93 S10 Blazer V6 CPI 4wd

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Old 02-25-09, 12:46 PM
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93 S10 Blazer V6 CPI 4wd

Hey guys
For a neighbor who is no mechanic (well, worse than me).

He got this vehicle a week or so ago, starts ok, runs ok at normal driving speeds. Rough idle and almost stalls when coming to a stop. He got the idle speed up a bit (dunno how, thought it was computer controlled?) and added SeaFoam after draining old gas and refilling. Has replaced fuel filter (which would be more hi speed problem solution). He said the Seafoam seemed to help...but still not smooth at idle. He keeps thinking timing...but to me that makes no sense.

Any suggestions on what to check? I was thinking more of a throttle body type issue.

btw...whats the difference between CPI and TBI?


Thanks
Vic
 
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Old 02-25-09, 02:29 PM
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central port injected the injector is below the upper intake.
would probably check codes for a starting point the egr was notorious for sticking open on these models if it has a code 32 would just pull the egr valve and clean it, they used to make a gasket with a screen installed to help prevent carbon from sticking the egr open. the elctronic egr is right below the throttle body part of the intake held on with 2 bolts.
if you dont have a code 32 might pull a couple of plugs one on each side of the engine to see what they look like a fuel leak under the intake will often foul the plugs on one bank if one is black and gas fouled and the other is burning clean you probably have a fuel leak under the intake a fuel pressure test will help to confirm it as it will drop pressure after shutting off the key.
 
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Old 02-25-09, 02:42 PM
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forgot to add the idle speed is computer controlled but there is probably an adjustment on the throttle plate base setting if he moved it much at all he will probably be putting it back once the problem is fixed causing the rough idle as it will probably be idling to high at that point.
 
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Old 02-25-09, 02:43 PM
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Hmm...this thing has a throttle body sorta thing in front of the intake manifold...is that CPI or TBI?

I have an OBDII scanner, but it says 94 and newer....I don't think he has any warning lights on (he's at work). Do you know the procedure for pulling codes? I know my old Dodge was key on, off, on, off, on...sorta thing.
 
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Old 02-25-09, 03:00 PM
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believe you can jumper a and b at the diagnostic connector under drivers side dash usually the top two on the right when looking at the connector and turn key on will flash each code 3 times starting with code 12
when I refer to the throttle body im refering to the throttle plate portion of the intake even though it doesnt have an injector there like on a tbi injected vehicle it still has a throttle plate believe its part of the intake on this model, but the injector is hidden and you cant really see it without pulling the upper intake. port injection actualy injects fuel to each intake runner where throttle body injection is more similiar to a carb where one or 2 injectors feed all the cylinders.
 
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Old 02-25-09, 03:09 PM
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Ahh ok...thanks, I understand about the injection now. You are correct, the throttle body is in front, but there are no fuel lines running to it. Clearer now. I've seen the type with injectors right into the TB...guess thats TBI? All I ever had were port fuel injection..one for each cyl.

Anyway...thanks! We'll see if he wants my help when he gets home.
 
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