No local parts stores rent NOID lights here, so we did not try that. Did listen to each injector with mechanic stethoscope and each injector is clicking open and closed.

And still no codes set in computer.

Did unplug injectors one at a time while it was running ran worse every time we unplugged one.

 

How old are the O2 sensors, and if new, what brand?

Although flaky O2s won't keep it from starting and running when cold; but then again, it won't be running on the O2s, but using the inbuilt tables, so it won't be reporting lean and keep enriching it.

Also, how tight is the exhaust to at least a foot downstream of the O2? If you've got an exhaust leak between the engine and the upstream O2 sensor(s), it'll read lean and keep enriching until it gets happy.

RwP

 

I don't know anything about the O2. We just got the truck, it is probably old though. Actually we still have it disconnected so there should not be any signal from the O2 going to the computer.

There does not seem to be any exhaust leaks in the system. We are rapidly loosing interest in this truck and may part out to try and get some of our money back.

 

Smh. I can't even

 

*facepalms*

Let's see.

The O2s are used in closed loop to let the ECU put the engine at stoch.

Disconnecting the O2s will drive it rich. And toss a code.

Praytell, WHY did you disconnect the O2s? Besides trying to make it not run?

RwP

 

The engine should run at least reasonably well with O2's disconnected, after all, the PCM doesn't use them until they warm up, and it ignores them at somewhere over half-throttle in any event. Running with them disconnected is a test to see if they are actually part of the problem. Since it doesn't run any different with them disconnected, they aren't the problem......

Trouble is, so long as the PCM is seeing some flavor of varying signal from the sensors, it assumes everything is ok. A slow sensor, or one that reads artificially high, or low, WON'T set a code..... so long as it reacts appropriately to the PCM changing pulse width..... There are far too many failure modes for the sensors that the PCM simply can't figure out.....

 

RalphP it would not start, or idle and ran like crap ran rich and had the glowing Exhaust manifold with the O2 connected.

Then disconnected the O2 and still ran the same crappy way. I do not think the O2 is the problem.

Timing is right, firing order is right, fuel pressure is good, injectors test ok, no codes on computer, changed coil, swapped map sensor and cam sensor from another running motor, checked EGR, changed cap and rotor, plug wires good, plugs good and gapped right, compression is good, fuel sync is within acceptable range, vacuum is steady.