Rough idle, running rich, totally stumped.

[Stick_fig5]

So I picked this up a month ago for $500, it runs and drives... barely.
Previous owner complained about lose of power, wouldn't go over 50mph, when I tried to drive it I burned through half a tank driving about 10 miles, so obviously running super rich, back fired like crazy, not all cylinders hitting (ignited the fuel in the cats once, that was fun..)

So far I've replaced
Spark plugs and wires
MAF and ACT sensors
Replaced cats with off road pipe, got a check engine light eliminator for the rear O2 sensors

I got it put back together and fired it up, it started rough and then cleaned up, idled perfect, sounded perfect, didn't make your eyes water from the fumes, I thought I had it, and then 3 minutes later it tried to die, idle back up and then went back to running horrible, eyes watering fumes, so im stumped at this point and could use some advice

 

[ttocs]

so you have not replaced the O2's yet?

 

[evilcw311]

Start checking vacuum lines.


Sent from my iPhone using Tapatalk

 

[SnakeBit!]

vac lines and/or iac check.

 

[07GtS197]

Any codes?

 

[Stick_fig5]

No codes, I cleaned the O2 sensors and iac, haven't replaced them yet, vac lines seem good but that's at a glance, I haven't specifically checked them, I'll update when I have

 

[ttocs]

smoke check the vac lines and replace the o2

 

[07GtS197]

Is it an auto? It sounds like a combination of vacuum leak(s) and o2 sensors. If it runs ok on startup and gets worse when it warms up I would think its the o2 sensors once it enters closed loop though it should go into closed loop sooner than that.

 

[Stick_fig5]

Definitely sounds like I need to replace the O2 sensors, on that note, since I have check engine light eliminators on the rears, do they need to work probably or could I get away with just replacing the front sensors?

Also It's a manual, I probably won't have time to check the vac lines until tomorrow evening, is there any particular hose that typically causes trouble? Or is it anyone's guess?

 

[evilcw311]

Could be any of the lines, could be a leaky intake gasket. Smoke test will give you best results.

Easy and cheap unless you have expensive taste in cigars lol myself!!!! Lol


Sent from my iPhone using Tapatalk

 

[96blak54]

Could be a cracked intake manifold, could be water in the plug holes, could be a cracked water crossover with the manifold.

 

[Silver95bird]

If the engine for any reason burns coolant, ie. The manifold fills up a plug well and it drops in the cylinder changing plugs, it'll wipe out an o2 sensor easy. Got any codes? I'd suggest testing the ECT resistance as well. Mine went bad and it ran like crap and burned a ton of fuel.

 

[Stick_fig5]

Update.

I didn't have a chance to do a smoke test or anything like that yet but I did have a couple hours to change the fuel filter, which helped a lot surprisingly, it runs smooth now, no rough idle at all, but dies after about 5 minutes of running, which makes me wonder if the fuel lines or Injectors might need some attention too. Thoughts?