O2 sensor not switching

sdw

Registered User
Finally have the car insured again but it is not running well.

No power at all.

One of my O2 sensors is not switching. When I swapped the sensors, they are both new, the same side is not switching.

The car hasn't run in many years so I guess it is possible the is a wiring issue i will work on that this weekend to figure it out.

Does anyone know which side HEGO 1 is on?

TIA

Sean
 
Good morning

Bank 1 HEGO 1 is the passenger side cylinder/exhaust manifold. Most likely the harness/connector is damaged. If you have a EVTM schematic perform ohms check.
 
" Bank 1 HEGO 1 is the passenger side cylinder/exhaust manifold. Most likely the harness/connector is damaged. If you have a EVTM schematic perform ohms check."

Thanks! I'm sure I would have started on the driver's side.

"can you retrieve codes. How is the condition of the fuel, check fuel pressure.
Cam sensor."

Thanks for the reply. Codes were of no help, though i will recheck the wiring on the cam sensor as it sits super close to the belt.

Sean
 
If the engine is misfiring, that will cause a lean reading at the 02 sensor. When an engine has sat a long time it is not uncommon that a valve will not be sealing or than an injector or two might be stuck/clogged.

Check for even compression. With the ignition disconnected the engine should crank smoothly, it should not sound like a galloping horse. This is a quick way to assess if you might have bad compression in one cylinder or two.

If it cranks evenly, then it might be that you have a non functional injector. Pull one plug and see if it is dry and clean or wet and fouled. This will tend to tell you whether the EEC is trying to compensate for clogged injector (dumping fuel) or if it isn't getting any fuel as the 02 sensor is indicating. Of course if you are unlucky and pull the one that is clogged you can be mislead, but it's a quicker test that often tells a story. If you have a thermal gun you can also check exhaust tube temperature. A non firing cylinder will read around 100deg vs firing cylinders more like 250-450 depending on manifolds vs. headers, etc.
 
Thanks for the tips Dave!

It is super easy for me to pull plugs and check compression so I will do that today as well as as check the condition of the plugs.

This seems like it would be more likely than wiring as the connectors look like they are in good condition.

Sean






If the engine is misfiring, that will cause a lean reading at the 02 sensor. When an engine has sat a long time it is not uncommon that a valve will not be sealing or than an injector or two might be stuck/clogged.

Check for even compression. With the ignition disconnected the engine should crank smoothly, it should not sound like a galloping horse. This is a quick way to assess if you might have bad compression in one cylinder or two.

If it cranks evenly, then it might be that you have a non functional injector. Pull one plug and see if it is dry and clean or wet and fouled. This will tend to tell you whether the EEC is trying to compensate for clogged injector (dumping fuel) or if it isn't getting any fuel as the 02 sensor is indicating. Of course if you are unlucky and pull the one that is clogged you can be mislead, but it's a quicker test that often tells a story. If you have a thermal gun you can also check exhaust tube temperature. A non firing cylinder will read around 100deg vs firing cylinders more like 250-450 depending on manifolds vs. headers, etc.
 
Problem solved!

Looks like Mr Dalke once again was correct!

Did the compression checks on all the cylinders. Everything was perfect. Looked at all the plugs everything looked fine except the plugs on cylinders 5 and 6 looked brand new.

I looked down at the engine thinking about what I was going to have to pull to be able to get the injectors out and there was injector 5 and 6 without their plugs connected :eek:

Engine was running on 4 cylinders and there was not enough heat being generated on the one side to switch on the O2 sensors.

After a long facepalm, a look around to see if anyone was laughing at me, I connected the injectors and went for a fun spin! :)

Now to fix my idle issue.

Thanks to everyone for their advice.

Sean
 
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