Major jerking/hesitation under load

[N_Jonesy]

Recently my phase 2 172 has developed a nasty problem to the point it is undriveable. It really begins jerking/kangarooing/hesitating at 2000rpm onwards, I have to pull over as it becomes undriveable, I have been lucky to make it home a few times.

So far I have changed the coolant temp sensor, crankshaft sensor and throttle pedal. The coil pack is sparking when the leads are taken off induvidually with the engine, although it's been suggest that under load the leads or coil pack could not be giving a strong enough spark. I've had an emissions test done and it came back nigh on perfect apparently so I guess the lamda is fine.

I would say the car is either not fueling properly or misfiring, but I'm no expert. I don't know what to check/change next really.

Any help greatly appreciated.

 

[MicKPM]

If the emissions are "perfect" then it stands that both injection and ignition are equally working perfectly. I'm guessing your emissions test was nothing more than a fast idle test at a local MOT station (?)

Start with a proper diagnostic session (code reading is a start but will most likely show nothing wrong). Then If the live data looks there or there abouts check the mechanical side. Personally though I wouldn't rule out a potential Lamda fault.

Mick

 

[N_Jonesy]

this is from the emissions test

co 0.00%
co2 14.50%
hc 7ppm
02 1.15%
NOx 0.00
rpm 2510 rpm
lambda 1.06

thanks Mick

 

[weeshawzy]

Are you getting any lights on your dash?

 

[N_Jonesy]

Are you getting any lights on your dash?

no mate no lights at all

 

[N_Jonesy]

My engine management light finally came on, so I hooked the car upto a cheapo eBay diagnostic code reader. It found one code, P0105. This relates to the map sensor, so I bought one from a scrap yard, changed it over and reset the eml. Although the car is alot better to drive, the problem still persists, I'm stuck with what to do next apart from put the car in a garage which I really cannot afford to do!


Does anyone have any suggestions as to what to try next?

 

[franx]

mine was doing about the same, turned out to be a faulty injector. Does'nt really show up as a specific fault either on computer, strange as that was

 

[N_Jonesy]

mine was doing about the same, turned out to be a faulty injector. Does'nt really show up as a specific fault either on computer, strange as that was

Hmmm, I have been thinking that it could possibly be a faulty injector, although wouldn't the problem be persistent rather than intermittent, some days the car runs lovely and then the next I have to pull over five or six times on a journey that is no more than four miles. Its really beginning to bug me now, I can see it having to go to a local renault specialist rather soon.

 

[sinnie92]

try disconnecting your map sensor, if its brown bread, it can make the car do what your describing + the car will drive 'somewhere' near fine with it unplugged.. (as a proofing of its condition, not a fix)

map is the little black connector on the left of the plenum.

 

[N_Jonesy]

I'm sure i tried to start the car with the map sensor unplugged the other day and it wouldn't start at all. I shall give it a go again tomorrow though to either confirm it is/isn't the problem.

After owning a 106 GTi that developed numerous problems and 'upgrading' to the 172, I'm beginning to wish I steered away from the world of french cars!

 

[sinnie92]

when you say unplugged, did you remove the whole sensor from the plenum? it definatly wouldnt start if so.

leave in plenum just remove wiring plug.

And french aint so bad, 1*2's are a rewarding drive when they are up and running (briefly)

 

[N_Jonesy]

I just unplugged the wiring and left the actual sensor in the inlet. Ill have another go tonight and see if it drives any better, although it was driving fine on the way to work this morning anyway. There is no consistency to the problem, it just does it when it fancies it.

I'm sure the clio will grow on me, especially once it runs well and I get some new springs on but at the moment I do miss my gti lol

 

[Tin cup]

There's a set of injectors on eBay for about £40 might be worth a shot, where about's do you live some one could swap there's over to test yours?

 

[Tin cup]

It still could be a fault coil pack

 

[N_Jonesy]

Coil pack seems fine at idle when tested, unless the spark is breaking down under load, I have one coming from eBay anyway, so will put it on for peace of mind.

My engine management light came on again, my code reader gave the P0105 code again which relates to the map sensor. I've had the sensor unplugged for two days now and it seems to be running better, so I guess I should get a new one rather than one from a breakers like I have changed it too. My only concern is that it's the wiring to the sensor, rather than the sensor itself.

 

[N_Jonesy]

Well I had continued driving the car with the map sensor unplugged, today i received the new map sensor, installed it and cleared the code. As soon as i went to pull away, the exact same problem, tried to drive it to see if it sorted itself out, but no good. So I unplugged the sensor and tried to drive the car and it ran fine again.

I suspect the wiring leading to the sensor connector is broken somewhere, unless anyone has any other suggestions as to what this could be?

 

[LeeJSA]

Did you ever resolve this mate??

 

[Big P Dog]

Hi, I have exactly this problem. Would really appreciate hearing if you resolved this @N_Jonesy. Cheers!

 

[Wobba]

And me...it's nice when people post solutions they found, which seems to be a rare occurrence.

 

[Big P Dog]

The problem in my case was the o-ring which seals the fuel line into the fuel rail. It was damaged which meant I didn't have adequate fuel pressure when accelerating. I put a new o-ring on and it solved it immediately!

 

[voltr0n]

This? If o-ring is broken, won't fuel flow?