Idle and engine fault code help

[alwayzsidewz]

Hi all,
I have the X16 SZ astra engine.
A short while ago, the head gasket went, due to a hose snapping off and me running dry in seconds on the motorway.
Anyhow, replaced Head gasket, plus head bolts, did new sparks and timing belt at the same time.
I also replaced the coolant temp sensor, as my cooling fan would not cut in, and the car ran as if it was real cold.
Started car up and idle was about 3k!!
Checked for air leaks, all fine, checked connections all fine.
Swapped old coolant temp sensor back in, idle dropped to about 1200 rpm
( I have no rev counter, so these care guesses )
Car on start up revs high, then settles to this fast idle, with the orange engine light aglow.
Did checks this morning, via the really useful ECU guide, and came up with the Throttle potentiometer ? sp high voltage error code
Checked the unit, cleaned it, it was all fine. Still got the issues and high idle.
Plus when you drive the car, it dips in power when you change up the gears.
Now stumped as what else to do?
Got MOT due on the 23rd and at present I am not sure what the hell the emissions will be like.
If anyone can help I would be so grateful.
I can rebuild a Toyota, but stuck on a vauxhall grr.. lol

 

[Andy_Mk3]

Have you checked the idle control valve? They can often clog up. Take it out and clean out the housing.

If not, then replace the throttle potentiometer. It's reading a higher throttle position than it should, thus giving the engine more fuel and gives a high idle. They're not expensive and not something that cleaning usually fixes.

 

[Lefthooker]

Hi, as said, cleaning the TPS (Throttle Position Sensor) wont do anything as it is an electrical device with no mechnics inside. Although I find it odd that it was working before and now the idle is playing up. I personally would look at the bits that have been changed and would make sure I really do have the correct temp sensor. there are loads of different ones, although they do look the same. If putting the old temp sensor in makes a change to engine idle speed, then thats another reason to make sure you have the correct temp sensor. Otherwise put the old one back in for the MOT and try to correct the problem once its been tested.

 

[alwayzsidewz]

ordered a New TPS and few other bits.
Think I will try your advice and swap over the sensors.
As my car under reads on the gauge I am going to swap the rad and the other tiny coolant sensor as well as see if that helps.
Cheers for all the help, will post up results once I have fitted new parts.

 

[alwayzsidewz]

Right finally fixed it.
Swapped Potentionmeter and Idle Control valve
Bit of a fiddle swaping out the ICV, had to take out the EGR.
Then got code for the Crankshaft position Sensor, so swapped that
Success!! idle back to normal, no more EML
Swapped back to new coolant temp sensor and all seamed well.
Few pics, I know its simple stuff, but I have now got in to the habit of pic taking while working

old vs new

Still going to swap in new temp sender and Rad fan switch, and hopefully that will solve my cool running gauge, and lack of automatic fan.
But pleased its all fine.
Weird how they were all fine before head gasket failure and replacement.
I can only think that the ICV got shagged due to the crap in the system, which in turn bust the potentionmeter.
I reckon taking out the crank sensor when we did the cambelt etc, they must have been a damged wire in it??
Arh well at least we are back and now ready for the MOT.
Wish me luck

 

[Lefthooker]

Nice one ... good to hear you had a succesfull day