vr not starting on the turn of the key (takes awhile)

[Chris 0]

quick question.

 

its not a massive issue but i would like to sort it.

 

when i start the vr from cold the starter motor will turn over for about 5 seconds or so before it fires up. if i turn it off and start it back up again, no problems, itll fire straight away, but, if i leave it for 10mins or so, regardless whether its hot or cold it will take 5seconds or so to fire again. its doesnt ever not start.

 

i no it doesnt sound like much but when it happens to you youll agree it feels alittle too long before it fires.

 

could this be a fuel pressure problem? i know my 16v fuel pumps on its way, it has been buzzing alittle loud recently every now and then? i could be wrong in thinking this, but its the only thing i can think that is slightly wrong with this car. when i first got the engine running a few months ago it started fine, pretty much on the key then i started having this problem. i took the inlet off for polishing a short while ago, when i started it it started fine, but again, the problem came back.

 

 

any ideas?

 

i dont expect it to start like a new car but it should definately start quicker than this.

[Toad 0]

The engine needs to rotate a certain number of times before the ecu recognises the crank and cam sensor positions.

 

MrBeige told me that.

[dirtytorque 0]

The engine needs to rotate a certain number of times before the ecu recognises the crank and cam sensor positions.

 

MrBeige told me that.

 

 

what he said.

engine just needs to get in sync b4 attempting to fire.

[Toad 0]

I've lost the ability to form coherent sentances without thinking long and hard tonight.

[Chris 0]

and the fact i havent been driving it doesnt really help.

 

cheers guys, makes alot of sense now.

[Neil VR6 0]

The fuel pump in the VR apparently has a one way valve in it to retain pressure between the pump and the engine so the fuel system is essentially primed for when you want to turn the engine on. If this is on the blink it can lead to starting issues which you describe. I have a similar problem:

 

viewtopic.php?f=1&t=71039

[Kevin Bacon 5]

Yeah it's a little ball bearing and spring arrangement. Sometimes the ball can lose it's seal, allowing the pressure to be lost in the rail, but it's quite rare. When the pump primes, it will (or would if it's healthy) build 4 bar of pressure within the 5 second prime time. So it could be a sluggish pump.

 

The engine needs to rotate a certain number of times before the ecu recognises the crank and cam sensor positions.

 

I think the VR6 starts in batch mode because inductive cam sensors don't usually give a strong enough signal when cranking. When the engine is running, the cam sensor kicks in and sequential injection resumes.

 

Both the crank and cam sensors are magnetic (no power supply), so they too can get weak with age.

[Chris 0]

Yeah it's a little ball bearing and spring arrangement. Sometimes the ball can lose it's seal, allowing the pressure to be lost in the rail, but it's quite rare. When the pump primes, it will (or would if it's healthy) build 4 bar of pressure within the 5 second prime time. So it could be a sluggish pump.

 

The engine needs to rotate a certain number of times before the ecu recognises the crank and cam sensor positions.

 

I think the VR6 starts in batch mode because inductive cam sensors don't usually give a strong enough signal when cranking. When the engine is running, the cam sensor kicks in and sequential injection resumes.

 

Both the crank and cam sensors are magnetic (no power supply), so they too can get weak with age.

 

 

maybe my pump is more f'd than i first thought, it only gives me a very quick prime. i can only hear it prime for about a second. its alway been like that, and thinking about it, the old 2l 16v that use to be in it had the same sort of issues, i just thought it was a crap engine.....

 

ill replace the pump first, if no difference ill try the crank and cam sensors.

 

 

cheers :salute:

[Neil VR6 0]

I phoned up my local VW garage about my problem and he reckoned the most likely culprit was the cam sensor as they tend to go more than fuel pumps in his experience of dubs of this age. Still, nothing's ever simple with Corrados!

[Kevin Bacon 5]

A dead cam sensor wouldn't stop the car starting as in your case though. It just puts the ECU over fuelling mode.

 

If it does rely on the cam sensor for starting (I'll need to check that out), then it might explain the lengthy starting if the sensor is going.....

[Supercharged 2]

CAM sensor No, the ECU requires a signal from the CRANKsensor before activating the FP relay tho...

[mattkh 0]

the ECU requires a signal from the CRANKsensor before activating the FP relay tho...

HI

Do you know, I am sure you will, what cranking signal the FEI unit on a 16v 1.8 KR uses to activate the fuel pump relay ?

[Chris 0]

ive replaced the fuel pump + filter etc, given it a good run around but still experiencing the delayed fire up after afew minutes of running it, hot or cold. do we suspect the crank sensor? just posted a wanted ad up for a good condition one but been told in that 'they either work or they dont'. not sure what to think. its got to be fuel related, just seem to me fuels not being let through quick enough (a few drops of fuel down the plug holes and it fires instantly as expected)

[dr_mat 0]

its got to be fuel related, just seem to me fuels not being let through quick enough (a few drops of fuel down the plug holes and it fires instantly as expected)

 

Jeez, confusing with two threads on the same subject.

 

Well that proves your crank sensor is fine. If you have spark then crank sensor is working perfectly. Change the FPR or look at your plugs see if any are flooded with fuel after you've left the car standing a while. Sounds like fuel supply probs, as you say.

[Chris 0]

its got to be fuel related, just seem to me fuels not being let through quick enough (a few drops of fuel down the plug holes and it fires instantly as expected)

 

Jeez, confusing with two threads on the same subject.

 

Well that proves your crank sensor is fine. If you have spark then crank sensor is working perfectly. Change the FPR or look at your plugs see if any are flooded with fuel after you've left the car standing a while. Sounds like fuel supply probs, as you say.[/quote:395dz46k]

 

lol we'll use this thread from now on :) . im sure the pumps good, its from a 80k 16v. injectors may need a clean but ive checked they squirt ok, plugs all spark as they should, FPR is the last thing to check i guess for this type of starting issue.

is it something that generally goes after awhile?

[fla 9]

i've just started getting this problem, although its more when the car is warm that it takes an age to fire up. Turns over brillantly, but wont fire up.. ecu relay is new as is the fuel filter, no fuel smell though. When it does start it'll run fine, no hesitamcy ofr anything. Yesterday it took a few cranks so i stopped cranking it, turned teh key back fully then tried again. It was even worse after that. This morning it started fine, then this afternoon after a short run its back to being crap again. seems to have coincided with the run-on function not working either, so i dont know if there is a link there? dont think so, mind you.

[fla 9]

ok this seems to have sorted itself out, meaning its going to be an intermittent problem, hence electrical more than mechanical perhaps? I've got a spare VW ignition switch, (which is actually fine), which i replaced some 4 years back with a GSF one, so maybe thats the problem.

Thanks for the pm Chris :wink: