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[GrahamT]

My 2.5 v6 (2001 facelift) has trouble starting from hot. No issues cold staring ever.

So I'm assuming the following;

Crank sensor - early signs of failure
Coolant sensor (ecu not gauge) - causing over fuEling
Lambda sensors

Is there a common fault or could these be the issue?

Does anyone have the GM part numbers?

Thanks

[Kevin Wood]

I would say less likely Lambda sensors as it would run closed loop immediately after starting, even from hot. I would be inclined to add weeping injectors to the list. It's just possible that's causing it to flood. Some live data would be useful.

[GrahamT]

I would say less likely Lambda sensors as it would run closed loop immediately after starting, even from hot. I would be inclined to add weeping injectors to the list. It's just possible that's causing it to flood. Some live data would be useful.

Thanks but I don't think it's the injectors as it's instant.

I can have the car running. Turn it off and it will fail to start instantly.

Since this cars a keeper i think I will just change the sensors above.  I just need the part numbers.

Thanks

[Kevin Wood]

If you can get it to a code reader that can do live data it would take the guesswork out of it.

You need to be a little careful to get the right 2.5 crank sensor, if memory serves, as there are a few possibilities.

[GrahamT]

If you can get it to a code reader that can do live data it would take the guesswork out of it.

You need to be a little careful to get the right 2.5 crank sensor, if memory serves, as there are a few possibilities.

I have a code reader and there are no stored faults and the engine management light has never come on.

So what ever the issue is nothing is working outside normal parameters.

[Kevin Wood]

Does it display live data? With that you could, for example, look at the ECU's temperature sensor and check the reading is plausible, so ruling out that sensor as the problem.

[GrahamT]

Does it display live data? With that you could, for example, look at the ECU's temperature sensor and check the reading is plausible, so ruling out that sensor as the problem.

No my code reader is basic. But if any of the sensors were working outside the normal range the engine management light would come on.

That's why I'm just going to change the most obvious culprits before it gets worse with genuine parts.

Hence the request for any other culprits and part numbers.

Thanks

[Mr Gav]

Hot starting issues used to plague Senators, Astra GTE`s and Cavalier SRi`s but not the Omega, the cause was the fuel pump relay getting too hot.

Might be worth a shot before you start spending money on cam sensors and the like if you can`t pin point the culprit.

[GrahamT]

Hot starting issues used to plague Senators, Astra GTE`s and Cavalier SRi`s but not the Omega, the cause was the fuel pump relay getting too hot.

Might be worth a shot before you start spending money on cam sensors and the like if you can`t pin point the culprit.

Thanks but the fuel pump really isn't the issue. Owning several mantas and cavaliers it's one of the first things I check.

[Doctor Gollum]

Hot starting issues used to plague Senators, Astra GTE`s and Cavalier SRi`s but not the Omega, the cause was the fuel pump relay getting too hot.

Might be worth a shot before you start spending money on cam sensors and the like if you can`t pin point the culprit.

Thanks but the fuel pump really isn't the issue. Owning several mantas and cavaliers it's one of the first things I check.

The fuel pump might deliver fuel, but is it at a suitable pressure?

[GrahamT]

Hot starting issues used to plague Senators, Astra GTE`s and Cavalier SRi`s but not the Omega, the cause was the fuel pump relay getting too hot.

Might be worth a shot before you start spending money on cam sensors and the like if you can`t pin point the culprit.

Thanks but the fuel pump really isn't the issue. Owning several mantas and cavaliers it's one of the first things I check.

The fuel pump might deliver fuel, but is it at a suitable pressure?

I did think this but the car drives faultlessly. It only had an issue with hot starts.

Once started from hot there are no issues. Drives fine, idles fine.

Literally the only issue is starting hot.

[Entwood]

Would it be possible/plausible to swap the ecu / gauge feeds from the temperature sensor over ?? That way you "might" a) solve the problem if the normal gauge side is working properly b) actually "see" the problem if the ECU side is not working by now action on the gauge ??

No idea if this would work, but without the ability to see live data it strikes me as a possibility ??  either that or is there someone close to you with a code reader capable of live data ??  North Wilts is a tad far from Rhyl or I'd offer !!  ..... 

[GrahamT]

Would it be possible/plausible to swap the ecu / gauge feeds from the temperature sensor over ?? That way you "might" a) solve the problem if the normal gauge side is working properly b) actually "see" the problem if the ECU side is not working by now action on the gauge ??

No idea if this would work, but without the ability to see live data it strikes me as a possibility ??  either that or is there someone close to you with a code reader capable of live data ??  North Wilts is a tad far from Rhyl or I'd offer !!  ..... 

To be honest I'd be just as happy with the part numbers I've requested as looking through all the history these parts have never been changed. They don't last forever.

Thanks

[terry paget]

http://www.omegaowners.com/forum/index.php?topic=96562.0
Most 2.5s use the Siemens crank sensor ( including my two current 2.5s and the two I have scrapped), as the above Forum guide states, but it's worth your checking before purchase.

[Nick W]

Would it be possible/plausible to swap the ecu / gauge feeds from the temperature sensor over ?? That way you "might" a) solve the problem if the normal gauge side is working properly b) actually "see" the problem if the ECU side is not working by now action on the gauge ??

No idea if this would work, but without the ability to see live data it strikes me as a possibility ??  either that or is there someone close to you with a code reader capable of live data ??  North Wilts is a tad far from Rhyl or I'd offer !!  ..... 

To be honest I'd be just as happy with the part numbers I've requested as looking through all the history these parts have never been changed. They don't last forever.

Thanks

they're also unlikely to be the cause of the problem. But it's your money. And time.

[GrahamT]

Would it be possible/plausible to swap the ecu / gauge feeds from the temperature sensor over ?? That way you "might" a) solve the problem if the normal gauge side is working properly b) actually "see" the problem if the ECU side is not working by now action on the gauge ??

No idea if this would work, but without the ability to see live data it strikes me as a possibility ??  either that or is there someone close to you with a code reader capable of live data ??  North Wilts is a tad far from Rhyl or I'd offer !!  ..... 

To be honest I'd be just as happy with the part numbers I've requested as looking through all the history these parts have never been changed. They don't last forever.

Thanks

they're also unlikely to be the cause of the problem. But it's your money. And time.

So a crank sensor when warm can't start to breakdown and cause starting issues. I think you'll find they can when they start to fail.

The ecu coolant sensor failing can't cause over fueling by telling the ecu that the engine is cold so give extra enrichment?

You're really helpful aren't you. I've experienced both these problems before.

I agree with the lambda sensors. But since there's no record of them ever being changed I'd like to do them anyway.

There's always a keyboard hero isn't there.

[Nick W]

So a crank sensor when warm can't start to breakdown and cause starting issues. I think you'll find they can when they start to fail.

The ecu coolant sensor failing can't cause over fueling by telling the ecu that the engine is cold so give extra enrichment?

You're really helpful aren't you. I've experienced both these problems before.

I agree with the lambda sensors. But since there's no record of them ever being changed I'd like to do them anyway.

There's always a keyboard hero isn't there.

Those could be faulty. But just changing them in the hope that it will fix your problem is inefficient and expensive when you find that the fault is elsewhere. There's a reason some basic diagnosis is our first recommendation. But as I said, it's your time and money.

[artsoul_no1]

Hi Nick W

Sent you a PM can you let me know if you got it and able to help either way

Thanks

[Doctor Gollum]

Have you done any work on the engine which resulted in unplugging everything at the back of the block

If yes, then you might have swapped the purge valve and ecu coolant temp plugs... They sit almost alongside each other and have the same type of plug. Only issue is that the purge valve is 12v whereas the coolant sensor is 5v...

Run it upto temp, then switch off. Attempt a restart. Then remove fuse 18 in the cabin. Does the car now start? If yes, then you need a new ecu coolant sensor. If no, then it's summat else.

BTW, Nick is usually spot on, so for a year old newbie with 66 posts, you're jumping to alot of conclusions

[moggy]

Hi i agree with DG,Nick is only trying to help mate.Dean.