High HC emission problem

[Joe82]

Hi there.

I have a Ford Fiesta 1.6 16V 100HP car, year 2003. On the emission test the HC value became high, more than 400. The consumption of the car is a little bit high. I made some tests with the Forscan program and here are the results on the attached images.

If I open the engine bay there is a hissing sound from the right side of the bay, maybe the brake booster. When inside of the car I push the brake pedal it has a hissing sound.

Sometimes the short term fuel trim value is -17% or +17%

Any idea? 🤔

 

 

[Static]

I'd say compression test the engine to be sure the fuel is not just getting pushed out past a sticky valve without being burnt off properly especially if consumtion has gone up. If it passes, could be injector leaking into the chamber.

Could get away with new plugs, leads and coil for a stronger spark to burn off fuel better.

Hiss noise is strange. Brake performance and different? Pass MOT check?

 

[Joe82]

It has 2 months old NGK Laser Platinum plugs. Th car runs very good.

Sometimes, rare, when I want to start the engine it won't start until I push the gas pedal.

The brake works great, passed the MOT check.

The MAF value is like 82mg, it should be more, like 400mg?

[Joe82]

I cleaned the MAF sensor and made some new tests, but it seems to be the same.

[JONATHAN_11_80]

What's the long term fuel trim value?

[Joe82]

33 minutes ago, JONATHAN_11_80 said:

What's the long term fuel trim value?

In the Forscan program there is only short term fuel trim. I could not find the long term fuel trim.

[TomsFocus]

Your lambda value has only just scraped through as well.  Which could indicate an air leak somewhere and would make sense with the hissing you're hearing.  The PCM might be trying to compensate for this by adding more fuel.  With such a high CO level I wouldn't be surprised if the cat is knackered by now though.

[Joe82]

2 hours ago, TomsFocus said:

Your lambda value has only just scraped through as well.  Which could indicate an air leak somewhere and would make sense with the hissing you're hearing.  The PCM might be trying to compensate for this by adding more fuel.  With such a high CO level I wouldn't be surprised if the cat is knackered by now though.

The cat or maybe only the OS2?

[TomsFocus]

1 minute ago, Joe82 said:

The cat or maybe only the OS2?

I'd suggest the cat with such a high CO reading, they get damaged by unburnt fuel passing through them.  You need to fix the fault causing the excess fuel (and HCs) before you can decide whether there's an issue with the cat though.

[Joe82]

24 minutes ago, TomsFocus said:

I'd suggest the cat with such a high CO reading, they get damaged by unburnt fuel passing through them.  You need to fix the fault causing the excess fuel (and HCs) before you can decide whether there's an issue with the cat though.

I see. I will try to localize the air leak. I hope the cat is still alive because it is an expensive stuff. 🙄

Thanks for your advises.

[Joe82]

I was at the service and they said that the hissing noise from the engine compartment is normal, it is the air that enters in the engine or something like that.

I made a PCM adaption reset and here are some results.

[JONATHAN_11_80]

Short term shows its adding lots of fuel.  Shouldnt be at -20. It got a vacuum leak.

[Joe82]

If I put my hand on the throttle body, the engine dies immediately.

If there would be a vacuum leak the engine should work on?

[Joe82]

I was today at the service and they located the hissing noise. It is the fuel pipe before the injectors. If they moved the pipe the sound changed. I attached a picture which pipe is it and where it was moved.

[Tdci-Peter]

On 8/21/2019 at 4:03 PM, Joe82 said:

I made a PCM adaption reset and here are some results.

Negative fuel trim means the engine is running too rich, ie not enough air or too much fuel. So that is the opposite of a vacuum leak. MAF problems, MAP problems (though a non-turbo petrol engine usually has either a MAP or a MAF, not both, but there are exceptions), O2 sensor problems, fuel pressure too high, or injector problems can all give negative fuel trim.

I see the trim seems to be varying a lot though, and without being able to check if there is a long term fuel trim as well, it is hard to rule anything out. I would have expected a reset adaptions to have zeroed any long term trim value though. So with high CO and HC values as well as negative trim, it looks rich rather than lean.

[Joe82]

On 9/24/2019 at 1:03 AM, Tdci-Peter said:

Negative fuel trim means the engine is running too rich, ie not enough air or too much fuel. So that is the opposite of a vacuum leak. MAF problems, MAP problems (though a non-turbo petrol engine usually has either a MAP or a MAF, not both, but there are exceptions), O2 sensor problems, fuel pressure too high, or injector problems can all give negative fuel trim.

I see the trim seems to be varying a lot though, and without being able to check if there is a long term fuel trim as well, it is hard to rule anything out. I would have expected a reset adaptions to have zeroed any long term trim value though. So with high CO and HC values as well as negative trim, it looks rich rather than lean.

In the Forscan program could not find the long term fuel trim. My OBD does not have a CAN switch. Does it matter or not on reading the LTFT?

The fuel consumption is reach and the car runs better, like it has more horsepowers.

Sometimes, rarely, It has an error without the engine light on, P0460 - Invalid fuel tank level message from instrument cluster. This error can be cleared.

[Tdci-Peter]

On 9/25/2019 at 3:43 AM, Joe82 said:

In the Forscan program could not find the long term fuel trim. My OBD does not have a CAN switch. Does it matter or not on reading the LTFT?

The CAN switch on the ELM adapter switches it over to access the MS-CAN bus. This bus goes to stuff inside the cabin, not to anything in the engine bay. It does not go to the ECU, and the LTFTs (if they exist) will be in the ECU. So the switch does not matter in this case. It is a bit hit and miss as to what PIDs show up on Forscan, I can not find one for IAT2 (the inlet manifold air temp), only for IAT1 (the air intake temp), on my car. I doubt if the Forscan team do much work, if anything, on 2003 or 2006 cars now!

The rare P0460 error sound like an intermittent bad contact, maybe in the tank sender, or in the wiring to the cluster. If the DTC was in the ECU, it would be just possible that it results from comparing the ECU expectations of level, based on injection pulse widths, with the sender reading, but this is unlikely, and extremely unlikely if the DTC is in the IC.

[Joe82]

On 9/25/2019 at 12:39 PM, Tdci-Peter said:

The CAN switch on the ELM adapter switches it over to access the MS-CAN bus. This bus goes to stuff inside the cabin, not to anything in the engine bay. It does not go to the ECU, and the LTFTs (if they exist) will be in the ECU. So the switch does not matter in this case. It is a bit hot and miss as to what PIDs show up on Forscan, I can not find one for IAT2 (the inlet manifold air temp), only for IAT1 (the air intake temp), on my car. I doubt if the Forscan team do much work, if anything, on 2003 or 2006 cars now!

The rare P0460 error sound like an intermittent bad contact, maybe in the tank sender, or in the wiring to the cluster. If the DTC was in the ECU, it would be just possible that it results from comparing the ECU expectations of level, based on injection pulse widths, with the sender reading, but this is unlikely, and extremely unlikely if the DTC is in the IC.

I downloaded the torque app and I could measure the long term fuel trim. Here are the results attached with STFT and LTFT. First picture with 800 RPM second picture with 4000 RPM.

PS: The fuel pressure regulator before the injectors has a strange hissing noise. Is that normal?

[Tdci-Peter]

54 minutes ago, Joe82 said:

The fuel pressure regulator before the injectors has a strange hissing noise. Is that normal?

I don't know how often these regulators fail, but a leaking regulator allowing too high a pressure to the injectors would be one cause of negative fuel trim and high HC. It is a bit expensive to replace it just to try, I see no sign of a pressure sensor either. Testing it sounds like a bit of a specialist job. Pressurised petrol has to be handled carefully!

It might be worth checking the return pipes are not blocked, and are allowing the excess flow back to the tank.

The LTFT values from the pics confirm that the overall trim (Long+Short) is negative most of the time.

[Joe82]

On 9/26/2019 at 7:13 PM, Tdci-Peter said:

I don't know how often these regulators fail, but a leaking regulator allowing too high a pressure to the injectors would be one cause of negative fuel trim and high HC. It is a bit expensive to replace it just to try, I see no sign of a pressure sensor either. Testing it sounds like a bit of a specialist job. Pressurised petrol has to be handled carefully!

It might be worth checking the return pipes are not blocked, and are allowing the excess flow back to the tank.

The LTFT values from the pics confirm that the overall trim (Long+Short) is negative most of the time.

I made some tests.

1) Removed the fuel tank cap, removed the return line from the FPR and I blew in the hose and I could hear the bubbling sound back at the tank.

2) Removed the vacuum hose from the FPR, started the engine and left it for a few minutes and no fuel comes out from the FPR. I think it means the FPR is good?

3) With the vacuum hose removed from the FPR and with engine on, when i put my finger on the vacuum hose the engine wants to die but suddenly goes on without dying.

4) My rear exhaust has a little hole. Drips out some water and petrol mixture. That hole can be ignored?

[Joe82]

One more thing. I don't know if it means something.

When the car is not moving and I push the throttle pedal the STFT goes to -25%.

When the car is moving and I accelerate the STFT is aligning with the LTFT near to 0 and stays there.

[Tdci-Peter]

8 hours ago, Joe82 said:

When the car is not moving and I push the throttle pedal the STFT goes to -25%.

When the car is moving and I accelerate the STFT is aligning with the LTFT near to 0 and stays there.

Logically, that stacks up with too high a fuel pressure. When the engine is unloaded, fuel demand is minimal, even when revving it up. The injectors will have difficulty in delivering the low fuel quantity if the pressure is too high. Result is too rich and low trims. When the engine is loaded, fuel demand is much higher, injectors can cope ok with high pressure.

But ---- and it is quite a big but!: I am no expert on fuel injected petrol engines, most of my cars have had carburetors! I had one PI car, a dreaded Vauxhall, I know more about diesel injection than petrol. I also know from bitter experience that my logic has been wrong before. So some extra advice may be sensible before splashing out on new regulators or fuel pumps.

As an afterthought, a leaking injector will have a similar effect, that is more significant at low fuel demands. But that would throw out the cylinder balance (I am fairly sure it is multi-point injection), and be more likely to cause an error message.

10 hours ago, Joe82 said:

My rear exhaust has a little hole. Drips out some water and petrol mixture. That hole can be ignored?

The hole looks like it is in the main silencer. That would be after the cat and all sensors. if so it will have no effect.

But I do know, from my Vauxhall experience, that holes in the exhaust prior to cat, or prior to either O2 sensor, can affect the rich / lean situation. Usually they will allow air in, and make the exhaust read lean (too much O2), so lead to +ve trims, but there could be exceptions.

On the other tests: Check on return line blockage: Fine, no blockage.

Fuel out of vacuum port on FPR: That just shows the diaphragm in the FPR is intact, not that the FPR works ok. TBH, I did not even know it had a vacuum connection, I guess the output fuel pressure is regulated to a constant value relative to inlet manifold pressure, which makes sense.

If a vacuum hose is disconnected, the ECU should see the extra air going in to the inlet manifold, and compensate. As it runs ok with the hose open, it seems to be doing this as expected. The rev dip is normal, the O2 sensor response is not immediate, and the ECU can not re-adjust until it gets the signal. So that also sounds sensible, and implies the O2 sensing loop is working ok, Which suggests, but not proves, that the O2 sensors are ok.

[Joe82]

The car got new:

Bosch Distribution kit and water pump.

Denso iridium spark plugs.

NGK spark plug cables.

Delphi MAF sensor.

The injectors were cleaned and tested, everything is fine with them.

The situation is the same. There is no any error. The car runs very good. With cold engine the STFT varies between +10 and minus 10 and when the engine is warm the STFT goes down to -25 and stays there.

[Joe82]

On 10/23/2019 at 6:08 PM, Joe82 said:

The car got new:

Bosch Distribution kit and water pump.

Denso Iridium spark plugs.

NGK spark plug cables.

Delphi MAF sensor.

The injectors were cleaned and tested, everything is fine with them.

The situation is the same. There is no any error. The car runs very good. With cold engine the STFT varies between +10 and minus 10 and when the engine is warm the STFT goes down to -25 and stays there.

Here are some results

 

[Eatonm112]

On 9/26/2019 at 4:20 PM, Joe82 said:

I downloaded the torque app and I could measure the long term fuel trim. Here are the results attached with STFT and LTFT. First picture with 800 RPM second picture with 4000 RPM.

PS: The fuel pressure regulator before the injectors has a strange hissing noise. Is that normal?

I think your fuel pressure regulator has a split diaphram which is why you can hear hissing so you car is running rich as a result. I would look at getting a new one