timing way to advanced

[mike367]

Hi, I have an 84 533i that I have been trying to get running properly to no avail. It has a miss while running, I have replaced and checked and rechecked items with no luck. I just found that the timing is running at 46 degrees at idle. I have found a receipt from the previous owner for replacing the reference sensor but not the speed sensor. I beleive they were both replaced because they are not the correct length (meaning they are to short to reach up to the mounting location between the intake and valve cover), could these sensors being incorrect cause the engine to still run, but run at an advanced timing.
I am starting to get frustrated, any input would be appreciated.
I just noticed that the receipt for the reference sensor is for a used sensor for a 1987 528e, would that sensor be compatible or is a completely different application?
Mike

[pldlnr]

The reference/speed sensors are not the issue. The 528e sensor will work just fine. It is highly unlikely that it is off by that much at idle. The timing on this car is controlled by the ECU and it is not adjustable.

How did you measure the timing advance?

[mike367]

The timing was measured with a timing light at the crank pulley.
A little background on the problem. The car failed smog (running rich) so the smog place will diagnose the problem for you. The guy doing the diagnosis is a BMW enthusiast, he checked for vacuum leaks, none found, checked O2 sensor operation, working properly, checked plug wires and plugs, all good. When he checked timing it is showing 46 degrees at idle and never changes. The car runs very rough at idle and at around 2200 RPM in cruise. We ran out of time and scheduled another appointment for Tues morning. I am just trying to come up with some more things to check to help with the diagnosis.
I am glad to know that the sensor from a 528e would not be the problem, I am starting to run out of ideas.
Mike

[pldlnr]

If it had vacuum leaks, it would most likely result in a lean running condition.

For a place to start, try the coolant temperature sensor. Test it for resistance per the Bentley manual. The CTS can result in a rich mixture when it fails. You can also check the wiring leading up to the CTS for a BMW installed resistor. The wiring at the resistor can fail and cause issues.

The CTS and resistor issue has been discussed a lot. Search will reveal more information.

[Jeremy]

AFAIK, the Motronic equipped M30s don't have timing marks on the front of the block. There is a TDC mark on the crank hub, but no reference markings on the block to line it up with when using a timing light.

Given this, wow in the world did he conclude A) that timing was 46 degrees advanced at idle and B) that it wasn't changing with revs.

Just because he had a timing light doesn't mean he could get the information he claims to have. Course, I could be totally wrong and the m30b32 might have timing reference marks, but I don't think I am. Even on the e12 m30 motors with distributors, the only timing mark is for 22 deg of timing advance, there is no other timing mark available. And that mark is on the flywheel, not on the crank hub.

[mooseheadm5]

Honest question: are you sure you are measuring the timing properly? It should not actually be possible for it to be that advanced.

Edit:
Jeremy,
Some timing lights have a dial that allows you to measure the advance- it changes the pulse timing until the TDC mark lines up again, then you just read the degrees of advance off the light.

[Kyle in NO]

No way the timing is 46 degrees advanced at idle. The engine could not run. Someone does not know how to check the timing on your engine.

Other ideas are a bad Distributor Cap or Rotor, bad Fuel Pressure Regulator, bad AFM, and its also possible for the timing chain to be timed incorrectly if someone has recently been messing around with things. Doesn't sound like this "BMW Enthusiast" knows what he is doing.

[Jeremy]

No way the timing is 46 degrees advanced at idle. The engine could not run.
...
Doesn't sound like this "BMW Enthusiast" knows what he is doing.

That's what I was trying to say. The m30 seems to like around 14 degrees advance at idle. I doubt it would even start if it was really 46 degrees btdc.

[Karl Grau]

46°???
Trying to hold a timing light and crack pipe at the same time is never a good idea. The Greeks knew it. The Carthaginians knew it. Now YOU know it.

Check here for some info on the aforementioned idle resistor and some other stuff: http://www.mye28.com/viewtopic.php?p=59 ... ht=#599662

[mike367]

Thanks for the suggestions, i got the Bentley manual out and did some more testing.
1. thermotime switch is working as advertised, it turns the test light on at the the cold start valve for approx 3 seconds at startup.
2. pinching the cold start valve fuel line has no effect when running so I don't think it is leaking fuel.
3. Coolant temp sensor wiring DID have the 270 OHM resistor soldered in line, I removed the resistor.
4. Coolant temp sensor resistance is right on the money at the specified temps.
5. idle air stabilizer valve is humming when key is turned to run. also removed valve and cleaned. resistance is 9 ohms (2 wire valve)
6. throttle position switch is new and adjusted per Bentley manual.
Even removing the resistor had no effect on the way the engine runs.
I am open to any suggestions for what to try next.
Mike

[AllenC]

Also-
Bentley's fuel injection section contains a table of electrical values measured at the ECU and Idle Control Module.connectors.

Your CTS may be good but its resistance value may not be read/seen by the ECU.

Double check the CTS connector wiring continuity to the ECU. Especially since you mentioned there was no change when you remove the resistor (if I recall, this would make your mixture leaner)

Good luck.

[Kyle in NO]

Check your cam timing. Sounds like it may have jumped or been set wrong. That could account for the false 46 degree reading your "tech" was seeing.

[Jeremy]

I have replaced and checked and rechecked items with no luck.

Before we start getting wild and crazy ... what, exactly, was replaced? Cap/rotor? Spark plugs? O2 sensor? Coil? AFM? Have there been any major changes to the engine recently (headwork, etc)? Did the problem start after any particular event?

Also: can you describe the "bad running" more completely? It it only under load? Is it a rhythmic kind of stumble? What, exactly, is it doing?

[mike367]

I will try to give a little history. I bought the car about a month ago. The only knowledge I have of the car is what I have in receipts. It appears this problem has persisted for at least 2 years now. Here is a list of parts that I know have been replaced either because I have receipts for them or they look new.
new cap and rotor
new plug wires and plugs
coolant temp sensor
thermotime (pn 13621274630)
timing chain and tensioner
2 throttle position switches
2 oxygen sensors (single wire)
water pump
in tank and external fuel pumps
fuel filter
engine fan
new clutch kit
fuel injector cleaning and flow testing
2 different ECU's
idle control module
new intake boot (afm to throttle body)
new air flow meter
new idle air stabilization valve
used speed and reference sensors (from an 87 528e)
new air filter box
I can't say if the flywheel has been replaced or not.
The head was rebuilt and I have not pulled the valve cover yet to check cam timing, nor have I done a leak down test.
I have replaced all of the old fuses with new ones and cleaned up the grounds. I removed the 270 ohm resistor in the Coolant temp wiring. I have checked the wiring to the ECU using the Bentley manual, all wiring seems to be correct and in good shape.
The engine always starts and runs, never feels like it is going to die, just idles very rough with a noticeable miss. You can really detect the miss listening at the exhaust pipe.It idles at about 1000 rpm and bounces around a little.It seems to rev pretty well and feels fairly smooth as it revs. Cruising along at 2200 rpm it stutters and stumbles, above or below 2200 it is not as noticeable. The temp gauge stays below the 1/2 mark.
I am open to any suggestions.
Mike

[Kyle in NO]

Definitely cam timing. Its probably been running like shit since someone reinstalled the head and didn't install the timing chain correctly. Its probably only a tooth or so off, easy fix.

[mike367]

Good call on cam timing, removed valve cover and it looks like the timing chain is advanced 1 tooth.
Now I need to find some time to correct this. With all of the parts that have been replaced to fix this I think when it is timed properly it should run like a new engine.
Mike

[mike367]

Since I now have to adjust cam timing, I have never done a timing chain on a BMW engine, I would like to hear any tips or tricks that might make this job easier and quicker.
Mike

[ahab]

It's not really too hard. I find removing the upper timing cover without destroying the head gasket to be the hardest part. You should get a timing cover gasket kit ahead of time. $14 from Pelican (plus shipping). Assuming you've gotten the cap and rotor business out of the way, I'd also remove the fan and shroud, then unscrew the chain tensioner first, use a rag to catch the oil. Turn the motor to TDC on the harmonic balancer and take a look at the cam gear. The 4 bolt heads should form a cross THROUGH the vertical plane of the motor. In other words, the cross should be at a lean like the motor. The locating pin should be in the 8pm position. There's a pic in the Bentley. If you think the timing is off, this cross should be biased one way or the other. Undo the 4 10mm bolts, DON'T DROP THEM, and pull the gear off. Hump the chain up over the teeth until you gain a tooth, the rotate the crank or the cam in the desired direction until you can get the gear back on the locating dowel. Bolt her back together.

Hope I haven't forgot anything but that's how I'd do it in my head.

[Area 52]

Are you certain of correct placement of plug wires into the distributor cap?...if the timing light is on plug wire #1 but wire #1 was inadvertantly placed into the wrong cap connection then this may explain the excess advanced timing reading and quite crappy idle.