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pocketscience
Joined: 23 Apr 2006
Posts: 1650
Location: Sydney, Australia... mate!
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 Posted: Wed Sep 03, 2008 1:16 pm Post subject: O2 Sensor - where'd you install it? |
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For the EFI guys who've installed an LC-1 or similar where exactly did you mount it? I've gotta drill and weld a bung onto my headers - only want to do it once! 
I know they have to be oriented above horizontal, and ideally where there is a mix from all cylinders.
Cheers,
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Whoever said you can't buy happiness forgot about Porsche!
81 924 N/A, GTS lights, Saratoga, interior, headers, Integral cam, EFI (sold)
95 993
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RC
Joined: 25 Mar 2007
Posts: 2637
Location: Australia
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| Posted: Wed Sep 03, 2008 2:05 pm Post subject: Re: O2 Sensor - where'd you install it? |
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| pocketscience wrote: | For the EFI guys who've installed an LC-1 or similar where exactly did you mount it? I've gotta drill and weld a bung onto my headers - only want to do it once!
I know they have to be oriented above horizontal, and ideally where there is a mix from all cylinders.
Cheers, |
Yes, thats right.
Only practical spot on the headers is after the final collector, in the large single pipe. Don`t recall how long that section is but around 100mm after should be OK.
Closer to the head will reduce your transport delay but you really want to sniff all cylinders. Transport delay can be calculated (with some difficulty and averaging) and entered into MS for closed loop and/or mixture control or autotune. IMO though it is better to set the VEs close and let MSlogger/viewer analyze and adjust them rather than autotune.
Give me a few days and I`ll get down the pit and check clearances for you or take a pic to give you an idea, should be similar pipes. |
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vemser
Joined: 06 May 2008
Posts: 46
Location: Russia, Moscow
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pocketscience
Joined: 23 Apr 2006
Posts: 1650
Location: Sydney, Australia... mate!
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| Posted: Wed Sep 03, 2008 2:53 pm Post subject: |
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Thanks guys - that's great.
Rog a pic would be great if you can manage.
Cheers,
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Whoever said you can't buy happiness forgot about Porsche!
81 924 N/A, GTS lights, Saratoga, interior, headers, Integral cam, EFI (sold)
95 993
69 911 |
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morghen
Joined: 21 Jan 2005
Posts: 9095
Location: Romania
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| Posted: Wed Sep 03, 2008 3:44 pm Post subject: |
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i've just installed one right after the turbo. I have a narrow band and it seem to read corectly. i'll have pictures posted on my thread today.
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968rz
Joined: 21 Aug 2006
Posts: 537
Location: S. E. Wisconsin
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| Posted: Wed Sep 03, 2008 4:37 pm Post subject: |
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Just an FYI; 02 sensors work best when HOT, 3 wire units have a built in heater so they work faster at start up. As RC mentioned get it as close to the head as you can (while still reading exhaust from all cyl).
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Rick
79 924 coupe Petrol Blue 3spd auto (wife's DD)
93 968 coupe Amazon Green 4spd Tip (my DD) |
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Rich H
Joined: 10 Jun 2007
Posts: 2665
Location: Preston, Lancs, UK
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| Posted: Wed Sep 03, 2008 5:35 pm Post subject: |
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I fitted mine inthe pipe infront of the centre silencer box, 3 reasons, 1: it can be orientated hoever you want, 2: you can remove it to weld your bung in (I silver soldered mine) 3: if it all goes wrong they are £20 to replace!
I haven't dialled in a delay, suppose I should, any ideas as to how long a delay I need? Its only just after the final collector.
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1994 Lotus Esprit S4 - Work in progress...
1980 Porsche 924 S2 DITC Turbo - Original spec
1978 Homo-Sapiens - Tired spec
1953 Landrover S1 - Pensioner Spec |
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RC
Joined: 25 Mar 2007
Posts: 2637
Location: Australia
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| Posted: Wed Sep 03, 2008 7:36 pm Post subject: |
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| 968rz wrote: | | Just an FYI; 02 sensors work best when HOT, 3 wire units have a built in heater so they work faster at start up. As RC mentioned get it as close to the head as you can (while still reading exhaust from all cyl). |
All o2 sensors are the most accurate at their designed operating temperature. With NB sensors of 1 or 2 wire, such as stock 924/931, (first gen) they are generally placed where temp is around 450-600*C. If they are hotter it will cause a rich reading. Later 3 & 4 wire heated sensors can be placed further down the exhaust stream and rely more on their own heat for regulation. Temp variations will still result in vastly inaccurate readings and they are only designed to be accurate at a 14.7 AFR anyway.
With modern aftermarket performance WB sensors and CONTROLLERS such as the Innovate unit Gavin has you can expect a generally linear scale between say 10 to 20 AFR. These sensors using 5 or 6 wires are also heated but the temperature is regulated by the controller. Better sensors are factory calibrated and most controllers have a calibration function and some can digitally compensate for some error.
Rich H wrote:
| Quote: | | I fitted mine inthe pipe infront of the centre silencer box, 3 reasons, 1: it can be orientated hoever you want, 2: you can remove it to weld your bung in (I silver soldered mine) 3: if it all goes wrong they are £20 to replace! |
I have mine there too. My excuse was bugger all room after my collector and too lazy to pull the RHD headers off again. Involves removing starter, steering shaft, engine mount & bracket and the oil filter & adapter. PITA. Works well although there is a relative long transport delay.
| Quote: | | I haven't dialled in a delay, suppose I should, any ideas as to how long a delay I need? Its only just after the final collector. |
I`m not sure if you have this feature with MS1, maybe with extra code?
Sensor delay for LC1 is 4-10 mS (same sensor as my JAW), set that to 7. Now the delay 2 or RPM parameter is a constant involving RPM and MAP. Best to do a datalog then try to determine the delay at various RPMs and MAPS then average them. IIRC mine is around 2900. That figure is just a number generated by simple maths.
Read the megamanual and these threads for more info.
http://www.msefi.com/viewtopic.php?p=186439&highlight=#186439
http://www.msefi.com/viewtopic.php?f=31&t=30779&hilit=%27transport+delay%27 |
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Rich H
Joined: 10 Jun 2007
Posts: 2665
Location: Preston, Lancs, UK
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| Posted: Wed Sep 03, 2008 8:01 pm Post subject: |
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My brain isn't up to working that lot out...! 
I'll sit down infront of Megatunix and play with the settings. I'm wondering if its the lag that is making my tune a bit cranky. I assume that if the lag is wrong (which it probably is) then any corrections are going to be happening to the wrong bins and the tune will be utter ballcocks.
I'll try and find the time tonight to have aplay, I want to rewire the injectors to 14 - 23 instead of 13 - 24 too see if mI can get it to idle properly, it a bit badgers arse atm.
Fancy a holiday to sunny (!) Preston to tune my car? 
Ta
Rich
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1994 Lotus Esprit S4 - Work in progress...
1980 Porsche 924 S2 DITC Turbo - Original spec
1978 Homo-Sapiens - Tired spec
1953 Landrover S1 - Pensioner Spec |
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flosho
Joined: 01 Jul 2004
Posts: 3160
Location: Eau Claire, Wisconsin
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| Posted: Thu Sep 04, 2008 2:01 am Post subject: |
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my AEM uego is in the stock o2 sensor location...
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Min
Joined: 04 Nov 2002
Posts: 2368
Location: Vernon, British Columbia, Canada
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| Posted: Thu Sep 04, 2008 6:58 am Post subject: |
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my lc-1 is in the stock o2 sensor location.
Min
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1980 n/a with EDIS and Megasquirt II Injection. 7 different colors and counting. |
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Rich H
Joined: 10 Jun 2007
Posts: 2665
Location: Preston, Lancs, UK
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| Posted: Thu Sep 04, 2008 5:34 pm Post subject: |
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I don't have a stock location, where is it?
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1994 Lotus Esprit S4 - Work in progress...
1980 Porsche 924 S2 DITC Turbo - Original spec
1978 Homo-Sapiens - Tired spec
1953 Landrover S1 - Pensioner Spec |
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morghen
Joined: 21 Jan 2005
Posts: 9095
Location: Romania
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| Posted: Thu Sep 04, 2008 6:33 pm Post subject: |
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euro models dont have the hole and thread...but if you take a look at the manifold you can tell where it should be.
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RC
Joined: 25 Mar 2007
Posts: 2637
Location: Australia
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| Posted: Sat Sep 06, 2008 8:26 pm Post subject: |
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You can see that theres not really sufficient room to fit the sensor before the flange. Its about 100mm after and has ample clearance all round. It works well there but would have a few milliseconds faster response if closer to the head. Not sure how long your outlet pipe is. Probably runs in similar location and you can see there`s not a great deal of room. Regardless of where it`s fitted there is some transport delay that should be measured, calculated and entered into MS.
Note the plug blocking the bung that was fitted to the Bursch headers. Only in one pipe. Could be used for an exhaust temp probe but assume it`s for an o2 sensor in the same location to stock. The stock NA system runs 2 pipes there so if Porsche fit it in just one pipe it is a poor design. Don`t know though and Morghen says its in the manifold which is logical for a single wire (unheated) sensor. |
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flosho
Joined: 01 Jul 2004
Posts: 3160
Location: Eau Claire, Wisconsin
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| Posted: Sun Sep 07, 2008 3:55 am Post subject: |
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Stock on a us 931, is about 16" away from the turbo on the downpipe..
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