Hello, I have a 99 2wd blazer that when idling it's like intermittent popping and when accelerating it's like constantly popping bubble wrap is best way to describe it. It's randomly throwing P0300 and rarely p0303 but was also popping p0304 until I changed all the plugs. I have tested fuel pressure and it seems correct so shouldn't be line, filter or pump. I have a parts blazer but wasn't sure if it's smart to steal the FPR from it and go with a new gasket/gasket maker to hopefully solve the issue.

Also the codes suggested fixes through the code reader I have are FPR, O2 Sensor, and/or EGR Valve and clean EGR and reprogram ECM. I have already swapped the EGr from the parts one to my main one with a brand new gasket but no ECM reprogram.

Basically just trying to see if anyone could help me verify it's for sure the FPR and what's simplest way to replace/fix it. Also not sure if it matters or not but it's currently straight piped I had to cut the muffler off to reweld it as it broke off flush at the muffler and would be impossible to weld on top of it without dropping whole exhaust.

Sorry I know it's a lot of info but hopefully everything is here that's needed for one you great people to help me out!

 

By "popping" do you mean backfiring?

1. What was the 10 min leak down value during the fuel pressure test. If it held the minimum value then I would not open the intake and replace the FPR, you might actually cause new problems.
2. Do you have a recent compression test? I so, what were the values?
3. How many miles on this engine?
4. Is that all of the codes?

After you answer these questions we can continue to figure out your problem.

George

 

Popping depends I guess sometimes I would call it a back fire other more like a misfire like a hear skipping a beat or something if that makes sense but also under accelerating at higher rpm definitely would call it back fire.

1. Didn't do a 10 minute leak down as just had a loaner AutoZone one but key on it was 60 psi and idling was 55.
2. Haven't done compression test
3. 100k-200k odometer is 200k but cant remember if one of the previous owners said he replaced a motor at one point or just the trans.
4. The only other code I can't remember the number but only ever popped one time but I think maybe the culprit of the whole issue was bank 2 lean. I say this as I have one of those Bluetooth OBD2 scanners and got on it and looked at live data and my bank 2 sensor 1 short term fuel trim is maxed at 92.99% from the moment it cranks up

 

Need to do a 10 min FP leakdown test.

When we discuss fuel trim you always need all 4 values: STFT1, LTFT1, STFT2, LTFT2. You add the STS and LT together for a given bank.

Can you graph O2 sensors?

Can you see misfire counts by cylinders

Can you measure CMP retard?

George

 

Hey so I got lucky as hell and literally all it needed was plug wires, I took the ones off my parts blazer for ****s and giggles before going any deeper in the motor or my pockets and literally runs like the day I got it well a little better since it has new plugs too but giant rabbit hole because DTCs suggested everything but plug wires as a fix

 

Glad your sorted.

George

 

Congrats! And the and final updates can br super useful.

And isn't it great when an easy fix works?