P0172 Code

[Buffdriver52]

Hello,

I recently bought a 98 GTS with 33k miles all stock and decided that I’d change out the original spark plugs and wires. After going with the oem plugs and “quality wires” plug wires the car was running fine… until. At idle it now sounds like it’s misfiring, and at low rpm range it has a lack of power until higher rpm then it pulls like an ox just fine. The physical feeling of the car at idle is not shaking me all over the place it just sounds extremely off. It is not throwing any codes either. I made sure I gapped all the plugs Correctly and places all the plug wires in there respective correct positions. I hooked up an OBD2 reader and though I don’t have a CEL, it read that I’ve got a p0172 (pending) system to rich bank 1. So my question is, where do I start with the multiple things that this could be causing the car to idle this rough and have a drivability issue at low rpm? Thanks!

 

[Steve-Indy]

First thing I would do is to check all of the connections on the plugs and coils. This would also be a good time to recheck that the wires are connected to the correct plug.

 

[TexasViper35]

If you don’t get any joy after following Steve’s recommendation (above), then since the plugs and wires were the last things you touched I would start by pulling each plug to inspect them, if you‘ve got a misfire it will show on that plug (or those plugs). Double check the gaps WYAAI, although I wouldn’t think it is the gap.

Where did you get the replacement wire set? They would seem suspect to me. If it turns out that the wires are defective RSI Racing makes and sells a very high quality set for these cars, not overpriced.

 

[texasviper]

It’s mostly something related to your repairs assuming it was running fine before you started making repairs. I suggest you begin by starting the car. Let it warm up. Then while the engine is warm and running, remove each spark plug wire. Be sure to use insulated gloves and insulated wire puller. Note the cylinder that changes the idle. Be sure to do this to each plug wire and don’t assume when to find one wire that changes the idle that it is the only cylinder with issues. Remove each wire one by one. I’m assuming that you used anti-seize compound on the spark plug threads? If so, be sure that none of the anti-seize compound is on the firing tip of the plug. Additionally, I recommend silicone grease on the plug wires. Only put the silicone grease on the inside of the rubber boot of the plug wires. It helps you made a good connection with the plugs when installing new wires. After you find the missing cylinder, check the plug for cracking, gap, etc. Then check the wire for resistance comparing the old wire. Hope this helps.