Engine misfires when cold but runs fine after warming up few minutes later?
My 97 SLS used to belong to my grandparents but old age and another car; they gave it to me. They also gave it to me because of this misfire problem it has. It sounds like it runs on 7 cylinders for the first few minutes and runs like garbage if you drive it. There is no knocks in the engine. I took it to autozone to get trouble codes and came back with a random misfire code. The car runs perfect after it is warmed up. I think it just needs a major tuneup. The car sat for 2 months when they brought it back from the dealer for a new water pump. Am I right about this problem? The car only has 82000 and is close for a tuneup.
No smoke from the exhaust except strong odor of gasoline.
- Anonymous1 decade agoFavorite Answer
Probably it just needs a new set of spark plugs.
- 1 decade ago
Usually strong other of fuel and rough idle at cold start up could meanyou have some injectors that are leaking overnight. If it were an ignition problem I believe it would misfire all the time weather cold or hot. Also how is your coolant level? If you seem to be adding coolant more frequently you could also have a minor headgasket leak. Leaking coolant into a cylinder overnigt and you start next morning will also cause a misfire until it burns off the coolant. You may not see smoke at tail pipe because it is a small leak but just enough to cause it to misfire. So take to a shop and have it stay overnight so that they can properly diagnose.
- 1 decade ago
> trouble codes and came back with a random misfire code. The car
> runs perfect after it is warmed up. I think it just needs a major tuneup.
You are very smart. The first place to look when you get misfire is the high voltage ignition section (spark plugs, plug wires, distributors, dist rotors, coils) - basically tune up.
> except strong odor of gasoline
That is because of all the unburnt gasoline being sprayed out the tail pipe. That is almost certainly in need of tune up.
- How do you think about the answers? You can sign in to vote the answer.
- Eric FLv 61 decade ago
sounds like it's time for a tune up, AC Delco plugs, wires and a coil pack as well.
Also a bottle of fuel injector cleaner, anything over $6 is good, Seafoam if you can find it.
random misfires are caused by things like a bad plug wire, not allowing a plug to fire correctly, or enough, an old plug that can't muster the correct spark, or a dirty fuel injector not spraying fuel into the chamber correctly (this is most common).
it can also be bad oxygen sensors, vacuum leak, or worse.. leak at the intake manifold.
- Anonymous6 years ago
I would also say a minor head gasket problem. Especially about the part where you said it needed a waterpump. I once pressurized a cooling system up to 16 psi overnight and found the head gasket problem fouling out the plug until it burnt off and ran fine.Source(s): http://DiagnoseCarMisfires.com
- 1 decade ago
What's an SLS?