Six8888

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

LS-ONE_DAY

Done anything to the car recently? That means there are multiple random misfires in the cylinders. It's not good.

Six8888

nothing recently

Six8888

Only recent even was moving from So Cal to Houston Texas

Six8888

Can an 02 sensor cause this?

BOBS99SS

iTrader: (2)

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?

crazyelf

iTrader: (21)

O2 sensor has done this to me before.

Darkman

iTrader: (2)

A flashing SES indicates that the system is detecting emission levels/conditions that threaten to ruin the catalytic converter.

bristol16

iTrader: (36)

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.

Old Geezer

iTrader: (3)

AT WFO, the O2's are not "in the picture"......

wildcamaro

iTrader: (15)

Get it checked, prob a dead cylinder

LS1121

iTrader: (17)

fuel pump going?

Six8888

if it was a dead cyl wouldn't it run rough all the time?

zracer323

iTrader: (12)

Bad spark plug, spark plug wire or coil pack can cause this as well.

massls1guy

iTrader: (9)

Exactly, this happened to me. I had a bad spark plug wire that only gave me the flashing SES under acceleration.

baalic

iTrader: (8)

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.

LS-ONE_DAY

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.

baalic

iTrader: (8)

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..

bristol16

iTrader: (36)

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.

baalic

iTrader: (8)

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...