Possible Crank Sensor?

[Roon 29 1 Cars]

Hi guys.

 

Driving home last night my engine whilst I was sitting at 65 starting missing constantly. Got it home tested the battery alternator all is good.

 

We restarted it which is did but not very well and does idle ok ish but under load misses. Then after some messing about it Didnt start at all.

 

Bumped it and it ran and missy again. Took it up the road and it sorta cleared brung it back won't start.

 

Thinking crank señsor? Just bought a new one to try.

 

Am I right in thinking that's the issue?

[Tom Fenton 1,526]

Come on buddy, give us a f***ing clue, WHAT ENGINE!!!

[Roon 29 1 Cars]

Oh yeah gti6

[Anthony 1,000]

Crank sensors in my experience seem to either work or not work - don't tend to cause mis-firing or random non-starts.

 

Given that it's a GTi-6, I'd guess that a failing coilpack is far more likely as a source of a misfire.

[petert 554]

I had a faulty crank sensor recently. The car would start fine and run ok most of time. Occasionally for example, whilst sitting at the lights, the engine note would change. I'd go to drive off and have zero power. Restart the car however, and it would be fine again, until next time, maybe 2-3 days later. It was like the ECU lost it's reference. I replaced the sensor and the car hasn't missed a beat yet.

[Roon 29 1 Cars]

Yeah mine can be like that a bit now and again.

 

Going to try it tonight.

 

If it was coil surely it would at least fire up. It's not even doing that now. Coil pack will be my next guess.

[welshpug 1,626]

stop guessing, and check stuff!

[dcc 855]

could be fuel pump

[jackherer 543]

I got a handheld digital oscilloscope a while ago for problems like this, I've seen several 205 16vs now with running problems caused by interference affecting the crank sensor and the only way to know what is going on is to look at the square wave from the sensor at the ECU connector.

 

The 'scope I got only cost about £40, do a google for ARM DSO Nano DSO201. It's small and cheap enough to keep in the car and drive around with and as it has limited data logging you can refer back to the waveform when the problem actually happened.

[GLPoomobile 958]

stop guessing, and check stuff!

 

That's all very well, but some people don't know what to check and how to go about those checks. So they ask on here for guidance. The random guessing game approach is usually taken by those who are less experienced.

 

Roughly translated - don't be a d*ck, throw the guy a bone

[welshpug 1,626]

bones have already been thrown

[Anthony 1,000]

If it was coil surely it would at least fire up. It's not even doing that now. Coil pack will be my next guess.

You'd think so, but I've seen it before where a failing coilpack has made a GTi-6 a real pain to start - not the usual firing easily but only on 3 cylinders that you'd usually get, but rather lots of turning over and eventually catching and spluttering into life.

 

Certainly a misfire that's worse under load would have me typically looking at the coil firstly, then sparkplugs and MAP sensor. Most other parts would typically give issues that wouldn't generally be affected by load.

[Roon 29 1 Cars]

As said my experience is poor with these lumps so use to fords which to be fair have been spot on. Only thing ever to go wrong like this was ICV and TPS.

 

I've ordered a few bits as I need spares anyway. Have coil pack crank sensor a Giuide to go by what should be putting out etc so booked a day off tomorrow to try and get to the bottom of it

[Roon 29 1 Cars]

Quick add on how hard is a fuel pump on these and is another standard 1.61.9 8 valve one fine to use?

 

Noticed it doesn't seem to be priming sure of it. Would the above symptoms do this?

[Anthony 1,000]

Fuel pump is easy enough to swap - two fuel pipes, a wiring plug, and a handful of 8mm head bolts - and yes, a good 205 GTi item is fine to use.

 

They differ between early (Phase 1 / 1.5) and Phase 2 cars, so make sure that you get the correct type.

 

However, failure symptoms don't sound like the pump itself to me - they tend to either just suddenly die completely, or more usually, become weak and not deliver the fuel flow they're supposed to, making the engine run lean at higher revs. The later you don't tend to notice so much on 8v engines, but the increased fuel demands of a 16v / Turbo engine tend to highlight it, hence my comment about using a good pump.

 

GTi-6's don't seem to prime all the time anyway after an initial prime, and regardless, the fuel pump relay or a dodgy alarm is probably more the culprit. If you unplug the battery/ECU and reconnect it, the fuel pump should prime for around 10 seconds or so next time you switch the ignition on.

[Roon 29 1 Cars]

Thanks for that info Anthony really helpfull

 

It's not got a alarm at all luckily.

 

A lot to try out today.

[Roon 29 1 Cars]

Ok so changed a few bits tested power in places and nothing.

 

All it does now is turn over with not so much as a cough or splutter. Took the return off and there is no fuel coming out at all.

 

The fuel pump I can't hear prime so tested that. has no power going to it whatsoever.

 

Going to try changing that tomorrow.

 

Anyone know where the fuel pump relay should be on a gti6 conversion?

[welshpug 1,626]

Same as it would be originally, near the ecu

[Roon 29 1 Cars]

It's not there my Ecu is in the engine bay., I had one go on my old 1.6 and as tou say by the ecu. when you click the ignition on i get a clicking coming from the boot and there's a relay back there.

 

Hate this s*itty cowboy wiring loom!

[welshpug 1,626]

Yes it is, it will be near the ecu.

[Anthony 1,000]

As above, it will be somewhere in the vicinity of the ECU, possibly hiding underneath the expansion tank.

 

Look for a black or brown relay that's about the size of a large box of matches.

[Roon 29 1 Cars]

Thanks guys ill get looking tonight. Have a fuel pump ready if its that but a simple relay would be easier and cheaper.

 

Is the relay a 306 item then?

[ORB 227 1 Cars]

They are on a lot of cars. Does not look like a normal relay per se, I'll try get a a picture.

[Roon 29 1 Cars]

I've just rang the dealer. It's a updated 'improved' relay so 44.93 inc VAT.

 

Old part number was 19203N

New 454935.

 

Really appreciate all this help guys currently renting a car and that isn't cheap trying not to give up on her.

[Roon 29 1 Cars]

The fuel pump, look right? For a phase 1 D plate