Am new to Pico and this forum. I didn't expect to have to dip my toe into all of his so soon but here goes.
We have had some issues with a 2003 Clio . We get a P0170 Fuel Trim Bank 1 error. We got it (pre Pico Starter Kit ) about 70 miles ago. I checked for manifold leaks using a lashed up smoke tester and it appeared O.K. so I cleared the fault. 50 miles down the line Engine Management Light has come on again. The code is P0170 again. The Freeze frame data obtained via a scanner was ............
I have just been looking up info re the Short and Long Fuel trims and their implications. I have a scanner and a Pico starter kit and I am interested in following any suggestions which will sort it.
I have just been looking up info re the Short and Long Fuel trims and their implications. I have a scanner and a Pico starter kit and I am interested in following any suggestions which will sort it.
Last edited by Robski on Mon Feb 25, 2013 11:08 am, edited 1 time in total.
Before I packed it in I was a lecturer in computing. My main hobby is cars, and I attempt to look after a Jeep Grand Cherokee and a Hotchkiss Jeep. My daughters car is the Clio. I understand some of the theory but don't apply it on a daily basis, and the idea of having a Pico kit was to use it to investigate further and educate myself being honest. I have been reading the article in Car Mechanics which uses the Pico and it seemed to be one place to start.
I will report back with regard to the fuel trims in an hour or two, after I have got the car warmed up and the scanner hooked up.
With regard to the second request, the scanner is an Autel MaxiScan MS509.
Are all the values for both STFT and LTFT negative ?
Long term fuel trim at minus 96 is a pretty high figure regardless what condition these values are taken under.
Negative LTFT at minus 96 % - that could indicate that the engine is running rich and one way to verify this - is to look at your lambda values.
BTW I looked at some datasheet from Renault and according to them DTC P0170 ( REANULT DTC DF398 ) has this something to do with the canister bleed solenoid valve.
A quick way to check this valve - is to disconnect the vacuum hose from the valve that runs to the intake manifold and remember to seal the hose ends. Now look at your serial tester and look after changes in LTFT and STFT - if there are any !!!
As Liteace mentioned fuel pressure should also be checked.
There are other opportunities or steps to diagnose the issue we can use later on in the process.
In relation to posts which have now been removed (see point 5) there is a need to emphasise a few points:
1)
This forum and Pico Technology staff are here to support any customer who has, or is looking to purchase a PicoScope. We are not here to fix cars for free, we are here to help customers or potential customers learn how to use our products, to assist in the fixing of their cars whether they are a private owner or a business. If our existing forum users wish to contribute to this they can, if they do not agree with the sharing of information they are perfectly within their own right not to post it. It is personal preference.
2)
Pico Technology do not want to sensor this forum, freedom of speech is just that. Bordering on making things personal, or the pushing of strong opinions however will not be accepted.
3)
We have many different levels of experience on this forum, and we would all do well to remember that. The use of “text” online is complicated as there is no facial expression or emotions included. This means a joke may come across as condescending, a simple remark may come across as rude and offensive, this should also be kept in mind.
4)
If you want to discuss the positive and negative effects of helping Joe Public then feel free to do this, in a thread that is not personal.
5)
I have removed the posts in this thread which did not contribute to the OP question.
IF YOU WISH TO HELP, PLEASE DO.
Please do not attempt to discuss the above within this thread (posts will be deleted). Let's keep it on topic.
If you have any issues please feel free to send me a private message.
Connect your scope up to the lambda sensor and a second channel to the MAP/ MAF (which ever you have on this engine). This should give you a better idea of whats happening in terms of fueling.
Would be useful if you save the waveforms and upload them on here so other members can see them.
It is my intention to use the Picoscope to assist in finding the problem with the Clio and shall follow the sequence set out below by Matt. I shall report back the intention being to post plots based upon what has been done for the benefit of all.
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Info fro Matt(mteste03)
Everyone will do the test slightly differently but this is what I would do.
Warm engine to normal operating temp
Run engine at 2000 rpm for a few mins
Allow to idle
Then accelerate the engine to full RPM and hold very breifly, then completly remove your foot from throttle so the engine quickly returns to idle. This is your wide open throttle test (WOT)
Try and get enough time on the scope so you see say 5 seconds before the acceleration and 5 seconds after. This way you can see lambda switching at 2000 rpm and how quickly it reacts to full throttle request. In same way you can see how the lambda reacts to the fuel being cut off during over run when you quickly return engine to idle.
Do you understand what you are looking for from lambda - ie switching from rich to lean during 2000 rpm and rich throughtout acceleration etc. If not message me back.
Be very careful doing WOT test as you don't want to hold engine at max rpm for long at all. Also don't do this test if your cam belt is near its replacment interval or over due as it could break under extra stress!!!!!!. Please don't try this if you are not 100% sure of what you are doing. Lots of videos on you tube that show the test so check these out.