I just bought my 98 eldorado about a month ago woith 90k on it. Two days ago i went to start it and it backfired and now runs for crap. I took it into the dealer where i bought it and they told me it was the plugs, wires, and it needed an injector cleaning. All of that was going to cost 700 dollars which included the 80 diagnostic fee. I said screw that and am having a trusted mechanic do it for 550 dollars. My question is is this a fair price and is this what the car needs. It has a real rought idle and stumbles when the rpm is belong 3000. If i try and punch it and will gain maybe 500 rpms, start to stumble and gain about anouth 200 really slow and then gain 500 rpm's really quickly again. it isd like riding a bucking bronco. Any suggestions would be greatly appreciated, thanks, jeremy
Could be anything, but it sounds like it's running really rich. Simple thing to check, is to pull off the vacuum tube off the fuel pressure regulator to make sure the diaphragm isn't broken... If fuel is leaking out of it, it is. Does it set any codes?
$700 for plugs, wires and an inj cleaning is highway robbery. "your mileage may vary" If your wires were really (and I do mean really) bad, it could cause your problem. bbob says to spray the wires in the dark with plain water, and to check for arcing. If this is the problem, you can easily replace the wires yourself for a little over $120(?) and 30 minutes of your time. That's for factory parts too. You can get aftermarket wires for $30, but you have to keep them away from just about everything, including themselves... don't ask me how I know
Search my previous post for a complete how to on changing your wires and plugs.
The backfiring and bucking might be caused by a leaking injector. Pressurize the system by turning the key to ON but not starting the car and look at the injectors to see if one is leaking/sticking open.
As noted those symptoms could be caused by any number of problems.
First check to see what error codes you have, and post them back here.
With the high mileage you have, worn out spark plugs are at the top of my list.
I recommend getting either:
The original type, AC Delco 91-450 (dual platinum)
or Champion 3013 (platinum)
I specifically do NOT recommend Bosch plugs, of any style, for this engine; they are poor performers.
Next on the list would be the spark plug wires, they are near their expected lifespan. Use OEM plug wire set.
Specialized cleaning is pretty much a way to separate you from large amounts of your cash, with a small benefit.
I recommend changing the spark plugs first and "seeing" what difference that makes.
Misting the wires with the engine running in a dark place can show you if the wires are leaking electricity, if so replace them.
Both of these are simple things to do. As for cleaning the injectors I would use 10 oz. of Marvel Mystery Oil in a full tank of gas to do a gentle cleaning.
MMO will not fix any broken parts, but does normally help make the engine run smoother. Strong fuel injectors cleaners can be harmful to your fuel pump, by damaging the insulation of the submerged windings.
You will also probably need to clean the EGR valve, mouse holes and the runner ports.
All of this can be done by the "do it your-selfer" with basic hand tools.
Sorry i havent responded back lately but been busy with the holidays. I got the plugs and wires replaced (all oem parts) yesterday by a friend and it runs lots better. I also ran a injector cleaner through it and all seems to be good now, but my gas milage is still a little off and i really havent been able to run it real hard to see if there are any weak spots due to the snow (gotta love wisconsin). I would check for the codes but im sorry to say i dont know how and only have dial up and pages here take forever to load. will look at the egr sometime this week and let you know of my progress, thanks for all your help and info.