rough start up breakthrough for dk and spaniel

[scotsjohn]

I have to admit to being a right twat on this; I've been looking at it the wrong way round. My rough running came in when the thermostat opened and the blue sender heated up. The ECU was driving the revs down too far. DK and Spaniels is the reverse; the hot sender gives smooth running, lifting the engine out of an unstable mode.That being the case I'd say the sender and loom are ok as the ECU's getting a signal through. The sender wouldn't appear to be that critical,not sending a variable message to the ECU, just a basic on/off action. Someone else has posed the question, what else governs start up, what have we got ?

[supercharged spaniel]

right i will do cheers lads....gonna leave it for now im sick of the sight of it ha ha..havent checked this earth thing you speak of..is this the one on the near side chassis leg hidden in the thick of the loom?  defo next to do is to check the resistance of the wire on the ecu loom plug back to this sensor. thank yoooo

[supercharged spaniel]

I have to admit to being a right twat on this; I've been looking at it the wrong way round. My rough running came in when the thermostat opened and the blue sender heated up. The ECU was driving the revs down too far. DK and Spaniels is the reverse; the hot sender gives smooth running, lifting the engine out of an unstable mode.That being the case I'd say the sender and loom are ok as the ECU's getting a signal through. The sender wouldn't appear to be that critical,not sending a variable message to the ECU, just a basic on/off action. Someone else has posed the question, what else governs start up, what have we got ?

well ive thought about this too...i spoke to a vw specialist and the bloke said 'well your sensor is obviously sending a signal and so are the wires because the engine or ecu is reponding to the info given by it' but can the wires just be faulty? or like you say...is there something else controlling start up?

either way ill check the wires but i need a little info to get started as its not something i have experience of doing...

say i take the big connector off the ecu and start checking the loom side of the plug for resistance?  looking at the faq thing it says: ignition on pin 6?  (for the coolant temp sensor remember) but when ignition on at 20deg and 80 i think it says pin 10? why does it change? hows it not always pin 10?  another thing..we should be testing ohms here? but the table says it should be 0 volts? and 1.5 volts etc? hows that?  it could be plain obvious to someone whos clued up on this side of things but im delving into the unknown here..some help is greatly appreciated.

also (quote) 'Make sure the earth pins on the ECU harness have almost zero resistance to the negative on the battery'  .  a little more detail here would be great...earth pins are 13 and 19 so what do you do exactly with the multi meter?


'Then just go round each sensor that connects to the ECU making sure there is almost zero resistance between the sensor pin and the pin in the ECU connector'  so is this a case of one wire (of the multimeter) on the loom pin and one on the ecu and checking resistance?

[scotsjohn]

Took the bull by the horns and fired up without blue sender connected. Engine ran at smooth fast idle(1100rpm) till thermostat opened. That made no differance, still 1100 adjustable with idle screw up or down.Plugged in sender and normal service was resumed ok. Does the  idle screw setting on it's own provide a base line that the ECU modifys courtesy of the blue sender to suit engine temp.

[DKnight]

fired up without blue temp sender in???

it shouldnt start?

[hayesey]

yeah it'll start without the blue temp sender in it'll just be in limp-home mode though and will run shit. 

The idle screw just lets a certain amount of air past the throttle plate to allow the engine to idle, more air = higher idle.  The blue temp sensor is used to adjust fuelling according to engine temp, colder engine = richer mixture. 

[supercharged spaniel]

well today im gonna start by stripping the loom mon the chassis leg and check these earths....see what we got.

[supercharged spaniel]

right well today i stripped the loom down and checked the earth crimp and found nothing...then i started stripping it around the lambda/starter/knock sensor plugs and found a horrendous bodge on the starter plug???  some gimp had cut the plug (loom side) on the live red wire and soldered two single core wires into the gap?  looked awful!!!! the two wires were also stripped half way along and twisted togther?  obvioulsy didnt have a thick enough section of wire so made do with 2? 
anyway cut i out and soldered the loom section back to the plug as they should have done!  re wrapped and all good.  going to start checking the voltage on the loom for the blue sender in an hour or so...
ordered some genuine vag loom tape to re wrap the loom tape ive stripped too which is around 4 quid a roll and arrives wednesday so hopefully i cn find the problem before then.

[supercharged spaniel]

just a quick note....i will NOT be defeated!!!

[DKnight]

well i fired mine up to show pinches the problem and it did it rough for about 20seconds and that was all, so i have altered it, but not cured it...

ive lost intrest in it so im going to see what else i can think of...

[G4O LP]

Solve this please haha I dont have the problem but I read this thread like 3 or 4 times a day to see what the cure is to this frustrating problem for you guys.

[supercharged spaniel]

ha ha...well ive not checked the values on the loom as yet but will do this week.

I did notice this morning which im not sure ive mentioned but is worth a good mention, is that the car does not idle high as it should on cold start?  it starts and idles at the normal speed it would when warm?  so around 950rpm not 1100 ish that it should? obviously miss firing at the same time.  it only idled properly as a cold start when i put a warmed temp sensor on the plug, the other day...does this indicate anything or spark any new ideas? 

what about throttle body?
isv?   these are two things i havent changed but only cleaned..

without checking the loom with a multi meter i havent found any apparent breaks or problems and the earth crimp was perfectly clean under the wrap...cleaned the earth straps on the inlet manifold too.

[supercharged spaniel]

looking through the bay again today ive noticed that there is quite a lot of oil vapour build up around the isv...now i cleaned it a while back just before summer and i put new jubillee clips on it on both ends and tightened them on tight and i know my boost pipes are as they should be so im not thinking dodgy charger seals but a possible leak on the case of the isv?  either its leaking and when the sensor says cold....open more its got a leak which makes it open but loose pressure??? i dunno im stabbing in the dark here but its electronically controlled so its possible its just not working properly either...dan knight reckons the issue came soon after fitting another 'cleaner' isv.  some one explain some good reasons why this could be at fault please!  the oild vapour is defo from the isv and not anywhere else everything else is bone dry....

[supercharged spaniel]

oooo ooo i also suffer from a slight hic up on ilde every so often too which im convinced is linked to this ongoing problem...idle control valve...idle miss...see the link?  wink wink...ha ha..

[DKnight]

well as it is freezing outside i thought i would go have a play

my car blue temp sender was reading 7.00 i think

and the 4 spare senders i had in garage, ranged from 4.23, 5.24, 4.27, 4.20

so it is this figure that is effecting it im so sure, its like the sensor is getting too high a reading, causing it to borderline not run...

now how to fix it? not sure, its like the waterhousing needs flushing, or i dunno, but the blue sensor is the problem, for sure...

an answer would be for anyone to check their blue temp sensor from cold before starting...