This month we heard about a great case study from one of our distributors (AESwave.com) that we simply had to share. Based on a 2002 Chrysler PT Cruiser this case study has been put together by Adam Robertson, instructor for the CARQUEST Technical Institute, in the Western United States.
The throttle must be wide open to start this 2002 Chrysler or the spark plugs will foul from excessive fuel. Once finally running, the vehicle will stumble, yet can be driven if kept above about 1200 rpm. If you let it idle, it will blubber down and try to stall. Black smoke puffs from the tailpipe at times. Check engine light is on. Continually sets a P0172 (rich condition bank one). There are no other codes.
This vehicle uses a speed density system, which is a MAP sensor (not a MAF). In this type of fuel control system, proper vacuum is critical. We are working at about 4000-ft above sea level and the idle vacuum is about 13 inches. It will achieve about 17 inches when free revving at about 2500 rpm. The O2 sensors are soot fouled but when warmed enough are pegged near 1v. The fuel trims show a rich condition but this vehicle is hesitant to go into closed loop. A tremendous amount work by various shops has been performed on this vehicle to no avail.
Vehicle obviously running rich:
Where is the excessive fuel coming from?
What equipment could I use to determine this?
What systems do I test?
This month we have a great case study from Dott. Luca Camertoni of P.C.B. Technologies. This case study covers the diagnostic journey to solving a poorly 2009 Renault Clio...
This 2009 (MK3) Renault Clio 1.5 dCi engine had a complaint just after starting where a strange noise occurred for a few seconds followed by the MIL illuminating and the engine entering recovery mode.
A quick scan revealed the following stored codes:
2.DEF DF007 common rail pressure sensor circuit
1.DEF DF885 Pressure rail
This engine uses a Siemens SID 305 control unit with a flow regulator to fuel pump inlet, and a pressure regulator at the pump outlet. If the inlet receives no signal from the control unit no fuel enters the pump, resulting in no pressure in the fuel rail. When the outlet receives no signal from the control unit, its internal spring regulates the pressure in the rail at just 50 bar.
Do you recall our Scope School articles? Did you know about them? Did you miss out? Well not to worry...we've uploaded the articles to our site and over the next few newsletters we'll feature the articles to help you along.
We featured "Scope School 1: Introduction to PicoScope" not so long ago, so we've included a link to that and will move straight on to "Scope School 2: The next step".
Scope School 2: The next step
You may have experimented with the various techniques we covered when capturing waveforms (see Scope School Part 1). The features of PicoScope we covered included the Home and Auto icons, and the Automotive presets menu. We also covered the all-important key elements when going it alone and capturing a waveform from scratch: Voltage, Time, Trigger, and Probe. I have to say, with all the scope features available, as a new user to PicoScope the Automotive presets menu are a godsend so don't panic. With this knowledge now in place you can now move onto further valuable features of PicoScope that will make life so much easier as your experience and confidence grows.
Now you've made that all important capture, your job now is to evaluate the waveform, and look for the information contained within. Often, at a glance the waveform may look perfectly normal, but analysis is the key to a successful diagnosis and here you will need to Measure and Zoom specific areas of interest within the waveform to reveal the hidden detail. In this example we use a 12 V injector, but the theory behind the tools and their use applies to any signal you capture.
At your disposal you have numerous Signal rulers that will enable you to measure the minimum and maximum values of all waveforms on screen. The image below demonstrates the minimum and maximum values of a 12 V injector waveform using the Channel A signal rulers. Click on the signal ruler handle adjacent to the top of your vertical scale and drag down to the location of interest within your waveform, and repeat this process to get your minimum and maximum value positions. The numerical value of the position of the signal rulers on the screen will be displayed in the Ruler legend at the top of your scope screen. Each channel has its own set of signal rulers available.
You also have a set of Time rulers to enable you to accurately measure the time of an event within your capture. Click on the white Time ruler handle located at the bottom left corner of your scope screen and drag to the start point of interest within your waveform, and place a second Time ruler at the end point of your area of interest. The numerical value of the position of the time rulers on the screen will be displayed in the Ruler legend at the top of your scope screen.
Following the recent software and hardware updates to our PicoDiagnostics NVH kit, we are now offering a route for owners of the PP858 PicoDiagnostics NVH kit to upgrade their Pico NVH hardware.
The new hardware allows you to take full advantage of our latest version of the PicoDiagnostics NVH software, which supports identifying up to four independent vibrations simultaneously.
The upgrade kit contains the 3-output interface box and three coloured BNC cables all of which are compatible with your existing TA143 accelerometer.
Matt Williams of Professional Diagnostics recently assisted Pico Technology in presenting at the second AutoInform Live event. A weekend of innovative technical and hands-on training, powered by OESAA (Original Equipment Suppliers Aftermarket Association ) and organised in conjunction with Frank Massey to provide visitors with a 'Hear it, See it and Touch it' experience.
Delegates were treated live on-vehicle training, demonstrations and diagnostics, IMI certified courses, troubleshooting tips and business know-how from industry experts, advice on how to repair and replace the latest OE parts using the best tools for the job and fit and forget technology. The two presentations that Matt (supported by Pico's Jon Parker on the Saturday and Phil Rutt on the Sunday) gave covered PicoScope Hints and Tips, and In-cylinder Diagnostics with the WPS500X Pressure Transducer. The presentations were followed by a Question and Answer session.
During the presentations a Toyota vehicle was available for practical use, and full advantage was taken to show off the WPS500, our Flexible COP and Signal Probe, and our new 30 A current clamp (used for parasitic drain testing).
Please visit Pico Exhibitions for the latest list of exhibitions and trade shows that Pico and its representatives will be attending.
Thanks to our continuing success and growth Pico are always seeking talented people to join our company.
Please visit http://pico.jobs/ to see our current vacancies. We look forward to hearing from you!
Our latest software releases are available as free downloads. To check which release you are using, start the software and select Help > About.
To make sure that your Pico newsletter reaches your inbox every month, add firstname.lastname@example.org to your email address book or safe list. If you found this newsletter useful, please recommend it to your friends and colleagues. Back issues are available from our newsletter archive.
Pico Technology, James House, Colmworth Business Park, St. Neots, Cambridgeshire, PE19 8YP, England
Tel.: 01480 396395 (+44 1480 396395)
Fax: 01480 396296 (+44 1480 396296)
Pico Technology North America Inc.
320 N Glenwood Blvd.
Tel:+1 800 591 2796 (Toll Free)
Fax:+1 620 272 0981
Web technical support: www.picotech.com/tech-support/