6.0 eng, When first started for the day, it runs very rough and wants to die if I don’t give it a little throttle until it warms up. Then it works fine for the rest of the day (even if it sits for several hours). Check eng. Light blinks for a minute or two then goes out. FYI…Could not get my OBD tester to give me any codes. (Changed batteries but that did not help.) Tester didn’t say “no codes” it just kept resetting to “turn ign. On and push test”. Any ideas what I need to check for the cold rough idle problem?
Clean out the idle air control valve, EGR valve and also the throttle body-
November, 27, 2011 AT 2:01 AM
When you were trying to check codes, was the ignition 'on'? If the check engine light is blinking, this is a warning of catalyst damaging misfire. If it is only misfiring at cold start and clears up, are you going through any coolant. It indicates to me, the possibility of either sticking valves, sticking injectors, or non-combustible liquid entering cylinders. It is also a possibility of the intake gasket leaking when it is cold, and seals up with metal expansion. You would expect to see p0171, p0174, and/or p0101, if it were an unmetered air leak.
November, 27, 2011 AT 7:26 AM
Yes, when I was trying to check codes, the ignition was on. The check engine light only blinks while the eng. Is running rough. After about two minutes, the engine smoothes out and the check engine light stops blinking. The engine works fine for the rest of the day and the check engine light does not come on again until the next time it runs rough. Regarding the coolant level, I have not checked it but there has not been any indication of low coolant such as a low coolant light and the eng. Has not overheated due to low coolant. I went out to try the OBD tester again. (Innova 3120). The only indications I get (with the ignition on) is the emission status lights blink green, then green and yellow blink, and finally, the green, yellow and red are on solid for about a half second. Then the OBD goes back to telling me to turn on the ignition and press the on/test button. (But still no codes show.)
Just to make sure my OBD reader is working correctly, I just hooked it up to my 04 Tundra and it says there are no codes presently stored in the vehicles computer so I don t think there is a problem with my tester. There might be a problem with the plug under the dash. Is there another place under the hood to plug into?
November, 27, 2011 AT 5:50 PM
There are no other diagnostic connectors. In reading your fist post, you changed the batteries in your tester? I have not dealt with, or even seen a self powered tester, all are powered off pin 16 of the data link connector that you plug into. I am wondering if there is power at that terminal. It is powered off the cigar lighter fuse in the underhood fuse block. If you look at how the cigar lighter sits in that vehicle, it is in gravities favor for things like gum wrappers, coins, earrings, and other conductive items. It is very common that the fuse is open. It is the first check I make when my scan tool won't power up. Yours powers up on it's self battery, but I would check that fuse, check the receptacle first for coins and such or the fuse will blow when replaced. Does that scan tool display data, that will be in your favor.