Hesitaion when accelerating

[Big Iain]

Im convinced there is a slight hesitaion in the revs @ 4k (not all gears) when accelerarting, it doesnt happen all the time and im pretty sure its done it since I bought it last year. I have changed 2 coils since I bought it have I got another on the way out? and its just lasted since the others were replaced? dirty fuel injectors? fuel filter? spark plugs?

Air filter is all nice and clean. The reason I think its fuel related is because of the slight sooty marks on the exhaust.

Anyone?

 

[minerton]

hi
ive never noticed a difference in the running of the engine until a coil is completly burnt out,
ive also had two go
only part i can help with unfortunatly,
adam

 

[WONGY]

Hi sounds like oxy sensor, same thing happened to mine with sooty exhaust.

Check my tips in this post should help

viewtopic.php?f=13&t=8555&p=73065#p73065

OEM bosch oxy sensors can be bought here for 30% of dealer prices:

http://myworld.ebay.co.uk/citroenservic ... X:SELLERID

Hope this helps

 

[Tim]

Wongy - where are the 4 oxy sensors and how do I check them?

Big Iain - I too had this problem which develooped over 3 months. Turned out my fuel pump had disintegrated and eventually broke meaning the car would die at 4000rpm ie no acceleration. It also misfired and stalled regularly.

I'm convinced my oxy sensors or cats are now damaged and that this is what causes the coils to go off once every couple of weeks. The car is running great but every couple of weeks the engine light flashes and it goes off a coil but when I start it agin the next day its foxed for another few weeks....

This may not be an actual coil failure but a dodgy oxy sensor which if not sending the correct voltages back to the ECU as with any lambda sensor this will cause hesittion, misfiring and poor running.

Could be a
the source as to why so many coils fail due to knackered lambda sensors.... :s

 

[WONGY]

There are 4 sensors, two at the front of the engine on the cats I think, two at the rear on the exhaust.

Checking is via OBD, mine threw up a P0120 / P0300 code I think though it did not threw this up originally just poor running occassionally. The Renault Dealer picked it up on their computer, plus I asked them to test them manually and they found that 2 not 1 were malfunctioning vs OBD said 1 only.

They are only 50 notes each for the OEM Bosch part and once fitted my mpg and performance went up substantially especially when I binned my custom exhaust for a Janspeed! Unfortunately that meant me pushing a bit harder on the throttle and at least been partly to blame for my gearbox failure last month!

 

[Tim]

Cheers Wongy!

So is it best to bring to a dealer an dget them to manually check them or if I had a good mechanic how would he / what would he use to check them?

We all know Renault hourly rates and parts are extortionate!

 

[k1ano]

Also try recalibrating the throttle - I think there is an article in one of the manuals on how to do it.

Martin

 

[Tim]

Wongy said something about resetting the throttle body?

Ignition on 10 seconds, ignition off 10 seconds, turn on engine and let idle for a minute...

Can't for the love of me see what this does? :s

 

[k1ano]

The throttle is fly by wire and has a self calibrating actuator on the throttle body - the reset is to ensure that the throttle response at the engine is aligned with the pedal operation - I guess in case any components are replaced or removed for any reason. Apart from a bit of stepper motor activity in the engine bay you probably wouldn't notice anything - unless of course there is an improvement in throttle response

There is also a way of re-calibrating trim factors in the ECU aswell - which can sometimes improve the cars running.

I think both procedures are in the on-line manual. I will try and dig the details out later ...

Martin

 

[Tim]

Cheers Martin....can the oxy sensors be manually checked to see if they are malfunctioning? Do you need a voltmeter or something? What should they be reading?

And what is this online manual you speak off?

 

[k1ano]

Here we go ...

Fault Finding Manual

Some of the sections below are the first occurance of diagnostics, there are sometimes more section later on.

1. Throttle re-calibration page 6.
2. Injector fault diagnosis starts on page 22 (may be useful for SimonLM)
3. Throttle pedal diagnostics page 31.
4. Throttle actuator diagnostics page 34.
5. O2 sensor page 43 - 46.
6. Good old coil checks starts on page 56.
7. There are some multimeter checks which can be done starting on page 172.
8. Some common faults starting on page 91 i.e. starting, poor idle, driving ...

I am not sure how easy some of the above things to do are without the clip, but the manual is very good and gives an insight to the workings of the Vee to many people will make various degrees of sense

Engine Manual

The above engine manual contains a section explaining idle calibration on page 84. Basically disconnecting the battery for a couple of minutes will trigger this stage.

I am also looking at mixture control and adaptive richness adjustment on pages 84-87 to work out exactly what is going on

Martin

 

[Tim]

Cheers Kiano!

I realised these are in our knowledge section and like you have just spent the last few hours learning all about the stuff you have just mentioned! Not a lot you can do without the ClIp though...

 

[k1ano]

I do think an OBDII reader is useful as an alternative to the CLIP, perhaps not as functional, but they do report any error codes stored on the ECU.

Some of the multi-meter tests can be done and of course the diagnostic and fault finding sequences listed are useful to work through when faced with a problem I suppose most people would just take their car to Renault ... I guess some of us are just very inquistive with a thirst for knowledge :approve:

I liked the section which basically said don't perform any fault finding until the car has been attached to the CLIP - there is your £47 quid surcharge fee.

Martin

 

[Big Iain]

well... last night starts it up and it sounds like a bloody scooby. New coils tomorrow and it better not be any of the rear ones again