Bit of knowledege and advise please

[Keyo 47]

Hi all,

 

VR6 very late model N reg 157 k Shrick VGI

 

I have the bad start when warm and engine is feeling a bit slow.

 

I have all ready repaced the MAS Sensor, lambada, catalitic, PVC valve and hose and given the car a a good service, has had new sparks and leads etc, ignition coil.

 

After reading on here alot of people are mentioning the below

 

Crank sensor part number if possible ? is this the same as a cam sensor ?

 

Blue temp sensor part number if possible025 906 041 A this is 2 pin but I have seen 4 pin mentioned ? Is this the fan switch as it has been changed by th

 

FPR Regulator is this the right number 078133534C , is this 3 bar or 4 bar.

 

Any advice would be much appreciated I tend to go for Bosch parts or anything thats going to last.

 

Thanks lads,

Edited December 21, 2018 by Keyo

[_Matt_ 26]

I've had similar issues and replaced most things too - Crank, Cam, Coil, leads, Coolant sensors, Thermostat, FPR, Fuel Relay. None of it made a difference unfortunately.

 

Recently I installed a one way valve at the fuel pump and it seems to have made some difference. This was on recommendation of a few chaps on here. I usually like to understand how something has fixed the issue but don't get it on this one. The FPR is supposed to maintain pressure in the rail so a one way valve keeping more fuel in the line shouldn't make a difference. Cold starts are fine so you'd assume the issue would be present when cold if it was a fueling issue. I'm not aware of whether the fuel pump serves more fuel on cold vs hot starts.

 

My other port of call is the injectors. I'm similar mileage (151k) and believe they've never been serviced. Leaky fuel injectors would cause warm starting issues as they leak fuel held in the rail into the cylinders. When warm this would flood the engine but when cold most of it will have evaporated. Worn injectors also cause performance issues and idle vibration (I have this too). I'll be whipping them out for servicing (

[Keyo 47]

I would say you are probably spot on with your prediction , Im near Birmingham anyone know a good place to get the injectors cleaned in that area. I would say mine have never been serviced either.

 

So I have purchased

Blue temp 025906041A OEM VW O ring and clip

FPR 4 Bar Bosch 078133534C

 

What was the part number for your can and crank if you dont mind me asking.

[GlosterOx 0]

Recommend Mr Injector: https://www.mrinjectoruk.co.uk/

[_Matt_ 26]

I was going to use mrinjector too. He has quoted 85 to do all 6. Can’t remeber if that was plus VAT.

 

It is probably worth changing the blue sensor (can do without draining coolant if you are quick - make sure you get the old o-ring out). FPR can be a bit of a struggle to get out of its housing and you’ll likely chew the old one in the process.

[Keyo 47]

Is it worth replacing the two sensors either side of the blue sensor?

 

That does sound like a good price I think I need to do my seal Valves to.

[fendervg 30]

The other two sensors are for the coolant temp gauge in the dash and for the radiator fan control unit - not a bad idea to replace if they haven't been renewed, but also not essential if these are behaving normally - it's as easy to do all 3 while you're in there.

 

MrInjector seem like a good choice. I would also very carefully hunt for intake system vacuum leaks. I had terrible idle/cut-out issues and it turned out to be this - check out the PCV valve and assembly and the lines that run from beside the fuel rail under the air box.

[dr_mat 0]

I would definitely say temperature sensing could be a big part of this. Obvious thing is to scan the ECU and see what it thinks is going on.

 

Leaky injectors would drop fuel into the inlet manifold, not in the cylinders themselves, though im sure there are many ways they can cause issues.

[SteveM 10]

The blue 2 pin temp senders typically register around 200-250 ohms across the pins when the engine is at normal operating temperature. They were a constant source of hassle back in the day on the Polo G40's. Pattern part items didn't seem to last very long and their values were often outside of tolerances.

[Keyo 47]

Thankfully I have ordered the blue temp sensor VW OEM from parts international.

[a_riot 0]

Thankfully I have ordered the blue temp sensor VW OEM from parts international.

 

You can test that sensor easily enough if you have a ohmmeter and can boil some water, so no need to throw good money after bad. In fact many of those parts you've replaced can be tested. You'll eventually go broke if you repair the car this way, and it can add red herrings to the issue as well.

 

If the crank sensor was bad, the car wouldn't start at all. If it was the one way valve on the fuel send line, you'd have good warm starts but hard cold starts.

[Keyo 47]

It is true what you say but I use my corrado every day and really dont mind changing the parts for peace of mind as the car is over 20 years old so they wont have long life left, also will maintain the value of the car, but like you mentioned not a cheap way of doing things and probably a bit ocd.