Thermool

Since I got my truck (4.8 v8 automatic) with a bit over 50,000 miles it would start cold and not rev above 1,000 rpm and go back to normal idle, it just stays at normal idle (550 rpm). It use to have a hot starting issue too where it was very difficult to start and it took two fuel pressure regulators in a span of 15,000 miles to get it right and its been fine ever since. The truck now has 115,000 and still has the cold start issue. All plugs are new, fresh air filter, and fuel filter (as of 110,000), even replaced the idle air control valve and a cleaned throttle body.

It has always run normally, but every truck with this motor always revs to above 1,000 rpms and goes back down to normal idle at running temperature. The dealer has always said there is no problem but this is too wierd. Any and all help is appreciated.

MDTAHOE

Do you have access to a scan tool that shows data? It is possible that the ECT (engine coolant temperature) sensor does not know the engine is cool there for it will not bump up the idle. You could verify this by looking on the scanner. If you not not have a scanner you could try to replace the sensor it is pretty cheap. Just make sure you get the one for the computer not for the gauge.

YOTA

try autozone the 1 near my house has 1 when my 2001 ford focus(piece of **** car!!) trans started acting up they checked it for me and got it fix before the car died(blew tranny) bad seal.first was a sensor.

Thermool

That is what I was thinking MidTahoe. If you mean a scanner that gives all sensor input on a display thru the Diagnostic port I'll have to try that; see what the voltage is. My experience tells me that it was this colant temp sensor, but there has always been a code of some kind; guess these OBD2 cars work with bad parts till they can't. BTW, where is this part, I'd imagine it would be near the thermostat housing? Is this scanner available to rent at NAPA, Autozone, Pepboys, Kragen?

YOTA, I hear the 2006 and up model are alot better.

Thermool

Yes I changed the ECT Sensor, no change. It does drive stronger but its still annoying that it won't idle normally. Any more info is appreciated or any service bulletins I can tell the dealer would be appreciated.