Fuel pump/starting problem for the electricians and experts

[Javier]

diagnose it, specially if not an intermittent fault (about 1300 ohms between coil terminals in M50, both terminals open to third shield wire)

With a tester with frequency reading, you may be able to get a signal cranking the engine with the CPS unplugged to DME, CPS is a magnet inside a coil, when the steel tooth approaches it, the magnetic flux grows stronger and induces a voltage at coil terminals. Generally, also a small AC voltage reading will appear in the coil terminals when cranking.

Javier

[azale]

So 500,000 ohms sounds bad right? Would that kill spark and fuel injection?

btw- I received my Technical Information System CDs tonight from my eBay purchase. What a complete waste of money. Three CDs labeled 1, 2, & 3 with a permanent marker. So of course, I was shocked when they didn't work well.

Remember, you don't always get what you pay for, but you almost never get what you don't pay for.

[Bill R.]

on the e34's or any of the older cars... Its mainly for the newer cars Just out of curiosity where did you get your tis that it consisted of 3 disc's ?

So 500,000 ohms sounds bad right? Would that kill spark and fuel injection?

btw- I received my Technical Information System CDs tonight from my eBay purchase. What a complete waste of money. Three CDs labeled 1, 2, & 3 with a permanent marker. So of course, I was shocked when they didn't work well.

Remember, you don't always get what you pay for, but you almost never get what you don't pay for.

[Kalevera]

Excellent pictures.

Those are indeed candied coils. It's hard to say if it's the DME, but my money is on a fried final stage driver or 5; it could be fine given that it's flashing 1444 at the dash -- but I don't think that motronic 3.3 will report on the condition of the coils (therefore the final drivers). Before doing anything else, I'd check the position sensors, just to rule them out. I haven't seen this happen, but I've heard about it multiple times, both from people I work with and from the IAI crowd. #5 is the most common location for the problem. Some say it takes at least 3 worn coils to do it; others say a bad ground will cause it. Pull the DME and visually inspect pin #88 -- once a resistor is fried, the short can get it hot enough to melt plastic. Pop the cover and have a look at each of the 6 resistors/inspect and smell for damage. Find a known good DME and a set of new coils and swap 'em in/test.

But before doing any of that, be sure to do a few resistance and output tests on those sensors, inspect all grounds for bad wiring.

The starter solenoid piggybacks the starter -- from what I remember of the textbook stuff, the two most common types are mechanically intertwined. The starter turns the ring gear, which lives between a friction plate or a torque convertor, depending on the kind of transmission in the car, in the trans bellhousing.

EDIT: oh yeah, and TIS is a necessity. The latest (last) version was one CD, though -- it's now all online. Without buying a bound manual or a set of microfiches, it's the easiest and cheapest way to get basic repair info and TORQUE specs


best, whit

[Javier]

So 500,000 ohms sounds bad right? Would that kill spark and fuel injection?

Locate and unplug the Crankshaft position sensor connector (CPS) and test resistance straight from their pins, there will be 3 pins there, one for the grounded shield and two for the pick up coil. You should have about 1300 ohms between the two coil pins, and open circuit from the shield pin to the coil pin (any one of them), having very high resistance value means the coil is opened.

If OK and the reading at DME plug is still 500K, there should be some weirdness between the CPS plug and the DME plug.

See attached picture for CPS plug (X6203) location and connection pin out (note it's seen the female side of the connection).

Javier

[azale]

Apparently, I got the TIS from some software pirate on eBay. One disk was supposed to be te TIS for every BMW model from '88 to '98 or something like that and the other 2 CDs are the ETK for all the models. It's probably the 20th derivative copy from the original and is suffering from de-evolution. I emailed the seller for a refund or better disks.

Lowell: What is the final stage or the nebulous "#5"? Are those addresses on the DME, underneath the cover? I will check it out tonight if the CPS is working well. Now I'm wondering who told me the starter was up front.

I will get to the CPS connector tonight but that means I have to remove the manifold. Thanks for the pictures, especially of the connector but I think the location picture is inaccurate. The wire for my sensor disappears under the intake but the picture looks like it should be on the passenger side. That would be easier, but I don't think I'm that lucky.

I guess replacing the sensor means removing the engine fan and clutch?

I hope this solves the problem. I'll write tonight after I test the CPS and I'll order the part for a big victorious repair on Monday.

[Bill R.]

Apparently, I got the TIS from some software pirate on eBay. One disk was supposed to be te TIS for every BMW model from '88 to '98 or something like that and the other 2 CDs are the ETK for all the models. It's probably the 20th derivative copy from the original and is suffering from de-evolution. I emailed the seller for a refund or better disks.

Lowell: What is the final stage or the nebulous "#5"? Are those addresses on the DME, underneath the cover? I will check it out tonight if the CPS is working well. Now I'm wondering who told me the starter was up front.

I will get to the CPS connector tonight but that means I have to remove the manifold. Thanks for the pictures, especially of the connector but I think the location picture is inaccurate. The wire for my sensor disappears under the intake but the picture looks like it should be on the passenger side. That would be easier, but I don't think I'm that lucky.

I guess replacing the sensor means removing the engine fan and clutch?

I hope this solves the problem. I'll write tonight after I test the CPS and I'll order the part for a big victorious repair on Monday.

[Javier]

intake manifold for 1993 and not 1994!

Are you sure yours is a 94? Just enter the Vin (last 7 characters) in the on-line ETK and get production date. 1994 corresponds to 9/93 to 6/94 production for 525i.

Just curious.

Correction: Just found that M60 and M50 name the connector the same, so the posted picture is for M60 instead of M50. Guess you'll be having a good time working this sensor issue.

Javier

[azale]

Originally posted by Javier
Guess you'll be having a good time working this sensor issue.

Been there done that.

I just removed the plugs for all the coils, bolts keeping the manifold on the block, bracket bolts underneath the manifold (at great cost to my sanity), vacuum hoses, air tubes for the throttle body, and for the alternator, and then I lifted that cursed intake manifold. I followed the sensor wiring into the heart of the beast and wiggled one hand in there to pull the connector from its bracket. But I had to get two pairs of pliers to separate the plug.

Then I tested contacts 1 and 2 to find 700,000 ohms of resistance. When I turned the engine over it did nothing . . . not even a hint of movement.

I will order my new sensor tomorrow and it will probably arrive on Monday or Tuesday.

Do I need to buy new gaskets for the intake manifold? The old ones look to be in very good shape.

I will get the VIN number to check on the correct year.

Do I need to coils or can I wait a paycheck or two?

This weekend I will be on Mackinaw Island soaking up some horse manure odor. I'll let you know if the sensor fixes the problem.

[Kalevera]

Mackinaw! Been a few years since I holed up in the Grand Hotel. Like the bridge, though. Surely you've heard the story about the Yugo flying over the edge.

Since you have the intake off, replace the gaskets. I'm relatively certain that the connector could've been reached by just removing the intake. Install the sensor, confirm that the engine is operating again, then replace the coil packs.

#5 refers to the fifth cylinder. Direct fire ignition is a different case than the single coil found on earlier cars (or two coils on the V12s). It would most likely appear as a misfire on your car.

best, whit