1990 350 Tuning tips

[Hardcore]

I'm going to start doing some basic maintenance on my new K5 (Tune-up, tranny flush, compression check, radiator flush, etc). The truck runs fine and their are no codes. The previos owner says it's been a while since he worked on it.


1) Should I change the O2 sensor, it's the original one?
2) Is there a prefered spark plug, hotter range or colder range spark plug.
3) Does the 350 prefer to be cold, will I benefit from a 160 or 180* thermostat?
4) How do i go about cleaning the TB?
5)What are some other things i need to look for in the engine tune-up?
/forums/images/graemlins/1zhelp.gif
Thanks,

Corey /forums/images/graemlins/k5.gif

 

[heavy4x4]

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1) Should I change the O2 sensor, it's the original one?

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Yes.
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2) Is there a prefered spark plug, hotter range or colder range spark plug.

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I just run stock replacements.
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3) Does the 350 prefer to be cold, will I benefit from a 160 or 180* thermostat?

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No, put in a 195 degree thermostat. The engine will keep dumping in more fuel (I guess you could call that more performance) if the temp is at 160 or 180. These computer controlled engines need to run at proper operating temp.
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4) How do i go about cleaning the TB?

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Rebuild kits can be purchased for fairly cheap, and I hear it's not a hard job at all. Otherwise, just run some fuel injector cleaner through the gas. I like dumping a can of Seafoam in my gas tank every once in a while too.
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5)What are some other things i need to look for in the engine tune-up?


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Check the timing. Check any other sensors that may be due for a replacement.

 

[K5Jimmy]

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Should I change the O2 sensor,

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Get a Delco....I paid $46 for a Bosch from Autozone only to find out it was F***ed right outta the box....
I paid $41 for a Delco at a different parts store...Lesson Learned....
195* Tstat...

 

[rick88blaze]

I bought the bosch +4's and i've been really happy with them. small performance gain and about 1 or 2 mpg increase.

 

[sled_dog]

I know on some vehicles they can be set by the way you drive. And IO know people who have disconnected the battery for a couple hours and the computer reset itself so it was then set for the way the person drove it. Does this work on a 90 TBI?

 

[mosesburb]

Heavy4x4's post is right on /forums/images/graemlins/thumb.gif! Follow his advice and you'll be good to go! Some engines like a 180 stat some don't. One of my vehicles likes a 180 (tad bit more power) but my other one doesn't (no change in perf). I would never run a 160 stat. Usually the temp won't get high enough to put the ECM into closed loop. High fuel consumption is usually the result. Just my $.02. Have fun!