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Discussion Starter #1
Ok, I've got an '84 crossfire that has #4 &#6 cylinders not firing. Those plus were oil fouled. The RPM's are up and down and very inconsistent. It drives like crap and affects the trans shifting too. Could this be a vac leak?? I've got new GM plugs,wires, EGR, TPS, ECM, Cap, fuel filter. HELP!
 

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im not up on vettes owning one for 3 days now, but my daily driver 72 lemans told me that when the plugs are fouled with oil, there are a fiew culprits to blame,
1 = leaky valve seals, allow oil to fall down to the combustion chamber
2 = horrible piston ring seal, allowing oil to come up the cylinder walls
3 = leaky head gasket, is not likely as oil will be in your radiator and water will be in your oil pan. again, not likely if your car is still running.

my cause was absolutely hammered valve train, the seals, guides and the valves them selves were toasted along with the cam and timing chain.
I remedied this by getting a remanufactured long block and upgrading from 350cu to a 400 in the old pontiac. been going good for 5k so far.

do you notice any smoke coming out of the exaust?
and maby you can try and throw a set of new plugs all around and run you car for a bout 3 hours or a days drive, and then inspect the fresher plugs it might give you more information about the situation
 

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do a leak down test, and a vacuum test,it should tell you about 90% of what you need to know about the engines condition and a great deal about where to look for problems:thumbsup:

first DON,T PAY FOR IT :down: ...DO IT YOURSELF!!! :thumbsup:
IT WILL COST LESS EVEN AFTER PAYING FOR THE TOOLS AT MOST GARAGES.

http://www.centuryperformance.com/vacuum.asp

http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=93547

youll find that youll gain basic skills, own new tools and PAY LESS MONEY
:thumbsup:




read this

http://www.xs11.com/tips/misc/misc3.shtml

http://www.goodvibesracing.com/leakdown%20Tester.htm

http://www.globaltoolsupply.com/cgi-local/SoftCart.exe/online-store/scstore/p-P1-275.html?E+scstore

http://www.tavia.com/cat8.html#3



http://www.motorcycleproject.com/motorcycle/text/leakdown.html

http://www.xs11.com/tips/misc/misc3.shtml


http://goodvibesracing.com/Leakdown%20Tester.htm
1) For most accurate results, engine should be up to operating temperture.

2) Remove all spark plugs.

3) Rotate crankshaft until piston being tested is at top dead center of compression stroke.

4) Screw the spark plug adaptor hose into spark plug hole making the sure the o-ring is seated properly.

5) Connect the spark plug adaptor hose to the coupler of the leakdown tester.

6) Connect leakdown tester to a good source of compressed air, preferably a filtered and water trapped source.

7) Adjust the regulator on the leakdown tester so the the LEFT HAND GAUGE indicates at least 10 pounds less than your sorce pressure. The leakdown percentage conversion table shown below is based on regulated pressures of 100, 90, or 75 psi.

8) Read the RIGHT HAND GAUGE (differential gauge), then look up gauge reading on the conversion table below to get actual leakdown percentage. After noting percentage of leakage, turn the regulator knob counter-clockwise to relieve the pressure. This reduces the shock to the gauges. If you ever get an unrealistically low pressure reading on the right hand gauge, there is a finite possibilty that something is blocking the small orfice located within the hex tube located between the regulator and the main body of the leakdown tester.

9)To remove any obstruction that may be lodged in the metering orfice, unscrew the hose coupling assembly from the aluminum body. Ultilizing a 1" wrench, remove the knob assembly from the regulator. Blow compressed air in the opposite direction (from the coupling end) to clear the orfice. Re-assemble the regulator and the coupling.

NOTE: DO NOT ATTEMPT TO REMOVE THE BRASS HEX NIPPLE BETWEEN THE REGULATOR AND THE ALUMINUM BODY. DAMAGE MAY RESULT.



http://www.maximausa.com/technical/leaktest.html

http://www.meyerracingonline.com/leak.html

http://www.compressionking.com/leakdown.htm

http://www.lcengineering.com/TechNotes/TechNote47.htm
 
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