My 97 GTS breaks up and backfires after it warms up. Help!!!

[drexelu97]

My 97 GTS runs fine for the first minute when it's cold. As soon as it warms up it breaks up and backfires. I checked all of the plugs and they look fine. Could it be something else with the ignition system or a vacuum leak in the intake?

 

[Viper Wizard]

drexelu97,
Are you sure the wires are ok? How is the idle after it warms up? Dose it idle or idle very rough? Need more input [description of symptoms].

 

[drexelu97]

The idle is rough after it warms up and it sits there and backfires at idle. Do you think I should start with new wires? Can I identify which cylinder or cylinders is missing? Also If I am driving it clears up once in a while then starts breaking up again. I have also noticed the paint on the rocker started to get discolored on the left side just above the cat. Could the cat be clogged or is it getting hot because of the miss? Thanks in advance for your help.

 

[1TONY1]

Have you checked for codes.....ign switch on and off three times, leave it on the third time and count the times the ck engine light comes on. It will show numbers like 12, 27, 55 is the end of test but always two digits together. What I recomend most is get a scantool on it that will show actual 02 readings. Watch that side sill closely are you will burn it bad. My guess is that you have a air/fuel problem after the 02 heats up and it goes into closed loop. Get it cked asap with a scantool so you don't hurt the paint. Note: a scantool is not a code reader like you buy at autoparts. Most garages should have one and it only takes a few minutes to put it on.

 

[drexelu97]

Thanks for the help. I did hook up a snap on scan tool and got no codes. I did not look into the readings for the Oxygen Sensors but I will try that.

 

[Viper Wizard]

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by drexelu97:
The idle is rough after it warms up and it sits there and backfires at idle. Do you think I should start with new wires? Can I identify which cylinder or cylinders is missing? Also If I am driving it clears up once in a while then starts breaking up again. I have also noticed the paint on the rocker started to get discolored on the left side just above the cat. Could the cat be clogged or is it getting hot because of the miss? Thanks in advance for your help.

<HR></BLOCKQUOTE>

To me it sounds like wires? You can tell witch cylinder is miss firing: Start at the left side because that's the side that is getting HOT. If a cylinder is not firing it causes the cats to run very HOT. If you have a pair of "Wire Pliers" / if not, take a regular pliers and wrap elc.tape around the jaws to make them soft.
While your Viper is idling pull the spark plug wire off the plug one at a time and see how much the idle changes: If the idle drops down that cylinder is firing, but it back on. Go the the next cylinder: If no change in idle, more then likely that will be the cylinder that has the problem.

If you need them I have them in stock, just give me a call.

 

[drexelu97]

Sounds like a good plan. I do have the pliers. Thanks alot for your help. This is the first time I used this website to help out and It is very useful. Hopefully I can help someone out next time. Once again I appreciate all of the useful advice.

 

[1TONY1]

If you are looking for a dead cyl you can also use a temp gun on each exhaust pipe to find the cold one. Do this while idling, probably easier to do with headers but it should work on manifolds too. Heats shields may have to be removed. ta

 

[GTS Dean]

I'd start with wires, but it could be a symptom of coil pack problems, or cam/crank position sensors. How's your battery voltage?

 

[JonB]

1) Plug Wires
2) plugs, even tho they 'look fine'
3) Coilpak
4) O-2 sensor
5) tiny chance its a bad battery, not likely

Mileage is helpful......greater the miles, the greater the liklihood as above....