Low RPM miss?

[ArkansasMystic]

My 96 Cobra is missing/sputtering at low RPM's. In a drag race situation (go all out from a stop) it runs great. If you're driving along and downshift then punch in, runs fine (dropping into the 3-4k RPM range). However, when just taking it easy, say cruising in 4th at 2-3k RPM and then flooring it to go, it just falls on its face. You can ease into it and it works fine. It has been going on for about a month or so, but hasn't been bad until recently (colder weather, could be a coincidence though). It's not something just when the engines cold or hot, pretty much all the time. I have a CEL, and had it scanned when the problem first started. Only codes were rear o2 sensors (no cats, MIL's went out). I'm thinking plugs/wires should fix it, but also have heard similar symptoms when the front o2's need replaced. The guy that I have always used for mechanic work has quit doing it for a while, so I'm left out in the open. I'm not mechanically inclined, every time I work on the car something goes wrong, so not really wanting to get into this myself, I'd rather pay someone to do it then put up with the headache. If it's something like o2's, they should be easy to replace without taking it anywhere. What do you guys think it is? Thanks for any input.

[04_S/C_GT]

How long has it been since ur last tune up?

[ArkansasMystic]

No idea. I'm thinking about taking it by a local shop and have them do a tune up regardless. What all should be included in a tune up, and do you think it will fix the problem? Thanks.

[04_S/C_GT]

What I've always heard:

Plugs and wires--60000 miles
Air Filter--every other oil change
Transmission Fluid--30000 miles
Fuel Filter--30000 miles
Brake Fluid--30000 miles
Throttle Body, Plenum, MAF, And PVC Cleaned--30000 miles

Definitely possible. Even the smallest clog could cause the motor to act funny and the car probably needs it anyways. If it has been a long time since the last one then u will even notice a small power gain and might even shave some time at the track.

[oxman]

wow,,if that's the case i think my junk needs a tune as well lol

[ArkansasMystic]

The car has 127k miles, and I've changed the oil 3-4 times since I've had it, changed the filter probably 2 changes ago. The rest, couldn't tell you. I'll take to the local shops, see what all their "tune ups" consist of and probably have one done, couldn't hurt anything, even if it isn't my problem. Guess that'll come first, and I'll put subframes on hold for a while.

[ArkansasMystic]

Showtime is gonna help me put on new plugs/wires and clean the MAF next weekend, hopefully it'll fix the problem. Thanks a lot.

[04_S/C_GT]

Sweet! Keep us updated.

[ArkansasMystic]

For safe measure I went by autozone and had it scanned. It pulled a P0420 code, which would be something with the rear o2's. I know my MILs quite a few months back, so it makes sense. I have new MILs built, should be installing them next weekend and hopefully that will fix the codes. Would that code/problem cause the sputtering though? Thanks.

[stumbaugh]

We are gonna get her running good man, i figure it will run better under full throttle to.

[ArkansasMystic]

I've finally got a mechanic with a scan tool that will be taking a look at it next Tuesday. He can monitor the spark at each plug and do some things we wouldn't be able to do, so I'm gonna have him take a look at it to remove some of the guess work. It runs fine full throttle, so that just makes for a fun drive.

[ArkansasMystic]

Just a little update. Still throwing P0420, gotta get those MIL's put on. No other codes were present. We drove around, and he finally got it to show up misfire on plugs 1 and 8, so looks like you guys were right. I'm also gonna be replacing the fuel filter. Any other maintenance I need to do to complete the tune up? Thanks.

[5spd GT]

It is going to be your wires more than likely, not the plugs.

Arching wires or ones with moisture can cause the misfire issues you are describing.

I have seen that happen a couple times. Good Luck Preston and let us know how it turns out.

I do not believe it is the 02's at all.

[ArkansasMystic]

I've got MIL's I built, just can't remember which way I put the resistors in so not sure which way to hook them up. For about $5 you can get some stuff form any autoparts store (sparkplug non-fouler) and modify and it is suppose to eliminate the CEL. I've read a write up on it on SVTperformance. Not sure when I'll get to putting the plugs/wires on, busy week with finals coming up.

[denniswhurley]

Hey man let me know when you and showtime are going to do the work and ill come help. As i have said this is my first pony but mechanics are the same ford chevy or mopar...LOL So let me know if the old man here can lend a hand. I think Showtime has my cell # now Adios

[ArkansasMystic]

We're probably still gonna put some MILs on it, but I'm gonna have the guy with the scan tool do the work, I've been so busy lately I havent had time to meet up/hang out. Thanks, and I'm sure we'll have some projects going on in the future and could use an extra hand.

[ArkansasMystic]

Got the tune up completed, I can't believe the difference. Either I didn't notice it getting worse, or the car has never ran right. The sputtering was around 2k rpms, so this morning I pulled out of my driveway, drove in 1st at 2k for a little bit, then floored it and broke the rear loose and had to let out. I've driven in much colder weather and never had that happen. Sure, I can slide the rear around using the clutch, but never happened from a roll. It pulls really hard, much better. Not sure if it was just worn out plugs, or if going from 8.5mm MSD wires to 9mm FRPP made the difference, but either way, runs like a champ. Thanks guys!

[stumbaugh]

So what your saying is that ur wanting to race now...lol j/k

[ArkansasMystic]

LOL, can't hook now. I just wish I could make a few attempts at breaking 11.25 before the car sells. We'll see!