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I have a 1992 Hyundai Excel with 126K miles. The other day ...

Sent to Car Experts January 13 2006 at 3:24 AM
   

I have a 1992 Hyundai Excel with 126K miles. The other day it started running very badly - happened all at once. Investigating, I found out that the middle two cylinders are not working (removing spark plug wire has no effect on engine performance for middle two cylinders). This is probably the injection control since it happened all of the sudden to two cylinders. Do I have to change the engine control module? What checks should I make next? PS spark is working I can here it and see it when I pull plug wires off.

Thanks, Scott S.Optional Information: 1992 Hyundai Excel 1.5 LAlready Tried: Pulled plug wires from suspect cylinders and engine speed does not change (engine will not idle by itself - needs a little accel. pedal).

Edited by Customer (name blocked for privacy) on January 13 2006 at 3:31 AM

Customer (name blocked for privacy)
Answer
January 13 2006 at 4:24 AM (1 hour and 25 seconds later)
         
ACCEPTEDCheck Mark

Greetings, Scott;

The first thing I would recommend before going any further is to perform a compression test. If the head gasket is leaking between cylinders #2 and #3 it would result in a loss of compression on both cylinders at the same time.

THe fuel injectors are individually controlled on this engine. If you obtain a noid light from your local auto parts store (about $10) or a logic probe from a place like Radio shack (about $20) you can then check for power and ground pulse at the fuel injector plugs for the affected cylinders to see if you have a control system problem or not. Note: do NOT use a 12 volt test light to check for fuel injector pulse; the test light does not have a high enough input impedance and the resulting high current flow through the test light can damage internal ECU injector control circuits.

Take a stethoscope or a long thin screwdriver held to the ear, and place it against each fuel injector to verify that they are clicking and sound the same when the engine is running.

You may also want to swap spark plugs and wires (if they will reach) between the cylinders that are working and the ones that are not to see if the problem oves; obviously the coils are generating sufficient voltage to fire the plugs, but you really don't know if the spark is jumping the electrode gap or grounding through a faulty spark plug. If this engine design has teh plugs set way down in wells in the head (my information does not show any illustration), it is also possible for spark to jump from a wire with faulty insulation to the well of a plug tube where you cannot see it when it is assembled, effectively grounding the cylinder.

My repair manuals show this engine as having a distributor. REmove the distributor cap and carefully inspect for any signs of carbon tracking between cylinders inside the cap; this can result in spark plugs cross firing (firing at the wrong time), resulting in an engine miss even though spark will be present at the wire ends.

I hope this is helpful to you; if so, an accept would be most appreciated! Thanks!

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January 13 2006 at 4:52 AM (27 minutes and 36 seconds later)
         
Thanks. This gives me more things to try. I would hate to junk the car over this - I think that it is something I can fix.
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January 16 2006 at 4:45 AM (2 days and 23 hours later)
         
Sorry,
Thought that I had already accepted this answer. Have just done so again. The first suggestion from your expert was what was wrong with my car - blown head gasket between cylinders 2 and 3. I would not have thought of it.
Reply
January 16 2006 at 4:47 AM (1 minute and 45 seconds later)
         
PS.
I whish I knew that you guys accepted Pay-Pal before I charged it to my credit card!
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