New Opti Fixed My Low RPM Stumbling Problem
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Joined: Mar 2004
Posts: 669
From: San Jose, CA
New Opti Fixed My Low RPM Stumbling Problem
Yes..another "low RPM stumbling" thread.
So you've heard the story. Car hesitates/stumbles up to 2000rpm, then car takes off. Doesn't matter if engine's warmed or cold early in the morning. Sometimes "feels" like it's going to stall, but doesn't. Just idles very rough and front end of car shakes until the car finally gets going. Don't see much at high RPMs for higher gears. Basically during acceleration from a stop.
So this is what happened in my case. Yours may be different, but that's what this boards about...some bit of information might help you out.
- Car has 93K miles, so actually not too bad before the stumbling started.
- Got worse over time, finally several "misses" sent my car into the shop. Didn't want to create bigger problems driving with random misses.
- Not the O2s, replaced all (4) about 3K miles ago. Was getting codes after header install about slow to heat O2s, so decided to change all (4), since they were original ones.
- Not the fuel filter.
- Not the plugs, because they're new when installed the headers about 5K miles ago.
- So checked the stock wires...some damage to insulation so probably arcing to headers. Started with new Taylor OTVC wires. Engine was a little better, but still had a miss in cylinder 3. Checked the #3 spark plug, and looked fine.
- Since same cylinder, so assumed it was the opti, not the coil.
- Checked opti and it's upstairs neighbor....Mr. Leaky Water Pump...and showed signs of coolant leaking onto the opti.
- Replaced opti and water pump.
Car drives fine now. No stumble and pulls harder than recently due to new wires and opti.
Hope this helps somebody out there, since I've read all the threads about stumbing/hesitation when I first started seeing signs of it. Just sucks to know your car stumbles and sitting at a red light when a Mustang or funny looking subcompact pulls up besides you. Can't race, because don't know if I'm going to redline or goof around the 2000 rpm range.
So you've heard the story. Car hesitates/stumbles up to 2000rpm, then car takes off. Doesn't matter if engine's warmed or cold early in the morning. Sometimes "feels" like it's going to stall, but doesn't. Just idles very rough and front end of car shakes until the car finally gets going. Don't see much at high RPMs for higher gears. Basically during acceleration from a stop.
So this is what happened in my case. Yours may be different, but that's what this boards about...some bit of information might help you out.
- Car has 93K miles, so actually not too bad before the stumbling started.
- Got worse over time, finally several "misses" sent my car into the shop. Didn't want to create bigger problems driving with random misses.
- Not the O2s, replaced all (4) about 3K miles ago. Was getting codes after header install about slow to heat O2s, so decided to change all (4), since they were original ones.
- Not the fuel filter.
- Not the plugs, because they're new when installed the headers about 5K miles ago.
- So checked the stock wires...some damage to insulation so probably arcing to headers. Started with new Taylor OTVC wires. Engine was a little better, but still had a miss in cylinder 3. Checked the #3 spark plug, and looked fine.
- Since same cylinder, so assumed it was the opti, not the coil.
- Checked opti and it's upstairs neighbor....Mr. Leaky Water Pump...and showed signs of coolant leaking onto the opti.
- Replaced opti and water pump.
Car drives fine now. No stumble and pulls harder than recently due to new wires and opti.
Hope this helps somebody out there, since I've read all the threads about stumbing/hesitation when I first started seeing signs of it. Just sucks to know your car stumbles and sitting at a red light when a Mustang or funny looking subcompact pulls up besides you. Can't race, because don't know if I'm going to redline or goof around the 2000 rpm range.
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sleeperZ96BT
LT1 Based Engine Tech
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Jun 5, 2005 09:33 PM
