1.6fsi crankshaft sensor

J

Jonathan Wilkins

Member
Having misfire problems with my 1.6. Done plugs,coil packs, earth point behind light,thermostat and temp sensor. Car runs fine when it's cold but has an intermittent misfire when warmed up. Decided next step would be the crank sensor. Have found where it fits onto the engine but the other end disappears behind the inlet manifold and I can't see how on earth I could get to a connection without taking half the engine to pieces. Any help would be appreciated
 
I would strongly suggest you investigate fuel injectors.
You are spending money in an useless manner replacing those parts that do not need it.
Is the MIL light on ? Or is it sometimes flashing ?
Have you had the car scanned ?
 
No engine lights have ever been on. When we first got the car the misfire was happening all the time and it didn't get up to temperature. There wasn't even a thermostat in there plus the temp sensors are so cheap it was daft not to change it. Now it only misfires when it's up to temperature and being driven. I suspect someone has already changed the crank sensor as they couldn't get to the bit under the inlet manifold either and just cut wire and used bullet connectors. There's only two wires though and I notice the connector on the new one has three. If I got vagcom what would I be looking for?

Have read that the egr's clog up as well as the inlet manifolds but can't find any guides for cleaning these

I did think we had a dodgy injector when it was misfiring badly before I did the thermostat. Hope it's not as that's a job I can't do

Oh. I did a compression test and all was ok
 
Hi Jonathan,

Like many on here I've chased misfires on my 1.6fsi (now 134000miles) and done injectors as well as all the components you have mentioned. I've got to thinking that my in tank fuel pump is suspect- this has 2 modes- one where the engine is cold or where under high load where it seems to fuel normally and the other in normal lean burn mode where it car seems hesitant and misfires and I think the in tank pump may be starving the high pressure pump driven of the camshaft causing misfire due to reduced fuel. Others have replace the in tank fuel pump wiht success. I know that I could test the pump by putting voltage across it and measure the fuel delivered but I don't know how I could get it to switch between modes and prove it was the pump. They're available from ECP for under £100 so it might be worth a punt.

Any thoughts from others welcome.

P
 
muggles said:
Hi Jonathan,

Like many on here I've chased misfires on my 1.6fsi (now 134000miles) and done injectors as well as all the components you have mentioned. I've got to thinking that my in tank fuel pump is suspect- this has 2 modes- one where the engine is cold or where under high load where it seems to fuel normally and the other in normal lean burn mode where it car seems hesitant and misfires and I think the in tank pump may be starving the high pressure pump driven of the camshaft causing misfire due to reduced fuel. Others have replace the in tank fuel pump wiht success. I know that I could test the pump by putting voltage across it and measure the fuel delivered but I don't know how I could get it to switch between modes and prove it was the pump. They're available from ECP for under £100 so it might be worth a punt.

Any thoughts from others welcome.

P
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A2Steve advertiosed one today?

Did you not see it? It is worth asking him if it is still available.

But if, like me, you have a misfire on a specific cylinder I am not sure how a faulty fuel pump can cause that, it feeds all 4 cylinders.

Steve B
 
I don't think my misfire is on one specific cylinder but it definitely only happens when the car is fully warmed up and under load. Perhaps that's why a previous owner took the thermostat out!

The fuel pump caused all sort of problems on the mrs's previous golf diesel and from a quick search the seem to be a problem across the entire vag range

Have found a new one for £66 from eurocarparts. Looks like I'm doing a few hours overtime tomorrow :(
 
As Birchall as already stated A2steve as advertised a new FSI fuel pump still in the box for £20 if memory serves, hes a top block and will get it to you quickly
 
So changing the intank pump would have no effect? My problem only occurs when the car is warmed up. I'm guessing that the engine being hot or cold would have no influence on the fuel pressure regulator?
 
I would doubt it but as you say its only when the engines hot it could be many things but injectors come to mind as when the engines cold the injectors run fully open as on choke as such then when car reaches a certain temp they cut back, my 1.4 petrol had miss fire problems ocassionally and after swapping complete fuel rail , pressure valve and injectors with a second hand unit it cured my problems but its no easy task finding the exact cause for such problems as youl find out reading through other threads ... good luck with getting it sorted
 
How hard is it to change the fuel rail/injectors Just changed the injector seals on my mazda 6. Took half an hour to do all 4. Guessing this will a bit more time consuming!
 
Jonathan Wilkins said:
How hard is it to change the fuel rail/injectors Just changed the injector seals on my mazda 6. Took half an hour to do all 4. Guessing this will a bit more time consuming!
Click to expand...
I would put aside a day.

They are tucked away at the back of the engine under manifolds and pipes. Perhaps 4 hours to change all injectors if you have done it before?

steve B
 
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So I'm thinking the fuel pump should be ok as it's working harder when the engines cold? Is there anyway of knowing if a particular injector is faulty whilst still on the car?
 
Jonathan Wilkins said:
So I'm thinking the fuel pump should be ok as it's working harder when the engines cold? Is there anyway of knowing if a particular injector is faulty whilst still on the car?
Click to expand...
Hi,

VCDS will often show a persistent misfire on that cylinder if the injector is bad.

If it is not singling out specific cylinders then that MIGHT mean that the problem lies elsewhere.

Steve B
 
Jonathan Wilkins said:
I don't think my misfire is on one specific cylinder but it definitely only happens when the car is fully warmed up and under load. Perhaps that's why a previous owner took the thermostat out!
Click to expand...
Mine did the same : it ran fine when started from cold, and misfired when hot. (MIL was on and sometimes flashing)
It was a faulty injector (but had all 4 replaced).
If the fuel pressure wasn't high enough, the ECU would know it from the pressure sender and would adapt (fueling/ignition) accordingly, but I don't think that would result in misfires.
 
All this is in my thread for exactly the same symptoms, but...

I've got exactly the same issue on my FSI but I'm also throwing codes for the Camshaft being excessively advanced & in the measuring blocks the ECU is requesting x degrees of retard on the inlet cam but actual position isn't moving from 0. The symptoms this is causing are poor performance etc. and the Rosstech website says potential causes are fuel pump relay or camshaft position actuator. I get misfire multiple cylinders and misfire cylinder 3 and I'm quite sure an injector could be the issue, but i'm checking the timing on the cambelt, the actuator and the oil galleries (where I can) for any build up of sludge.

The FSI is really an advanced engine even for today, I'm trying to avoid injectors where I can because they are £100 a pop, 4 injectors is nearly what I paid for the car!!!

I don't know what your car is like, but it doesn't ever sound or feel like the car is suffering from a misfire except for idle where the car stutters every now and again, but when i'm moving it just feels like somebody throws a switch and the car suddenly has no power! I can hear the induction from the engine like it's trying to go, but just doesn't go!!

I'll update any progress through my thread, there is a way of doing a test through basic setting and once I know i'll let everyone else know.

Nick
 
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