'99 Q45 ignition coil replacement

[Benosn99]

I replaced one coil at the dealership already and promised myself I'd do the rest myself (too much money to have them do it!). I'd say I'm very handy, have a variety of tools and, most importantly, the guts to try this. It's my understanding the coil is just an electrical part so it should be easy to swap out, but I'd really like some specific procedures or maybe a pic or two of the engine compartment to verify what items I have to take out first to get ot the coils. I have an ohmeter and plan to take readings to determine the bad one(s)... but I may just replace them all and be done with it! Help would be appreciated! Thanks!

[elwesso]

very RARELY do coils go bad, more common on your generation, but I hope you arent planning on replacing all 8?????!!!

[Benosn99]

Yes, I was planning on it... but maybe not now! Symptoms: Everything works fine except at stop light, I get a slight, variable, "stumble" from the engine... pasenger can't always feel it but I can because I'm "connected" via the gas pedal (and everything runs great at higher RPM's). Replacing the coil in this car (and in my old Q45) always fixed the problem. $645 to fix one... and they want to replace all of them while the engine's apart. Makes sense, but I have no desire to stuff $2,500 in the car.

Sounds like you suspect something different. Thanks!!!

[elwesso]

Hit up autozone and see if you have any codes... They will read em for free, report back with what they said and we'll tell you what they REALLY mean (dont always judge codes by their face value)

could be something like a knock sensor (which wont throw a CEL)

ALSO, does it idle smooth but just stumbles, or does it idle slightly rough.

[maxnix]

Symptoms: Everything works fine except at stop light, I get a slight, variable, "stumble" from the engine... pasenger can't always feel it but I can because I'm "connected" via the gas pedal (and everything runs great at higher RPM's). Replacing the coil in this car (and in my old Q45) always fixed the problem. $645 to fix one... and they want to replace all of them while the engine's apart.

Coilpacks are $174 from Joe. Easily installed if you are experienced and/or have a torque wrench. OBD II gives codes as to which cylinder is misfiring, and coilpacks interchange with other locations to aid in deductive diagnosis.

There is a previous thread about this problem already, so try a search using stumbling as the search word in the body and subject of recent posts in this forum.

[Benosn99]

Thanks for the ideas!!! I appreciate it! I think Autozone is a great idea and will provide very useful info!

I threw some injector cleaner in last night and it's been running fine... although I'll bet that will end in a few days.

It idles smooth but every so often will stumble... clearly seems like a one cylinder "skip" or "hiccup". Periodically, it seems like more than one cylinder, i.e. two in a row or something like that but infrequently.

[texasoil]

Unlikely to be a bad ignition coil. When they go--there is so much voltage they just fry. It could be wrong spark plugs, dirty fuel injectors (since it did improve with FI cleaner, that is STRONG indicator saying get a BG44 clean job done.

[maxnix]

A little help on coil pack replacement.

zerothread?id=117157

[bullittandy]

Search past threads as several 97+ Q's have this problem. I had it for a brief time but it dissappeared after I changed several items.