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There's a knack to it


Shackleton

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Spent a good hour trying to coax my new 3.9 Vogue into starting this morning, and then the whole arvo trawling here and the wider net for answers. I went back to the P/O (my uncle) to ask what he knows about the situation. He told me this:

The RR will be reluctant but will start - so long as you don't touch the throttle, just put the key in and crank. It'll do that kind of gaining momentum deal until fully running. But if you touch the throttle, game over. It'll give the odd catch most times you try and start it but will never actually run unless you leave it over night and follow correct throttle-less procedure. By times today I did get a good old bang of fuel if I'd been standing on the throttle and then got out of the car so presumably it's flooding.

This is not something I've be able to find on the net. Does it sound familiar to anyone, is it a known foible? It's a '91 3.9 EFI (presumably hot wire)

George

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Can't answer your question, but when I had just bought my V8 Disco 3 I picked my daughter up from school. As I was early I turned th engine off, girl arrived with Pals in tow showing them our new car.

I turned the key and hit the gas to give a good V8 start (showing off) and it cought and stalled, four times this happened. Final tome I left my foot off the gas completely and it started just fine. Kids ripped my girl to bits about carp car,I guessed that the throttle was burning all the fuel before it had more fuel to keep running?

Marc

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I would guess at a pinhole leak in the fuel system allowing drain back to the tank, so runs too lean until the system is purged. The blow back could be because there is enough fuel vapour going through the engine unburnt to condense in the exhaust until the engine fires, which detonates the fuel in the exhaust. A very small leak will allow air in when the system is depressurised, but not allow fuel out under pressure. This is the main cause when Tdis are hard to start, usually in the injector spill return system.

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When I say leaking injector, I mean it is leaking while switch off, into the cylinder most likely, easy test though, pull the rail compleete with injectors and turn on the fuel pump a few times and see which is dribbling, does mean removing the plenum though.

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Does the ECU go into "flood clear" mode (zero fuel injected) when you floor the pedal? I know some vehicles do. That would explain no start on full throttle.

As for the original problem, if fuel was leaking out you'd have to have a hell of a leak - the pressure regulator regulates the return to tank, so unless the fuel pump running flat out still couldn't keep up with the leak it would build pressure, it would just likely drop at high engine loads - starting would be unlikely to be affected.

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Gosh I'm trying to even remember if there's an ECU on a Hotwire car!? It's that long since I took the 3.9 out of my other classic that the details are forgotten. I'll be tackling trailering the Vogue tomorrow, here's hoping it starts and I'll hopefully get some time to do a little investigating in the eve. I'll report back with any findings. Thanks guys.

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Yes there is an ECU :P Under drivers seat on hard dash, passenger footwell on softdash.

No flood clear on the hotwire ECU, or so I have been told in the past -certainly never worked for me to get a flooded engine going!

Megasq.... oh never mind :)

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I had a similar cold starting issue on an old Mitsubishi Galant Turbo, any touch of the throttle meant removing the four screws

holding the top of the single point injection plenum and mopping a pool of petrol up !

Massively over fueling.

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Yes there is an ECU :P

Ok ok I remember now

Drove (and trailered) it today, it took about 10 seconds for me to remember I was supposed to have bought my D2 as a runabout between RR's. I'm in love.

Anyway didn't get a chance to do any proper testing but what I learned is that it starts willingly from hot or cold so long as the throttle is virgin. In fact it was on the button this morning. The only other clue I have now is that with anything other than light throttle there's a hesitation - like a tiny splutter/miss when acceleration is asked for.

This is ringing bells with me now but I can't quite remember?

Thinking of doing a full ignition revamp FF, just for peace of mind.

How did you sort it Nige?

George

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Ok ok I remember now :D

Drove (and trailered) it today, it took about 10 seconds for me to remember I was supposed to have bought my D2 as a runabout between RR's. I'm in love.

Anyway didn't get a chance to do any proper testing but what I learned is that it starts willingly from hot or cold so long as the throttle is virgin. In fact it was on the button this morning. The only other clue I have now is that with anything other than light throttle there's a hesitation - like a tiny splutter/miss when acceleration is asked for.

This is ringing bells with me now but I can't quite remember?

Thinking of doing a full ignition revamp FF, just for peace of mind.

How did you sort it Nige?

George

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Ok ok I remember now

Drove (and trailered) it today, it took about 10 seconds for me to remember I was supposed to have bought my D2 as a runabout between RR's. I'm in love.

Anyway didn't get a chance to do any proper testing but what I learned is that it starts willingly from hot or cold so long as the throttle is virgin. In fact it was on the button this morning. The only other clue I have now is that with anything other than light throttle there's a hesitation - like a tiny splutter/miss when acceleration is asked for.

This is ringing bells with me now but I can't quite remember?

Thinking of doing a full ignition revamp FF, just for peace of mind.

How did you sort it Nige?

George

Sounds all the more like air being sucked into the fuel system. Such leaks are hard to find as they are so small they don't let fuel out. Just be methodical - check each metal union for wear on olives and for tightness, check fuel lines for splits, chafing or loose fit over barbed fittings. Check the fuel filter's o-rings are in good order and that there is only one o-ring in each position (I had once accidentally installed the new o-ring in the top casing without removing the old one, with similar results).

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If it's behaving odd about throttle you can check the throttle position sensor, the Lucas system is sensitive to this (needs to be adjusted just right) and the design means the wires split & fray for a pastime. Full info on the hotwire is in the technical archive.

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If it's behaving odd about throttle you can check the throttle position sensor, the Lucas system is sensitive to this (needs to be adjusted just right) and the design means the wires split & fray for a pastime. Full info on the hotwire is in the technical archive.

3.9s throttle position sensor is preset there's no adjustments.

I'm sorry but perhaps as u are unable to help u should give up in this thread... ie. "flood clear" mode...?

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Well I just googled that to double check, and you most definitely can adjust Hotwire TPS.

Perhaps if all you can do is spray incorrect information about then you should give up on this thread... i.e. "flood clear" mode... :stirthepot:

:P

On the final page of the Hotwire Diagnostics download in our own tech archive it talks about how the TPS must be adjusted to between 0.29 and 0.36v when closed.

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This may help;

https://github.com/colinbourassa/rovergauge

Free software but you need to make up a lead

I downloaded this and made my own loom. The connector is NLA, but it's possible to bodge custom build something to suit.

A very worthwhile tool that costs very little. You can't do a whole lot with it, but it's what you can see with it that is most useful, hence a valuable diagnostic tool.

All error codes can be read, so if you have an iffy sensor somewhere this will certainly make finding it easier.

Edit to add that I found a huge amount of knowledge on the 14CUX on TVR forums, all the way to custom mapping the Lucas ECU :o

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... and have a windows based machine

Thanks task, will def look into that, probably when all else fails

There's a .deb and also source so you can compile it yourself on Linux, I'm sure it could be made to work on an Apple Laptop too if that's your perversion ;)

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Not convinced I've gotten away lightly yet but I've found the root of the dodgyish idle thats for sure. Could this be the cause of the starting issue too?

The air bypass valve has been abused. I was [gently] wiggling the wiring plug to remove it so I could remove/check the ABV, when the whole ABV started to wiggle too. It snapped off! Have a look below, it was being held on by a mere blip of good metal, as evidenced by the tarnish/dirt on 90% of the break that was obviously letting air in. You can see the shiny piece that is fresh metal where I snapped it. The valve itself was gunked solid so no way it was operating anyway. I see them for £10 on ebay, are these ok?

The tie wrap tight on the body suggests someone knew something wasn't right, just not quite what.

post-1811-0-44784800-1454775434_thumb.jpeg

post-1811-0-51164000-1454775611_thumb.jpeg

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