The hot and cold resistances of temperature sensors tend to be fairly standard. A few thousand ohms cold and a few hundred hot from memory. That's the easiest thing to check first. Of course plugs and leads might be sensible things to replace if they're old.
My Lupo (T reg 1.4l 16v petrol) isn't starting properly if the engine is warm (i.e. stopping at a petrol station). You have to turn it over for a while or let it cool. It's happening most times (so should be easy to show a mechanic). When I do get it started, it's running as if the engine is cold. So it's idling at 1200rpm, if you remove your foot from the accelerator (i.e. changing gear) there is a lot of engine resistance. It takes as long for the car to get back to normal again as it does when starting from cold.
My guess is a sensor has gone and it's resetting the car to cold run. Any more detailed suggestions than this?
Regards,
Tim
OK, so I've never owned a car with a computer or that takes any input from temp sensors etc, but my old bangers have often taken many turns of the starter after a long run when running hot. The solution is to press the accelerator to the floor ONCE and hold it there while turning the enngine until it fires. DO NOT release the accelerator or press it again as you will risk flooding the carb.
Graham
Find someone friendly with VAG-COM. Get the codes read. If there are no stored codes, perform a throttle body alignment.
To find someone with VAG-COM, go to a forum for one of the main VAG brands (Seat/Skoda/VW/Audi), and there will usually be a list of people that will help for beer or for free.
Assuming it is not something silly then it sounds like a failing crank sensor
You can also see what temperature the ecu thinks it is which will tell y= ou =
if a temperature or coolant sensor is up the swanee.
There hasn't been a car sold in the UK with a carb since 1992 tho AFAIK .. apart from the Lada Riva. a T-reg Lupo is hardly an old banger, the advice you have given won't work with it like on old bangers with carbs unfortunately ..
Mike P
Indeed. I'd forgetten about that. VAG-COM can read most sensor values in real-time, and indeed log them. You can graph the results in Excel, so an intermittent, starting to fail sensor would show.
That's the definite way to find a failed MAF on a TDI, by the way. You graph expected against actual values while hooning the car around the block flat out.
Works on some flooded things.
Yep. Some modern cars have a programmed flood clearance that you activate by flooring it while cranking.
The advice does have some validity; some cars will detect flooding, and prevent a start. The software will detect "cranking+non-running+throttle-wide-open", and will stop firing the injectors to allow the flood to be cleared. This is actually the method of starting a flooded Ford as advised in the owner's handbook.
Nissan and others do something similar.
Chris
Fair enough, I stand corrected, sorry Graham!!
Mike P
Well most modern cars don't flood in the first place :-) Some have to put instructions in the handbook for when they do...
You can create a flooded engine situation with a Zetec and others easily. Start it from cold, switch it off almost straight away, then try and restart it. 50% of the time it will have flooded.
The point is, some manufacturers have been clever enough to have written software that enables you to recover from a flooded engine. It would seem sensible that the instructions are indeed then in the handbook :-)
With things like Micras, also notorious for flooding, it often means removing the fuel pump fuse before extended cranking in order to recover.
Chris
Yes
But most just don't flood in the first place.
In message , Mike P writes
Robin Reliant but I suspect that's stretching the definition of car.
I guess this thread is long since dead, but...
Turned out to be little more than the temperature sensor. The dash temp gauge wasn't working and this is the same sensor for engine temp. A coolant change wasn't even required. Simpler than I expected really.
Regards,
Tim
the info that the temp gauge was inop would be a useful clue
Yes that it would, sorry. I didn't think the two were related. I had an old Fiesta that temp gauge always seemed a little on the cool side. When I replaced the coolant sender, I think the sender for that was just for the gauge. I think temp sensors/senders were a tad different in those days as well, because this would happily move from just top of cold to just below warning, my more recent cars just report a nice 90C.
Regards,
Tim
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