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[VXL V6]

I wonder if these V6 manifolds are available in this country?

 http://www.bilforumet.no/omega/154892-grenr-r-v6-omega.html

Much improved over the GM standard ones.....

[Elite Pete]

If we could get a set of those I know a bloke that could make them up in stainless steel. I went to see him a couple of months ago and he said he has the exhausts in stock but he would need the car for a week to make some manifolds which is where the expense is.

[Elite Pete]

Just had a thought, I dont think they will fit due to the position of the steering box

[VXL V6]

Need a guinnea pig meega and that bloke to fabricate a set that can be used to copy.

Also have to be aware of the 3.2 pre cat issue.... even better, find a way to trick the ecu and remove them. The main cat does a good enough job on it's own.

[Elite Pete]

Need a guinnea pig meega and that bloke to fabricate a set that can be used to copy.

Also have to be aware of the 3.2 pre cat issue.... even better, find a way to trick the ecu and remove them. The main cat does a good enough job on it's own.

This is where the expense is, he was saying it can take upto a week to get the right run for a manifold. He also said it wouldnt be worth it for one set of manifolds so I gave up  

He does do a very nice cat back system with or without the centre silencers

[cem_devecioglu]

In order to get performance increase from those manifolds I think first inlet and outlet diameters must be increased a bit..(just like the mod I saw here)

[Kevin Wood]

I like those.  

Someone has swapped all the keys over on their keyboards though.

Just had a thought, I dont think they will fit due to the position of the steering box

Quite possibly. They are clearly quite different left and right.

Also have to be aware of the 3.2 pre cat issue.... even better, find a way to trick the ecu and remove them. The main cat does a good enough job on it's own.

I think I could sort that. Bin the pre-cats and synthesise a signal that looks like a post-cat lambda output (but is nothing of the sort!) and keeps the ECU happy.

Kevin

[cem_devecioglu]

Also I think with those, low RPM torque values will be worse..

Necessary variable valve timing..

[VXL V6]

I think I could sort that. Bin the pre-cats and synthesise a signal that looks like a post-cat lambda output (but is nothing of the sort!) and keeps the ECU happy.

Kevin

To bin the pre cats am I right in thinking a standard set of downpipes could be swapped in place? I presume they run from manifold header to main cat (only cat in earlier models)?

......Or would you just leave everything in place, snip the signal cables off the first sensors and piggy back them onto the second sensors?

[Kevin Wood]

Pre cat Lambda sensors would have to stay because they control the fuel mixture, so bosses would have the be fitted to the manifolds for those.

The smaller pre-cats (in the elbow of the exhaust) would go. Not sure if you'd need the downpipes. The manifolds would probably extend further than that, looking at them.

The post cat Lambda sensors (which are before the main cats but after the pre-cats) would go and be replaced by a circuit that mimics their output signal.

I reckon it'd work. Goodness knows how you'd fit them in the car!

Kevin

[VXL V6]

Pre cat Lambda sensors would have to stay because they control the fuel mixture, so bosses would have the be fitted to the manifolds for those.

The smaller pre-cats (in the elbow of the exhaust) would go. Not sure if you'd need the downpipes. The manifolds would probably extend further than that, looking at them.

The post cat Lambda sensors (which are before the main cats but after the pre-cats) would go and be replaced by a circuit that mimics their output signal.

I reckon it'd work. Goodness knows how you'd fit them in the car!

Kevin

I'm guessing this circuit would have to mimic a cold start waveform to satisfy the warm up period (Control by relay switching from the cat heater feed maybe?) then switch to a waveform that would satisfy closed loop operation.

Or am I way off the mark?  

[Kevin Wood]

I'm guessing this circuit would have to mimic a cold start waveform to satisfy the warm up period (Control by relay switching from the cat heater feed maybe?) then switch to a waveform that would satisfy closed loop operation.

Or am I way off the mark?  Roll Eyes

Nope. That would pretty much do it. Lambda sensor heaters are normally on all the time after engine start, though. They're not pre-heaters AFAIK, but you could probably fool it with a timer that simulates cycling of the sensors for a minute or two after the heaters fire up and then switch to a constant rich signal. You'd also need an artificial load on the heater output as the ECU will detect an open circuit otherwise.

Kevin

[VXL V6]

I'm guessing this circuit would have to mimic a cold start waveform to satisfy the warm up period (Control by relay switching from the cat heater feed maybe?) then switch to a waveform that would satisfy closed loop operation.

Or am I way off the mark?  Roll Eyes

Nope. That would pretty much do it. Lambda sensor heaters are normally on all the time after engine start, though. They're not pre-heaters AFAIK, but you could probably fool it with a timer that simulates cycling of the sensors for a minute or two after the heaters fire up and then switch to a constant rich signal. You'd also need an artificial load on the heater output as the ECU will detect an open circuit otherwise.

Kevin

Actually, isn't the cold start program invoked by the ECU reading the CTS signal? I guess a decent ceramic resistor across the heater supply would provide a load to fool the ECU.

OpelScan can produce some good graphs to work from for the sensor outputs, though the timebase isn't as good as a good scope.



Cheers
Andy

[Kevin Wood]

That's handy!

I would imagine a simple resistor will work for the heater as you say. My guess is that the ECU will look for some activity on the post cat sensors when cats are cold to verify that the sensors are actually working and then for them to go quiet when the pre-cats are up to temperature. Just a guess though. :-/

Kevin

[iggy21uk]

I'm guessing this circuit would have to mimic a cold start waveform to satisfy the warm up period (Control by relay switching from the cat heater feed maybe?) then switch to a waveform that would satisfy closed loop operation.

Or am I way off the mark?  Roll Eyes

Nope. That would pretty much do it. Lambda sensor heaters are normally on all the time after engine start, though. They're not pre-heaters AFAIK, but you could probably fool it with a timer that simulates cycling of the sensors for a minute or two after the heaters fire up and then switch to a constant rich signal. You'd also need an artificial load on the heater output as the ECU will detect an open circuit otherwise.

Kevin

Actually, isn't the cold start program invoked by the ECU reading the CTS signal? I guess a decent ceramic resistor across the heater supply would provide a load to fool the ECU.

OpelScan can produce some good graphs to work from for the sensor outputs, though the timebase isn't as good as a good scope.



Cheers
Andy

Glad to see your making good use of your Opelscan

Ian