chevy running rough

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Can anyone help? I have a 1993 Chevy Lumina 3.1 liter V-6 car, I just recently had the heads machine and a valve job done on the car about 8 months ago and the car was running excellent. About a month ago the car started to run real rough. So I replaced the spark plugs, wires, air filter, and fuel filter. The car still ran rough I even tested the fuel pump to ensure it was functional probably and it was. I ran some fuel injection cleaner through the system several time and still no change. Here are the symptoms: When the car is idling it sometimes surges up and down like it is having hard time breathing. When you are driving down the road and the transmission shifts down into it final gear the car begins to run rough. When you hit the gas to accelerate the car stumbles, dribbles, and shakes to try to pick up speed. The car also hard starts in the morning only, if you wait several hours and come back the car will start right up. If you listen to the tail pipe in sound like the car is missing, it putters.

posted by  running man

Check for spark from all of the plug wires, I have seen several of those cars have one or more bad coil packs as well as ignition modules.

posted by  srober32

Check to see if you have connected all your plug wires to the right places and call an auto shop to see if you have the correct firing order.

posted by  FordFromHell351

Firing order is on the coils if they are original. The cylinders on the block are as folows, standing at the bumper looking in the hood, starting on the left front bank:1,3,5 rear bank;2,4,6. Does any one out there know which coils are for which cyliders? osborste?

posted by  srober32

ok check the wires to the attachment if they match then check the plugs one/2 will be blackened/wet from not firing(weak/no spark) the car missing maybe a coil going bad or a bad driver in the ignition module
bad egr/map/vacuum leak(map code)/tps would trip service eng light

posted by  osborste

I think your book may be wrong on cyliders, osborste, but then again I thought I was wrong once... :laughing:

posted by  srober32

you had me wondering so i checked a couple of my chev manuals plus went and check my 97 malibu 3100 they matched the pic just match the coils and towers in the pic

posted by  osborste

I checked all the wires and plugs and they are good. What is the best way to check the coil/ignition module to see if it is functioning properly? If I take the car to a mechanic to put it on a diagnois machine will he/she be able to tell me what the problem is even though the car is not throwing an engine light?

posted by  running man

I checked for a spark at all of the cylinders but I couldn't get a spark from cylinders #2and #4, but I don't think, think two cylinders are not firing, if so the car would probably not stay running. Is there a better way to check for a spark coming from the coil/wires?

posted by  running man

I checked to ensure all of the wires were connected correctly and they were. I have a Haynes manuel that shows the correct firing order and I follow it.

posted by  running man

Common problem, you may have a bad coil. Hell, I had a four cylinder that ran on two cylinders, so a 6 running on 4 is not that big a stretch.

posted by  srober32

What is the best way to test the coil? Can I take it off the car and take it to a shop or can it be tested on the car?

posted by  running man

there 's couple possible problems here
1 you have a bad ignition wire bad plug or the connection between the coil and module(its a blade terminal) has rusted off

cure try changing the wire and plug for cylinder's 2 and 4 with another wire and plug from a working one if you still dont get spark on 2 and 4 then remove the coil from module and check the connection between them normally when a coil goes it kills both never seen one quit on one cylinder yet but its possible i guess

posted by  osborste

Thanks for all of your help, I end up replacing the coil and ignition module with a one from the junk yard and it fixed my problem. The car is running excellent now.

posted by  running man

Excellent! :thumbs: Chalk one more for me. :mrgreen: lol

posted by  srober32

[QUOTE=srober32]Excellent! :thumbs: Chalk one more for me. :mrgreen: lol[/

VERY GOOD SROBER YOU DID IT FIRST

posted by  osborste

Sometimes I think that the engineers should work on the cars they design, and then they wouldn't put the coil packs on the front of the engine where all of the salt spray and road junk hits it day after day. :laughing:

posted by  srober32

According to a Haynes manual, arent cyl 2 and 5 paired on the same coil as well as 1, 4 and 3, 6 paired on the coils? Be careful on wiring ----On a GM 3.1, I think cyl 1, 3, and 5 are on the firewall side and 2, 4, and 6 are on radiator differing from the standard numbering conventions.

posted by  tbaxleyjr

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