DEAD 7 - POBC Help required please

[MereCat]

POBC please can I get your help and advice in diagnosing a problem with my K series 7.

 

I have a 1600 K on TB’s with an Emerald ECU. Some of my symptoms seem to be the same or similar as a number of recent posts re engine developing a misfire type scenario and then dies but not entirely sure hence my post.

 

7 does start but dies as soon as any throttle is applied above 2K rpm (on current map) or will start to hunt and then dies as soon as it starts to warm up 70 degrees according to ECU (on either Map). At this point if I blip the throttle it gets very lumpy and I get some very loud pop and bangs from the exhaust. I also notice a mechanical type whistle (not all the time) when priming ignition (hear this from front of car aswell as fuel pump priming at rear).

 

Recent electrical work done, come on to that shortly, but don't think its related.

 

Symptoms

 

Day 0 (on way back from having work done)

 

Alternator light on / off, car seems to be missing but only slightly and a little more popping and banging from over run than usual.

 

Day 1

 

Afternoon run out, same symptoms as before with acceleration not as brisk as normal.

 

Evening run out 11 / 13 degrees. Car is noticebly missing now and some very loud bangs from the exhaust. Lights on when travelling home.

 

Day 2

 

Early morning run out and a stop to the garage for fuel requires a bump start due to not firing. Alternator light is on after exhausting battery and a run down A404 sees noticeable misfire which then seems to settle at 3000 rpm. Light goes out and I then put lights on which feels as though someone has pulled my car backwards, (noticeable deceleration). As soon as I come off gas, engine revs drop off and it wont idle. Revs picked up and massive misfire back which then results in car becoming un driveable.

 

3 AA vehicles and 6 Hours later I am home!

 

I suspect that the deceleration was due to low voltage in the battery.

 

7 is now home, undriveable and looking sorry for itself.

 

 

Diagnosis

 

I have run the car on both old and new maps (the original map that the car came with) just in case the current one had developed a glitch, but same symptoms for both. When the engine is running I also notice some odd sounds coming from cambelt housing (new belt and tensioner last year) that are louder than before (recently prognosed as tensioner bolt too tight, not yet adjusted) but again suspect and hope that this is not related. It has not been run for 5 weeks.

 

Having had recent work undertaken (Master cut out switch and new rear number plate light) I thought I would start at this point by way of a process of elimination as no issue beforehand. I believe this to be a coincidence as work was undertaken at a very reputable 7 specialist. It could also be a faulty part? If so I would have thought a dodgy Master switch would be a case of on/ off? Would I be right?

 

I have plugged in the PC with engine both on and off.

 

I am running an early Emerald ECU and through live adjustments I can see that battery voltage levels seem to be dropping when the engine is running until it starts to warm up 5-10 mins and then I have 13.6V on the battery which would confirm the alternator is OK?

 

I have changed the battery (New), but when I turn the engine off the battery now reads 12Volt having now lost charge. If the alternator is charging surely this would not drop, or does it need to run for a while to recharge the battery back to its starting point of 12.4V?

 

IF the battery is not charging my initial thought was that this could be affecting voltage to ECU / sensors which could be impacting fuelling etc?

 

Assuming Switch and Alternator are OK I was going to look at TPS next, although I would guess that idle starting to drop when warming up and then hunting would be more related to fuelling surely, as I am not touching the TPS?

 

Could a voltage drop in the TPS affect how it would run? I would expect this to cause misfire, but perhaps only on application of throttle, or am I incorrect in my assumption?

 

If I am wrong then a faulty sensor or wiring might be the cause of the problem, at which point I would check signals etc. When I blip the throttle with engine off the ECU can see this which confirms to me that wiring is OK, but perhaps a faulty sensor? I have a new TPS but would need some help fitting in terms of settings and how, IF this is the issue (another post perhaps).

 

If its not TPS then what would you suggest my next step should be?

 

1. TB’s balanced correctly? (recently diagnosed as reduced air intake on one but nothing to impact driveabllity, minor adjustment required). Could this have now stopped working? It does start and run initially though.

 

2. Fuel Pump (Filter was replaced new last year). Whirs when priming engine but I believe could be an option. Could I have an intermittent pump i.e. primes OK on initial start but develops issues when running (poss bad earth)? It might explain why it would not start at the garage after fuel and when engine has warmed up).

 

3. Crank sensor (although again it runs OK ish (little lumpy) until it warms up. If it was this surely it would not fire?

 

4. Fuel pressure regulator (spark plugs would indicate running lean although when initially mapped were black) and have been replaced same time as battery. Could a FPR deteriorate over time, hence change in colour of plugs? Fuel economy is reduced but only since new map was applied. How would I check fuel pressure (I believe its 3 Bar in old money and 43.5 Psi) in new?

 

Have I missed anything else obvious? It seems odd that the fault seems to have crept up on me i.e. something failing slowly and now I have the same fault everytime I fire her up.

 

As you can see this could be a day or a week(s) but sun has been shining and any help would be greatly appreciated.

 

Many thanks

Paul

 

[Stationary M25 Traveller]

Have you tried disconnecting the lambda sensor ? Unplug it in the lead connector. If the car runs fine, then get a new sensor on eBay .... take the number off the original.

[MereCat]

Hi Ian,

 

no LAMBDA on the car (96 K), but thank you for the first reply and help.

 

Paul

[Stationary M25 Traveller]

It won't be that then !!

 

Good luck with sorting it

[tbird]

I don't know where the ECU actually measures the Voltage but It sounds almost as if Alternator is cutting in and out,

using multimeter what voltage do you get at Alternator and at Battery, assuming you can get engine to run

and is you alternator single wire or does it have a sensing wire and is that sensing wire connected / have good clean connections .

NB this wouldn't explain all symptoms but may be a starting point.

 

Tim

 

 

 

Edited by - tbird on 29 Jun 2013 21:47:14

[Paul Deslandes]

The TPS is usually supplied from a stabilised 5V regulator in the ECU so the battery voltage would have to go very low before affecting the TPS voltage, by which time everything else would have stopped. However I would check the TPS output voltage to the ECU as some of your symptoms certainly suggest ignition timing being way off and even variable. Perhaps its either faulty or just loose. The Emerald website has a number of manuals which presumably include the procedure for adjusting your TPS. I think I'd start there.

[david nelson]

If you can attach the ecu to a laptop have a look at all you can.

 

I had an issue and drove all the way to the 2 Steves only to find it was a loose conection on the water temp sender. The car was hot but the map said it was cold.

 

David

[MereCat]

Gents,

 

thanks for your help with replies to date.

 

So having looked into this a little more it seems that I can trick the engine through live adjustments to keep running (dial out hunting) which would make me think I am running too lean and so the map needs some adjustment, although confused as to why it wont run now after all this time? Still suspect a fuelling issue and reason for trimming fuelling was to see if it was a faulty FPR (runs ok when cold i.e. cold start richer fuelling / hunts when warm...too lean).

 

I have also noticed alternator light is on for 10-15mins and then goes off but on ECU no sign of voltage increasing (slow drop the longer it runs) which would indicate that I do have either a dodgy connection or its fried. Seem to remember it showed voltage increase after 10mins running yesterday.

 

Might be a combination of two. I shall confirm alternator and wiring to sensors etc (auto electrician) and then look at adjusting map.

 

If it is the map does anyone know why this would develop a problem all of a sudden? Could it be mechanical related?

 

Thanks again and update later.

Paul

 

 

[Paul Deslandes]

Once the engine starts the battery voltage should start to increase immediately as it's charged by the alternator. The warning light should go out straight away and yours not doing so would suggest that you either have a faulty connection or a fried alternator regulator.

 

You shouldn't have to tweek a map provided the sensors and injectors are working correctly. The ECU reads the sensors, e.g. air and water temperature, crank position and the TPS, and, at any given revs, computes ignition timing and the amount of time that the injectors should open for. As you have noted, this also requires that the fuel pressure doesn't change. If a sensor is giving bad readings, change the sensor. not the map.

 

If your battery voltage is dropping as you describe, any or all of the above could be operating incorrectly and giving false readings, hence your symptoms. Also, the fuel pump may not be giving sufficient fuel pressure if the voltage is really low.

 

I'd leave your map well alone until you've sorted out the voltage issue, otherwise you'll fix one problem only to be presented with another.

 

If you do want to tweek the map, do make sure that you have a copy of the original before you start so you can go back to it if you cock it up.

 

Paul

[MereCat]

Paul,

 

thanks for your reply. Agree electrics first at which point check sensors. I trimmed ECU fuelling as wanted to see if it was not getting enough fuel i.e. my only known way of checking FPR is faulty or not. Once engine was at 80-90 degrees could blip happily with my more familiar sounds , but fuel trim had been advanced, so i guess change FPR then?

 

Might seem like a daft question but I know where TPS / Water / Crank / Air sensors are, FPR on fuel rail, pump (inside or outside tank) just below filler neck? Is there a fuelling sensor before I change the regulator? Engine is definitely running lean according to ECU on idle. As per my original post the spark plugs seem to have got lighter as its been used on the new map (originally black) of which I have now changed although strangely enough fuel consumption is down 25%. Exhaust is according to Oily the right colour for my state of tune.

 

Would you also know what the base voltage reading should be for TPS?

 

Any of the above (answers or observations) would be of help if you know and can spare a few minutes.

 

Many thanks

Paul

[Paul Deslandes]

Hi Paul

 

fuel pump most likely internal to tank at right hand end. The external lump is the fuel filter in the line from the pump to the fuel rail. There's no fuel pressure sensor, only the regulator which maintains the correct pressure by allowing excess fuel to return to the tank. The more throttle and therefore the more fuel being burnt by the engine, the less fuel going back to the tank.

 

I'm not familiar with the Emerald ECUs but a quick read of the setup instructions suggests that it autocalibrates the TPS within the software, provided that it can be swung over the full range of throttle opening. This is similar to the DTA but very different from MBE for which you have to set the voltage. The procedure looks pretty straight forward though provided you have a laptop and cable and the Emerald software loaded.

 

If you change the pressure regulator unless you have a fixed pressure version, you'll need to adjust it. Can you borrow a fuel pressure gauge and do you know the correct pressure, usually about 3bar (45psi). You could check the pressure with your existing setup.

 

Paul

 

 

[MereCat]

Hi Paul,

 

Thanks. I think we have found a solution just getting her ready to try but it turned out that the live brown cable which I think was previously fixed to the battery before Master Cut out was installed had worked loose from its connection on the starter motor. So we had an intermittent feed which was braking the connection to the alternator and as such the circuit. It was not charging. Fixed that and tested with meters and all seems good. Now charging and engine sounds normal. No requirement to trim map.

 

Only issue that I might have now created ( changing water temp sensor to dash gauge) is that I might have over tightened it! I undid it but can't remember if it is meant to be flush with the water rail Or just enough to tighten ? If so I seem to have not got it flush but do have what I would say is bits of a seal ( paper of sorts) but shredding like swarf . Please tell me I have not knackered this?

 

If ok I shall take her out and report back shortly

 

Thanks

Paul

[Stationary M25 Traveller]

You can use a thick liquid type thread sealant (not a thread lock), or a few wraps of PTFE tape around the sender, but you need metal-metal contact to make the circuit. Perhaps you could use a hose clip to trap an earth wire to the body of the sender if using PTFE tape.

[Paul Deslandes]

Its great whern its something obvious like that. Glad to hear its all working properly now.

The sensor only needs to be tight enough not to leak. If its not leaking then I'd leave it alone. As Ian says, if you insulate it with PTFE tape, you'll need to make an electrical connection from the body to the chassis. Otherwise you won't get a reading.

If it ain't broke, don't fix it.

[Markiebabes]

Great news Paul 😬

[Cookie Monster]

Paul

Sorry to hear of your woes - John was telling me a few weeks ago.

Hope it's all fixed now!

[MereCat]

😬 😬 😬 big grin on my face! Just been out for an hour and she is running lovely.

 

I am amazed that something as simple as a drop in voltage cold affect the running so much, just goes to show my lack of engines... ( but I am learning )

 

I would like to thank everyone that has helped me with my problem , Paul, Ian , Tim, David and Mark / John (Bio) in the wings your help was very much appreciated .

 

Phil, I was beginning to question if I had broken something reflective.

 

If anyone needs a mobile auto electrician around High Wycombe I can recommend a good one and and he is a petrol head too.

 

Cheers

Paul

 

[tbird]

Glad its sorted, thats the problem with bl006y ECUs , low voltage give random faults taking you down all sorts of dead ends, now you can enjoy the heatwave

 

Tim