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maldini Alfa Arna
Joined: 08 May 2010 Posts: 4 Location: Gothenburg, Sweden
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Posted: Sat May 08, 2010 4:34 pm Post subject: Boxer 16v - Idle advise needed! |
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Im actually pleased the way the engine is running, but the Swedish MOT-staff are not impressed.
The engine was oscillating between below 2000 - slightly above 3000rpm with a steady pedal when one tries to achive 2500rpm steady idle. I've had the idle valve off, cleaning it as good as I could and the sprayed some 5-56 in it before i had it attached again.
With the engine off it's possible to hear the throttle click-noise from the switch just as the throttles are about to open, which sounds all ok. BUT, when I moved the throttle switch so that it was on all the time, it was possible to keep a steady idle at, e.g. 2500rpm. This does not feel right, but it is running normally.
However, at the MOT it failed the exhaust requirements at 2500rpm, and it had the following readings (requirement in brackets).
CO 1,9 (0,3)
Lambda 0,94 (0,97 - 1,03)
So, it's running rich, but the lamda sensor is new (original bosch), so why is that? Should it not compensate? If I disconnect the air mass meter the engine is running very rough, and almost stalls. When I disconnect the temp sensor (to the motronic) the engine stalls directly.
Any thoughts or advices?
I think the next step for me is to buy a wide band lambda sensor, so i can see what's happening when I do different kind off suff. But advices are very welcome anyhow. |
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evans Alfa Arna
Joined: 15 Nov 2006 Posts: 23 Location: Greece
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Posted: Sat May 08, 2010 5:36 pm Post subject: |
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I guess it might sound really silly as an answer, but have tried with another AFM unit? |
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BigAl P4

Joined: 06 May 2003 Posts: 2995 Location: U.K Surrey
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Posted: Sun May 09, 2010 12:12 pm Post subject: |
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Have you checked the output from the CTS "temp sensor"?
It maybe giving an incorect output making it run rich or a steady faulty one which will make the ECU run default mode limp home run rich mode and maybe fluctuating between the 2 states.
You can also check the output from the Lambda sensor to see whats happening by using a DMM "multimeter" on the black lead, you should see about 0.45V fluctuating higher and lower, around the 0.2 - 0.8 i think. _________________ x2 33 16v
pictures http://www.alfa-pages.co.uk/viewtopic.php?t=5203 |
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maldini Alfa Arna
Joined: 08 May 2010 Posts: 4 Location: Gothenburg, Sweden
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Posted: Thu May 13, 2010 10:24 am Post subject: |
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evans wrote: |
I guess it might sound really silly as an answer, but have tried with another AFM unit? |
No, I haven't. But I have tried to disconnect the cables to the AFM unit at idle, and then it was running very rough, and when I pushed the throttle it was almost stalling -› guess the engine doesn't know how much air it receives with the AFM disconnected. |
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maldini Alfa Arna
Joined: 08 May 2010 Posts: 4 Location: Gothenburg, Sweden
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Posted: Thu May 13, 2010 10:59 am Post subject: |
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BigAl wrote: |
Have you checked the output from the CTS "temp sensor"?
It maybe giving an incorect output making it run rich or a steady faulty one which will make the ECU run default mode limp home run rich mode and maybe fluctuating between the 2 states.
You can also check the output from the Lambda sensor to see whats happening by using a DMM "multimeter" on the black lead, you should see about 0.45V fluctuating higher and lower, around the 0.2 - 0.8 i think. |
Now I have checked the CTS (what does the "C" stand for? C-Temp-Sensor). Thanks for the advice! However, it seems like its working like it shuold. These were the readings I got:
Ignition on, before start in the garage (ambient temp about 20degC): 3.7V
Warm engine, about 85deg on the temp gauge: 1.24V
Warm engine, after some time on idle, about 90deg: 1.01V
Guess the CTS is working like it should then?
I was not so sure of between which pins to measure the lambda signal. You mentioned the "black lead", but which other source should I measure on? I measured on the cable beside it (orange), but then got a steady 13.9V, which is the voltage of the battery, so that was something else. The green one is just the warm up cable, right?
[img]http://image_url[/img] Hmm, didn't manage to attach the picture, whatever..
I found a helpful description of the Motronic ML4 at http://openpdf.com/ebook/motronic-ml4-1-pdf.html "Bosch Motronic 4.1: GM Copyright Equiptech 1"
It's for an Opel, but the general function and the sensors of the Motrinic are the same. It says that the Throttle switch has three states, Idle, Full throttle (enrichment) and "In between". Till now I thought it was just to detect idle, and the rest. I will try to find the three states the next time Im in the garage, hopefully tomorrow. |
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BigAl P4

Joined: 06 May 2003 Posts: 2995 Location: U.K Surrey
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Posted: Thu May 13, 2010 11:16 am Post subject: |
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Hi maldini ,
C = Coolant, have a look at this for correct CTS readings
http://www.alfa-restoration.co.uk/jetronic/tempsender.html
The Lambda sensor has 1 black wire, the signal and 2 white wires, the 12v to heat it up. Just peel back the rubber cover on the black wire, attach the + from your DMM and the - to the battery.
Do you get the problem when the engine is cold?
Have you tried with the lambda sensor disconnected?
I have used that description, it is quite good
What is the history on the car, how long have you had it, any problems before, what year is it, does it have a cat, what are the emission laws in your country, have any mods been done, like the 5 min AFM mod, that will make it run rich.
20 questions over
Maybe some history and some pics in the introduce youself could clear up a few things Welcome BTW _________________ x2 33 16v
pictures http://www.alfa-pages.co.uk/viewtopic.php?t=5203 |
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lee16v 16 Valve

Joined: 29 Jun 2005 Posts: 1429 Location: Devon, UK
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Posted: Thu May 13, 2010 2:19 pm Post subject: |
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A related question to this.......
When is the TPS supposed to 'click'? On mine it's just after the throttle starts to open. Are you meant to have it set up so that the TPS opens before the throttle or is mine normal? |
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Admin Site Admin

Joined: 19 Feb 2003 Posts: 1223 Location: Stafford, UK
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Posted: Fri May 14, 2010 12:19 pm Post subject: |
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Hi
From memory the TPS has 3 positions, the first of which is under 5 degrees of throttle opening.
All the best
Keith _________________ I owe, I owe, its off to work we go.
Bimota Forum
Stafford Christmas Lights
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lee16v 16 Valve

Joined: 29 Jun 2005 Posts: 1429 Location: Devon, UK
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Posted: Sun May 16, 2010 3:29 pm Post subject: |
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Cheers Keith. Would seem as if mine is working ok then. Should there be an audible click on all three positions then? As I can only hear it on the first. |
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bobbber P4
Joined: 14 May 2003 Posts: 2162 Location: The Greatest Town on Earth - Swadlincote, UK
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Posted: Wed May 19, 2010 10:42 pm Post subject: |
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Lee, three positions, so should be two clicks.
From idle (switch in idle position). Slight bit of throttle, the butterflies move a bit and then the first click (switch in open throttle position). Continue to open the throttle and just before it hits the bump stops, second click (switch in full throttle position).
Any further questions, please ask! I'll explain the entire thing at spa. Three months I spent reading the bloody documentation on the 33 injection system... think I *just* about understand it now! The series III documents are very Alfa garage orientated, where they understand all this stuff already. The series II injection supplement has all the information (and explanations) you need. Remind me to bring you a copy in exchange for the rubber aid pipes you promised
BTW... Keith, when I put , it comes out as kittens!
B _________________ Fiat Bravo 165 Sport |
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lee16v 16 Valve

Joined: 29 Jun 2005 Posts: 1429 Location: Devon, UK
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Posted: Thu May 20, 2010 5:13 am Post subject: |
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Cheers for the info dude. I don't seem to have the full throttle click then......
The rubber s e x pipes are all cut and ready for insertion!!  |
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Admin Site Admin

Joined: 19 Feb 2003 Posts: 1223 Location: Stafford, UK
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Posted: Fri Jun 04, 2010 3:38 pm Post subject: |
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lee16v wrote: |
Cheers Keith. Would seem as if mine is working ok then. Should there be an audible click on all three positions then? As I can only hear it on the first. |
Think the position when it is almost closed is there to allow it to recognise when you have backed off, so it can cut the injection with a closed throttle at reasonable revs to save fuel.
From a Dutch manual I think the 2 position is at about 55 degree open. Central pin is the common one, with it connecting one other pin when closed and the other pin instead when wide open.
The "kittens" thing is just to annoy spammers.
All the best
Keith _________________ I owe, I owe, its off to work we go.
Bimota Forum
Stafford Christmas Lights
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