Cold starting probs - Part Two

[Anonymous]

Right.....I've still got cold starting probs with my GTE.

Before, the prob was there on damp starting sometimes, so I changed the dizzy cap, rotor arm, plugs and leads which made things miles better....it was starting miles better with no probs..BUT, since the recent very cold weather, it's being a bugger to start.

To me, it's like trying the start a carbed nova without any choke, so I recon there's a fault with the inlet-air-temp-sensor.
In the Haynes, it says that it should turn on below 17 deg.C and be off above this, so does this turn on the auto cold-start system, making the mixture richer for cold starting?
Once it's up and running, it runs a bit rough until the temp is up a bit.......you know if you push the choke in too soon on a carbed Nova how the car's hesitant and feels under-powered?
Well, it's just like that until it gets warm......just like it's running too weak for the temperature.
Once warm, it's fine.

I'm going to check all the sensors following the Haynes.

One thing I have found, is that if I turn the fuel pump on and off a few times before starting (ignition on and off so I can here the pump priming), it fires straight away and stays running as if doing that builds up the fuel pressure making it start easier :-/

Have other peeps had this prob, and if so, how did you sort it?

Cheers lads and ladies ;)

[Anonymous]

Sounds to me that you've got low fuel pressure, possibly a dodgy fuel pressure regulator or a system leak somewhere. If the pressure is bleeding off over night, then first thing in the morning you'll have next to none, possibly leading you to think it's the cold/ damp mornings? Just a thought.

[Anonymous]

The thing is, it's fine when the weather is warmer....it starts instantly, so that can't be the problem.
Anyway, the GTE fuel system doesn't retain it's pressure anyway, not like the Multec central and multi-point systems.
In the Haynes, it's got warnings about the high-pressure of that fuel system, but says nothing about it for the Bosh L3.1 system.
With the Bosch set-up, you can disconnect fuel pipes without having to depressurise the system.

Looking at the Haynes again, there's a Coolant temp. sensor and Oil temp. sensor as well as the air intake temp. switch so I'll check those too.
Also, I'll check the supplementary air-valve as it describes.

Well.....it seams I've more or less answered my own question!

[Anonymous]

I had a very similar problem on my Gte at the start ov the year when i was even more clueless about engines, The bloke at the garage replaced a temp sensor i think it was under the dizzy cap just under the head gasket but i could be wrong!

Twitchin like a pigs eye!

[Anonymous]

That ones the coolant temp. sensor.

I've noticed actually that my temp gauge doesn't seem to move even after a longish drive. It might be just me not being very observant though :p I'll be going for a decent drive tomorrow, so I'll take note as to whether the gauge works or not.
I know on the GTE that this sensor is more complex than on a carbed model, as it feeds info to the ECU as well as to the dash gauge.

I'll test it as in the Haynes and see what happens.

Any idea how much a new sensor would be, if I find it's faulty?
Or.....what other cars can I nick one from....I'm thinking along the lines of scrappy, and fit in pocket...just to try ;)
They might be fooked too, but maybe worth a try.
(I know 1.8i Astra and Cavs use same Bosch system..same sensors?)

Cheers mate ;)

[Anonymous]

sounds like fuel to me aswell m8.
iv got similar probs but i have 0 inlet or oil temp connected but it still starts fine, just a bit lumpy until warm

[Anonymous]

Like I say though, it starts spot on when the weather is a little warmer, but it's only when it's cold that I have the problem.......it's exactly like trying to start my Antibes with no choke....it will eventually start, but not as it should.


I went on a decent run yesterday an I noticed that the temp gauge did not move at all, so I know for definite that the coolant temp sensor is not working....or at the very least, it's not sending a signal to the gauge, which probably means it's not sending on to the ECU either.

I'm sure fuel pressure is ok 'cos when the ignition system was all fooked (dodgy leads, corroded contacts in dizzy etc etc), it struggled to start a couple of times in warm damp weather, and I got a smell of fuel under the bonnet like you do when you've flooded the engine. I've already checked for fuel leaks too and there isn't any, apart from my stupid filler cap none-return valve letting fuel splash out of the filler......I've not had time to fit the new valve yet....but that won't have any effect on starting.

I'll check the fuel pressure regulator anyway though just in case, but surely if that wasn't right, then it wouldn't run right?
Once it's started and got a bit of warmth into it, it runs spot on....like a dream in fact....it's JUST cold starting.

Anyway......I'm off to the scrappy for a few odds and sods so see you guys later ;)

[Anonymous]

Im sure i got charged ?17 for my sensor, i should have dun wat ur going to do, ratch about in a scrappy.

Twitchin like a pigs eye!

[Anonymous]

I know that on the Astra injection the coolant temp sensor is a seperate one from the temperature guage. Meaning if your dash guage works or not it won't affect the ECU. Temp sensor is around the altenator somewhere, the dash gauge is on the inlet manifold.

[Anonymous]

Interesting......looking in the Haynes for Coolant temp sensor, the only one it mentions for the GTE is the one under the dizzy which connects to the ECU.

BUT......looking in the Haynes at the wiring diagrams, it shows P12 (track 458 for 88-89 models) which is the coolant sensor for the ECU. It shows no connection to the gauge on the dash, so it is definitely a separate one!
There you go...question answered again! Good old Haynes.....I wish it had a separate wiring diagram just for the GTE though...make things a little easier.

The one for the gauge is P5 (track 270) which is the same for the 1.2 and 1.3......I'll have a look for it tomorrow.

I ended up not going to the scrappy today, so I'll go tomorrow instead. Hopefully, the Astra one will be the same and there's loads of MKIII Cavs to look at too.

I noticed that the inlet air and oil temp switches are in series which means that the ECU will only get info from them if both are switched on.....presumably at start up if the air AND oil are cold.
It makes sense really.......if the engine is hot, but the inlet air is cold, you don't want the engine thinking it's cold and hence making the mixture richer 'cos it won't start. So, for the mixture to be made richer for cold starting, both the inlet air and oil have to be cold.
In the summer, the oil will be cold in the morning, but the inlet air might be warm, so again....you don't want the engine thinking it's so cold that it needs choke......I'm sure you get what I mean.
The mystery is though, Dicko says he's not got either of these connected but his still starts fine :-/

So, looking at the evidence (lol), it would seem that the inlet air and oil temp switches are probably not the problem since Dickos starts fine without 'em, which leaves the coolant sensor.....which is the bit that Darren had replaced to sort his same problem.

Right....coolant switch it is then...fingers crossed!

(sorry about the long posts!)

[Anonymous]

Well....today it's been a bit warmer...all the ice and snow has gone......and the car started instantly, so it's definitely only a problem caused by the cold.

Oh....and my temp gauge was working today....it was probably just so cold before that the engine wasn't having chance to get warm enough to move the gauge!
It has been -8 to -10 a few mornings :O