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SES light flashing

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Old Jun 23, 2012 | 03:56 PM
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My SES light flashes but only under heavy acceleration, if I floor it while on freeway for example the ses light flashes and it seems to run rough, when I slow down the light stops flashing and it runs normally. Any ideas what this could be? Thanks in advance
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Old Jun 23, 2012 | 04:11 PM
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Done anything to the car recently? That means there are multiple random misfires in the cylinders. It's not good.
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Old Jun 23, 2012 | 04:25 PM
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nothing recently
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Old Jun 23, 2012 | 04:26 PM
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Only recent even was moving from So Cal to Houston Texas
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Old Jun 23, 2012 | 04:26 PM
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Can an 02 sensor cause this?
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Old Jun 23, 2012 | 05:15 PM
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I have never heard of a 02 sensor causing a misfire, i had a flashing ses light in the beginning parts of tunning my car, its a big cam car, but when i took it back to my buddy i never had the problem since, but mine would occur doing around 30 mph, im sure someone can give ya some better ideas, did you have it scanned? What codes came up?
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Old Jun 23, 2012 | 07:07 PM
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O2 sensor has done this to me before.
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Old Jun 23, 2012 | 07:29 PM
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A flashing SES indicates that the system is detecting emission levels/conditions that threaten to ruin the catalytic converter.
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Old Jun 24, 2012 | 07:15 AM
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Get the code checked at a local parts store if you don't have your own scanner. Flashing light and running rough usually means a misfire P0300-P0308 has probably set the light, it can usually give you a heads up as to what cylinder to start checking for a problem. Not a good idea to make it keep flashing, could potentially damage the engine or the cats if you have them like Darkman said. Once you know what cylinder it is on you can start swapping parts until the misfire moves. If it's a P0300 (random misfire) it could be a fueling issue or any number of other problems. Get the code checked first so you know what you are dealing with.
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Old Jun 24, 2012 | 08:37 AM
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AT WFO, the O2's are not "in the picture"......
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Old Jun 24, 2012 | 08:57 AM
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Get it checked, prob a dead cylinder
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Old Jun 24, 2012 | 09:12 AM
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fuel pump going?
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Old Jun 24, 2012 | 12:48 PM
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if it was a dead cyl wouldn't it run rough all the time?
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Old Jun 24, 2012 | 01:39 PM
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Bad spark plug, spark plug wire or coil pack can cause this as well.
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Old Jun 24, 2012 | 09:11 PM
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Originally Posted by zracer323
Bad spark plug, spark plug wire or coil pack can cause this as well.
Exactly, this happened to me. I had a bad spark plug wire that only gave me the flashing SES under acceleration.
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Old Jun 24, 2012 | 09:16 PM
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Ok i just went through a ton of bug hunting myself, i had the ecact problem, with a few others. Changed my cat, parts of the proem fixed, still ses light, changed maf too. Car runs like a ******* champ now. I too thought missfires because that's what tech said. They were wrong. New MAF and CAT and voila!!


Try those.
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Old Jun 24, 2012 | 09:17 PM
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Yeah...I had it happen after I installed my headers...forgot to plug the coil pack in and drove it like 60 miles on the highway afterward like a dumbass. Luckily I think everything ended up alright.
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Old Jun 24, 2012 | 09:18 PM
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On that note, flashing ses light at idle, is usually a misfire. I had that too once... But what your explaining sounds line what i just fixed. 500 bucks and 2 months of hunting later..
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Old Jun 24, 2012 | 09:19 PM
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Buying a new maf and cat are quite a bit more expensive than getting the code pulled for free and swapping around a plug, wire, and coil if possible...all of which is free.

Find out what the problem is before you go pissing away money on parts. It's possible it is maf and/or cat but I would make sure before I started blindly throwing parts at it.
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Old Jun 24, 2012 | 09:29 PM
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My code for it flashing, never came up. I did have a lean bank 1 and bank 2.


After over a year and a half running it with flashing ses light at heavy acceleration like that, messing with plugs, coils, wires. Etc. Well, nothing helped. I downed my car for 2 months. First thing they did was change the cats, that fixed a lot of my problems as at high rpms, it would stall out a little and get hung up at 5100 rpms, not shifting and not accelerating. Cat fixed that, and that flashing ses light but my codes persisted. Tried cleaning MAF, didn't help, replaced MAF. No codes and no flashing ses. Fwiw, getting my cat replaced was 200, maf was 100.. Thats not a lot of money. And i paid someone to do the cat...
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