The Joy Of 240's, with issues...
 

After an uneventful drive from collecting the new 1993 240 estate, it's time to get stuck into the various little (I hope) niggles prior to the MOT which is due in a couple of weeks time.

Aside from consumables like windscreen wipers, I need to

1. Repair the tailgate brake light. Suspect the hinge wiring or earth, it 'glows' all the time the car is running, no idea if it lights up on the brake pedal.

2. Repair the rear light clusters. Both are held together with tape, but all the bits are there. 20+ years of building RC aircraft will help with that bit.

3. The biggie. Engine light on.....Fault codes are 113 (injector fault), 221 (compensating for extremely rich or lean at cruise) & 231 (compensating for rich or lean at cruise). The first 2 codes result in the engine warning light being lit, the 3rd does not.

I have reset the codes, they return along with the warning light as soon as the car is started. Things checked so far in limited available time.

MAF resistance measured at 3.1 Ohms, within range for the LH2.4 system, so presumed OK. No error codes for MAF either.

Checked inlet hoses for damage, all OK.

Lambda sensor (3 wire type) resistance measured at 3 Ohms cold, 6 Ohms just after starting so will check that it's 13 Ohms hot tomorrow. Need to check voltage output when running also to ensure it is signalling the ECU correctly.

Injectors. Listened to all 4, they are clicking nicely. Resistance on all is the same and pretty much at spec at 15.6 Ohms (book says 16). Not sure if there is a value in a noid test since they are all clicking so assume getting a signal.

Hopefully going in the right direction. No smoke on idle or under load. Got a bit of time the next few days so hopefully nail the engine light issue, the rest is just good old fashioned mechanics.

You can get a new harness for the tailgate as well as new rear lights from Skandix. I bought complete light units for 140 Euros a pop, because it's a lot easier not to fiddle around changing over bulb holders to a new unit. The factory replacement lights even had bulbs in.

It sounds like you know what you're doing diagnosing the fault codes. I've never had a faulty injector code come up. It's always been MAF or coolant temp sensor related.

Just double check that the concertina hose from the MAF to the throttle body is sound - being plastic and old, it will have become less flexible and could be letting in air

The plot thickens..

A spare hour in a break from decorating.

Brake lights all working. Blown fuse to start with, I reckon the units full of water did that. Tailgate light fine. NSR lamp blown and contacts mucky, all cleaned up. Easy problem fixed.

Engine light continues! Tested the lambda sensor. Cold resistance 2.5 ohms, with the temperature gauge up a bit, 5.8 ohms, way below spec of 13 ohms. Voltage between sensor and ground started at 0.5 - 0.8 as it should do, but as soon as we got warm it dropped to 0v. Going to get under the car at the weekend I hope and check the wiring, but I suspect I need a new O2 sensor Despite the 0v output, the engine ran considerably worse when I disconnected it.

A code reset and the 113 injector fault has gone. The remaining are lean/rich so if the lambda is not feeding back that would make some sort of sense.

Oh, I removed some of the considerable moss growth too...

I'm not sure that code 113 means a injector fault.
From memory it's a rich (or incorrect) mixture, so probably a symptom of a failed lambda sensor.

A decent run out this morning to get new wiper blades and warm the whole car through to test the O2 sensor. At idle, 0v static. Needed to get the revs above 2000 rpm before it started to respond, the fluctuated between 0.1v and 0.8v, so near spec. Resistance was 5.8 ohms. Unless the throttle position sensor has an input (it's not clicking off idle, I need to remove it and test outputs are closing), then I'm going to remove the O2 sensor at some point and replace.

Also removed the tail lights today, all held together with tape and full of water and mould. After removing I have ended up with quite a jigsaw to put together, but it's all there so nothing a few hours with glue and sealant won't fix. If I get it sorted for an MOT then I may splash out on new rear light clusters.

It's meant to click off when the throttle is closed, and make a click the instant you move the throttle. You set this just by loosening the screw and turning it.

If it's not set correctly, the most likely explanation is that someone has adjusted the throttle stop screw to increase the idling speed. That's wrong - the throttle stop is pre-set, and if that results in too low an idling speed then something else is incorrect.
I can't recall - have you cleaned the throttle body and butterfly with a bottle-brush and carb cleaner? Also as suggested check the convoluted hose for splitting along a corrugation or rubbing on the inner wing.
It's hard to spot a crack - it flexes as the engine rocks. Remove it and hold it up to the light while flexing, or shine a torch down it in the dark.

All in all a successful morning of fettling. Rear light clusters were repaired last night at the dinner table, and refitted this morning. Not perfect, but no longer full of water and held together with tape. Getting the remnants of tape off the bodywork around the light took quite some doing though!

Checked the throttle position sensor, after slackening the retaining bolts I now have it set to click just as the throttle opens. I did wonder if this would give the excess fuel code with the ECU thinking the throttle flap was open when it was actually at idle, and yes, a code reset has now cleared the engine warning light. Hurrah!!
On the down side, the idle is now dog rough with a terrible pickup. When I bought it the previous owner did say that it was rough, and the garage had played with the idle which made it a little better, so I guess that @Clifford Pope you may be right.
Throttle body will come of as soon as I buy a gasket, it is in dire need of a good clean.
Another bit of digging to find out why the petrol guage isn't working, and sure enough I've found the corroded connector at the tank. I may have a go as soldering it, will see how the afternoon goes...

Also remove the Idle Air Valve and clean the sliding shutter. I find its soots up surprisingly quickly- even though it's only air going through it. I use a small artists's brush, fairly stiff. You can turn the armature inside using the wooden end of the brush, give a squirt inside with carb cleaner or WD40, and then the brush end to remove any dirt released. Finally blow through it to clear any liquid remaining.

Idling will also be affected by all the breather hosework - the flame trap, small hose to the inlet manifold, and the very small hose in the brass nipple connection to the manifold.
I think even the black box oil trap can affect idling if it is coked up.

Well the petrol gauge won't be working anytime soon, the remnants of connector were too corroded to accept any solder. I guess a sticky note of how many miles before filling will do for now, and a new sender etc in the longer term.
I'll order up a throttle body gasket and get onto that side of things next, but even in the current state it may well be worth a pop at an MOT....