E34, changing plugs, is it absolutely necessary to disconnect battery?...

[EricV]

I plan to change the plugs this weekend, and in the past I've disconnected the battery to positively be sure I won't fry my DME when pulling the coils. Nowadays, I have a baby seat that's a PITA to put in and out, and I would love to not have to get to the battery. Thanks, as always, for your expertise!!

Eric

[EricV]

b/c I have had an ongoing "power problem." It's a '93 525, BTW, at 97K. Overall, it runs great, but as long as I have had the car, on some days/trips it feels a little sluggish, and then at other times (about 30%) it accelerates like a raped ape. Love those times. So, I know something is retarding something, be it fuel flow (changed fuel filter and plugs last summer) or whatever. It's been maintained exteremly well, but I'm not sure what to do about that on again off again power issue. Very frustrating. As it happens so intermittently, the mechanics say they're seeing no issues. Any advice on order of attack? TPS? Thanks!

Eric (again.)

[Travelfeet]

not to short or ground anything that shouldn't be, and of course keep the key out of the ignition. I've had no problems with 2 rounds of changing plugs...

not sure about your intermitant lack of power though...

[RobPatt 93 525ia@122K]

Eric,
I'd hesitate, but think I know what you mean... feel the same about my 93 525ia w/122K.... I've swapped plugs (and coils) a few times and never d/c the batt.... though do so at your own risk! I probably should, and think I will because then I can clean the terminals...and yeah, I got a PITA carseat too. The car's "personality", dare I say, almost seems to depend on a combination of:
- fuel quantity (less gas=less weight) and quality
- time of day or night (hot or cold outside, humid?)
- and especially: using A/C or not

My car is also well maintained, but those seem to be the big variables.....
Take care, Rob sends....

[ryan roopnarine]

um, eric.....i've been in a situation where the car's motor was turned over with the dme disconnected and nothing bad happened....about 10 rounds of spark plug changes with the battery connected, one instance of the car running with spark plug wells filled with water, nothing bad happened...methinks that something would only happen if you have a major karmic imbalance coming down the pipe for repayment. might wanna try a stronger fuel injector cleaner like bg44k if your trying to troubleshoot a lack of power, that is, if you aren't having it professionally done somewhere else. when it gets to 95 here, i find that nothing makes up for the lack of power.....and i suspect that a local gas station might be running 90% fuel.....i wouldn't be surprised with the prices the way they are...cars won't even (noticably) burp with 80%, surprising to me.

[EricV]

...most of the time it's feeling bogged down, I'm tooling along, and then, all of a sudden, withthe pedal at the same position, it breaks loose and the car takes off very strongly. It kills me b/c I know the car has better pick up, but something is literally holding it back. At those times, I'll pass right by my neighborhood to enjoy the moment and probably burn more gas then ever slowing down and accelerating. :D

Thanks for your input guys!

Eric

[ryan roopnarine]

are you sure that your climate control isn't engaged without your knowledge when this is happening? the compressor on my car makes the tranny hunt like nobody's business when i'm decelerating, and makes me have to put my foot into the 2200 rpm range before i start making decent power.


...most of the time it's feeling bogged down, I'm tooling along, and then, all of a sudden, withthe pedal at the same position, it breaks loose and the car takes off very strongly. It kills me b/c I know the car has better pick up, but something is literally holding it back. At those times, I'll pass right by my neighborhood to enjoy the moment and probably burn more gas then ever slowing down and accelerating. :D

Thanks for your input guys!

Eric

[EricV]

I also truly appreciate you taking the time to give it thought!

[johnnyBimmer]

hi from john up in canada! I just installed the new boch platinum plus 4 on my 1994 530 I e34 m60 engine and it's 0n 315,000 kilometers and i did not diconnect Battery!
these plugs are around $20 each canadian , worked great withmy new yellow jacket OPTIMA jell filled batery up here in canada for 40 below zero starts! the OPtIMA delivers full voltage and amperage instantly at crank start and is constant voltage during long storage not to screw up on board computor! have not had false trans prog
since! john blouin canada!

[Gooch]

I have a '94 525. I've notice that the warmer the outside air temp, the sluggish my car is. Has to do with the density of air going into the engine.
On that first cool autumn day after summer my car feel like it gains 25 HP.
This is without the AC on.

[RobPatt]

and I think I feel a difference....My car is regularly driven about 8 miles a day, in stop and go traffic..... so with the $62 BMA tune up kit (plugs, filters, etc), a full tank of 93 chevron, and the 11 ounces of BG44K for $18 bucks, AND finally, running in S3 on the 55mph roads, things are clearing out.... the car does feel better..... Erik, perhaps you have a brake dragging or something? parking brake? the surge you describe is kind of weird.... good luck. let us all know! Rob sends....