Low idle/stalling

[Trstrugar]

My truck is a 1994 k1500 with the 5.7l. I have fixed a few issues with this truck from the previous owner, including re wiring the IAC valve, replacing the o2 sensor, and fixing the vacuum line from the map sensor to the throttle body. All were easy and fixed all the codes. Now the truck is not throwing any codes, but wants to idle really low, somewhere around 200 with extremely low oil pressure, and wants to stall out. When the truck is first started up it sort of pulses with the rpm gauge until it calms down and then idles very low. I had heard this can sometimes be caused by a faulty ground wire, as my oil pressure gauge is erratic but eventually lets me know where it's at. Any advice is appreciated!

 

[Trstrugar]

Also I meant to add that it seems to get worse the more warmed up the engine is.

 

[matt sorrentino]

Hmmm i would check the fuel pressure, timing, and just in case see if by any chance the IAC is stuck. Since you had bad wiring maybe it got stuck open (or close) just few thing off top of my head

 

[matt sorrentino]

Oh also since you mentioned it gets worse with a warm engine check the coolant temp sensor is by the thermostat in front of your TBI unit

 

[SwatDawg15]

Oh also since you mentioned it gets worse with a warm engine check the coolant temp sensor is by the thermostat in front of your TBI unit

My 94 was acting the same way.. this fixed it.

 

[Trstrugar]

I went and got those sensors, I will try replacing them and see if it makes any difference. It seems to me that the idle is in general low. I know manual tbi adjustment is not recommended, but there seems to be a good deal of play in the throttle cable. I will try tightening it a little bit as well and see if that makes any difference.

 

[Trstrugar]

I cannot get any check engine light when the truck is running, but when I run the codes I am getting a 44 for o2 sensor. I have dual exhaust and headers with just a Bung welded on one of the pipes for o2 sensor reading. I don't know if this would cause it to idle low and want to stall but maybe someone else has better experience with this than me. Thank you!

 

[Trstrugar]

I adjusted the throttle cable and tightened it a little bit. It doesn't want to stall or anything now, but it is running lean due to my exhaust setup/ 02 sensor issues. And the oil pressure seems to really be low when the truck is warmed up. I am not hearing any bad noises from the engine and it seems to run good. Should I just keep running it like this for now or is it bad to keep it running lean and with the oil pressure a bit low. This all being said the oil pressure gauge has been erratic since I got the truck, and I am not completely sure how accurate it is.

 

[Dahead76]

As far as the oil pressure, I had a simular issue with my 97 with the 454. At idle it would show 5 lbs or less and my check gauge light would come on. It ended up being the oil pressure sending unit. If you replace yours make sure you go back with a AcDelco sending unit. The lean issue could be from a vacuum leak.

 

[Trstrugar]

Where is the oil pressure sending unit located?