: Missfiring issue



pjm10626
06-17-12, 01:39 PM
Went into a store came back out started my car and it shut off after a few seconds. So I tried it again. It turned over strong and didnt start up. Tried it again and patted the gas a little and it started so I reved it some. It was sputtering then I let off the gas and the car shut off again. I got the car to start again so I could move it into a different parking spot to leave it. The check engine light did come on. My car has 50 k miles. Completely stock.

I found someone i know with a scanner. We hooked it to the car while it was running. It said misfire on a single cylinder at first then it started showing misfire on different cylinders.

The fuel pump was on and working. Im thinking something w the computer or a vaccum leak or possibly a crack in the intake, Any ideas?

Does any one have an idea of what could be the problem or encountered the same problem before?


Any help will be appreciated greatly

darkman
06-17-12, 01:49 PM
Did you get any of the misfire code numbers?

How recently did you add fuel - a bad tank of gas?

A problem with a single fuel injector can unbalance the entire bank and cause misfires on the other cylinders on that same bank.

pjm10626
06-17-12, 09:18 PM
I dont remember the codes, it just started on one cylinder then started jumping to different cylinders. one of the cylinders had more misfires than the others though. Would that be the one most likely to be messed up?

i have had that tank of gas in it over a week. I had around 1/8 tank of gas left when this happened. I have wondered if that could be the cause as well. would it run correctly then at the end of the tank run bad?

I am taking it this week to a shop. I just wanted some v owners advise since they may have had a similar issue.

darkman
06-17-12, 09:31 PM
It is not a good idea to run too low on fuel because it can cause any contamination in the bottom of the tank to be picked up. In theory it can also cause the the tank to collapse. In any event, filling the tank would cure these problems. (A clogged fuel filter will not usually cause a low speed misfire, but will cause a power loss at high loads and speeds.)

This list of individual issues that can cause a misfire is long and is best narrowed using the specific error code as a starting point.

VisBoss550
06-19-12, 09:21 PM
my '04 V is having these problems and i got the problem diagnosed as the coils needing to be changed but then another shop told me the valve springs needed to be replaced.......so im saving up to have both replaced just to be sure

dangrus
06-19-12, 11:29 PM
I think I would get a 3rd opinion.... I would add gas and change the filter as well. Also, check your harmonic balancer, I have seen a few posts where it is messed up. A miss fire code can be a result of harmonics.

Cadillac Cust Svc
06-20-12, 03:29 PM
Pjm, Very glad to see you're planning to get your V in to a shop for a thorough diagnosis. If you'd like me to investigate anything further on your behalf, I'm always just an email away at Katie_Lucille@gmexpert.com. Hope the feedback from owners has been helpful to you so far!

VisBoss, please feel free to email me as well if you'd like more examination of your two potential repairs!

Best,

Katie
Cadillac Customer Service

PISNUOFF
06-20-12, 04:20 PM
How logical does this sound?

1. Multiple coil packs all the sudden went bad at once.

2. Multiple valve springs are broken all of the sudden at once.

Both are highly unlikely. It could be an input that controls fuel or spark. All the sensors would trigger another code that would be stored in the PCM. Check all the electrical connections on the motor and look for burned/shorted wires first. Then I would fill with fresh 93 octane fuel and swap the fuel filter. Both are easy and cheap. If that doesn't help your best bet would be to take it somewhere to have it scanned. The dealer is probably your best bet for that.

darkman
06-20-12, 06:15 PM
If the engine is stock, it has single beehive valve springs. When these break the result is typically not just a misfire.

pjm10626
06-23-12, 11:54 AM
Wel i got the car back from my local shop in the west ga area. He replaced a single valve spring on cylinder #1 and changed the spark plug. Now its running as strong as ever. Thanks for all the help. I would have never guess a broken valve spring but that's what it was.

PISNUOFF
06-24-12, 01:38 PM
Nice! Did he change them all or just the one?

pjm10626
06-29-12, 06:52 PM
just did the one broken one.