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603racing · Bigcoupe supporter

We were racing the Dark Shark at Gateway Motorsports Park yesterday. The Shark was awesome on track. We started getting a lot of smoke (most likely blow by) when we made one short left hander. The turn is a fairly tight 180 degree turn at about 3,500 rpm in third gear (3.73 diff). The turn takes about 5 seconds to complete, then upon exit we would get a huge cloud of smoke out the exhaust. It is possible that we overfilled the oil, but that's not really the issue I'm concerned about. Later in the day we started to feel down on power a bit. We checked the plug wires, they were good, we changed the plugs, let the car cool off, still down on power and a definite miss at idle and mid range.

Spark plugs were a bit white (lean condition) and had a bit of oil on them which was expected with the blow by we experienced.

We are planning on checking both position sensors on the fly wheel as well as doing a compression test. The motor does not knock, there is no noise from the head. Anyone with ideas, feel free to shout them out. I will provide updates after we get a chance to check sensors and compression.

Also, we are planning on trying to find an oil pan baffle to keep the oil down in the pan.

Brucey · 6 Series Guru

slant block M30 gives oil starvation/oil surge on left handers; this is well known.

Starvation will be seen on a pressure gauge, but surge will throw oil up the bores, and the results thrashing around allows oil past the oil control ring. It also creates not so much a 'mist' as more a 'deluge' in the crank-case breather system. Both can make smoke.

BTW hard use with stock plugs can lead to a pale-coloured plug too, so don't assume lean running until you have tried one or two grades cooler plug. Also some oils burn to a pale ash and that can fool you too.

If it is lean and missing at part throttle then an air leak or other fuelling error has to be suspected. Might be worth installing a lambda gauge to keep an eye on it.

cheers

603racing · Bigcoupe supporter

We've been chasing a rough idle for a year. It smells rich at idle, but it idles rough so it might not be burning the fuel properly. We were going to try adjusting the air flapper in the meter, but now we have to diagnose this engine problem first. The rough idle could be a vacuum leak. The ran perfect at or near full throttle which is why we suspected the meter. It's a Euro, so no O2 sensor to worry about.

Previously we had tested the crank(flywheel) sensors, new coil, entire fuel system including new fuel pumps and filters and FPR and fuel line, relays, swapped computers, new spark plugs, new plug wires, noid light test on the injectors, fuel pressure. All tested great. We still had vacuum leak and airflow meter on our list but it was not a top priority since the car ran so well at wide open throttle.

Anyway, thanks for the tip. We know about the slant 6 oil starvation, which is why I have the other post looking for a pan baffle. We'll check for vacuum leaks. Are there common leak locations on the m30?

Brucey · 6 Series Guru

603racing · Bigcoupe supporter

Very good point, I sometimes don't think in Barische (sp?). I often fall back to my american muslce car knowledge which sometimes doesn't work... as in this case. I completely disregarded the cam/distributor seal, and a few others. We've had the valve cover off a few times. We did have an oil leak at one point at the cam seal.

Thanks for the additional information.

603racing · Bigcoupe supporter

I have some additional information after doing some diagnostic work on the car.

Compression numbers from cyl. 1 to 6:
150
140
140
130
140
135

Two of the numerous vacuum lines had cracks in them. The two lines with cracks were connected to the intake and cold injections system. I will be purchasing new ones. Also, one of the wires to one of the thermostat housing sensors was broken. It goes to the sensor that is to the far driver side of the housing. Why the heck does it have three sensors? Think

Also, a couple of the fuel injector connectors on the harness were cracked/broken. Tested ok, but still not good.

Anyone know if that broken wire on the thermostat would cause symptoms like a miss at idle and the car being way down on power at WOT?

Chris Wright · Senior Member

I'd do a leak-down test to see where the cylinders are leaking.
__

Here is another take on the vacuum leak list - Vacuum leaks, line routing and hose size:
http://bigcoupe.com/phpBB2/viewtopic.php?p=107414#107414
____________

The three sensors, from the driver's side to the engine side, are: The Temp Gauge Sender (in the dash), the Thermo-Time Switch, and the Coolant Temp Sensor (CTS). The CTS goes to the ECU and is the most important. The engine can run like it is possessed if this sensor or its plug are bad, but it sounds like it is the Gauge sender that has the broken wire? It just has spade connections right?

CTS and Injector Replacement Plugs, Pigtail (with Photos):
http://bigcoupe.com/phpBB2/viewtopic.php?p=116442#116442

CTS Test Values:
Coolant
Temp .......... Ohms
14ºF = ... 8200 - 10500
68ºF = ... 2200 - 2700
176ºF = ... 300 - 360
_____

GripGreg · Bigcoupe supporter

Chris, would my stock '82 Euro be a slant block? How can I tell?
I'd rather not mess with anything, but,,,,,.

Brucey · 6 Series Guru

you can tell by the fact that the block is, er, slanted. All M30s in E24s are....

cheers

603racing · Bigcoupe supporter

I am in process of refreshing the fuel unjectors since we had them out of the car. Putting new seals and screens in them, they are soaking in fuel injector cleaner as we speak. After a good 24 hours of soaking I will blow them out with air them spray them with cleaner and blow them out again. This process worked very well with some junky old 17# injectors I put in my e30. Side question, are all yellow top early e24 injectors the same pressure?

Six new injector harness connectors have been ordered, the original ones are cracked and easily broken.

Also ordered a couple of the larger vacuum lines that run off the valve cover/intake. They were very hard and starting to crack. One broke into several pieces as I pulled it off the valve cover.

Hopefully these repairs will resolve our issue. We are still planning on doing a leakdown test, just haven't been able to source the equipment yet.

Brucey · 6 Series Guru

re injectors; the same bosch part number was used at different pressures in different 6ers. Obviously the flowrate varies with pressure used.

cheers

603racing · Bigcoupe supporter

I'm running a 3.0 bar FPR on my motor. I'm just wondering if could use slightly larger injectors to get a bit more fuel to the cylinders. Information regarding early Euro motors gets a little cloudy when I start looking for specific parts. I have the 011 ecu and stock b34 10:1 compression motor.

603racing · Bigcoupe supporter

Finally got back to the car last night. Replaced the fuel injectors with some higher flow ones out of an old 944. They seemed to work fine at idle and while running up the RPM's in neutral.

We cleaned out the fuel screens on the fuel cell, replaced the main fuel filter, and replaced the nest of vacuum lines under the intake/airbox. The old vacuum lines were very dry and cracked. We also replaced all of the fuel injector harness connectors, including the idle controller and cold start injector connectors.

All this work seems to have fixed our problem. It started and idled well, revved well, seemed fine.

Now that it's running well we can tell the idle controller is bad.

16 days until the next double 7 enduro at Gateway Motorsports Park!

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