back fire

[covi1234]

i have replaced the crankshaft position sensor. one from car quest. it dose it random when you start it up. not every time. what do you guys think

 

[lesterl]

Shorted Dist Cap? Sticking valve? Where does it backfire, intake/Exhaust?

 

[covi1234]

its through the intake. i could have sworn it was the crank shaft position sensor. how do i check if its the dist cap?

when it dose backfire it runs rough for just a second then goes away. it may not do it again for awhile. never sets off the service engine light and never has a stored code.

 

[lesterl]

tell us a little more about your rig. There have been many iterations of the 350 over the years...... year would be a good start.

 

[covi1234]

1997 tahoe 5.7 v8. 159,000 miles. only run 93 in it. new radiator water pump brakes. new plugs. back fire happens every 20-30 starts. through the intake. runs rough for 10 or less seconds. any other info you guys need? also new crank shaft position sensor

 

[lesterl]

I would replace cap and rotor (use AC Delco parts), has the intake been taken apart? To do the MPFI upgrade? Did some of the tubes get swapped?

 

[covi1234]

mpfi upgrade? intake has not been off. car and rotor sounds like a good place to start. i haven't replaced that since i have owned the car…thats been 6 years

 

[lesterl]

Get an AC Delco/ Delphi cap/ rotor, others are prone to shorting/ etc..

MPFI upgrade is available for these trucks as the original poppet injectors were prone to messing up, so they went to an injector at the intake port style (MPFI VERSION) instead of having the injectors sitting in the pod and having the tubing run to poppets in the intake (CSFI VERSION).

Let us know how it goes.....

 

[debbie]

Hello, where is the crank shaft position sensor located on a 98 Tahoe LT? Thanks for your help.

 

[lesterl]

http://www.tahoeforum.com/showthread.php?p=654331#post654331