I've been gettin these codes for awhile. I cant figure out why my truck seems to think its running rich and lean at the same time. I notice that my check engine comes on right when the thermostat opens. It will stay on for around 30-45 seconds then it will go off. All the sensors have been replaced along with all the vacum lines, EGR valve soleniod, IAC, fuel pump, fuel pressure regulator and fuel filter. The EGR valve hasn't been replaced but has been cleaned. I relpaced the injectors with a set I had out of another intake due to the tips being gone off of most of them. The set i put in had the 4 small holes in it instead of the tips not sure of any other differences but i still have the same problem. Any input will be GREATLY appreciated I'm at my wits end on this.

 

The above issue went away with warmer weather now thats its getting cold again its back. Anybody have any ideas?

 

Did you change the oxygen sensor?

 

It is new Bosch brand to be exact

 

Year, engine, transmisson? Any other codes?

 

91 5.0l E40D. No other present codes.

 

The only idea I have for you is the coolant temperature sensor. It's something that could easily cause those two codes and you said it seems temperature related.

 

Im beginning to wonder if i have a ground problem since that does mess with all resistances that the sensors give out. Ill start checking grounds in the morning maybe that will get me some where.

 

I would take another look at the injectors.

The tips that you mentioned are part of the injector seal kit and not the injector itself.

Anytime you pull an injector it's a good idea to replace the seal kit. The seal kit typically has four parts:

2- O-rings (upper & lower)
1-plastic washer
1-plastic "hat" (that goes on the spray end of the injector)

If the injector isn't properly sealed that could give you a vacuum leak on the intake manifold.

ETA: If they were gone, the pieces of the original hats might be down in the lower intake manifold.

It's a hard call with any used injector. You can test them electrically but there's no way for most folks to know what the spray pattern is when it's down in the engine. The steel tips do wear unevenly off a 90 deg. angle. If that creates a crossing of the individual spray streams it would cause the fuel to atomize poorly.

A vacuum leak and poor fuel atomization could give you a lean/rich thing ?

 

When i installed the injectors i put new caps and rings on them. Plus ohm checked them and cleaned with chem tool. The injectors i took out had a tip about the size of a ink pen point. The ones that i put back in had the 4 tiny holes. I was told that the ones that have the holes are for a 5.0L H.O. or a 351. That didnt solve anything anyway. It only does it when it is cold out last night it was 40° when i went to work. Got off work it i was 52° and it did not do it. I also used the old harness and wired them to a battery and put fuel through them they all were spraying pretty much equally.