Share Posted December 5, 2022 nonflammable will not burn! in or out of the cylinders. therefore, it will not find a vacuum leak. you need a fuel in order to get a combustion response. Ohh!!! I’ll try that then…. Thanks Link to comment Share on other sites More sharing options...
LastDeadLast Posted December 5, 2022 Share Posted December 5, 2022 Ohh!!! I’ll try that then…. Thanks One thing I did with my 85: I got a vacuum gauge and made a baseline reading. In my case right at 21psi. After that, I started unplugging and plugging individual lines from the intake manifold; brakes, EGR, cruise control, etc. and see if there are any changes in vacuum. This won't tell if you if you have a vacuum leak in the intake, but it might tell you if you have a significant leak in one of the various vacuum components. And of course it only works at idle. Also, If you already don't have one, I would also grab a code reader from AutoZone or Amazon. I have this one: Innova 3145 with this extension: Innova 3149 Extension. -Shannon Link to comment Share on other sites More sharing options...
Socnarftrucks Posted December 5, 2022 Author Share Posted December 5, 2022 One thing I did with my 85: I got a vacuum gauge and made a baseline reading. In my case right at 21psi. After that, I started unplugging and plugging individual lines from the intake manifold; brakes, EGR, cruise control, etc. and see if there are any changes in vacuum. This won't tell if you if you have a vacuum leak in the intake, but it might tell you if you have a significant leak in one of the various vacuum components. And of course it only works at idle. Also, If you already don't have one, I would also grab a code reader from AutoZone or Amazon. I have this one: Innova 3145 with this extension: Innova 3149 Extension. -Shannon Ooh wow!! Didn’t know there was OBD1 code reader!! Would it register anything even if there’s no “Check Engine Light” on? Link to comment Share on other sites More sharing options...
Socnarftrucks Posted December 5, 2022 Author Share Posted December 5, 2022 Ooh wow!! Didn’t know there was OBD1 code reader!! Would it register anything even if there’s no “Check Engine Light” on? Many thanks! I will use that approach and also order the reader!!! Link to comment Share on other sites More sharing options...
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