Baffled Again with Driveability Problems

BradInTexas · Post by **BradInTexas** » Thu Aug 20, 2009 9:19 am

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...

grumpsjr · Post by **grumpsjr** » Thu Aug 20, 2009 9:23 am

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.mclemore@att.net (b.mclemore@att.net)> 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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T.Hanson · Post by **T.Hanson** » Thu Aug 20, 2009 1:26 pm

I didn't see that you've checked the combo relay. See FAQ.

I'm hardly an ace trouble shooter, but when I pulled the wiring harness during my rebuild I got enlightened. Darned if the big long complicated harness isn't two distinct pieces, that use the combo relay to be one.

Becoming rather obvious, if the relay circuits in the little box get crunchy a whole lot of goofy things might happen down the line.

And just to be a stubborn geezer, unless you find an ace tuner old enough to have known M30's inside out, or the art of trouble shooting the old way, what makes you think a modern computer, plug in diagnostics, parts swapper technician will be able to fix your jalopy any better than you can ?

If it's not your only ride, never give up.

Ha !

BradInTexas · Post by **BradInTexas** » Thu Aug 20, 2009 2:15 pm

I was thinking I had swapped the combo relay, but it was with another old one. I've had one burn up before, and come to think of it, the symptoms would fit the "on/off" nature of the problem. I do know a brilliant BMW guy but at $85/hour I'd rather fix it myself. As an engineer by trade, it just bugs me when I can't get to the bottom of something.

grumpsjr · Post by **grumpsjr** » Thu Aug 20, 2009 2:22 pm

In my case, I did replace with a known good combo relay to no effect, and given that I'm an accountant by trade and do have access to an E12/M30 specialist, the $85/hour is rapidly becoming worth it.

Brian

On Thu, Aug 20, 2009 at 12:15 PM, BradInTexas <b.mclemore@att.net (b.mclemore@att.net)> wrote:

I was thinking I had swapped the combo relay, but it was with another old one. I've had one burn up before, and come to think of it, the symptoms would fit the "on/off" nature of the problem. I do know a brilliant BMW guy but at $85/hour I'd rather fix it myself. As an engineer by trade, it just bugs me when I can't get to the bottom of something.

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Lenny D. · Post by **Lenny D.** » Thu Aug 20, 2009 2:35 pm

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.

grumpsjr · Post by **grumpsjr** » Thu Aug 20, 2009 2:50 pm

Lenny,

I appreciate your insight, and you've definitely made some good suggestions, which, believe it or not, I've followed, checking and inspecting wiring and connectors and replacing more than a few. I don't want to discourage you from continuing to give good advice, but I wonder if it would be out of line to tone down the sarcasm just a bit?

I think your point is perfectly well-taken otherwise. If you're frustrated with us (whoever that might be) for not picking up on your suggestions in the past, I apologize. It has not been my intent to frustrate you, nor to misinterpret your post - it just began to read like a bit of a dressing-down.

I'm glad you've got your E12 sorted - enjoy the drive!
Brian

On Thu, Aug 20, 2009 at 12:35 PM, Lenny D <bass51@cox.net (bass51@cox.net)> wrote:

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 wrote:
Quote: 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.

HTH

'80 528i

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T.Hanson · Post by **T.Hanson** » Fri Aug 21, 2009 1:35 am

I loved it. Envisioning the quiet wisdom from experience, getting fed up with the whippersnappers, or acro-dumb butts. ( Whether true or not.)

BTDT : Been there done that. Phew, almost had to peel potatoes.

I like the bold words. Wow ! O.K., I'm loaded for a connector surge. And the sage observation fooling around with thirty year old jalopies is so far past nuts, there's only six of us left.

Until somebody with $ 14,000 makes seven.

YouTube · Post by **Peter Florance** » Fri Aug 21, 2009 6:21 am

I made a tool out of #12 solid wire with 1/4" male tab on one end and .110" on the other and used it to test every combo relay, ignition module and engine harness to fusebox contact

Many were loose, but not detectable until tested one at a time.

BradInTexas · Post by **BradInTexas** » Fri Aug 21, 2009 8:57 am

Years ago, on my old harness, when the combo relay burned up (and took the wire ends with it), I did just as suggested and made new, soldered ends. When I swapped engines, I just took the harness that was with the new engine. I think all the other bits (relays, coil, AFM, computer) are the ones that were on the car when it was running great (before it ran out of oil on my son-- a different story). So the harness is the last un-swapped bit. I am under a bit of time pressure, as I'd like to get it to my other son who is in college in Abilene tomorrow. It is either this one or the '87 528e (that needs a valve job and I am loathe to put another penny in it). So I'll swap the harness and see.

One last question: should the ballast resistor be hot to the touch after running? I'd expect it to be warm but not hot.

One last comment: I appreciate all the responses and inputs, but I'd rather not see this board go the way of mye28.com. I am too old for "WTF's", veiled (or blatant) condescension, etc. I have been at this a long time (I have four 5-series in the driveway now) and I learn something new from almost every tech forum post, whether from novice or expert. 'Nuff said.

Thanks again. Brad
"

Milan · Post by **Milan** » Fri Aug 21, 2009 9:13 pm

Lenny, i'm with hanson, i loved it. i could say more but why.

under the radar · Post by **under the radar** » Sat Aug 22, 2009 6:41 am

brad, i've got the same troubles as you on my '79...runs great...for a while, then runs like crap. i too have a "burn your fingers" hot ballast resistor. is that normal?

Brian Smith · Post by **Brian Smith** » Sat Aug 22, 2009 10:40 am

BradInTexas 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. (snipped) If anyone has any other ideas...

Brad,

I'm not sure what this conclusion would mean, and certainly not being a smartalec, but the above history would suggest to me that the car might be "eating" distributors. If a new alternator, for example, worked great when installed and then a day later it was ruined by a faulty external voltage regulator, changing the wiring to it wouldn't fix the problem long-term. Nor would another alternator. Since a replacement distributor apparently solved the problem, is there a way you can test that distributor now, after it has been used in your car? Sometimes testing a part against benchmarks is more fruitful than trying a replacement just to see if improvement happens, there's a lot that can be wrong.

BradInTexas · Post by **BradInTexas** » Sun Aug 23, 2009 2:26 pm

Swapped the front half of the wiring harness (ignition side) and put in a new combo relay but no joy. Found out the ballast resistor can easily get hot (it is a resistor after all) so probably not the problem. I have a buddy with a Sun engine analyzer that I am going to try Monday. I won't be surprised if it is something simple-- it usually is.

Brian: you might be on to something re the distributor. I marked the distributor to make sure it wasn't moving. I know that is unlikely, but that's how it drives, like the timing is set wrong, then I reset everything and it runs well (once), I park it and it is back to square one, that could easily be due to it being warmed up by the time I have finished re-timing. Needless to say, I didn't drive it to Abilene this weekend.

Lord willin' we'll see the end of this thread due to the mighty Sun analyzer!

YouTube · Post by **Peter Florance** » Sun Aug 23, 2009 5:54 pm

Sticky distributor advance mech?

Firstfives.org