Renault 0.9 TCE Misfire
Discussion
Car is a Dacia Logan with the Renault H4B 900cc turbo three pot, port injected. It has 37k miles on it, has regularly serviced and has been utterly reliable for the last three years or so.
Recently my wife complained of it sounding lumpy and hesitating when cold, and I could hear a definite misfire under cold idle. As the engine warmed and the idle speed dropped, the misfire disappeared.
There are no engine codes present, either OBD2 or Renault specific. Looking at the misfire counters in the live data, I see misfires being detected between 1300-1500RPM under no load, at engine speeds above and below and above this the misfire disappears. If I bring the engine up to 2000RPM or so and pull the speed down by slipping the clutch, I don't see any misfires.
With the engine cold the misfire counts are mostly on cylinders 1 and 3, with the middle cylinder showing about 1/4 of the outer values. Once the engine has warmed the misfire count is predominantly on cylinder 3. Additionally the accumulated knock detection counters are showing about 20% more on cylinder 3.
The plug change interval isn't too far off so they were replaced, but it made no difference. Moving the coils didn't move the warm misfire count to a different cylinder, and just to be certain I borrowed a good set of coils which also made no difference, so it seems unlikely this is ignition related.
The fuel trim in closed loop at warm idle is +4.7% long term, and between -8% to -10% short term, so a net reduction in fuelling. The oxygen sensor is switching quite happily at idle, though obviously flatlines at 0v when misfiring occurs.
I'm thinking this is possibly a fuel delivery problem on injector 3 which is working especially poorly at low duty cycles pulse widths, but this wouldn't explain why it idles smoothly when warm, and I would have expected greater positive fuel trims?
Recently my wife complained of it sounding lumpy and hesitating when cold, and I could hear a definite misfire under cold idle. As the engine warmed and the idle speed dropped, the misfire disappeared.
There are no engine codes present, either OBD2 or Renault specific. Looking at the misfire counters in the live data, I see misfires being detected between 1300-1500RPM under no load, at engine speeds above and below and above this the misfire disappears. If I bring the engine up to 2000RPM or so and pull the speed down by slipping the clutch, I don't see any misfires.
With the engine cold the misfire counts are mostly on cylinders 1 and 3, with the middle cylinder showing about 1/4 of the outer values. Once the engine has warmed the misfire count is predominantly on cylinder 3. Additionally the accumulated knock detection counters are showing about 20% more on cylinder 3.
The plug change interval isn't too far off so they were replaced, but it made no difference. Moving the coils didn't move the warm misfire count to a different cylinder, and just to be certain I borrowed a good set of coils which also made no difference, so it seems unlikely this is ignition related.
The fuel trim in closed loop at warm idle is +4.7% long term, and between -8% to -10% short term, so a net reduction in fuelling. The oxygen sensor is switching quite happily at idle, though obviously flatlines at 0v when misfiring occurs.
I'm thinking this is possibly a fuel delivery problem on injector 3 which is working especially poorly at low duty cycles pulse widths, but this wouldn't explain why it idles smoothly when warm, and I would have expected greater positive fuel trims?
stevieturbo said:
LimSlip said:
FWIW a set of injectors from a very low mileage engine fixed this issue.
very unusual.Did you get the injectors tested to see what was actually wrong ?
I have a similar issue with my 0.9 tce powered sandero (Gen 2). 22,000 miles from new, serviced every year. The car is now idling incredibly rough, and has an awful shudder to the point where the whole car moves back and forth at around 1200 rpm. The car also seems to bog down awfully. For example - 2nd to third gear change today coming onto the m6 from the m6 island, the car bogged from 2,600 to around 1,200 rpm
I predict the coil packs, spark plugs, or injectors - maybe a mix of all three? Is this a common thing with this engine? It has progressively worsened from when I bought the car at 21,000 miles.
I predict the coil packs, spark plugs, or injectors - maybe a mix of all three? Is this a common thing with this engine? It has progressively worsened from when I bought the car at 21,000 miles.
I’ve just rebuild one of these engines, though it was a lot higher mileage.
Timing chain failure, looks like the plastic casing around the chain rails had disintegrated and broken off causing the chain to skip. Unfortunately also bent all the exhaust valves, despite some sites claiming its a non-interference, clearly not!
The plastic bits must have been floating around in there for a while initially as the owner had been claiming various misfiring and rough running issues in the months prior.
Timing chain failure, looks like the plastic casing around the chain rails had disintegrated and broken off causing the chain to skip. Unfortunately also bent all the exhaust valves, despite some sites claiming its a non-interference, clearly not!
The plastic bits must have been floating around in there for a while initially as the owner had been claiming various misfiring and rough running issues in the months prior.
HighSidedMedia said:
I have a similar issue with my 0.9 tce powered sandero (Gen 2). 22,000 miles from new, serviced every year. The car is now idling incredibly rough, and has an awful shudder to the point where the whole car moves back and forth at around 1200 rpm. The car also seems to bog down awfully. For example - 2nd to third gear change today coming onto the m6 from the m6 island, the car bogged from 2,600 to around 1,200 rpm
I predict the coil packs, spark plugs, or injectors - maybe a mix of all three? Is this a common thing with this engine? It has progressively worsened from when I bought the car at 21,000 miles.
They're known to be hard on plugs so I'd start there. I predict the coil packs, spark plugs, or injectors - maybe a mix of all three? Is this a common thing with this engine? It has progressively worsened from when I bought the car at 21,000 miles.
I very nearly bought a Sandero Stepway with the 1.0 TCE version of this engine 3 years ago. When I test drove one (brand new at a dealer) the engine did seem a little rough at startup but was smooth when warm.
I then drove a Clio with the same engine last year, again I just didn't like it. I actually drive a Megane shed with the 1.4 TCE engine and that felt like the smoothest engine in the world when I drove it home compared to the 1.0.
I just don't trust these three cylinder engines, all of them seem to have an inherent problem that will occur at lowish mileges. I have seen LOADS of cars with this engine for sale on eBay with either chain issues or "chain just replaced" (and I assume they just want to see the back of the thing).
I would be mighty pissed if the engine had an issue at 22K miles, that is like brand new to me.
I then drove a Clio with the same engine last year, again I just didn't like it. I actually drive a Megane shed with the 1.4 TCE engine and that felt like the smoothest engine in the world when I drove it home compared to the 1.0.
I just don't trust these three cylinder engines, all of them seem to have an inherent problem that will occur at lowish mileges. I have seen LOADS of cars with this engine for sale on eBay with either chain issues or "chain just replaced" (and I assume they just want to see the back of the thing).
I would be mighty pissed if the engine had an issue at 22K miles, that is like brand new to me.
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