That O2 sensor code is for the heater circuit. It could be the wiring, voltage, ground or the sensor. If your not down with the electrical testing then swap pre cat sensors and see if the problem follows. That said, a malfunctioning heater/circuit can cause problems but probably not such extreme performance issues on a warm engine under a load, unless the lack of a cat makes a functioning heater circuit more important because the sensor runs cooler. I just don’t have enough experience with cat removal to know the answer to that one.

Your trims are higher on that bank, that sensor looks lazy or there is some fuel control issues and you mention cylinder 2 misfires. That sensor may be having more than one problem, again a swap might help us here. If that’s not it then we need to move on.

Did you confirm fuel pressure after the new pump? What brand did you use? I think the record here is either three or five new ones in a row for a certain aftermarket brand pump.

After every component swap, proper function should be confirmed. Same with the MAF. Sometimes inferior replacements cause new problems.


George

 

For the fuel pump I let a shop do it. They said it was OEM. And I tried to check the fuel pressure with a harbor freight tester. It was $15 and checks vacuum and fuel, but I can’t get it to fit for some reason. Today I’m going to the parts store for a new MAP sensor. I broke the rubber seal taking it out, so figured I might as well go ahead and replace it since I’m close to 200k miles.

 

Ok so I changed the map sensor and only code I have now is cylinder 2 misfire. I pulled the spark plug and this is what I see. It’s burnt looking on top and rusty in the middle as you can see. What could that mean?

 

One cylinder having a light misfire problem (no flashing CEL) is unlikely to cause a vehicle to not be able to accelerate. Since you are looking at misfire counters you need to be sure that CMP retard is within spec. You can also look under the old distr cap for carbon tracing indicating a distr timing problem.

You really need to confirm fuel pressure before reloading the parts cannon. Initial charge pressure and leakdown. Then if that’s OK, pressure when the engine struggles. This is the easier half to diagnose that’s why we usually start here. Electrical problems get more involved.

This should work for most things:



Your local parts store may also have a loaner.

This can be so many things that you need a logical plan to keep cutting the possibilities in half until you find it.

 

Ok I just tried to test fuel pressure and it stayed at 0. I assume I have this setup wrong? I put one bolt on it then stuffed the hose into the end of it

 

You want to attach the threaded portion of a fuel pressure tester like this:




To the fuel line schrader port that looks like this:




at the back of the intake plenum near the distr like so:



Everything must be threaded, tight and leak free.

George

 

these are all the attachments I have. I can’t find a threaded one that will fit. Bad kit maybe?

 

I’ll buy another fuel pressure tester tomorrow, but I went ahead and checked my vaccum. I ran it from the T on the right side to the back of the intake. It stayed right there

 

I think most consider 17-18 a normal idle vacuum for these motors so that looks good.


George

 

Testing Fuel pressure now. It was 50 psi when I cranked it and over the span for 20 minutes it slowly went down to 39 PSI. It’s been 20 minutes so far as I’m typing this. Bad fuel pressure regulator maybe?