I hate this
I just drove my son-in-laws completely stock 02 SS w/165,000 miles, from Washington DC to Albuquerque NM over the last 3 days. For you military folks, yes thats Andrews to Kirtland. I have no tools and am flying back home Saturday.
Soon as I crossed in to N.M. as I let off throttle to take the usual state line picture, it died as I put the throttle back down. Running around 75 mph at the time, I steered to right lane thinking I have to get this off the road, and 5 seconds later it came back to life. Called my in law who was in front of me, we pull over and look it over. Nothing obvious under hood. I take off again, its sputters a few times as I'm shifting thru the gears, then seemed to run ok once up to speed. Then a few minutes later, while cruise was at 75, pulling up a hill, it died again. was almost completely off the road and came back to life again. I babied it the next 100 miles running about 65. If I was more than slightly on the throttle, it started sputtering. If I ease the throttle, I could run 65-70. Any faster than that, or a hill that required more throttle, it would die.
My first thought was fuel pump. The longer I drove it, fuel filter. I don't know, What do you guys think?
Do you have an SES light....?
My thoughts.....failing 02 sensor(s). Won't always give you an SES light. Very easy to change with one crescent wrench....and getting the front end up in the air a little bit.
It takes 5 minutes to change one.
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If it is a bad 02 sensor.......go to a PepBoys or Advanced Auto and buy 2 new FRONT Denso brand 02 sensors. Get OEM parts numbers if you are stock.
PepBoys or any shop can put them both in in about 15 minutes....so don't let them rip you off on labor.
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When we got off the Interstate and was moving slow, it would be running rough and died on me at a stop light. Started right back up, ran rough, I revved it a couple times, then it was fine till I took off from the light again. Anything more than light throttle, it was bog, run rough till I let off.
SES light had shown for about an hour while he was driving it 2 days ago. We been switching vehicles and it was never on when I was driving it. Or with him either
If it is a bad 02 sensor.......go to a PepBoys or Advanced Auto and buy 2 new FRONT Denso brand 02 sensors. Get OEM parts numbers if you are stock.
PepBoys or any shop can put them both in in about 15 minutes....so don't let them rip you off on labor.
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This sux being 1800 miles from home and having a problem.
Thanks for your suggestions so far
This sux being 1800 miles from home and having a problem.
Thanks for your suggestions so far

If an engine shuts off instantly it can be a failing Crank Shaft Position sensor...but they do not cause bogging and rough running.
If it starts bogging....then you give a lot of throttle, does it take off? Or does it bog worse?
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We didn't check mileage but he did keep most of the receipts. Off top, I'd say no, gas mileage didn't change.
They're just moving here this week.
When you start an LS1 when the engine is cold, the 02 sensors are not controlling anything. They do not come into play until the coolant is ABOVE, I believe 122*F, so only the MAF sensor is controlling fuel metering. It takes a good 5-10 minutes to get the coolant above 122*F.
If it did not act up when it was cold.......thats another indication that its MOST LIKELY a bad 02 sensor(s).
Because after the coolant passes 122*F, then the 02 sensors become active and they control all fuel metering during normal to medium throttle driving and the MAF does nothing. When you go Wide Open Throttle....after the coolant is passed 122*F, then the MAF will also come into play, and along with the 02 sensors they will BOTH work together to meter fueling, as long as you are at Wide Open Throttle.
I think you found your issue.
BUT....I still think you should get a scan to confirm its the 02 sensor(s) not switching properly, before spending money to buy new ones. WHY...because these cars have so many weird things that can cause these issues you're having. Just so you don't waste time and money......
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It sounds like it started up OK after dying, but that still doesn't entirely rule out a fuel pump issue. I'd recommend a pressure test, also under load if it looks OK at idle. Look for 58-60psi under all conditions, including loaded WOT.
You may also be experiencing a weak/failing injector(s.) I'd want to watch misfire counts and fuel trim data on a scanner while the rough running is happening.
Something simple....how is the air filter? Such a long trip might have resulted in a blockage (especially if it was already old), and/or if it's a K&N style it might have finally sprayed enough filter oil on the MAF to cause issues. So an MAF and air filter inspection would be in order as well.
It sounds like it started up OK after dying, but that still doesn't entirely rule out a fuel pump issue. I'd recommend a pressure test, also under load if it looks OK at idle. Look for 58-60psi under all conditions, including loaded WOT.
You may also be experiencing a weak/failing injector(s.) I'd want to watch misfire counts and fuel trim data on a scanner while the rough running is happening.
Something simple....how is the air filter? Such a long trip might have resulted in a blockage (especially if it was already old), and/or if it's a K&N style it might have finally sprayed enough filter oil on the MAF to cause issues. So an MAF and air filter inspection would be in order as well.
But like I said...it could be a million things.
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Thanks again, I appreciate the help. LS1TECH is a good thing.
Fuel trim, misfire and DTC data would give a better picture and hopefully point in a certain direction.







