General Rough Running & No Power

[Motorhole]

Okay, so I”˜ve broken something on my car.

Fitted the Condor Speed Shop engine & gearbox mounts yesterday. Obviously jacked the engine up 2 inches or so to remove old mounts and put new ones in. Since I”˜ve put everything back together, the car”˜s been running like a sack of shite.

Sounds okay at idle, but sounds strained when revved. No power, flat as a fart at any rpm. Sounds awful from inside the car.

Noticed when I came back from my test drive that the engine control module relay had been popped out the loom where the fuel rail cover had put some pressure on the loom against the bulkhead. Popped this back in, no difference - must”˜ve still been a connection though because from what I gather from wiring diagram, engine shouldn”˜t run at all with this removed? Been over the car today, checked everything - vacuum leaks, connections, fuses, relays, engine earths - all looks good so I”˜m at a loss for what I”˜ve done. Any help or suggestions regarding where to look would be great!



Edit: forgot to say, engine”˜s a 1996 M52B28

[Motorhole]

Also, what are people using to read codes on their M52s? I”˜ve got a bluetooth dongle and torque on my Android phone and that”˜s worked great on lots of cars. But on my BMW (with a round OBDII - standard OBDII adapter), it can”˜t read the ECU.

[Brianmoooore]

I use BMW's DIS diagnostic program, but to run with the early non full OBDII stuff, it needs an ADS interface between the 20 pin round diagnostic socket and my laptop.

[Motorhole]

Thanks Brian. That seems well priced and will probably do the job - what”˜s an ADS interface and what does it do?

Any ideas on my running probs? I suspect it”˜s missing as it just feels crap, lethargic and generally out of balance. I hope I”˜ve not cocked up engine/box alignment - but I guess if that were the case, I”˜d also feel it through clutch/gearbox? As it stands, with the new mounts, gearchange has never felt so good!

How would I go about finding which cylinder it”˜s missing on, if that”˜s the case?

[Brianmoooore]

what”˜s an ADS interface and what does it do?

That's the sort of question Google was invented for!

Your symptoms sound a bit like camshaft sensor failure, which is common, but I can't see any obvious connection with changing the engine mounts.
These are sophisticated engine management systems by E30 standards, and diagnostic code reading equipment really is needed to work on them.

[Motorhole]

Thanks again. Yeah, I gathered - reading codes would make it much easier for me to find somewhere to start. You”˜re right - it”˜s most likely something that”˜s happened as a result of moving the engine around to fit the mounts, although as I”˜d not driven it for around a week beforehand it is a remote possibility it was there before. However I replaced the camshaft sensor when I completed the build around Sept. last year so would be surprised if that needed doing again.

Given the lack of time I have between now and my trackday on 24th May, I might just have to get lubed up, bend over and get a reputable garage to sort it.

[Motorhole]

Now with sound. First bit outside the car - sounds harsh and reluctant to rev but not too untoward. Second bit inside car where it sounds a lot worse. That 'thrumming' is engine related too. As I said, no power at any rpm, compared to previously: silky smooth, free revving and responsive.



Trying to source some diagnostic kit, but I don't even own a laptop - gone all tablet tech. It might take a while to sort out...

[Brianmoooore]

You ideally need a laptop with a serial port. I have a Dell D630 especially for the job, bought for peanuts off of ebay.

[DanThe]

Is it possible you damaged the loom when jacking the engine up? It is all very close back there!

[Motorhole]

Is it possible you damaged the loom when jacking the engine up? It is all very close back there!

I think that”˜s the most likely explanation, although I can”˜t figure out what. Continuity checks confirm that DME relay deffo has power at both red terminals and is connected to all injectors & ICV. All injector grounds run back to the ECU - Pins 5 & 6. Fuel pump relay checks out equally well and I”˜ve swapped the relays out for different ones with no result, so I don”˜t know what is back there to get broken...

I did remove the throttle body and noticed that there was a lot of fuel sitting in the inlet manifold - don”˜t know whether or not it was there before though. I”˜ve also managed to confirm it”˜s definitely NOT misfiring - at idle anyway - by pulling coils one at a time.

Is it really possible that I could”˜ve dicked up engine/gearbox alignment somehow? In such a way that I couldn”˜t feel it through the shifter and whatnot? Because gear change etc are all perfect (on the move) and it still starts on the button.

Idle doesn”˜t change if MAF unplugged. Coughs and splutters when you try and rev it with the MAF unplugged, but goes back to normal when it”˜s plugged back in. I believe this is normal expected behaviour?

Otherwise I”˜m out of ideas until I can get some diagnostics on it.

Edit: Just a thought - does the ECU case have to be grounded?

[Brianmoooore]

Edit: Just a thought - does the ECU case have to be grounded?

Unfortunately, no.

[Motorhole]

Finally source myself some diagnostics kit.

So progress since: I”˜ve completely taken apart and removed the intake manifold, hoses etc, checked everything and re-assembled with miticulous care. Checked for continuity between all sensors and their respective ECU pins to make sure I”˜ve not damaged the loom - and I”˜ve found no issues. Fired it up and problem was still there.

Plugged in code reader and initially, I got:
Exhaust flap error (normal I gather?)
Fuel tank ventilation valve (normal as I”˜ve done a CCV delete?)
EWS Error (can”˜t remember the exact error)
TPS
MAF

I cleared all the errors and ran the car up again. Only the exhaust flap and fuel tank vent valve errors re-appeared.

Ignition timing was 7 degrees kw cold and as the engine ran for a bit, it slowly moved to around 13 degrees kw. I don”˜t know whether this is normal or not. However intake temp. was reading at 68 degrees, which I did think was high given the engine had been started cold and only ran for 5 minutes or so!

Idle isn”˜t fine actually. It”˜s not terrible, but there”˜s quite a lot of vibration and an occasional ”˜bumble”˜ from the exhaust, like a mini backfire.

Not sure where to go from here now though.

[Motorhole]

Wasted more time again this morning.

Tested the TPS. Resistance looked good and changed smoothly with throttle movement as expected.

Pulled all the plugs. They looked clean and normal. No deposits, no powder, no soot.

To be doubly sure of no intake leaks, I bought some carb cleaner and went over the lot as the car idled. No change in rpm. Also checked throttle body/manifold seal and manifold/head seal the same way and all fuel injector ports.

One thing I have noticed is since I put everything back together, I can no longer hear the fuel pump prime? It did it yesterday, when I started the car the first few times. But today, the car started fine - no abnormal behaviour apart from the subject matter - but couldn't hear the fuel pump prime.

Once more, out of ideas short of either dropping at a BMW specialist to deal with (expensive) or ripping out engine and box and starting again (really don't want to do this for obvious reasons). Unless anybody has any further constructive suggestions?

[rich318i]

try the taking off the oil cap off while its running and see if the engine note changes. If the engine note stays the same might be a leak at that side of it..

Rocker cover gasket or cracked rocker cover

Ive seen one that had a MAF fault code and it was the rocker cover gasket

[Motorhole]

Some progress potentially. Spent some more time today. Noticed when plotting cam sensor response, the amplitude and width of the spikes wasn't consistent. Tried running the engine with cam sensor unplugged. Injectors went into batch mode as expected but engine ran a hell of a lot better. So either the sensor is faulty or my squeezing the loom has damaged the shielding for the cam sensor wiring. Feel better now its been narrowed down, but might be a little while before I can fix it

Edit: good call Brianmooore!

[Motorhole]

So this saga is ongoing. It's a shame I can't work on my car every day, it's a week between spannering sessions at best. Anyway...replaced the camshaft sensor with a new OEM sensor. Didn't fix the prob. Pulled loom and insulation apart - no visible damage to any of the sheathing. Put everything back together. Camshaft sensor looks good on the diagnostics now - consistent peaks and whatnot. But I got an intermittent crankshaft sensor error. It came back when I cleared it twice, then it went away and never came back.

Running the car with the cam sensor unplugged now seems to make no difference to the way the car idles and revs, except that the injectors make a crapload of noise (expected).

Going to replace the crank sensor on the basis of the intermittent error. Failing that, I don't think I've got any choice other than to try a new loom.

Any further suggestions welcome

[heathy325]

I had similar issues with mine and ended up being the crank sensor so my money's on that

[Motorhole]

New OEM crank sensor, still not fixed. No longer getting the intermittant crank sensor error on diagnostic but camshaft sensor error has come back? Wtf?

Checked AGAIN for continuity between sensors and appropriate ECU pins, AGAIN no problems. Again, wtf?

My next move is to just take the damn wiring harness out the car completely, bring it home and spend an afternoon - whenever the hell I can find one - to go through it wire by wire, end to end.

Loosing my rag with this now. F*cking engine mounts should”˜ve been a simple 1 hour job, I”˜ve done it before. It”˜s summer, I should be out driving the thing but it”˜s stuck in a garage, wasting away tax and insurance while I can”˜t figure out what”˜s wrong. I don”˜t have much in the way of free time and there”˜s nothing fun about spending it doing this

[Motorhole]

Well I found the source of the intermittent crank sensor error. On inspection of the old sensor, the insulation around each of the 3 wires as they go into the connector was stripped and they could easily touch. Got the loom out the car now, so going to go through it with a fine toothed comb tomorrow night. Just one question - what's the easiest way to extract pins on these connectors?

[DanThe]

Unless the loom is obviously damaged I wouldnt waste your time pulling it apart

The pins can be a bitch to remove and its a job for special tools really

What brand sensors did you fit?

[Motorhole]

Yeah, I was beginning to think as much. At least it will be easier for me to check continuity for everything with it out of the car. I was hoping to be able to replace the shielded crank and cam sensor looms with ones from another loom just to be sure but I can't see any signs of damage on the casings so if it's that much of a ballache it's probably not worth it.

Both OEM sensors were from BMW.

This was the state of the connector on the old crank sensor:

[Motorhole]

Right so went through the loom tonight. Checked every strand of wire for damage and checked inside the boot of every connector for dodgy connections/missing insulation etc. Checked every single circuit link for continuity - ECU pins to sensors, DME relay to power injectors, ECU pins to ground etc etc. Marked everything off as I went. Found nothing of note so I”˜m 100% happy the loom is not damaged.

I think given what I found with the old crank sensor - if I can resolve the intermittent cam sensor error that has raised its head again, I might get somewhere. Only other thing - and imho its highly unlikely - but it”˜s not possible that the crank sensor shorting could damage the ECU?