idles fine then throws code P1258 - The 1947 - Present Chevrolet & GMC Truck Message Board Network

hubdawg · 10-04-2021, 01:46 PM

Just finishing my swap for 2004 LS 5.3 hooked up to a TH350 in my 72 blazer It'll start fine and idle for about five -ten minutes then starts missing and it sounds like it's running on four cylinders. No code until it starts missing. I looked up the code and sounds like an overheat that makes it go into a safe mode. Sprayed carb cleaner around intake and no rpm change so I don't think it's a vacuum leak. Currently my temp gauge is not hooked as it is mechanical and I don't have electrical gauges. The electric fans do come on after a while and I do have heat through the heater. Is this caused by no temp gauge hooked up?

10-04-2021, 01:46 PM	#1
hubdawg Registered User Join Date: Aug 2017 Location: Colville Posts: 65	idles fine then throws code P1258 Just finishing my swap for 2004 LS 5.3 hooked up to a TH350 in my 72 blazer It'll start fine and idle for about five -ten minutes then starts missing and it sounds like it's running on four cylinders. No code until it starts missing. I looked up the code and sounds like an overheat that makes it go into a safe mode. Sprayed carb cleaner around intake and no rpm change so I don't think it's a vacuum leak. Currently my temp gauge is not hooked as it is mechanical and I don't have electrical gauges. The electric fans do come on after a while and I do have heat through the heater. Is this caused by no temp gauge hooked up? Last edited by hubdawg; 10-04-2021 at 02:02 PM.



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