Starting problem!!

[markh1]

Hi all,

After replacing the fuel pump, throttle pots, spark plugs and fuel regulator I am still having intermittent starting problems.

The car will turn over and the fuel pump will prime (although it does not sound like it is pressurising) but it won't fire when it is cold, although the problem seems like it only happens when it's cold.

Has anyone got any idea at all what it is or what part i should try replacing??

This is really going to scupper my chances of getting to Chatsworth!

[jammy_basturd]

Are you able to hook up to a laptop?

Congratulations on getting the MOT though!

Edited by jammy_basturd on Wednesday 21st April 16:02

[markh1]

I have just bought the bits to make up a cable to plug a laptop in. However it has only just come back from the garage where they had the laptop plugged in to sort out the emissions. The car is at the paint shop at the mo and won't be able to pick it up until tomorrow night.

However will the diagnostics actually show what the problem is if the problem only occurs on cold starting? Surely if the engine is running it is not going to show what the starting problem is? Or do you plug the laptop in before you start the engine??

Please forgive daft questions, vehicle electronics are not my strong point!

[jammy_basturd]

The ECU diag program will tell you if there have been any faults log, which might point you in the right direction and yes, you can plug the laptop in before you start the engine, which will allow you to monitor all the sensors whilst they are cold/trying to start the engine. It could be that there is a voltage problem, TP problem, lambda problem, etc. And if you can find any problems with the laptop then it should at least enable you to rule out a few things.

If you need any help with cables, or getting the software to run give us a shout.

[markh1]

OK that's great to know cheers dude!

I will not be able to do anything until tomorrow night at the earliest. I have booked friday off and will hopefully get it sorted then!

[Gazzab]

If you get yourself going and are starting hot on the way then can you get there ok? Once you are there then there are loads of owners, TVR mechanics around and so we can ensure you get all the help and tools you need to get going again for the return trip?

[JensenA]

Never dis-count the dumb things .......have you remembered to re-connect the sensor in the passenger side airbox at the front of the car? (Easy thing to forget)

[markh1]

Cheers Gaz, but I am worried about actually getting it going in the first place to get up there

Alan, I am 99% certain that it's plugged in.

I spoke to the garage and they said that there was a fault code showing that not enough charge was getting from the alternator to the ECU, apparently when not enough charge gets to the ECU the ECU won't send power where its needed (I'm guessing the plugs)

So....

There must be a problem with the wiring from the alternator to the ECU. Anyone got any suggestions as to what wires I replace or that are worth checking?

Cheers,
Mark

[Steve_T]

There won't be wiring directly from the alternator to the ECU to monitor the charge rate - the alt just charges the battery (via the big fuse). Somewhere I have a DC amps clamp meter that can check the rate if it helps, I don't think it will ...

Anyway, the ECU can only monitor battery voltage - it does this to adjust the injector duration and I guess maybe the timing - the voltage is shown in the diagnostic software. Does the starter spin over and if so is it laboured or at normal speed? If it's turning slowly and you have another vehicle at hand with a fully charged battery I would try jump starting to see if you can get the car to go. I also have the ECU software and a suitable laptop - where are you based?

Edited by Steve_T on Wednesday 21st April 18:52

[Gazzab]

Steves idea of jump starting sounds good. Poor battery can do strange things. Make sure you hook it up properly and don't fry anything.
Maybe a silly one but have you tried with fuel cap unscrewed? If your not venting then it can't suck the fuel.

[markh1]

Steve,

I am in Ashtead just south of Epsom Where are you roughly? I don't have the car until Thursday evening or first thing Friday morning unfortunately

I spoke to Ridds on the phone just now and like you told me that there is no feed from the alternator to the ECU. The starter is not laboured when cranking but ridds suggested that the battery could be down on voltage or the ECU is not reading the voltage correctly. When I get the car back tomorrow eve or friday I will have a look at what voltage the battery is holding.

The low voltage/faulty voltage reading makes sense I think because the problem only seems to occur when the car has not been started for a while. When the car has been running the problem does not occur, maybe because the battery has been charged up??

Tomorrow I will get the body shop to stick a volt meter over the battery and if it is down I will see if I can get an ultima red top on next day delivery from somewhere!

Again, cheers for all the help!

Edited to add: Gaz I have not tried it with the fuel cap off, I will also try this.

Edited by markh1 on Wednesday 21st April 19:18

[Gazzab]

Per the battery thread I have just ordered an 072 for 59 squid. From eBay. Hoping it will fit.

[Steve_T]

I'm in Surbiton so you're not far away. I have just put a diagnostic lead in, so may be able to help if you need. SBD Motorsport (also in Surbiton) carry the pins for the loom side of the ECU connector if you need some, I've found them very helpful.

[markh1]

Thanks Gaz, I will have a look at that thread.

Steve, that is very kind of you! I may need your help on Friday but I will do what I can on my own - don't want you making unnecessary trips.

[markh1]

Big thanks to Peter (Tanguero) his website... http://www.tvr-cerbera.co.uk/ enabled me to make a lead to go between the ECU and laptop. I will hopefully test it out tonight!

It looks a bit messy but should do the job!

[high52kojak]

I hope it works!

You dont actually need the resistors in, they are to enable mapping I think?

[Steve_T]

Mark, you don't need the resistors in the lead - that's for mapping with a regular MBE ECU. All you need is send, receive and ground (pins 45, 46 and 12 in the ECU connector) - I'll dig out the post with the info.

ETA: http://www.pistonheads.com/gassing/topic.asp?h=0&a...

Edited by Steve_T on Thursday 22 April 09:29

[FarmyardPants]

markh1 in his rebuild thread said:

For some reason it was not firing even though the fuel pump was pumping fuel through (although it was not straining like it should do when pressure is achieved in the rail) The fuel regulator and pump are both new. I got it started in the end by putting a direct 12v feed to the fuel pump from a spare battery and spinning the pump for a while. I then went to start the car and it fired up. It had no problem starting when the car was warm. Any suggestions??

Is this the same problem? Did you change the fuel pump relay?

[markh1]

Steve, will the resistors stop the lead working? Am I ok to leave them in there? or should I take them out?

Rog, yes this is the same problem. I have spoken to TVR power and they said that the relay won't make a difference. If the relay does not work then the pump will not work at all.

[Tanguero]

markh1 said:

Steve, will the resistors stop the lead working? Am I ok to leave them in there? or should I take them out?

The lead will work equally well both with and without the resistors.

The purpose of the resistors is to protect the programming side of the circuit. This functionality is not actually used in the TVR version of the ECU without modification, but the resistors will protect it if you have them. They are not necessary for the lead to function and they do not stop it functioning if they are there. The diagram is from MBE and therefore is the manufacturers recommendation.