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Discussion Starter · #1 ·
Right.. I have a bit of a problem.

Details: mk4 golf, 98 agu.

Had an intermittent misfire or surging problem over the last year or so. Now, today when driving to work I noticed the temp gauge was hanging on one notch below 90 (it normally never budges from 90) Once I had arrived at work about 6 mis later it was back on 90 again. it slowly moved back up to 90 during this period.

Now, I had the surging (thought this was the maf on it's way out?) and noticed the temperature gauge irregularity again on the way back home tonight (same route as this morning). I'm sure i've read on here something about a temperature sensor that can cause a surging issue ?

Would this throw up a code ? The gf's mate is comin' over tomorrow night and her bf runs his own garage and has vagcom [:)] so I can get it checked then [Y]

Any help much appreciated guys.. cheers [Y]

Could either of these posts be a similar problem ?

http://www.uk-mkivs.net/forums/430826/ShowPost.aspx

http://www.uk-mkivs.net/forums/379933/ShowPost.aspx
 

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The temp sensor will show a fault code with Vag-Com if it is faulty, it should specifically say if it is that or not aswell in the fault codes section, and also, the emissions will probably be on if that is indeed the problem! [:)]
 

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Discussion Starter · #4 ·
Bump !!

Had it scanned and it only showed the passenger door lock module "Implausible Signal" code that I knew about..
 

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For the sake of ?25 its better to change the temp sensor because sooner
or later it will die anyway. As long as you have a black bodied one in
there then go to the dealers and get a green bodied one.

If a new sensor doesn't solve the problem then check all pipes for
splits or cracks. If not and the temp gauge is still fluctuating after
a new sensor it could be a water pump.

However, the waterpump on its own wouldn't give the surging you mention
which makes me think its the signal from the temp sender.
 

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Discussion Starter · #6 ·
For the sake of ?25 its better to change the temp sensor because sooner or later it will die anyway. As long as you have a black bodied one in there then go to the dealers and get a green bodied one.
If a new sensor doesn't solve the problem then check all pipes for splits or cracks. If not and the temp gauge is still fluctuating after a new sensor it could be a water pump.
However, the waterpump on its own wouldn't give the surging you mention which makes me think its the signal from the temp sender.
Cheers for that help there [:)] [Y]

I'll check to day to see if I have a black bodied temp sender. I'll check for any obvious splits and cracks too. I hope it's not a water pump as I only had it replaced in oct 04 when I had the cambelt done too.

Why would the signal from the temp sender cause that surging issue ?
 

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The signal the sender recieves tells the ECU how warm the engine is and
how much fuel to supply. If the signal is fluctuating it could cause strange fueling until it logs a fault code. Then the ecu will disregard the signal and guesstimate fueling.

It just seems a co-incidence its all happening together!
 

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Discussion Starter · #8 ·
The signal the sender recieves tells the ECU how warm the engine is and how much fuel to supply. If the signal is fluctuating it could cause strange fueling until it logs a fault code. Then the ecu will disregard the signal and guesstimate fueling.
It just seems a co-incidence its all happening together!
Aaaah understood now [:)]

See pic.. Is this the temp sender ?

Posted Image


On another note, i'm now waiting for the volkswagen assistance bloke to arrive, as my bonnet is now stuck due to the catch sticking ! [:(] [:mad:]
 

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Discussion Starter · #12 ·
No problem at all Dan, at least you didnt try and fit a coolant senser in there!!
hehe.. *bang* goes dan's engine. I'll ask the vw techy bloke when he arrives in a minute, if he can get the bonnet open too.. [:S]
 

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that's yer Air Intake Temp sensor in the inlet manifold. Probably worth removing and giving a clean with electrical cleaner as they get a bit mucky over time :eek:)
 

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btw, if you're changing your temp sensor - to avoid losing lots of coolant, I left the cap on the header tank. Also make sure your engine's stone cold!!
 

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Discussion Starter · #16 ·
Cheers guys and pat [:)] and tom [:p] [;)]

I had the vw assistance guy out, he got the bonnet open again. didn't take too long thankfully. Think i'll look into getting a new release mechanism on soon though.

I'll keep an eye on this problem for now and get them to stick a new one in when it goes in for it's annual service soonish and replace it myself if it goes sooner. Might try cleaning the air intake temp sensor in the manifold too, in the mean time, as pat said above.
 

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Have you had you water pump replaced yet, as the fluctuation of temperature could because the plastic impellor on the water pump is breaking to small pieces? If you haven't done it yet, get it done. It should of really been changed with the cambelt and tensioner around 65,000- 80,000 miles (even though the dealers say 108,000 miles).
 

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Discussion Starter · #18 ·
Have you had you water pump replaced yet, as the fluctuation of temperature could because the plastic impellor on the water pump is breaking to small pieces? If you haven't done it yet, get it done. It should of really been changed with the cambelt and tensioner around 65,000- 80,000 miles (even though the dealers say 108,000 miles).
Aye.. done in oct 04 same time as the cambelt.
 
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