93 k1500 5.7 driveability issues

[cramer_77]

Got a truck at work that has got some problems. Heres the run down, we replaced the engine approx. 19k ago(customer ran it low on oil), replaced distributor and spark plugs approx. 10k ago, replaced cap and rotor 7k ago. Replaced distributor again 5k ago. This time in the shop we have replaced the pickup coil(out of specs), distributor cap, rotor, wires, plugs, both coolant sensors. Whats happening is truck will run extremely rough when cold, then about the time it gets warm truck will smooth right out and run like a champ. Truck ran fine after we replaced all the ignition stuff until it got up to temp, then it wanted to keep dieing. Now, its exactly opposite, runs bad cold, smooths out warm. Didn't know if anyone has ran into this before or might know somewhere to look. Took truck on a drive, got about 1/2 mile down the road and it starts bucking and running bad so i pulled over into a parking lot. Sitting there idling it kept acting like it wanted to die, and the scanner was reading no rpms. Drove it back to the shop, was never able to get above 3rd gear, and it died twice trying to get it back into the shop. Thanks in advance.

[old_master]

Is this a Vortec or TBI engine?

[cramer_77]

its a TBI motor

[j cAT]

Originally Posted by cramer_77

its a TBI motor

you do not mention any fuel testing or checking of any kind..this with hot/cold running problems could very well be the fuel supply erratic..

the egr valve is another componet that can create poor engine operation ...

[old_master]

Check the warm air intake system: air cleaner diverter valve, temp sensor, exhaust shroud & tube. With the weather you've been having lately, (30 to 50 degrees) this system is extremely important to prevent ice-up in the throttle body during warm up.

Also:
Check injector spray pattern
Check wiring at injector connections
Check fuel pressure
Check fuel filter for restriction
Check TPS wave pattern, (make sure it's smooth)
Check MAP sensor

[cramer_77]

just thought i would update some people on this, after having another mechanic friend stop by the shop for a couple of hours, found the distributor at fault. Replaced the distributor and truck runs like a champ. Sad part is that if my boss had listened to me then the truck wouldn't have been in the shop nearly as long.

[old_master]

Originally Posted by cramer_77

....Heres the run down, we replaced the engine approx. 19k ago(customer ran it low on oil), replaced distributor and spark plugs approx. 10k ago, replaced cap and rotor 7k ago. Replaced distributor again 5k ago.....

The parts are getting worse, time to find a new parts supplier.

[j cAT]

Originally Posted by old_master

Time to find a new auto parts supplier.

the supplier must be the scrap yard !