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Another starting problem


steve_r

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My 2006 Roadsport VVC160 refuses to start. I have read some posts but haven't found a solution to my problem yet.

Situation is as follows: battery fully charged, starter motor is turning the engine, ignition is delivering sparks, fuel pump primes the fuel to the injectors, but it appears that fuel is not injected into the cilinders.

Immobilizer seems to behave a bit odd as I don't get the usual beeps and indicatorsignals when disarming. So I guess next step is to reset immobilizer to rule out a malfunction of it although I would believe nothing will work when immobilizer is on.

Any suggestions?

 

 

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If the ECU fuse was gone, unless the wiring has been chopped around a lot, the engine won't crank as the starter solenoid runs through this fuse. If it's an immobiliser problem, after standing for some time you will normally be able to start the car for about two seconds before it dies, thereafter it will refuse to start for a while. Is this the behaviour that you are seeing?
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@revilla: situation is as you describe. Fuel pump doesn't start again whilst cranking. Later on this week I will get some help from two bachelor students in automotive technology. One of them owns several K-series engined cars and is quite familiar with them. They will bring scopes and other fancy equipment. I will point to the crankshaft position sensor or wiring as per your suggestion.

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Sounds good, much easier to diagnose these things hands on than over the web so I'm sure they will get you sorted. Don't forget to report back on here what they find as it always helps us all to learn from the experience. Good luck :)
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  • Area Representative

I just has something very similar while on the IoW Blat. The engine just cranked and did not fire at all. It turned out to be the Distributor cap and the central carbon rod was not making a good contact with the rotor arm. Once the rod was pulled out a little further on it's spring and the rotor cleaned, the car started. The plugs were sparking but weakly.

Piers

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Not yet sorted. Had to postpone the students coming last week. They will have look tonight.

We will have a look at the fuel delivery and I will point to the crankshaft position sensor or wiring as per revilla's suggestion.

How do we easily access the fuel pump if needed? Can it be done via trunk or do we need to get under the car?

Will give an update late this evening or latest tomorrow. Thanks for all interest and support.

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The fuel pump is inside the tank, runs immersed in the fuel as part of the assembly that also contains the fuel level sender. I think (I've not had to access it myself) it's a case of removing the boot floor and then removing the whole assembly from the top of the tank.

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Really getting frustrated right now. *censored*

Battery fully charged, starter motor is turning the engine, ignition is delivering sparks, fuel pump primes the fuel to the injectors, but engine still not firing up. Crankshaft position sensor checked and found to be OK.

Since fuel pump stopped while cranking we fed the pump directly with 12V. No firing up as immobilizer kicked in. Resetting immobilizer, no result. We by-passed the immobilizer, fuel pump starts again while cranking and for a split second we thought the engine would fire up. Unfortunately battery and our boosters out of power. Next attempt scheduled later on this week.

So last attempt later on this week and then call in the pro's. Main suspect is the immobilizer. Although I have read many threads related to resetting I'm still not sure whether I have reset correctly.

 

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Do you have the two button remote ? Turn ignition on. Set (arm) immobiliser by pressing the lock button. Wait until red LED settles to a slow flash rate. Then press unlock. Hear relay click and red LED extinguishes. Then press starter. If LED flashes while ignition on, you need to turn ignition off and start again.
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OK - If you have confirmed you have sparks, that in itself is enough to suggest that the crank position sensor is working as the ECU wouldn't be firing the ignition without a good crank signal.

The fact that the fuel pump primes rules out any problems with the pump, wiring to the pump, pump relay in MFRU etc. So it would appear that the ECU is not even trying to turn on the fuel pump whilst cranking, although it is firing the ignition. Which I think is an odd state of affairs.

Common wisdom is that the "immobiliser disables the fuel pump". There are two things wrong with this theory:

  • Firstly, if that were all it did, it would be far too easy to bypass. One Scotchlok at the MFRU and you could drive it away. I can confirm what you have found - if you explicitly power up the fuel pump on an immobilised engine, it still won't start, so the immobiliser has clearly caused something else such as ignition or injection to be disabled.
  • Secondly, the immobiliser doesn't disable anything. It isn't connected to anything other than the ECU, certainly not to the fuel pump. All the immobiliser does is exchange an encoded "password" with the ECU to confirm that it has "permission" to run. The ECU is what disables things, simply by failing to operate them if it doesn't get permission from the immobiliser. One consequence of this is that nearly all immobiliser-related problems will present the same; whatever causes the problem (immobiliser armed, immobiliser missing or unplugged, immobiliser wiring fault, immobiliser faulty, immobiliser code not programmed into ECU, supply voltage drop during cranking upsetting immobiliser etc. etc.) the result is that the ECU does not get the correct coded response to its handshake request and shuts down the engine.

I've worked on a couple of cars recently with immobiliser issues and the behaviour has been very similar in both cases, which is unsurprising given the above. For some reason, you can normally initially start an engine (provided that the fuel pump has primed, which it only do once within a given time delay period) which is immobilised or which has an immobiliser fault. It will normally run for about two seconds then shut down. I don't know why it works this way, but knowing that the initial handshake between the ECU and an OBDII device is performed at a very very slow bit rate (5 baud!) it may be that the signalling between the ECU and immobiliser is similarly slow and rather than delaying start, the ECU starts and gives the immobiliser a couple of seconds grace period to respond.

Given this, what you are seeing doesn't sound typical of an immobiliser issue to me. Your engine will not even fire up initially after a fuel pump prime. Failure to start could be down to many things but given the failure of the fuel pump to start during cranking even though it primes, I would be more inclined to suspect a possible problem with the ECU.

If it is of any help, my car is also a VVC 160 (2003) and I'm a bit of a mad collector of spare parts, so I do have a spare ECU / immobiliser / key fob set all ready programmed together and tested and working. If you wanted to borrow them I'd be happy to post them out to you. Changing them over is very easy - to be honest just to prove the point, you wouldn't need to remove anything, you can just disconnect the plugs and plug them into the replacement units (you will need to swap them over as a complete set, you won't be able to try swapping one bit at a time for elimination as they are coded together and programmed to work as a set, your existing ECU will not work with my immobiliser without reprogramming and the symptoms would be very similar which would be very confusing).

You are more than welcome to borrow them to get the car back on the road.

BM me your details if you would like me to send them.

Cheers,

Andrew

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I agree, JV. Andrew is a superstar. *clap*

Andrew, many thanks for your kind offer and support. Tomorrow one of the students helping me out will bring an ECU / immobiliser / key fob set (originally from a MG TF160). You will be the first to know if it works. 

Steve

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Andrew, she's alive!!! *bounce*

Yesterday we fitted the MG TF160 ECU / immobiliser / key fob set. At first no improvement of the situation. Until we found out we forgot to connect the ground lead of the ECU. Once fixed some promising noises emerged from the engine. By then we ran out of battery/booster power. 

Overnight I charged both battery and booster. This afternoon with full battery the engine still didn't want to fire up. Well it did, but died after a second or two. It looked like another immobilser issue. Then, all of a sudden, Lukas (one of the students) got an idea: let's re-fit the original ECU / immobiliser / key fob set. Immobiliser disarmed, igntion on, finger on the starter button and ..... BRUM BRUM BRUM ROAAARR!!!

Well, we guess that by disconnecting the original ECU / immobiliser / key fob set for a prolonged period of time it misteriously got completely reset. Most important is that I'm back on the road.

Andrew, a thouisand thanks for your continious support and information. 

 

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First thing ... really glad to hear it's working again!

Second thing ... there's something interesting going on here. Recently I was helping Mucus72 with his K Series starting issues (he lives about 3 minutes from me - I'll BM him a link to this thread). In some ways the problem was similar to yours, in his case the engine was acting as though immobilised but only intermittently. It would prime, fire for two seconds then shut down the fuel pump and injection. Sometimes. Other times it would fire up and start just fine. It got to the point where it was maybe only one time in five that it would run. After scratching our heads and trying all sorts of other things, we swapped over the complete ECU / 5AS set for one of my spares and it fired up OK. Then we put the old ones back on, having changed nothing ... and the problem was gone! As far as I know it's been perfect ever since. He's been over at Anglesey and the Evo Triangle over the last couple of days, so it must be better than it was.

The only possibilities I can think of are i) as you say, a prolonged period of disconnection causes some kind of reset, or ii) the problems may have been caused by poor connections at the ECU plug and just plugging and unplugging a couple of times has scraped the contacts clean a bit and fixed it.

Not sure which theory I favour to be honest; i) sounds unlikely to me, there are certainly no great big capacitors inside either the ECU or 5AS that would hold a huge charge to power it for a while and I would have though everything would be discharged and fully shut down within a fraction of a second of disconnecting. After that, I can't really see that they would be aware of the passage of time and powering off for 1 minute or 1 week would be pretty much the same. On the other car we had tried swapping batteries so we had powered everything down for short periods several times without it making a difference. ii) might be possible, but they are pretty well made and well sealed connectors with gold plated pins (on mine, at least) so it seems a bit odd that they would suddenly go bad just sitting undisturbed, but who knows, maybe a bit of moisture got in over the winter?

Oh well, one way or another, something about removing the ECU and 5AS for a while seems to have fixed similar problems twice now, so it's good to have this documented in the archives even if we don't fully understand it. It always feels a lot more satisfactory to be able to say "we found the fault, it was X, we fixed it by Y" rather than "we fiddled around and it works now", but as you the most important thing is you (and Mucus72) are back on the road enjoying your cars.

More than happy to help in any way I can if the problem ever flares up again.

Cheers,

Andrew

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Just to comfirm, my car has been started probably over 50 times during the bank holiday weekend - Angelsey track day and an all day blat in North Wales. Not once has it failed to run (and continue running). Which is a night and day difference to 4 in 5 failures to keep running prior to Andrew switching ECUs and immobilisers. And then switching back to originals. Note that my failures to start were all still a problem with replacement ECU and immobilisers. The fix came when giving up for the evening and refitting all original parts. The solution from this point forward will be known as 'Jiggery Pokery'. 

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  • 2 weeks later...

What a GREAT read!

Sorry to hear that you have had starting issues with your K's, good news you are back on the road. Bought my 2005 R300 last year with no problems as yet, but I will certainly know where to come if and when something crops up. 

Great advice and `process of elimination` thinking.

Graham

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