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Questions specifically about a Petrol powered Citroen C3 (usually engine or fuel related problems).
Forum rules One question per topic.
Petrol engine related faults, like injectors, error codes, overheating.
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Does it idle OK?
Any deterioration in performance below 2000 RPM? Drives fine below 2000?
At 2000 RPM does the engine die or does it feel like the accelerator has stopped?
Anything else the engine is doing strange?
The engine idles fine.
As far as I can tell there are no other issues with the engine.
When it reaches 200rpm, it kinda dies/drops to idle for a second and then goes back up. It keeps doing this until I reduce the revs to below 2000. Kind of like a bouncing pattern.
The guy who towed us home mentioned it might be a blocked exhaust but when we checked the exhaust the pressure at the end seemed fine and the normal amount of smoke was coming out of the exhaust.
Also, this morning i checked to see if maybe it was working fine again and it seemed to want to rev to 2500 this time before the same problem occurred.
Marcianyn wrote: ↑Mon Jan 06, 2020 10:23 am
The engine idles fine.
As far as I can tell there are no other issues with the engine.
When it reaches 200rpm, it kinda dies/drops to idle for a second and then goes back up. It keeps doing this until I reduce the revs to below 2000. Kind of like a bouncing pattern.
The guy who towed us home mentioned it might be a blocked exhaust but when we checked the exhaust the pressure at the end seemed fine and the normal amount of smoke was coming out of the exhaust.
Also, this morning i checked to see if maybe it was working fine again and it seemed to want to rev to 2500 this time before the same problem occurred.
I wouldn't have thought that the exhaust would be blocked. As far as I know there isn't a filter in the system fitted with a petrol engine; it is usually the diesel DPF that blocks. It sounds to me that the car. for some reason, has gone into limp mode.
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If there were engine failures that the ECU could detect and record, I would assume the engine light would come on. It might not throw up a light for temporary faults but this doesn't seem to be in the temporary category.
Could be the coil pack or a vacuum leak. However the engine ECU is pretty good at spotting coil pack faults and will typically turn on the engine light.
As far as vacuum leaks go they don't tend to hide, then pop out at a certain point but you could try the electrovalve.
Check to see that all the connections to do with the inlet manifold are secure I.E. the connection from the brake booster to the manifold, the breather hose from the rocker cover to the manifold (look for cracks in these lines too), loose screws mounting the manifold. Remove the injectors and check the orings are seating (I'd do that last as it's unlikely).
The purge control (electro) valve is the brown cylindrical device attached to the top left hand side of the engine (as viewed from the front of the car). There is one tube going to the wheel arch (sort of) and one tube going to the inlet manifold. Pull the tube going to the manifold off at the control valve and and block the tube. It's possible the valve is popping open under load.
Another thing to check might be the fuel pump. That involves removing the schrader valve in the end of the injector manifold and measuring the volume of fuel discharged over time. I don't have a specification for that but I would expect around 3-4 litres per minute(?), so a substantial amount. The fuel pressure specification is 3 bar but that requires a measuring device.
The last thing might be the crank angle sensor but that involves replacing it.
I have checked with the scanner for fault codes, but came up empty, as suggested by the lack of an check engine light. I have also checked the lines around the manifold and can't see anything wrong there. All connections look alright.
Have tried my best to block the tube going to the inlet from the purge control valve but that didn't do anything.
I did hear a small hissing I think when listening in that area but not sure if that was always there or not.
Will probably hand it over to the garage tomorrow as we do need the car working.
One involving the throttle body, an internal fault.
One with a sensor needing adjusting.
And to add insult to injury the radiator went as well so now we have decided to get rid of the car as it has become uneconomical to keep fixing all these things.
So if anyone needs some spare parts and lives around Leeds, let me know.
I don't know if you are going to come back to the forum but could you do us a big favour and add a bit more information to your post (if possible)?
With no fault codes how did the mechanics trace the faults to the throttle body? Had they seen this before? Did they replace the throttle body or repair it? The engine ECU can spot throttle peddle and throttle body discrepancies. So if one is not following the other it usually throws this up as a "coherence" fault and the engine light comes on. So, if you are pushing down on the peddle but the throttle wont go past 2000 revs the engine ECU should "see" this and throw up an error...theoretically. Is this a failure mode the ECU wont capture?
I cant think of any sensors that can be adjusted. Or anything that can be adjusted off the top of my head. Can you allude on that? Did they replace a sensor? Do you know which sensor it was?
I have seen people complain of faults like yours but have not seen a resolution, the posts just peter out!
