grumpsjr wrote:This sounds a lot like the ongoing issues I've had with my 528iA. I'm giving up and taking it to a mechanic in the near future as I've done everything you've done, plus computer and coil, and suspect wiring harness issues as well.
Brian
On Thu, Aug 20, 2009 at 7:19 AM, BradInTexas <b> wrote:
I never have made the 528i run correctly since the transmission and engine swap. So last nite I swapped out the distributor, re-timed the car and it ran great. I couldn't believe the difference. Power across the range, winding out nicely, easy to pass traffic on the interstate. This morning I start the car and it will barely drive down the block. Right back to where it was: backfiring, no power, like it has a rev-limiter at 2800rpm. I have swapped AFMs, distributors, cleaned and tested all the injectors, looked for vacuum leaks, set the throttle body, checked the grounds, etc. Running out of ideas. It is like there is a swtch somewhere that makes it run great at times. I think all that is left is the wiring harness (I used the one that came on the engine instead of the one off the car), computer and the coil. If anyone has any other ideas...
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I do.
As I have ranted on the old board as well as this one, when you have run out of options of parts-swapping, can verify good known working parts, remember this: These cars are almost 30 years old. They were never designed to last this long (in total).
Having said that, let's back up a minute. Before you go parts-swapping, chasing the elusive, intermittant, sometimes it runs great, sometimes like $h!t problem, think about this. Most (not all) mechanical parts usually fail eventually, they have a useful life span (and by now we have a pretty good history of their typical lifespan). So when something breaks, or fails, it is broken and stays that way until the part is replaced. Easy to diagnose.
The elusive problems are harder to diagnose because whatever is wrong does not stay that way. Very frustrating. But cool heads must prevail to METHODICALLY eliminate suspect parts (i.e., do ONE thing at a time, and WAIT for an evaluation before proceeding to the next dart-throw).
So....you say you suspect your wiring. I say you should look not at the wiring (it is metal with a plastic insulation; if the metal is still covered by the plastic, the wiring is probably good - the most anal among us will actually measure resistance through a length of wire to ascertain its electrical integrity. And unless a PO has butchered the wiring through indiscreet hacking, I would say a good visual inspection will determine a harness' physical attributes and its capability of proper electron flow) but at the
CONNECTORS . Did i say that loud enough? Grounds are the worst, and the most suspect, but they are all less-than-ideal by now.
Think for a moment all the years of engine heat (and cooling, (and freezing)) of little plastic wiring connector assemblies found under the hood (and all over the car) along with those of you (us) who live in extremely humid environments and you will find, upon careful inspection, that the factory
CRIMPS that bind that metal wire to a
CONNECTOR are
OXIDIZED! WTF? That means the electrons are not happy and cannot flow to their proper destination as the engineers designed. Sneaky, huh? Remember what I said about these cars being, um, how old was that?
If you are going to want a car this old to operate reliably and as designed, you must take a restorer's POV (point of view, for those acronymically challenged) and evaluate EVERYTHING.
Well, that's nice, but how do you fix it? You assemble a gaggle of appropriate replacement connectors, chop off the piece of OXIDIZED wire end and SOLDER the new connector to the fresh piece of wire. Now, good electron flow, just like 1980 or thereabouts but better, since the factory didn't do this because it was 1) too time-consuming, 2) too expensive, and 3) they
didn't expect these cars to still be around by now. Point of the story? You are on your own. At this age, these (any) cars are in a way different place regarding care. And why boards such as this exist.
Too much trouble? Can't solder? You can always take your car to a $99.00/hr. mechanic who will look at your car, spray some throttle body cleaner, stick some injector cleaner in the gas tank, sneak up the timing a scosch, and say 'your car's ready.'
How do I know this?
BTDT I resolved all my drivability issues by doing this, and mind you, I haven't done ALL of the connectors, but anything involving spark, and most importantly, micro-volatge of the L-jet system has been addressed. I love the way my E12 runs.
Best of luck.