Injectors / Electrics

[Pauls SLR]

I have a 2002 k series SLR, running wasted spark with an Emerald ECU.

A few weeks ago I decided to go for a blat and so opened the garage, but the car refused to start - it was turning over but not firing. Expecting visitors later that day I didn't have a chance to investigate so closed up the garage and aborted the blat.

The following weekend I thought I'd try again. The car turning over well but not firing. I narrowed it to no signal getting to the injectors. Noid light on any of the injector connectors gave no light and also on the connection between engine loom and injector loom the same.

I checked continuity between the ECU plug and the injectors and this all seemed OK. Also checked continuity to the coil as I believe the +ve to the injectors comes from there{?) Reconnected all the connectors, then out of curiosity put the Noid light back on and it flashed light. Car started normally! Assuming I just had a loose connection I hoped the issue was sorted and went for a lovely long drive. Just as I returned into my village the car stalled and I had to coast down a hill and home. Same symptoms, no power to the injectors but checked continuity in the loom and all seemed OK.

I spent the rest of the day checking out the various connectors and wires in the loom with a multimeter. Couldn't find any issues but couldn't get the car to start. Got fed up and left it.

Starting afresh today I plugged the laptop into the ECU. Only thing I found that I wasn't expecting was that as I tried to start the car the Lambda was showing as rich in the live adjustments tab, even when the engine was turning over but not running. Assuming a problem with the Lambda sensor I unplugged the connector but wasn't sure which pin did what on the connector. Plugged it back together and now the car starts and runs as it should.

So - it might have been the contacts in the connector or a dodgy wire and moving the wires around has temporarily sorted that. It may be a dodgy wire somewhere else and I've just disturbed / moved that, or it could be the Lambda sensor itself?

Sorry for the lengthy post but trying to be thorough!

Questions are - would a failing Lambda sensor cause the ECU to stop sending power to the injectors? Same if it was just the connector failing or a dodgy wire from the Lambda? Is it normal for the live adjustments for the ECU to show as rich even when the engine isn't running?

Otherwise I've got a loose wire somewhere that I cant find and even though the car will run I'll be paranoid every time  I go out in it??

Any other ideas?

Thanks in advance

Paul

[Piers300]

I had a bad case of failing to start (R300 2004) The engine would crank, with a spark, but the injectors would not fire. Squirting fuel into the throttle bodies and it would start immediately. Turned out to be a bad earth on the ECU.

 

Piers

[7 wonders of the world]

I found several dry / bad joints in the stock CC loom, mine even lost its power feed on the rollers at emerald resulting is unwrapping the loom and wiggle testing...... not a got loom

 

Current car I made a new loom from scratch 

If yours is dead now then its ideal to start from one end and wiggle test it.

[SLR No.77]

I too re-made my loom for my SLR, it had been substantially messed with in the past and was plain unreliable. All new connectors fitted correctly with a proper tool and the correct wires running where they're supposed to, it's been perfect since. It's also worth using a jointing gel at all the connectors to prevent the green death getting in and causing voltage drops.

 

 

[Pauls SLR]

Thanks all. I feared that but not sure my wiring skills run to a whole loom. Perhaps if I can find an old loom to pick apart to get an idea of the wiring. At least I can now start / use the car.

I have to say the standard loom with the various incorrect runs and random connectors has always felt like the worst part of the installation so it would be nice to have a custom loom without all the doubled over cables and twists and turns. 

[SLR No.77]

IME it's mostly the engine loom that gets messed with and bodged, the car loom is generally reliable.

[Pauls SLR]

Yep.  I wasn’t planning on touching the car loom at this stage: maybe a project for my retirement 

[anthonym]

My TPS Emerald thread is all about this, without yet a solution. However, fwiw I am in the process of (meaning the new lamda loom wires are 35cm too short) fitting a new lamda sensor. My engine is/was running 10x too rich and failed mot for it so off the road and has my attention.

My entire engine loom is brand new, freshly fitted. Except this sensor which came from a French scrap yard years ago. Can it tell lies to the ECU? I would love to know. Maybe I will be able to comment further later tomorrow. 

Anthony

 

[anthonym]

Ps I have my K old loom in bits here, which bits do you want to trace? I’ll do some pics.

pps ime it won’t be a bad wire, (fried wires excepted) it will be a bad connector. Check the famous purple wire connector, near the ecu. Stu spotted mine was naff and apparently it’s common. That was the beginning of the end for my engine loom. Six duff connector breakdowns on tour later I decided enough was enough.

 

[revilla]

Anthony, I think you mean 10x too high HC emissions and not 10x too rich You would have an R500 flame thrower if it was that rich!

[anthonym]

yes that's exactly what the test guy said. 

a local Swiss this morning observed that in Swissland there is no such thing as too rich..  I think they must use a different expression for this. Cultural variety spotted.

[Pauls SLR]

Indeed. It was actually one of the crimped connectors in the plug onto the ECU. I found wiggling the connector allowed me to start the car and the wiggling it again stalled it. 

I’ve put a new crimp connector in and although I haven’t  been for a test drive tonight it starts and runs in the garage. 

If it stays reliable for now a custom loom might be my over the Winter project. 

 

Paul