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Discussion Starter · #1 ·
Hi

I've just bought a 2 pin sensor to address hunting/poor idling but am wondering if I whould replace the 4 pin sensor as well.

Can someone give me a noddies guide to what the 2 pin and 4 pin sensors do.

Cheers
John
 

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One tells the ECU how hot your engine is. The other controls the temp. gauge. I can never remember which is which. I should but I don't sorry. No harm in swapping both but if your temp. gauge is working as it shoul dthen you could hold off a while on that one perhaps.

Vac leaks and relay 30 are the other two areas to look at.
 

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Ah the 4 pin does the aux pump...been noticing mine seems to be running more lately, and my battery isn't sounding too good. Is there a chance the snesor is on the way out causing the pump to run too long ?
 

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Ah the 4 pin does the aux pump...been noticing mine seems to be running more lately, and my battery isn't sounding too good. Is there a chance the snesor is on the way out causing the pump to run too long ?
Quite possibly. When mine went the temp gauge initially started getting a bit erratic and then went to one extreme or the other (can't remember which) and the aux water pump started to run almost continuously. I ended up disconnecting the 4 pin sensor to stop the pump until I got a new sensor. It sounds like a new sensor will fix your problemT:
 

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2 pin is ECU - so you've bought the right one!

4 pin is temp gauge and aux (electric) water pump. If you're temp gauge is working as expected, then it's probably fine.
Hi, have read this before, but my aux water pump would run on and drain the battery, so with the engine off and my battery charged up, i stood in silence listend to the pump running, then disconected the "4" pin and did nothing, so i disconected the 2 pin and whallah!! The pump stopped! Also the wiring to the 2 pin is much bigger than the wires to the 4 pin, that would also lead me to think the 2 pin is for the pump,+ for the last 6 months ive been driving around fine with no battery drain and the 2 pin left disconected, with every thing else all workin, ie temp gauge and ecu working fine!!
4 pin ecu/temp gauge
2 pin aux water pump

Hope this helps matters.
Cheers
 

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Ps, also i did have a fault with my van, By the way mine is a 2.0l petol also, earler in the year it started playing up cutting out and coughing and splutting, and lots of BLACK smoke, only inermitantly,and i changed the 4 pin sensor and its been right as rain ever since!! Except it has a odd habit of cutting out on me when pulling up to a roundabout on the odd ocasion that ive not yet been able to put my finger on yet. but i can live with this and drive it as i try to resolve the issue.

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4 pin ecu/temp gauge
2 pin aux water pump
That's definitely not the standard setup - I wonder if you're van's been re-wired at some point?

it has a odd habit of cutting out on me when pulling up to a roundabout on the odd ocasion that ive not yet been able to put my finger on yet.
This is classic vacuum pipe problem. Try replacing the small bore (3.5mm) vacuum pipe which runs from the right-hand side of the inlet manifold (as you look at it) to the fuel pressure regulator and to the ECU. They perish with age and start leaking. Should sort your problemT:
 

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That's definitely not the standard setup - I wonder if you're van's been re-wired at some point?



This is classic vacuum pipe problem. Try replacing the small bore (3.5mm) vacuum pipe which runs from the right-hand side of the inlet manifold (as you look at it) to the fuel pressure regulator and to the ECU. They perish with age and start leaking. Should sort your problemT:
Cheers, for yr post, ive replaced all the vac hose, right from ecu back to the fuel presure reg, the lot. it did make it better as the old pipe was perished. and ive replaced the relay for the ecu up above the glove box. but every one in a while it will cut out on pulling up to a junction, i look down and the battery light has come on and the sreeing feels heavy, some time if i catch it i will just let the clutch and bump start it, i was wondering if it could be the idle control valve? but ive checked that and it seems to be working ok?

Cheers
 

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Cheers, for yr post, ive replaced all the vac hose, right from ecu back to the fuel presure reg, the lot. it did make it better as the old pipe was perished. and ive replaced the relay for the ecu up above the glove box. but every one in a while it will cut out on pulling up to a junction, i look down and the battery light has come on and the sreeing feels heavy, some time if i catch it i will just let the clutch and bump start it, i was wondering if it could be the idle control valve? but ive checked that and it seems to be working ok?
I'd check the idle switch in the Throttle Position Sensor (TPS) is working properly? (is it maybe a bit sticky and not working every time?) I'd also check for any air leaks around the inlet manifold. Wouldn't harm to put some carb cleaner through the throttle body & ISV - might help clear things out. Hope you get it sorted.
 

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Discussion Starter · #12 ·
Cheers, for yr post, ive replaced all the vac hose, right from ecu back to the fuel presure reg, the lot. it did make it better as the old pipe was perished. and ive replaced the relay for the ecu up above the glove box. but every one in a while it will cut out on pulling up to a junction, i look down and the battery light has come on and the sreeing feels heavy, some time if i catch it i will just let the clutch and bump start it, i was wondering if it could be the idle control valve? but ive checked that and it seems to be working ok?

Cheers
I have found my problem (uneven idling/hunting) and it is the ISV seal between the ISV and the throttle box. I could not get a replacement anywhere in the UK or Europe, apparently obsolete now and scrappies throw these away when dismantling for parts. I have ordered a replacement and spare from the states at an extortionate price (£70 inc delivery for the two), But the van runs likes lumpy at idle without it so I've bit the bullet, if anyone cant get one from a scrappy and fancies splitting the cost with me I may part with the spare. You can check your ISV seal by packing grease around the seal to temp block any leak. This is what I did and the can idles like a good un. This is not a long term answer as the grease runs off when the throttle box gets hot. I also tried silicone gasket but its too difficult to get a good seal so I gave that one up. Some people have used other types of tube 1" diameter x 19mm bore but I was advised against this incase the pipe broke down under heat and crumbled into the air intake.
 

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I'd check the idle switch in the Throttle Position Sensor (TPS) is working properly? (is it maybe a bit sticky and not working every time?) I'd also check for any air leaks around the inlet manifold. Wouldn't harm to put some carb cleaner through the throttle body & ISV - might help clear things out. Hope you get it sorted.
Would take throttle body off and use some carb cleaner and a toothbrush to give it a good clean a new gasket is only a couple of quid from VW , I also sprayed some carb cleaner through the idle valve to give this a clean too , just did mine last week and its made quite a differance.
 
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