Blinking "Service Engine Soon" Light in 97 Tahoe

[POSTahoe]

So I have this Tahoe, but its become a real pain in the wallet, so I went out and bought an Isuzu Diesel pickup just to have something reliable, because the Tahoe surely isn't. Among it's long list of problems, recently the "service engine soon" light has started blinking. It was on already, but that was just an O2 sensor. I know that the blinking means that its a "misfire condition", but I was just wondering if anyone else has had this problem so I dont' replace my entire ignition system if I don't have to. Any help would be appreciated.

[GMMerlin]

Well lets start with some basics.
Do you feel the misfire?
If so when?

The ignition system is 1 of 4 parts you need for proper combustion to take place.

A faulty O2 sensor can cause a misfire by changing fuel trims.

[POSTahoe]

Yes, I can definitely feel the misfire, its very noticeable at low rpms, especially when I come to a stop. It's not so noticeable at high speeds. Sometimes it wont misfire at all, but lately, it wont stop misfiring... maybe that will help...

[GMMerlin]

The next thing is to determine which cylinder is misfiring.
You can do this by removing one plug wire and see if the engine performance changes.
The cylinder that does not have the change is the cylinder that is misfiring.

[POSTahoe]

Ok, so I just drove it around town for a bit to see if it would do it again, and, of course, it didn't do anything, just a constant "service engine soon" light. I recently replaced the plugs less than a year ago. I think I replaced them with bosch. I called my dad and he says that bosch plugs are known to be bad...?? If it's not the plugs, then maybe it is the O2 sensor??

[tykrz]

when that light is flashing, it's something you want fixed ASAP or you risk damaging the engine or the cat's

[POSTahoe]

Yea... that's what I hear, I had to drive it about 30 miles in that condition last night. I'm not going to drive it anymore, I'll just stick with old, ugly, and reliable (p'up) until I can remember why I bought the tahoe in the first place.

[tykrz]

Being a 97 model, I'd change out the dist cap, rotor, plugs (I'd put back in OEM) and plug wires along with fuel and air filters and PCV valve. That takes care of basic tune up work which at that age it more than likely needs anyway. Then I'd go from there. Make sure the basic mechanicals are ok ( ie : no vacuum leaks, etc) before you get carried away going into the electronics of it.

[Crasen]

You might want to try going to an autozone or another parts store when they are not that busy and have them read the code, it will probably tell you which cylinder is misfiring, it makes troubleguessing a lot faster. But new plugs and wires couldn't hurt, does it misfire when it is wet outside, good indication of plug wires. Plug wires really do not last that long, they ussually do not last as long as spark plugs, even though people ussually replace plugs more often then wires, that's because they are so cheap

[POSTahoe]

Yea, honestly, I have changed the plugs recently, but not the wires, I never knew they didn't last as long as the plugs... One thing I've been pondering on is that for a long while now, I've been driving it (well... I hardly ever drive it) with the O2 sensor faulty. Somebody told me that there's a possibility that since the sensor was out, the injectors are pumping excess gas and the carbon is in turn fouling up the new plugs, causing them not to work... Just a thought. I know what I need to do is bite the bullet and replace the cap, rotor, plugs, wires, and get a new O2 sensor... I just didn't want to spend all that money because I have bigger problems... like a bad torque converter and a bad AC compressor, along with needing new tires and just recently spending over $800 on new ball joints. Not to mention my stereo has stopped working and that's almost the most important thing : ) and I'm still making payments (but only 5 more to go and it's mine!)

Hopefully, after all that is taken care of, it will once again be a reliable beast for a little while.

Thanks for all the input guys