Thread: Flashing CEL but NO codes! ???

This is going to be a fun one... Today the engine started to misfire under moderate loads. It truly feels like a misfire, and if I set the parking brake out it in drive and give it some gas it constantly
misfires. the CeL also blinks when I do this.

much to my amazement, there are no codes logged. It sure would be handy if I could tell which of the six had the problem so I know what to start checking.

the trans fluid is a good color and level.

I I also hooked my scan tool up to another car I'm working in that will set a code repeatedly and it can find and read that code (that one is a grand am) I can also live poll engine sensors, so I know the tool is actually talking to the ecu.

Have ver you guys ever heard of a flashing cel with No codes???

Thanks
shawn

Flashing CEL = multiple cylinder misfire.
Does your scanner log pending codes?

you need a tune up real bad. or the cat is clogged up.

if you never did a tune up, or have copper plugs for over 12,000 miles, tune up first.

These are fairly new plugs and wires. About 6mo. They are auto lite 104's just regular, nothing fancy like platinum or anything


so random misfire... Could this be a lack of fuel type issue?

I have not considered the cat... So if I pull the O2 sensor and then try the same test it will either confirm or deny the cat, correct?

yes. up stream o2 removed. pre cat.

I was having trouble getting to the sensor cuz it was fully warmed up and I'm a vag... So I disconnected the cross pipe flange and got my leak that way. The problem remains. Do you agree this test method is satisfactory?

Actually, now that I'm working with it, it's even misfiring randomly when idling NOt in gear. But that comes for a few seconds, then goes away for like 30sec then comes back. So it does not even require load, although that does force the issue

this car was running fine up until this morning when the gf was dropping the kids off at daycare. Just totally random out of the blue

Fuel pressure 50 psi at idle. Move in response to throttle activity. One thing I do notice is the pressure almost instantly snaps up 5psi then down 5psi. Did it a couple times... I almost thought my gauge needle was stuck... But when i open close the throttle the pressure response is smooth.

after engine shut down, pressure stays at 50psi and holding

My gf assisted by power braking the trans while I watched the fuel pressure... It remains steady when it's missing. I don't think its fuel related

Starting fluid finds no vac leaks

I would check the coils and ICM, they are basically sitting on a heatsink on the cylinder head.

I had a spare good cool, so I swapped it into each position and it still did not fix it :-(. We can scratch that off the list.


Im gonna pull each plug wore off now and make sure spark gets all the way to the end of each wire

i tneeds to be a good leak, o2 bungs are pretty good. but even still it may misfire some.

its getting dark out soon, take it for a ride, get on it some but not to much as to make it flash cause thats bad news. then pull over in a dark area and look at the cat to see if its glowing red, or the manifolds are glowing red.

if its red, its clogged up for sure.

Ok Scotty, I'll do that test drive now. Thanks

Each wire delivered spark all the way to the end

wait for it to be DARK OUT 9 pm should do it

I think I found it! #6 wire was laying on the O2 sensor and its burned a hole right through it. Gonna slap a new one on in a sec... But I think we all know this find would cause all of my symptoms ;-)

Yup! That was it :-)
man those are always the hardest to find... The ones you think "can't be" because you replaced them not too long ago. I learned my lesson... Again


hey, thanks for all the quick replies and help!

good find!!!