you dont, unless they are cracked the failure would be internal

 

3 days of driving after replacing the plugs and coils. No CEL yet, hopefully it's all cured .

 

CEL is back. I haven't scanned the code, but assuming it's the same.

What's next on my list of todo's?

o2 sensor?

 

A compression test will not hurt and it is free! You can rent it and then return to AA or Auto zone for your money back. I have a towncar that had a broken valve spring that triggered the misfire code!

 

Never done a compression test, is it pretty easy to do?

 

It's a no brainer! Pull the fuel pump relay so it doesn't start when you crank it. Pull a plug and screw in the compression hose. Have someone turn the key to start for about 2 to 3 seconds while you watch the gauge and write down your reading. Move to the next plug,etc.etc. I don't have the desired PSI for the cylinders but someone here should have that info. If your suspect cylinder is close to all the others then you can rule out that cylinder (rings, valves, gasket, etc.etc) If it is much lower than all the others then it is $.
Hopefully it is not $$.

 

First check the code if it is the same. Swap the injector with another cylinder erase the code and if it comes back see if it move to the swapped cylinder.

 

I'll try to swap injectors and see if that follows the code first.

I ran the code today, same code.

We also did a Fuel Rail Test for pressure. When we turned the key, it spike to just about 50 and then quickly faded to about 15. I am wondering if the fuel pump might be the issue?

When we turn it on, the fuel pressure stayed at 49.

 

50psi is correct, however it shouldnt be fading unless you turn the key off even 49 is acceptable however check it with the engine running and rev it up and see what happens to the pressure, it s hould stay relatively steady.

 

Since it's fadeing with the key is on, but not started, do you think I should just try to replace the fuel pump as my next step?

Or do you think it might just be the regulator and is it work replacing just that part, or do it all since it's apart?