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Model specific boards => Golf mk4 => Topic started by: jazz5000 on 06 June 2013, 16:46

Title: Doesnt start once hot
Post by: jazz5000 on 06 June 2013, 16:46
Hi
Have a 1.4.

Car starts fine first time its started for the day, Then when driven and parked up it will fail to start.
When i put the key to the start position there is no cranking. Only way is to bump start the car or let it cool down for around 20 minutes.

Not sure if its a starter problem or a sensor. Any help here guys.
Title: Re: Doesnt start once hot
Post by: rio_gti on 06 June 2013, 17:05
crank sensor?
Title: Re: Doesnt start once hot
Post by: jazz5000 on 06 June 2013, 20:01
Just scanned it with vagcom:

2 Faults Found:
16804 - Catalyst System; Bank 1: Efficiency Below Threshold
            P0420 - 35-00 -  -
16712 - Knock Sensor 1 (G61): Signal too High
            P0328 - 35-10 -  -  - Intermittent
Readiness: 0000 0000


Would this mean the crank sensor?

Title: Re: Doesnt start once hot
Post by: jamie16v on 06 June 2013, 22:16
Just scanned it with vagcom:

2 Faults Found:
16804 - Catalyst System; Bank 1: Efficiency Below Threshold
            P0420 - 35-00 -  -
16712 - Knock Sensor 1 (G61): Signal too High
            P0328 - 35-10 -  -  - Intermittent
Readiness: 0000 0000

it`s KNOCK sensor, not a good thing really, are you mapped? what fuel are you running?..
the non starting issue could be due to a sticky starter motor solenoid.. you need a new starter by the sounds of it.

Would this mean the crank sensor?
Title: Re: Doesnt start once hot
Post by: jazz5000 on 07 June 2013, 06:39
No not mapped as its a 1.4 :cry:

Just running regular supermarket fuel
Title: Re: Doesnt start once hot
Post by: jamie16v on 07 June 2013, 10:52
not starting once warm sounds like a coolant temp sensor tbh..
also supermarket fuel isnt the best for knock control.
delete the codes, and see what comes back!
Title: Re: Doesnt start once hot
Post by: SI74 on 07 June 2013, 12:13
I would go with along the lines of coolant temp sensor of the fuel one.
Title: Re: Doesnt start once hot
Post by: xxChrisxx on 07 June 2013, 12:29
Not cranking? Starter.
The fact that it bumps means the fuel and spark is ok. Try belting the solenoid with a mallet.

Also the knock is not the fuel you are using. The 1.4 is pretty agricultural as far as engines go and 95RON is 95RON is 95RON. So buying Shell fuel save, or Tescojuice, it'll have basically the same knock characteristics. As it all has to meet standards, or it can't be sold, in many cases it'll be the same fuel stock. The difference is lubrication and other assorted additives.

With a signal too high code, it's more likely that you've got a broken knock sensor/wire.
Title: Re: Doesnt start once hot
Post by: jamie16v on 07 June 2013, 13:36
i stand corrected, didnt read the bit where he said it`ll bump start..  sticky solenoid, and i also agree with the knock sensor wire.
Title: Re: Doesnt start once hot
Post by: jazz5000 on 07 June 2013, 15:49
Thanks for replies,

I have changed the coolant temperature sensor last month as i used to never get a reading on the clocks before.

When i try to start once its warm it does slightly crank very slowly and after around 3-4 tries it stops cranking.



Also where is the knock sensor located so i can investigate

Thanks
Title: Re: Doesnt start once hot
Post by: 52GTIPETE on 07 June 2013, 16:43
I will agree with S174 as because the coolant sensor is not working correctly the ECU cannot tell if the car is hot or cold and to put the choke on or off. Had the same problem on a 1.4 polo. Coolant sensor solved it.
Title: Re: Doesnt start once hot
Post by: 52GTIPETE on 07 June 2013, 16:44
Also missed the bit about slow cranking. Doh.  :laugh:
Title: Re: Doesnt start once hot
Post by: jamie16v on 07 June 2013, 19:05
Thanks for replies,

I have changed the coolant temperature sensor last month as i used to never get a reading on the clocks before.

When i try to start once its warm it does slightly crank very slowly and after around 3-4 tries it stops cranking.



Also where is the knock sensor located so i can investigate

Thanks
in that case it sounds like your battery is knackered. :tongue: it could also be the rectifier in your alternator not charging the battery!...
knock sensor is bolted to the outside of the block, looks like a ring type plug with a bolt going though the middle of it.
Title: Re: Doesnt start once hot
Post by: jazz5000 on 07 June 2013, 22:15
Battery is uprated from a BMW X5 for my sounds.
voltage is at 12v when i attempt crank
Title: Re: Doesnt start once hot
Post by: jamie16v on 07 June 2013, 22:25
hmmm....what voltage do you have when engine is running?
Title: Re: Doesnt start once hot
Post by: jazz5000 on 07 June 2013, 22:25
14.3v roughly
Title: Re: Doesnt start once hot
Post by: jamie16v on 07 June 2013, 22:27
ok, so you got 14.3 volts from alternator, 12v when engine not running, it turns a couple of seconds then dwindles away?..
Title: Re: Doesnt start once hot
Post by: jazz5000 on 07 June 2013, 22:36
First time you start car it fires up after few seconds,

Once its hot and you stall  :whistle:  or just turn engine off and try to start 5-10 minutes later it cranks very slowly like maybe 1 turn per second. After few seconds of this it will stop and not crank.

Now you mention it , it does sound like a flat battery as in the sound it makes.
But cant be flat as voltage is 12v and ignition lights and music dont cut off, and it will start no problem once it cools down.

Had this happen as well the other day in a car park. Had to get help and get the car pushed into the bay, It then started after i got it in the bay  :grin:  But turned off the engine and tried to start again and it wouldn't start. Came back 15 minutes later and it started no problem


Title: Re: Doesnt start once hot
Post by: jamie16v on 07 June 2013, 22:56
have you checked the cable and connections going to the starter motor for corrosion?.
also worth checking the earth straps etc.
Title: Re: Doesnt start once hot
Post by: kingaz on 08 June 2013, 06:10
Might be unrelated but my escort turbo did this..found out it was missing a heatshield and starter motor was getting to hot
Title: Re: Doesnt start once hot
Post by: jazz5000 on 08 June 2013, 10:32
Will check all that now and report back later today
Title: Re: Doesnt start once hot
Post by: mcgee9t2 on 08 June 2013, 11:04
My old car suffered the same problems, was the crank sensor.
Title: Re: Doesnt start once hot
Post by: jazz5000 on 08 June 2013, 13:07
Think iv found the problem

This is a picture of the starter motor wires:

(http://img534.imageshack.us/img534/522/img20130608125039.jpg) (http://imageshack.us/photo/my-images/534/img20130608125039.jpg/)

Will i be able to just solder it back or will i require a new connector.
If the latter what sensor is this?

Thanks
Title: Re: Doesnt start once hot
Post by: jazz5000 on 08 June 2013, 13:36
Seems that wire actually runs to the alternator?

So although its damaged doesn't look like fixing that will solve my starter problem
Will get this wire sorted today though.
Title: Re: Doesnt start once hot
Post by: jazz5000 on 15 June 2013, 09:18
Checked all the wiring to the starter. No problems there

If its the crank sensor would it cause the starter to turn slowly then stop?
Title: Re: Doesnt start once hot
Post by: xxChrisxx on 15 June 2013, 14:26
Checked all the wiring to the starter. No problems there

If its the crank sensor would it cause the starter to turn slowly then stop?

If its not turning over its not a sensor, as the starter has no electronics. You just send current to it. What happens is that the starter soaks up heat and the internal bits expand, which can cause it to be tight turning.

If it was turning over but not firing, then I would think crank sensor.

First thing i'd do is take the starter off, clean and re-grease it.
Title: Re: Doesnt start once hot
Post by: jazz5000 on 16 June 2013, 09:54
Ok will give that a try now

Title: Re: Doesnt start once hot
Post by: jazz5000 on 16 June 2013, 14:11
Ok
After more investigation

Does seem to be a voltage issue.

When driving battery voltage is at 13v.
And when cranking it goes down to 9v.

So going to change out the battery as it was getting old.

I have a bmw x5 diesel battery in, If i get the same again but brand new will it cause any other issue, Or will the alternator need to be swapped for a 180a?
Title: Re: Doesnt start once hot
Post by: jazz5000 on 17 June 2013, 16:21
Turns out the ground cable wasnt connected  :shocked:

Title: Re: Doesnt start once hot
Post by: rio_gti on 17 June 2013, 18:32
So it's sorted now???
Title: Re: Doesnt start once hot
Post by: jazz5000 on 17 June 2013, 18:35
hasn't given anymore trouble since in the same circumstances. So i hope so  :laugh:
Title: Re: Doesnt start once hot
Post by: jazz5000 on 18 June 2013, 22:30
Had same problem again,
So fitted a new battery.
So far so good
Title: Re: Doesnt start once hot
Post by: jamie16v on 18 June 2013, 22:38
I stand correct... haha  :cool:
Title: Re: Doesnt start once hot
Post by: jazz5000 on 02 July 2013, 12:46
Starting to have the same problem again.

Could it be a alternator problem?
As the battery sorted it for a while. So im thinking the battery is not getting charged enough.

However voltage is 14.2v when running etc

Title: Re: Doesnt start once hot
Post by: gazareth on 02 July 2013, 22:40
hi next time it does it try a pair of jump leads hooked up to another fully charged battery. if it fires straight up then you know the problem aint the starter anyway. is the engine overheating by any chance?
Title: Re: Doesnt start once hot
Post by: jazz5000 on 03 July 2013, 21:26
Last time it happened I jumped started it and it started straight away .
This is why I changed out the battery.

Don't think car is overheating . sits at 90. Sometimes less .
Happened last time once I did a drive on motorway. Rpms were at 5k so was probably running hot
Title: Re: Doesnt start once hot
Post by: Rhyso on 04 July 2013, 10:00
Last time it happened I jumped started it and it started straight away .
This is why I changed out the battery.

Don't think car is overheating . sits at 90. Sometimes less .
Happened last time once I did a drive on motorway. Rpms were at 5k so was probably running hot

Temp gauge should sit bang on 90; so sounds like you got a thermostat problem

Also what speed where you doing for your RPM to be sat at 5k?? :shocked:  Or were you driving around in 3rd gear??
Title: Re: Doesnt start once hot
Post by: jazz5000 on 08 July 2013, 14:49
Went to a garage to do a load test on battery,

They said battery is good.
The alternator is the problem. It is not giving enough voltage to charge up the battery.


Would a 150A alternator go straight in?
Title: Re: Doesnt start once hot
Post by: jazz5000 on 20 July 2013, 16:15
Fitted a 180A alternator in.

Very happy with the voltage now.

Previously dropped to 11.5v with heater/headlight/rear demister/bass on full/air ride compressor

 

Now it does the above and doesn't go below 13.5v.

Will do the big 3 tomorrow aswell