Tbi swap build thread - The 1947 - Present Chevrolet & GMC Truck Message Board Network

68 TT · 09-01-2009, 11:30 AM

You really need to data log what is going on to know what the ECM is seeing that makes it run poorly when cold then clean up when the engine gets up to temp.

It sounds like an open loop vs. closed loop issue to me. The CTS is a possible source giving the ECM faulty info but there could be several other causes.

Data logging is a good place to start. It helped me diagnose a vacuum leak that two mechanic friends thought was a fuel system issue. It will also let you see where you can fine tune the programming to suite your particular setup.

09-01-2009, 11:30 AM	#10
68 TT Still plays with trucks Join Date: Jul 2009 Location: Spokane, WA Posts: 3,574	Re: Tbi swap build thread You really need to data log what is going on to know what the ECM is seeing that makes it run poorly when cold then clean up when the engine gets up to temp. It sounds like an open loop vs. closed loop issue to me. The CTS is a possible source giving the ECM faulty info but there could be several other causes. Data logging is a good place to start. It helped me diagnose a vacuum leak that two mechanic friends thought was a fuel system issue. It will also let you see where you can fine tune the programming to suite your particular setup.



Register or Log In To remove these advertisements.

Register or Log In To remove these advertisements.