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172 cup idle issues - trouble shooting



browno

ClioSport Club Member
Evening All,

I am posting a thread on behalf of my brother who has just bought himself a tidy 172 cup which has an issue that we are trying to resolve thus far without success. The car itself is an 03 plate 172 cup with 79,000 miles, with 3 previous owners - it being bought from a local guy who is a Renault Alpine specialist, and who has had it 2 year (and did the cam belt 2 years/15k miles ago). It is completely standard apart from a power flex upper engine mount, and has had a recent coil pack, leads and plugs.

The car drives really well once on the move, but at idle or when moving off it is very lumpy and wants to stall as you move off, which is pretty poor - the engine is also quite mobile with quite a bit of vibration passing through into the cabin. Both of these characteristics are definitely not normal clio behaviour - I have a 182 which has been owned from new, and he owned a 172 for a while back when it was new too, so we know the cars, and this is totally different to my 182 (which does have a lumpy idle - but doesn't struggle to run)!

I have tried to capture the behaviour in the video below - the engine idles normally for the first 30 seconds or so after start (either hot or cold) and then starts to "chug" and seem as though it is struggling to keep running, along with quite a bit of engine movement as it rocks quite noticeably.

As we observed this (we hadn't noticed it when we looked at the car), we thought it should be an easy fix. There are no faults showing when plugged in, and so we thought we would begin by looking at sensors - and have used my 182 as a source of known good parts to save spending lots on a wild goose chase - so far we have swapped and tried the following with no improvement: inlet air sensor, MAP sensor, crank sensor (a new one was in the box of bits with the car), throttle body and coil pack, we have also taken out the injectors and all four appear to be firing and injecting at similar rates, and all four plugs are nice and grey and appear recently replaced.

I have looked on the live data while the car is running and can't see anything I can interpret as odd. We have also had it looked at by a friend (also an ex-172 owner) at our garage - and he has suggested checking the vac lines off the inlet for leaks/blockages. I was also wondering about taking off the cat to see if that has perhaps collapsed causing the engine to labour at idle. Beyond this, the only other thing that I can see to check is to get the timing tools in and check it is timed up correctly - and if that checks out onto compression checks.

This is proving somewhat frustrating as we were hoping that the car was as good as it had looked when we went to view - and want to get this sorted so that we can progress with fettling and improving the car ready for some fun in the spring, so any help and advice from the CS experts would be much appreciated!
 

npt

  BMW 320d- 172 cup
My 172 cup is exactly the same as you describe, again no fault codes and pulls like a train, cam timing is also bang on, I've yet to try and find a solution in other areas but will be looking into.it in the new year, with o bought another Honda ha
 

browno

ClioSport Club Member
Having got my timing tools today, we popped the caps to check the timing - and straight away could see the issue - and the cams are out of time. So we have begun stripping for a new belt and retime it.
Having done our 182 twice now, I am amazed by how much access there is in the cup thanks to the lack of aircon.
Stripping
26695396699_b29a86e46a_b.jpg
Untitled on Flickr
With the crank pin in place and trying to fit the horseshoe locking tool - I think it’s clear this is out! Amazing that it runs really!
38471303391_2cff452dde_b.jpg
Untitled on Flickr
So once we have a belt kit, aux belt and water pump sorted we will be removing the rest and getting it properly timed up (bearing in mind all of the guidance on how to not muck it up!), and hopefully will have a sweeter engine!
 

browno

ClioSport Club Member
are you 100% that you've got the locking pin right in the crank?

We have gone round at least 2 rotations of the crank to check for alignment (and done so twice!) - and this is the position where the crank pin goes in and that both cams are sitting with their slots below the centreline, so am confident it is right - just miles out! Will do a triple check on the TDC marks before we take the belt off to be sure, but I am amazed it ran at all with the cams so far out!
 
  dan's cast offs.
easy to either miss the hole completely or get it in the balance drilling. the tdc mark can be a pain if you look at it on an angle as well!!
 

npt

  BMW 320d- 172 cup
If the timing is that far out you should notice the severe lack of power tbh, plugs out and cofirm your at tdc is the easiest and best option
 

browno

ClioSport Club Member
Thanks for the comments - and double checking (before we remove the belt and risk breaking anything!) I think that we have been using the wrong crank pin (2 supplied in the kit - we had been trying the threaded one, which it seems is wrong) - so will rectify that and check we really are at TDC. I am sure that the cams are out as they don't align at any point in the rotation - but possibly not quite as dramatically as they appear in the photos above... will report back when we get back on it!
 

browno

ClioSport Club Member
Good news - we double-double checked tdc and the cams were still out - and the cam pulleys were also out relative to each other - so with the new belt kit fitted and timing checked half a dozen times we have built it back up and I am happy to report that it runs sweetly (we only ran it briefly for a few minutes due to the time, but it is clearly vastly different to how it was before).

I am happy to call that a result. Now just need to refit arch liners and wheels and we can try it properly... thanks all for your help and advice!
 

npt

  BMW 320d- 172 cup
I took it into work yesterday and it drove nicely, and was idling without issues, so I think we have sorted it! Thanks again to all for your advice.

Thanks think its something I'll need to look at again
 


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