M30'd Cab. With these symptoms, where would you be looking?

[MJJ_ZX6RR]

Afternoon all,

I am going to take my car off the road for a few weeks over the winter to try and fix the last of the hard to resolve issues. I am looking to build up a list of things worth checking as this one has stumped me for more than a year now.

I am not even sure if the underlying error is fundamental mechanical, electronics or even related to the engine transplant. Any input, suggestions or pearls of wisdom much appreciated.

The car
- 1988 E30 3-series, with an E32 M30B35 engine, autobox and both ECUs transplanted in - transplant done, but not finished by previous owner, I bought it as an unfinished project.
- I have owned the car for 18 months, and have done 3 or 4k happy miles in it. Outside of the symptoms described below, it drives well.
- Donor car's age unknown, mileage believed to be ~100k. Engine has EML fly-by-wire throttle, so I think this means the donor car had traction control fitted.
- Donor car fitted with lambda sensor in exhaust, lambda sensor unplugged and thus running default fuel map. Lambda plugged in makes no difference.
- Car still has E30 dash, not E32, so no EML warning lights nor the 2 line dot matrix warning screen
- Car fitted with BTB 6-branch and system.
- No E32 ABS/traction control sensors or switches transferred over.
- Engine has a nasty K&N cone air filter still as I have not managed to fit the E32 airbox in yet.
- Distributor only has a few mm clearance to the radiator.

The symptoms
- Car has a significant top end power deficit. The engine is very responsive and torquey up to 3k rpm, then rapidy runs out of puff. It will pull round to the redline, but it takes forever. I have an unmolested E32 735i to compare with, and I would say the E30 is slightly down on power everywhere compared to the E32, but over 3k rpm, there is a vast gulf of difference. Un-scientific 0-60 test in autobox sport mode is around 12 seconds, same unscientific test in the E32 is about 9 seconds.
- The car will misfire and stall when very hot, i.e. sitting in traffic for 15 minutes levels of hot. Coolant temp stays in the middle of the gauge, but once the engine bay gets very warm, the car will misfire/stall and prove very difficult to restart. Open the bonnet, wait 10 minutes and all is fine again.

What I have done so far, all unsuccesful
- Full inspection II, including new radiator, thermostat, HT leads, plugs, set valve clearances etc , etc.
- Confirmed that the electronic throttle potentiometer opens fully.
- Measured compression, all 6 within specification but #4 is lower than the others and at the bottom end of acceptable spec.
- Tried connecting Carsoft and Peake code readers, neither will talk to the car. The pin 14/19 trick does reset the service intervals, so I know that at least some of the diagnostics plug is connected.


I am at a loss now. A big part of me thinks it is related to the transplant, and that the car is in some sort of limphome mode. As the car has the E30 dash, not E32, the car has no way of telling me. As above, CarSoft/Peake do not talk to the car.

A small part of me thinks/hopes it is fundamentally mechanical, perhaps the dizzy is failing and being 3mm from the radiator does not help.

So, what sort of things would you guys be checking or replacing?

Thanks all,

Martin.

[gareth]

i'm not familiar with the fly-by-wire management, mine is operated with string

the non starting when hot may be the ecu temp sender (blue one on the thermostat housing) causing it to run rich. has that been checked / changed?

poor performance at higher revs could be a fuel pump or blocked fuel filter. have you checked these?

could you swap in an earlier loom, ecu and TB? or is that a little drastic?

[winx]

mine had problems when hot, would sometimes miss and then would just die and would need to be left for 10 mins to cool down before it would start again.
Finally found out that the coil was getting hot. Replaced it and it behaved perfectly...

[gareth]

that's interesting. my coil is on the clutch fluid reservoir bracket and doesn't suffer that problem. i should think it gets pretty hot there

[MJJ_ZX6RR]

Thanks guys, looks like I need to add at least coil and fuel filter to the list of things to replace. They are consumable items anyway, so makes a bit of sense. I think I will check the dizzy and rotor too, and probably replace them for good measure.

@Gareth, I am being a little stubborn on the fly-by-wire issue. The sensible option I am sure is to replace it with a cable throttle, but I really want to keep it. Partly because it then means the cruise control works, but mainly because I like the idea of having fly-by-wire. I shall soldier on for a while longer.

Martin.

[leeparkes]

Engine has a nasty K&N cone air filter

Id be getting rid of this first, is it shielded from the heat off the manifold?

If it helps M20 coils are the same as M30

[winx]

that's interesting. my coil is on the clutch fluid reservoir bracket and doesn't suffer that problem. i should think it gets pretty hot there

Exactly where mine was, now moved to the inner wing behind the headlamp cover...

[bss325i]

Thanks guys, looks like I need to add at least coil and fuel filter to the list of things to replace. They are consumable items anyway, so makes a bit of sense. I think I will check the dizzy and rotor too, and probably replace them for good measure.

@Gareth, I am being a little stubborn on the fly-by-wire issue. The sensible option I am sure is to replace it with a cable throttle, but I really want to keep it. Partly because it then means the cruise control works, but mainly because I like the idea of having fly-by-wire. I shall soldier on for a while longer.

Martin.

You can use cruise control with the cable set up and just use an E30 cruise control set up.

I would be binning the fly by wire in favor of a cable set up.

I seem to recall the electronic throttle body costing something silly like £500!

[tomson]

Thanks guys, looks like I need to add at least coil and fuel filter to the list of things to replace. They are consumable items anyway, so makes a bit of sense. I think I will check the dizzy and rotor too, and probably replace them for good measure.

@Gareth, I am being a little stubborn on the fly-by-wire issue. The sensible option I am sure is to replace it with a cable throttle, but I really want to keep it. Partly because it then means the cruise control works, but mainly because I like the idea of having fly-by-wire. I shall soldier on for a while longer.

Martin.

You can use cruise control with the cable set up and just use an E30 cruise control set up.

I would be binning the fly by wire in favor of a cable set up.

I would do this Martin, bin the fly by wire....

[MJJ_ZX6RR]

i'm not familiar with the fly-by-wire management, mine is operated with string

I would be binning the fly by wire in favor of a cable set up.

I would do this Martin, bin the fly by wire....

OK, I think I need to get this hint . Damn shame, I like the idea of fly-by-wire.

I have an unmolested E32 735i with cable throttle, currently thinking I should swap throttle setups between them. At least the E32 comes with all the traction control sensors and dashboard warning lights that EML expects.

Martin.

[leeparkes]

Did you sort this out?

[MJJ_ZX6RR]

Did you sort this out?

Nope, not yet. Bought new coil, dizzy cap, rotor, and fuel filter from Cotswold. Too damn cold outside to go and fit them

I also need to refit the #6 HT lead sensor wire, as I left it off when fitting new HT leads a few months back. I have not managed to work out how to dismantle an HT lead yet though.

I am going to try all these new bits first, and if it still struggles mid/high range, then I have no choice but to bin the EML. Or fit a V8 .....

Martin.