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Followup To
Question - O.K. will spray with carb cleaner while running..Compression test was not done with vacuum lines plugged off. Will this affect the readings? Will also check, the vacuum schematic may still be under the hood..My son owned this vehicle for several years and now my Brother has it and has had it for about 3 yrs..Thanks so much. Will keep you posted.
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Followup To
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Missing on one cylinder(2.8 engine) mew plugs, wires, dist. cap and rotor..compression 190..someone mentioned vacuum might be the problem but it seems to me that it would not just be one cylinder missing if it was a vacuum problem..can see gas being injected into the injector throat from two sides...grounded plug against frame and it is firing..any thoughts? Thanks
Ans
YES, A disconnected/broken vacuum line can cause a miss when the source of the vacuum connector is coming from or near the intake port that goes to a particular cylinder.
Let me know. We know whicj cylinder it is that is affected..Do you know of a drawing that is available showing vacuum lines specific to this vehicle? Thanks
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Answer -
FOLLOWUP: Did you by chance spray carb cleaner around the intake manifold area to see if the miss changed intensity ?. You may have an intake manifold gasket leak.
Also spray around the vacuum lines with the engine running to see if you can locate the vacuum leak.
autohelp
I have the manufacturers service manual for this vehicle but they do not provide a vacuum schematic in any of the oem books as tehre is a white EMISSIONS LABEL pated on the radiator support or underside of the hood or somewhere in the engine compartment showing the vacuum routing of the engine.
Your best bet would be to take a camera to a local junk yard and find your EXACT MAKE YEAR ENGINE and take a picture of this EMISSIONS label.
Is there a vacuum port coming off of the cylinder intake chamber of the effected cylinder ?.
Take several pictures of the engine and vacuum hose routing that you have and I may be able to straighten out the vacuum lines and e-mail you a fairly accurate drawing of how they should be routed.
Did you plug OFF all the vacuum lines from the intake and perform a compression test to see if the cylinder is LOW on compression compared to the other 5 ?.
I personally owned an 87 S-10 Blazer 2.8L for many years that I fully rebuilt and sold last year and I currently own a 1989 S-10 blazer that I am doing the same with.
e-mail your pictures to me at:
meperganfortis@msn.com
autohelp
AnswerPlug OFF all vacuum lines that are DIRECTLY connected to the intake manifold ONLY.
Compression readings should be the SAME on all cylinders.
Is this a carburated or fuel injected engine ?.
NOTE: IF this IS a carburated engine. Look directly in back of the carb as there is a vacuum port on the intake manifold that is hidden behind the carb and is a very common source for your vacuum leak.
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