ClioSport.net

Register a free account today to become a member!
Once signed in, you'll be able to participate on this site by adding your own topics and posts, as well as connect with other members through your own private inbox!

Really feint hesitation/miss at light throttle



RustyMojo

ClioSport Club Member
Yeah I’m not sure I’m a great example to anyone 😂 basically I’m a pathetic quitter! Who’s answer to resolving a problem is dropping money, throwing a hissy and sacking something off. For me though it was absolutely the right call. I was never going to get my old car to a position I was happy with and I had far, far more problems to address than the OP.
 

Martin_172

ClioSport Club Member
The rear O2 sensor keeps being mentioned, don't worry about it, it's not controlling anything. The cat will be fucked after years of this too. But if it's pulling fine up the revs it won't be doing any harm or causing the issue, it's just not doing its job and killing the butterfly's!

I've come across this problem a few times and it's almost always the front lambda sensor, don't assume the new one is ok as that can take you on a wild goose chase round every sensor and piece of wiring.

Get yourself to euro and get a genuine Bosch sensor, if it doesn't cure it, return it.

I would also be checking the white connector under the engine bay fuse box. It causes mayhem when it's not behaving.

This will be an easy problem to cure, your looking too much into it, think logical, start fresh with it.

People will say take it to a specialist and that is a great idea if you have one local who's good (which you said you don't) so at the end of the day it's a 20yr old 4cyl engine, it's not complicated. I've pulled my hair out with them in the past but just look at it with a clean head and don't assume the new parts are all ok
 
  2003 Clio 172
love this post Martin.........motivated me......thanks :)

yep, genuine bosch o2 went in but will replace as has been said. looking back, it's a year old now......service item almost imo.

I went to town on the white connector under the bonnet. cleaned, inspected and repeated several times, will do so again tho

oh yea, and fk the butterflies lol
 

Touring_Rob

ClioSport Club Member
  182, E46 M3, 1000RR
I think from input here it behaves just like a binary check to verify the cat is working but that might be wrong
My understanding is this. The rear lambda on these cars does not have an effect on fuel trim (short or long) and is there as a check catalytic efficiency. You can unscrew the rear lambda and cable tie it out the way, replace it with a bung and still not have a CEL.

I will look through some logs I have on another engine, close to 100kPa is a natural reading for a normally aspirated engine at sea level, 55kPa seems a little high at idle which might suggest a vacuum leak.

The air temperature sensor will also have a large impact on fueling.

out of curiosity what is your MPG like?

Your data from the fuel app looks wrong(ish). My understanding is that you should be getting a consistent voltage of between 0.1 and 0.6ish from the post cat narrow band lambda while yours seems high (rich) all of the time other than when you give what I assume is a throttle blip.

Ignoring that, I can see a huge lean section on both sensors, I assume this is from a decent throttle stab? Looks way too long (time wise). Its almoust as if the ecu has totally missed the enrichment event, does your fuel datalog map and tps readings also, they would be interesting to look at, both against O2.

Apologies if you have said this already, but after a large throttle stab does the idle take a long time to settle again?
 

Touring_Rob

ClioSport Club Member
  182, E46 M3, 1000RR
My understanding is this. The rear lambda on these cars does not have an effect on fuel trim (short or long) and is there as a check catalytic efficiency. You can unscrew the rear lambda and cable tie it out the way, replace it with a bung and still not have a CEL.

I will look through some logs I have on another engine, close to 100kPa is a natural reading for a normally aspirated engine at sea level, 55kPa seems a little high at idle which might suggest a vacuum leak.

The air temperature sensor will also have a large impact on fueling.

out of curiosity what is your MPG like?

Your data from the fuel app looks wrong(ish). My understanding is that you should be getting a consistent voltage of between 0.1 and 0.6ish from the post cat narrow band lambda while yours seems high (rich) all of the time other than when you give what I assume is a throttle blip.

Ignoring that, I can see a huge lean section on both sensors, I assume this is from a decent throttle stab? Looks way too long (time wise). Its almoust as if the ecu has totally missed the enrichment event, does your fuel datalog map and tps readings also, they would be interesting to look at, both against O2.

Apologies if you have said this already, but after a large throttle stab does the idle take a long time to settle again?
EDIT* didn't see Martins reply, good advice from him there.
 

Touring_Rob

ClioSport Club Member
  182, E46 M3, 1000RR
Last passing thought is that if the car is considerably better after having the battery off for a while, the fuel trims will have likely reset - this may well also point to the primary lambda as being the (or part of) the issue. I've had a car before where the primary lambda had degraded over time, the long term fuel trims would gently go to pot over a few hundred miles.
 
  2003 Clio 172
My understanding is this. The rear lambda on these cars does not have an effect on fuel trim (short or long) and is there as a check catalytic efficiency. You can unscrew the rear lambda and cable tie it out the way, replace it with a bung and still not have a CEL.

I will look through some logs I have on another engine, close to 100kPa is a natural reading for a normally aspirated engine at sea level, 55kPa seems a little high at idle which might suggest a vacuum leak.

The air temperature sensor will also have a large impact on fueling.

out of curiosity what is your MPG like?

Your data from the fuel app looks wrong(ish). My understanding is that you should be getting a consistent voltage of between 0.1 and 0.6ish from the post cat narrow band lambda while yours seems high (rich) all of the time other than when you give what I assume is a throttle blip.

Ignoring that, I can see a huge lean section on both sensors, I assume this is from a decent throttle stab? Looks way too long (time wise). Its almoust as if the ecu has totally missed the enrichment event, does your fuel datalog map and tps readings also, they would be interesting to look at, both against O2.

Apologies if you have said this already, but after a large throttle stab does the idle take a long time to settle again?
I was also told by Fred on here that if I was seeing 40mpg and 60mph in 5th then I wasn't far off good and that is what I am seeing at the moment in that scenario

Daily driving however it's sitting around 26/27mpg.

Air temp sensor hasn't been replaced but I think i can pull live data for that as well.

And with regards to the data I uploaded, it's probably too long for me to recall the exact scenarios so I might do some logging where i note the time stamp for a WOT run and a casual pull.

Cheers guys, appreciate the input

J
 

Louis

ClioSport Club Member
I was also told by Fred on here that if I was seeing 40mpg and 60mph in 5th then I wasn't far off good and that is what I am seeing at the moment in that scenario

Daily driving however it's sitting around 26/27mpg.

Air temp sensor hasn't been replaced but I think i can pull live data for that as well.

And with regards to the data I uploaded, it's probably too long for me to recall the exact scenarios so I might do some logging where i note the time stamp for a WOT run and a casual pull.

Cheers guys, appreciate the input

J
That's normal mpg for daily driving.
 
  2003 Clio 172
OK, grabbed a few logs. Will upload when home.

interesting that after the battery pulled last night, it is pulling like an absolute unit.

rear o2 was showing a historic error at start which I cleared.

it was there after the runs with no cel thrown.

rear o2 was around 400 before the spirited runs, near 600 or 700 after
 
  2003 Clio 172
Actually, these are RSTuner logs which I am assuming that not all of you will be able to open?

Perhaps I can just screen capture them as videos or the points that i might feel of interest. Leave it with me.

As for screenshots

1600266590862.png


So I reset the codes and pulled the following with the engine off

1600266625713.png


Took it for a little blast and we were looking at the following

1600266663573.png


And hey presto, this was back

1600266690950.png
 
  2003 Clio 172
Here is a WOT run, 1st and 2nd to limiter pulling on to motorway

 
  2003 Clio 172
right..... my mega seal between the cat and mid section (after both o2 sensors) was less than mega. blowing out at the top. sorted that.

also had a goosey at the rear of the cat and it is perfect. fine mesh, no damage and no blockages

:/
 

Touring_Rob

ClioSport Club Member
  182, E46 M3, 1000RR
Joke - nothing stood out to me as being awful however I am not used to looking at logs with a narrow band sensor. I would be swapping the front lambda sensor out for a genuine one and having another look to see if there are any vac leaks, under inlet, injector O-rings, servo pipe etc. your spray test was good, better off using propane or finding a garage with a smoke tester (buying a cheap smoke tester).
 

Touring_Rob

ClioSport Club Member
  182, E46 M3, 1000RR
Only thing that possibly stands out is your primary lambda does seem a little slow to respond, which for me would be another reason to swap it. I can see both going full lean on the over run with fuel cut which is good. Sensor should be transitioning from rich to lean in better than 100ms.

A good way to check this is to take a data log at idle and pull a vac line off the engine. Engine should go lean and in your logs you can measure the response time of the sensor.

It is possible that you have the wrong part installed giving iffy readyings overall. Or a vac leak, would be handy for someone else with an RS Tuner to share their long term fuel trim also and other general readings.

Did you look into your throttle body any more?
 


Top