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old skool
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Discussion Starter · #1 ·
i changed the intake gasket on my 97 Z71 1500 pickup with a 350 vortec. it has been a few months and ever since it has a code set, check engine light is on. it comes up o2 sensor so i changed it and light is still on. now it wont run when its cold it will cut off(stall) when idling and skip and buck at part throttle till it warms up and then it runs fine!i marked the dist. and put it back as it came out but someone said i need to set it by voltage. :dunno: help please it runs so bad now i havent drove it in a few weeks!!
 

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Bet you the dist. cap is covered in green.(inside).

Did you change it when you were in there?

Delco caps seem to keep out the moisture better than any others.

Poor spark.....bad o2s? :dunno:
 

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wich code is it exactly so we can get a better idea on whats going on? if only 1 bank is acting up then you can rule out the distributor all together- if both banks are throwing codes then you can look for the common thread that links them up.
 

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CPI injection is notorious on these motors. How many miles and what did it run like before you tore it down?
 

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Has this truck got TBI?
If so,maybe it's time to clean out the the injectors.
 

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Sounds to me like a vacuum leak around the intake manifold gasket somewhere triggering an O2 code due to the fact that it is running leaner and can't get it to not read lean no matter how much fuel it dumps. Double check your torque on the bolts and then spray carb clean around and see if the idle changes. When it warms up it is expanding and sealing itself off.
 

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General Useless POS
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tony moore said:
i changed the intake gasket on my 97 Z71 1500 pickup with a 350 vortec. it has been a few months and ever since it has a code set, check engine light is on. it comes up o2 sensor so i changed it and light is still on. now it wont run when its cold it will cut off(stall) when idling and skip and buck at part throttle till it warms up and then it runs fine!i marked the dist. and put it back as it came out but someone said i need to set it by voltage. :dunno: help please it runs so bad now i havent drove it in a few weeks!!
Was it a P0171 or P0174? If so, thats NOT an O2 sensor code, but a system lean code. Most likely due to the cam retard not being set and fuel timing is off. You probably marked the dist when you pulled it, but being off 4+ degrees can throw fuel timing off enough to code lean, but not out of sync.

Symptoms are as you describe. It may even feel like EGR is coming on too early. But thats the dist being out. The distributor in these trucks have ZERO to do with ignition timing. Its all fuel timing. Ignition is based off crank sensor

You need to hook up with somoene with a scanner that will show the cmp retard pid, and get it down to zero. After each adjustment you must rev the engine past 1000rpm for the pid to update.
 

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old skool
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Discussion Starter · #8 ·
okay truck has 130k miles it was running good before i changed intake gasket. i did change the cap and wires and plugs.i tried the vacum leak test and no leak i could find.not sure of code # but it was the o2 sensor on the left side. i even switched them to see if light would stay off. still has the same code but only started to run bad last few weeks! autozone checked the code so i hope they were right! my brother has it now he works at the city garage they have a scanner. just need some info. for him. i have some things for him to try now! thanks guys!!
 
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