'93 K2500 stumbling off idle and higher

[rick88blaze]

Since I got home from Iraq my '93 has started to act strange. It is missing at idle if I have it in gear and my foot on the brake. Then when I am accelerating it will miss or stumble and sometimes I hear a "pop" from the throttle body. It only does this stuff when the engine is warmed up. So far I have replaced the O2 sensor, changed the plugs, cap and rotor and the fuel filter. I was going to change the coolant temp sensor and put new plug wires on this weekend to see if that would help any and make sure my injectors are spraying correctly. If there's something else you think I should check please let me know. Thanks,

Rick

 

[cgassett]

Same happened to me when I came home from Iraq. I had fuel, I had spark so I did a compression check and found a dead cylider with a broken push rod and a bent valve, #5 I think. I think the cause was bad gas/ water in the fuel from sitting for so long. Vaccum lines and fuel pressure(the rubber boot on the fuel pump deteriorating and clogged filter), fowled plubs, arching wires, injectors, cap, rotor worn, are common causes for this on the TBI chevys. Put your hand on the injectors and feel how strong their pulse is and see if the fuel is spraying or dripping. I ended up taking that motor out and put in a GM Crate Motor and took all the smog crap off. Everything is great now; plenty of torque, descent milege(11 towing and 16 empty) for a burban towing a K20 on 42s and a 20' trailer and a couple thousand pounds of gear and beer. I felt it was cheaper to replace the motor instead of rebuilding the heads and have the bottom end fall out or I could have just rebuilt the original motor, but for $1600, cant beat it. It's a lot faster time wise and theres a warranty too.

 

[cgassett]

Rick, One more thing; Before you replace the temp sensor, just disconect it and see what it does from there. Most of the time when you unplug it, the idle will pick up and smoothe out a little. That's what it should do(controls the fuel delivery mapping). If the idle slows when you plug it back in, the sensor is fine.

 

[4xcrazy]

check your fuel pressure

 

[rick88blaze]

I think I found out what my problem was. The heat riser in my air filter housing tube wasn't opening once the engine warmed up so it was starving for air. I removed it and the truck runs great now. A hell of a lot better than before.

Rick

 

[cgassett]

Sweet, dont you love it when the fix is nice, simple and fast? have fun.