Shuddering and Hesitations

[CorporalAris]

I fixed this problem:

I realize that this is diggin up my old thread, but I ended up purchasing a engine code reader, and my problem was a bad Oxygen Sensor. It was causing the engine to run lean.

I own a 1995 Grand Am SS 3.1 V6. 140,000 Miles.

**This may or may not be related**
A month ago, the car began shuddering at low RPM's, especially while shifting. I opened the hood while it was running, at night, and saw sparks coming from the ignition coil/ignition wire connection. I replaced that ignition coil and all ignition wires.
** **

Now recently, the car hesitates slightly after it shifts, and shudders at ~30MPH, 50MPH, and 70MPH.

My mileage is also down near 15mpg when this is happening.

When it is idling, or in-drive, with my foot on the brake, the Check Engine Light will come on after about 3 minutes. All problems go away when this happens.

What is going on?

My car is using OBD1.5, Pontiac wants $200 bucks to tell me whats going on, and the cheapest reader would run me about $130 bucks.

[bszopi]

Since you replaced the coils and wires, almost sounds like the ICM might be going bad (the module the coil packs mount to).

[CorporalAris]

I replaced ONE coil. The other two weren't sparking like the first one.

Could this be a Fuel problem? As in the Fuel Pump or the Fuel Injection System?
Or Spark Plugs maybe? Haha, I'm really stretching my knowledge.

[bszopi]

If you only replaced 1 coil, it could be that the other coil packs are now going bad as well. What brand did you replace the original coil pack with?

[CorporalAris]

O'Reilly's Auto Parts: Master Pro Ignition - Direct Ignition Coil

The only reason the pack was bad was because it had physically cracked, and was sparking. The other coils appear to be fine.

[CorporalAris]

I ran some fuel line cleaner through, nothing. Gonna check/replace sparkplugs this weekend. Possible the fuel filter too.

[CorporalAris]

I ran some fuel line cleaner through, nothing. Gonna check/replace sparkplugs this weekend. Possible the fuel filter too.

Actually, I wonder if that coil pack went bad... It was a cheapo...

[SappySE107]

junkyard stockers are a good bet. May as grab the ICM as well. They are on ebay as well.

Sounds like EGR possibly. When was the last time the fuel filter and O2 sensor were changed?

[geoffinbc]

It sounds like a misfire. Most likely due to plugs. Change them all with STOCK AC DELCO PLUGS. If you used a cheepo brand of plug wires you may want to return them for some Delco ones too.

[CorporalAris]

I realize that this is diggin up my old thread, but I ended up purchasing a engine code reader, and my problem was a bad Oxygen Sensor. It was causing the engine to run lean.

[bszopi]

I am glad you did dig it up! There are too many times that people fix issues and never reply to the topic, so when the next person has similar issues, they don't know what the problem was so they can see if it is their problem as well. Glad to see you got it fixed as well.

[CorporalAris]

I am glad you did dig it up! There are too many times that people fix issues and never reply to the topic, so when the next person has similar issues, they don't know what the problem was so they can see if it is their problem as well. Glad to see you got it fixed as well.

Yeah, no problem.