4.3 Vortec Dead Skip or Miss at Idle


Doctorvette
06-27-2010, 12:37 PM
1994 S-10 Blazer with the Vortec 4.3 CPI

DEAD skip from idle and up. Just like the wire is pulled off.
Does NOT improve with "warm-up" or increased RPM.

Clean coolant and radiator, shows no water in the oil.

The engine is a 96 with the 94 CPI and acc.

I used my IR Thermometer to find #4 dead.

Pulling the plug wire and inserting a screwdriver showed a nice blue spark.

The owner installed a new plug on this cyl.

I'm leaning towards a injector or the things they put into the intake..

Any ideas.
I'm an old wrench, from the 60's
If this had a TBI or carb I'd be ok.. This CFI stuff is unknown to me.

I buy OE Dealer Service Manuals for any unit I intend to keep, BTW.

Thanks in advance
Doc

Doctorvette
06-29-2010, 09:40 AM
Since a "noob" here gets no response, I found the fuel pressure regulator may be the issue as I now remember that the engine had Too much oil ...

http://www.shopinjectors.com/techtips/

MT-2500
06-29-2010, 11:30 AM
Looking to buy for the ol Lady.

2 of the S-10 Blazers with the Vortec 4.3 have the same issue.

DEAD skip from idle and up. Just like the wire is pulled off.
Does NOT improve with "warm-up" or increased RPM.

Clean coolant and radiator, shows no water in the oil.

On one, a 96 I think, I used my IR Thermometer to find #2 the culprit.

Pulling the plug wire and inserting a screwdriver showed a nice blue spark.
Unable to pull the plug, sorry.

[Even though, usually a plug will fire sometimes, usually]

I'm leaning towards a injector or the things they put into the intake..

Any ideas.
I'm an old wrench, from the 60's
If this had a TBI or carb I'd be ok.. This MPFI stuff is unknown to me.

I buy OE Dealer Service Manuals for any unit I intend to keep, BTW.

Thanks in advance
Doc

You are welcome and I am old to but will try to help.

What year is other one and what engine codes and mileage and any service work done on them?
Might save on confusion to run a New thread/ post on other one.

Any check engine lights?

Pulling plug wire should check for spark and if RPM does not change with wire off you have a dead miss.
Pull plug and see what it looks like.
Black white or just wet?
Engine oil over full check for gas smell and coolant in oil?

Run a fuel pressure and post back readings.
And watch for fast leak down.



Check spark plugs and secondary ign if missing.

Doctorvette
07-10-2010, 07:33 PM
94 showing 177,000 miles, wear on seats, carpet, pedals and paint agree with odometer.

Had the vehicle for a week or so now [bought a Pig in a Poke if you will]

Many hours of research lead to clogged Poppet on #4

Dry plug, Blue Spark, found old EGR valve in back, new one on motor.

Will run fuel system pressure check, asap, [find fittings]

Put a can of Chemtool B-12 in 3 gal of gas, ran that out, another inj cleaner in full tank, ran for 45~ miles with no change.

I pulled the intake top half and removed the #4 poppet, sprayed good carb cleaner and stuck a toothpick with cleaner all around the ball over and again..
NO Good, still dead skip

QUESTION:
Can you remove the feed tube from each poppet and induce cleaner & compressed air to unstick ?

I went to the local Chevy dealer and printed out the TSB on how to unstick them with top engine cleaner but that procedure is half the price of rebuilt spider units and not something I'm not willing to do at home.

I'm low on funds, but if I have to buy a spider unit->>

FYI www.rockauto.com (http://www.rockauto.com/) has a "rebuilt" unit for cheap.
GB REMANUFACTURING Part # 83322101
{REMAN CPI FUEL INJECTOR ASSY}
$138.79
35.00 core
10.44 shipping
~ $185 minus the core IF they accept it.

Thanks
Doctorvette

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