"98 C3500 Codes: P0300, 1133, P0131

[smithrock]

My truck keeps coming up with these codes, I can clear them and it will run fine for awhile then the problem and codes come back. Usually after running for a few min. or so, it will start running and idling very rough, and you can smell unburnt fuel from the exhaust. I replaced the cap, rotor and wires a couple years ago but not the plugs. I thought maybe I have a clogged injector but a mechanic told me "ignition before fuel" and to change my plugs first.

I was thinking if my plugs are bad and not burning the fuel, thats where the unburnt fuel smell would come from, thus creating a problem for my o2 sensors and having those codes come up? Am I on the right track?

I'm kinda lost here. Anyone with ideas???

[pennzoil29]

First off, welcome to the forum , second, if you haven't changed the plugs, do so, and see if that makes a differance. If not, then it'd be my guess you'll have to change the O2 sensors. jmo

[smithrock]

First off, welcome to the forum , second, if you haven't changed the plugs, do so, and see if that makes a differance. If not, then it'd be my guess you'll have to change the O2 sensors. jmo

 

 

Okay, I'll try that. the guy told me to us AC Delco double platinum plugs, sound about right?

 

also, would the o2 sensors alone cause it to run and idle that bad?

 

 

 

Oh yeah, thanks for the "welcome' !

[pennzoil29]

First off, welcome to the forum , second, if you haven't changed the plugs, do so, and see if that makes a differance. If not, then it'd be my guess you'll have to change the O2 sensors. jmo

 

 

Okay, I'll try that. the guy told me to us AC Delco double platinum plugs, sound about right?

 

also, would the o2 sensors alone cause it to run and idle that bad?

 

 

 

Oh yeah, thanks for the "welcome' !

 

 

 

 

 

 

I just use the platinums. As far as the O2 sensors go, I have 169k on my truck, and I've never changed them. So I better knock on wood.

[smithrock]

I've got 186,000 +

I guess I should start with the plugs and go from there.

But would the o2 sensors by themselves cause it to run like that?

[pennzoil29]

I've got 186,000 +

I guess I should start with the plugs and go from there.

But would the o2 sensors by themselves cause it to run like that?

 

Quite possibly, but code po300 is an engine mis-fire, which leans me towards it being a faulty plug. I know they're about $6+ per plug, but in my opinion you're ready for a new set. Good luck.

[smithrock]

Anyone know what the correct sparkplug gap is on my '98 454 7.4L is?

[minibike132]

Anyone know what the correct sparkplug gap is on my '98 454 7.4L is?

 

It is whatever it is when it comes out of the box. Do not adjust a platinum plug, you will ruin the coating.

[smithrock]

I pretty much think my problem is the o2 sensors, any ideas on which brands to buy? Most exspensive doesn't allways mean better!

[L29er]

factory says .060, but i`ve heard guys running them at a little as .040, apparentley to get a smoother idle, i tried .050 and it didn`t change anything....

 

your 1133 and 0131 codes are for bank one sensor one, and as previously mentioned the 0300 is a misfire condition, i would do your tune up and reset the codes an see if the o2 code comes back, if so change her out.

[smithrock]

Okay, but what about the fuel smell from my exhaust? Is that from fuel passing the plugs that aren't firing? Or would 02 sensors alone cause this condition?

[L29er]

judging from your mileage inspect your plugs, cap and rotor, more than likley a bad plug causing bad o2 readings, check your plugs and go from there.....if an o2 sensor goes faulty your engine should default to an "open loop" and run according to a set map in the vcm.

[smithrock]

Would the idle air control valve also cause my problem? today I have codes P0131, P0161 and P1133 showing

[L29er]

Would the idle air control valve also cause my problem? today I have codes P0131, P0161 and P1133 showing

 

 

well if everything was cleared and those came back the p0131 and p0133 are bank 1 sensor1 and the p0161 is heater performance on bank2 sensor2, probly change you bank 1 #1 ( drivers side before cat), clear again and see if the p0161 comes back, if so change bank2 #2 ( passenger side after cat)

 

but make sure you checked the basic tune up stuff first...you could remove your IAC and see if it is dirty...

[smithrock]

What is a IAC? And where is it located?