Steve Wong Chip to help Idle issue?
Technical Guru
Rennlist Member
Rennlist Member
Joined: May 2002
Posts: 8,138
Likes: 122
From: USVI
The ECU really benefits from having an O2 sensor as an extra input. Without the sensor the ECU makes some huge assumptions that are almost never correct... Resulting in most of the behavior that you are experiencing. Assuming your bypass pipe has the option for one, I would start by adding one there and then, if that doesn't completely solve your issues, order the Steve Wong chip.
Technical Guru
Rennlist Member
Rennlist Member
Joined: May 2002
Posts: 8,138
Likes: 122
From: USVI
The O2 sensor is another feedback mechanism for the ECU. Without it the ECU relies entirely on the RPM sensor and the AFM to know what's going on. That will tell you how much air is coming in at and at what speed but not what happens after the fact. It assumes that all 6 cylinders ignite exactly the same and exactly the same as when they were when new, which they don't. The more inputs you can provide to the ECU the more corrections it can make to its idealized fuel assumptions. Slightly better fuel mileage would probably be another benefit? Less soot on your rear bumper?
Thread Starter
Rennlist Member
Joined: Aug 2012
Posts: 182
Likes: 0
From: Stockport uk
That all makes sense, thanks for the explanation. Perhaps Ill try the O2 Sensor then, just got to brave my way under the drivers seat this time and find the connector for the sensor that should have a plug in it!?
Opening up the DME was stressful enough lol!
Opening up the DME was stressful enough lol!
Thread Starter
Rennlist Member
Joined: Aug 2012
Posts: 182
Likes: 0
From: Stockport uk
yup, cleaned it out, wasn't too bad. Actually running my other C4's ISV on my new car at the moment just to see if there is any difference. There isn't. The original ISV thats on my other car is working fine too.
Nordschleife Master
Joined: Feb 2007
Posts: 5,095
Likes: 4
From: Cheshire, UK
I'm not sure what you mean by this. Your pic earlier shows that a loop out plug has been put in the O2 sensor plug. My guess is that this is all that they did when fitting the de-cat. To go back to an O2 sensor system you need to fit a decat with a hole that takes a sensor, then buy a sensor, screw it in and plug it in, in place of the loop out plug. You might not even need to fit another decat as it might be that you've already got the hole which is currently plugged with a bung.
Rennlist Member
Joined: Jun 2008
Posts: 804
Likes: 27
From: MN
Hunting down my low and fluctuating Idle issue (ISV/Adaption done) and I wonder if its something to do with the LWF conversion.
Sometimes on startup it stalls altogether. Othertimes fine.
Sometimes when slowing down for lights etc it idles ok, other times drops down to around 250/400rpm then back up, then down, then settles.
It does seem to idle just below 800, oil pressure ok.
Its got a Cat Bypass, without O2 sensor, G Pipe, LWF as above. Wondered if anyone has a chip that might help me out - or can point me to where I can get a new one? Is it the 911CHIPS.com in the USA that i need to get one from?
Anyone have a uk based 9tuning one?
Thanks everyone!
Sometimes on startup it stalls altogether. Othertimes fine.
Sometimes when slowing down for lights etc it idles ok, other times drops down to around 250/400rpm then back up, then down, then settles.
It does seem to idle just below 800, oil pressure ok.
Its got a Cat Bypass, without O2 sensor, G Pipe, LWF as above. Wondered if anyone has a chip that might help me out - or can point me to where I can get a new one? Is it the 911CHIPS.com in the USA that i need to get one from?
Anyone have a uk based 9tuning one?
Thanks everyone!
Good luck and let us know what you find.
Rennlist Stories
The Best Porsche Posts for Porsche Enthusiasts
Every Era of 911 Owner Explained in One Sentence
Verdad Gallardo
Thinking of Buying a Porsche? Do These 10 Things First
Joe Kucinski
Pixar Pals Turned Into 1-of-1 Porsches!
Michael S. Palmer
Theon Goes Full Carbon Fiber With Stunning New Build
Verdad Gallardo
Genius Porsche-Themed Gifts That'll Make Any Dad or Grad Smile
Joe Kucinski
10 Used Porsches Are Selling for Way Too Cheap
Joe Kucinski
Tuner Is Converting Porsche 911s Into Shooting Brakes
Verdad Gallardo
This Coachbuilt Creation Is A Modern Take on the Legendary Porsche 917
Verdad Gallardo
Is This Convertible Cayenne A Steal, Or A Returnless Investment?
Verdad Gallardo
Thread Starter
Rennlist Member
Joined: Aug 2012
Posts: 182
Likes: 0
From: Stockport uk
Boxsey - I must have mis read what the suggestion was. I thought I read that there was a loop connector at both ends... but now thinking about it, it wouldnt make sense to plug the ecu end, as it wouldnt be connected to it! Stupid me.
The DeCat already has a sensor hole, its just got a seal over it that needs to be removed and a sensor screwed in place. Think Ill try that first, then report further.
Took her out today... again, sometimes the revs drop fairly slowly and then idles ok, other times, they dip real low, surges up and down a bit, then settles. I make sure that all the fans / heaters etc are off I (makes for pretty cold driving!)
One thing that does seem to help... that I read off another thread about these things, is when slowing down, let the gears do the work, then when it slows to around 1k rpm, dip the clutch and the revs don't drop off quickly and idles ok. This isn't always possible though in traffic!
Thanks for everyones advice so far!
The DeCat already has a sensor hole, its just got a seal over it that needs to be removed and a sensor screwed in place. Think Ill try that first, then report further.
Took her out today... again, sometimes the revs drop fairly slowly and then idles ok, other times, they dip real low, surges up and down a bit, then settles. I make sure that all the fans / heaters etc are off I (makes for pretty cold driving!)
One thing that does seem to help... that I read off another thread about these things, is when slowing down, let the gears do the work, then when it slows to around 1k rpm, dip the clutch and the revs don't drop off quickly and idles ok. This isn't always possible though in traffic!
Thanks for everyones advice so far!
Thread Starter
Rennlist Member
Joined: Aug 2012
Posts: 182
Likes: 0
From: Stockport uk
Some news...
So I thought an update might be due....
I bought an O2 sensor, took half an hours worth of effort to try and get the bung out of the decat but with no joy :-( it's stuck.
Me being me... I also ordered a SW chip.. Couldn't resist the temptation.
It arrived last week, install straightforward, out for a drive and wow. Great. Nice steady revs, no stall, no dipping to 400rpm then back up.
I drove it around for about 45min, got back on the drive and ran idle adaption with the Hammer, as suggested with the instructions that came with the chip. Turned it off a happy bunny.
Didn't take it out till yesterday, and something has changed. Not quite as bad as without the chip, but not as good as day1. Dipping revs, not quite as steady.
Spoken briefly with Steve and he suggests that the O2 sensor needs to be installed (like many here have said!) and the adaption would be looking for O2 inputs too, hence the new problem.
So. Going to buy some heating apparatus today and try and get the bung out of the pipe. Would a drive before trying to get the screw out help too?
I bought an O2 sensor, took half an hours worth of effort to try and get the bung out of the decat but with no joy :-( it's stuck.
Me being me... I also ordered a SW chip.. Couldn't resist the temptation.
It arrived last week, install straightforward, out for a drive and wow. Great. Nice steady revs, no stall, no dipping to 400rpm then back up.
I drove it around for about 45min, got back on the drive and ran idle adaption with the Hammer, as suggested with the instructions that came with the chip. Turned it off a happy bunny.
Didn't take it out till yesterday, and something has changed. Not quite as bad as without the chip, but not as good as day1. Dipping revs, not quite as steady.
Spoken briefly with Steve and he suggests that the O2 sensor needs to be installed (like many here have said!) and the adaption would be looking for O2 inputs too, hence the new problem.
So. Going to buy some heating apparatus today and try and get the bung out of the pipe. Would a drive before trying to get the screw out help too?
Nordschleife Master
Joined: Feb 2007
Posts: 5,095
Likes: 4
From: Cheshire, UK
Having it hot first might help but the key to getting these things undone is a close fitting hex socket and a very long bar to use as a breaker. I usually use my jack handle for that purpose.
BTW have you checked to see if the bung was only srewed in originally and that it's not been welded to fix it in place?
BTW have you checked to see if the bung was only srewed in originally and that it's not been welded to fix it in place?
Thread Starter
Rennlist Member
Joined: Aug 2012
Posts: 182
Likes: 0
From: Stockport uk
a nice weld really would have been the icing on the cake!
Right.
1st attempt failed, still wouldn't budge. Was about to come asking for help but I could see what you guys would have said - if its not working, add more heat / bigger hammer etc lol.
So, more / quite a lot more heat, a little plusGas and off she came. RESULT.
Anyway, open up my new sensor, all excited, and its the wrong *** one! not the correct connector.
So, ordering up one from EurocarParts and its here Monday, so the car is in pieces for the weekend (already took the blower etc out in preparation before I checked the part!
One more lesson learnt!
An update next week...!
Have a great weekend, I'm working tomorrow but then doing some work on a friends R129 Merc on Sunday.
Right.
1st attempt failed, still wouldn't budge. Was about to come asking for help but I could see what you guys would have said - if its not working, add more heat / bigger hammer etc lol.
So, more / quite a lot more heat, a little plusGas and off she came. RESULT.
Anyway, open up my new sensor, all excited, and its the wrong *** one! not the correct connector.
So, ordering up one from EurocarParts and its here Monday, so the car is in pieces for the weekend (already took the blower etc out in preparation before I checked the part!
One more lesson learnt!
An update next week...!
Have a great weekend, I'm working tomorrow but then doing some work on a friends R129 Merc on Sunday.
Nordschleife Master
Joined: Feb 2007
Posts: 5,095
Likes: 4
From: Cheshire, UK
Unlucky James. A few get caught out by the wrong part which is usually cheaper but doesn't have the right plug. Ideally you want the Bosch one which will plug straight in and costs something around £100.
Three Wheelin'
Joined: Feb 2003
Posts: 1,782
Likes: 110
From: Cambridge/Boston, MA
Did you ever check for the jumper under the driver seat? If they used the jumper on the o2 sensor side, I would bet that they used the correct jumper beneath the seat too. These are the combinations-
Rennlist Member
Joined: May 2001
Posts: 13,507
Likes: 834
From: Auckland, New Zealand.
Any more details Boxsey? My car has no O2 sensor, but I can fit one with the new ÈCU. I'd like to order one while I'm traveling.