Engine Sputter After Dual Exhaust Install

[derek.cobia]

I have a 1989 K5 Blazer. About a month ago, I installed headers for dual exhaust. I pigtailed the o2 sensor wire, which threw the check engine light regularly - understandably so as 1) it was pigtailed, and 2) exhaust pipes weren’t installed. Aside from the check engine light, I’ve probably driven it 300 miles+ with no exhaust pipes and I’ve experienced no performance issues.

Fast forward to today - I had exhaust pipes installed from the headers back, ending with the muffler. The rest of the exhaust from the muffler back will be installed next week. No cat.

When I was driving home, there was an obvious sputter when accelerating in lower gears...to the point where I thought if I were climbing a hill any steeper than the one I was climbing, I might to make it. The sputtering continued on flat ground but only when I accelerated.

The o2 sensor is a single wire sensor (and again, pigtailed). Given the fact that I’ve been driving with just headers and I drove it to the muffler shop this morning with no performance issues (over the same terrain), and given the fact that the muffler shop wouldn’t have had to disconnect any spark plug wires to install pipes from the headers back, I have to assume the o2 sensor is the culprit.

Is that a reasonable assessment? Is there anything else that may be causing this? And if it’s likely the o2 sensor, could tailpipes fix the issue or do I need a new o2 sensor? Are true dual exhausts throwing off the sensor or is it likely because I pigtailed the sensor and now I’ve got back pressure? If it’s the o2 sensor itself, would a 4 wire o2 with heat sensor fix the issue or should I just buy another single wire with extra long length?

The o2 sensor is mounted just behind the collector on the drivers side of that means anything.

TIA for y’all’s help!!

 

[rampage]

You probably need a 3 wire heated O2 sensor with your headers.

 

[sweetk30]

You probably need a 3 wire heated O2 sensor with your headers.

x2 on this . if you still have a 1 wire non heated o2 its to far down the line for the engine heat to warm it up .

do a 3 wire o2 swap lots of simple write up's on this .

 

[Wes Harden]

Did the muffler shop get to close to the fuel lines on the right side? maybe heating up the fuel filter and your getting air bubbles.

 

[derek.cobia]

Did the muffler shop get to close to the fuel lines on the right side? maybe heating up the fuel filter and your getting air bubbles.

I don’t think it’s too close to the fuel lines and it doesn’t feel like air bubbles. I’d think If air bubbles were the issue, it’d be happening at idle and while accelerating. I’m new to all this though.

 

[derek.cobia]

You probably need a 3 wire heated O2 sensor with your headers.

Thanks! Any recommendations for a 3 wire o2 swap kit?

 

[rampage]

Thanks! Any recommendations for a 3 wire o2 swap kit?

Nope, sorry, I haven't swapped to a 3 wire.
Someone will chime in though.

 

[dyeager535]

O2 is out of the mix under WOT. If that's where the problem exists, it's not going to be (just) the O2 sensor. WOT anything O2 related should disappear. If it continues to stumble at true WOT, something else is going on.

Example of one, I ran a single wire O2 sensor for years with headers and dual exhaust, and the O2 would get hot enough to work the instant the throttle was cracked. Not like it idled terrible open loop (it shouldn't) but why not let the O2 sensor make things easier for me? Lol

I installed a heated O2 sensor simply to force the system into closed loop faster to get a cleaner idle with less tuning effort on my part. In a stock application, it's possible you could see some improvements at idle with a heated O2, but that should be the extent of it if the single wire was working properly in the first place. Especially since they came that way factory.