I have a 96 Cobra that isn't running right. When cruising along anywhere from 2-4k RPM's, you can floor it and it sputters really bad. I can drop a gear, floor it and it runs great. I can floor it from a stop and it runs fine. I've ran it at the local strip and it runs just fine there. Only problem is when calmly cruising around. I am throwing a CEL, but the only code I get is the rear o2 sensors (no cats). This has been going on now for a month or two. I always just thought I was in too high of a gear. I bought the car from my brother around April, he drove it last night and said that there was definitely something wrong, and it usually isn't like that. I've been running 91 or 93 octane gas (depending on where I fill up). Any suggestions on where to start? Thanks.
Sputtering??
- Thread starter ArkansasMystic
- Start date
fastfive_ogt
New Member
Try plugs and wires man. Sounds like an engine missfire. Alot of times when you load up the engine at low rpms like that it causes alot of stress on the ignition and if you got a bad wire or plug it will show up then. It may still run fine at higher rpm with load. Sometimes when I get a car that has random missfire detected p0300 I will take it out and put the car in manual 2 or 3 and start out with the throttle most of the way down. This loads it up nicely and if its got a miss it will ussually show up. If you got a IDS scanner you can see if MPLEARN has learned yet. If not this could be why its not setting a code for the miss. Hope this helps.
fastfive_ogt
New Member
fuel is much less likely than ignition. IE. plugs and wires..... Still possable though. which is cheaper and easier to do? Yeah do the plugs wires. If you have an IDS you can do a power balance test when this occurs to see what cylinder is dropping. Then you can test run a different wire on that cylinder and change the plug on that one. These are tactics I would use at work. Test fuel pressure KOEO. Watch for bleed down. These tests can be preformed but with out the IDS or scanner which reads missfire you are screwed. My money is on the plugs and wires.
02nightmaregt
To hell with your Mustang, I want to see your HOG!
hotcobra03
Active Member
Yep, all searches I have found just say it's time to replace cats, and since I don't have them, they can't be the problem. I've about got it figured out, I hope. The code is throwing the rear o2's because my MIL went out. I have new ones built, will try to get them installed next weekend and go from there. Last question, would the code I'm throwing cause the miss? Thanks.
hotcobra03
Active Member
I had them (mil)on my o3 and they didnt work.i was getting 420 with them on .turned rear o2s back on . no codes anymore
I'm still throwing the P0420 code, haven't put the MIL's on yet. I had a mechanic look at it, no misfire codes. Finally we took it for a spin and while driving he monitored the plugs, and it took a while but eventually plugs 1 and 8 showed to misfire. I've got plugs and wires on order, and will be ordering a new fuel filter sometime this week. Anything else I may need to do while I'm having him work on it? Thanks.
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