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Poor Fuel Consumption on 2.4 Auto

danny35 said:
I kind of left it on bad terms with the mechanic who carried out the service ......................................

I don't actually know which if any plugs actually need to be changed. It could be the coils for all I know. I will have to get them inspected.
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there may not be a misfire, you're only going on what the HDS guy said.

tbh this is impossible to diagnose over the internet, so you're going to have to bite the bullet and take it to a good Honda dealer (not all Honda dealers are of the same quality) and ask them to do a full check and give you a report. That alone will set you back about £100, and be prepared for a very long list from them.
 
freddofrog said:
there may not be a misfire, you're only going on what the HDS guy said.

tbh this is impossible to diagnose over the internet, so you're going to have to bite the bullet and take it to a good Honda dealer (not al Honda dealers are of the same quality) and ask them to do a full check and give you a report. That alone will set you back about £100, and be prepared for a very long list from them.
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Sounds like a nightmare tbh! I will have to wait and see what happens...see if I can find any other symptoms and maybe get the guy who did the original check to come back and re-diagnose the car or provide me with the original codes, and to check all the plugs. I honestly hate going to dealers and will try and avoid that option.
 
danny35 said:
Sounds like a nightmare tbh! I will have to wait and see what happens...see if I can find any other symptoms and maybe get the guy who did the original check to come back and re-diagnose the car or provide me with the original codes, and to check all the plugs. I honestly hate going to dealers and will try and avoid that option.
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Honda dealers are usually far better than any other type of dealer (franchised or independent). They are very much held accountable by Honda UK, who will often take the customer's side in any dispute. But, this depends on how old the car is of course, and what the dispute would be about. Whilst they charge a lot of money per hour, they do know more detail about the engines. If you haven't found anyone to trust on diagnosing issues with this car, you're in trouble. If you don't want to spend any money on it, and if you can't do anything yourself, best thing is to just live with it. At the end of the day, you're doing about 5,000 miles per year, and the difference between 18 mpg and 25 mpg (you won't get more than 25 mpg on 14 miles per day) is as follows .....

5,000 miles @ 18 mpg = 277 gallons
5,000 miles @ 25 mpg = 200 gallons

77 gallons = £346

IMO you cannot reach 25 mpg without spending £346 to reach 25 mpg, but if you wait for the summer, you may find that the car reaches 25 mpg anyway.
 
edgeoftime said:
As both you fred and dan live in london and I only just outside why not meet up so we can see the car and hear it running?
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I live 2 hours drive from London John ...pay attention LOL

I could maybe go to Milton Keynes with my HDS

and toolbox
 
I don't know If you are both being serious, but I would be very happy to meet up somewhere.
 
danny35 said:
I don't know If you are both being serious, but I would be very happy to meet up somewhere.
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I can't speak for John but I'd go for MK (Northampton would be more convenient for me distance-wise, but from what I know of MK, the roads around MK are more convenient)
 
freddofrog said:
I can't speak for John but I'd go for MK (Northampton would be more convenient for me distance-wise, but from what I know of MK, the roads around MK are more convenient)
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Sorry Fred got my glasses on upside down!! LOL

Must do better.
 
freddofrog said:
I can't speak for John but I'd go for MK (Northampton would be more convenient for me distance-wise, but from what I know of MK, the roads around MK are more convenient)
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That would be great Brian..it's very kind of you to offer.. Milton Keynes would be good but we can do wherever you prefer. You up for it John?
 
Fair play to Brian for offering ***istance here, first port of call has to be a full diagnostic or else you will be changing stuff left right and center.

as for revs increasing when the AC is turned on, that is normal behavior.

Re: CL500, certainly no status thing wrong with me, its a fine motor and its at a stage in my life where its now or never in terms of getting one.
 
LOL what do you mean wrong with you? I was just kidding fella, like Mr Corbyn I try not to do personal, sorry if it came over like that, it's none of my business what you decide to drive ;)
 
I don't mind, although I have no clue where that is. We would also need to confirm with Brian. When were you thinking?

Edit: We can pick a day when it's not forecast to rain.
 
toffee_pie said:
Fair play to Brian for offering ***istance here, first port of call has to be a full diagnostic or else you will be changing stuff left right and center.

as for revs increasing when the AC is turned on, that is normal behavior.

Re: CL500, certainly no status thing wrong with me, its a fine motor and its at a stage in my life where its now or never in terms of getting one.
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he's already had a diagnostic from a "mobile mechanic" with an HDS (a proper one I think, mine is a chinese clone).
 
freddofrog said:
yeah I wasn't thinking of this weekend either LOL
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Yes,I am stuck with the family this whole weekend. Maybe sometime next week, whenever is good for you both.
 
freddofrog said:
yeah I wasn't thinking of this weekend either LOL
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is there a day when it doesn't rain these days? certainly in Ireland it seems to be raining every day of the week.
 
toffee_pie said:
is there a day when it doesn't rain these days? certainly in Ireland it seems to be raining every day of the week.
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apparently it's because the jet stream is strong and just below the uk, but it will shift further south and weaken in a week or two causing cold weather, but some sites predict an unusually mild February

this site goes to 17 January http://www.netweather.tv/index.cgi?action=jetstream;sess=

so does this one (select by date) http://www.metcheck.com/UK/jetstream.asp

this one only goes 5 days ahead but has a good animation (scroll all the way down) http://www.newquayweather.com/wxjetstream.php

if you'd seen this a few days ago it would have scared you to death http://earth.nullschool.net/#current/wind/surface/level/orthographic=-16.77,57.46,1223/loc=-1.470,50.422




edit: so MK might have to wait until February :eek:
 
Hi Brian, I am actually a member in that forum and use it regularly.

I am looking to get the issues looked at much sooner, especially before February. Don't worry if you can't make sooner, I will then just take it to a mechanic next week. These problems are bugging me and I really want to get it diagnosed and fixed asap and enjoy the car.
 
I am not confident enough to mess with the spark plugs. The spark plugs may be an issue but there is definitely something else wrong. The reason being that when the mechanic reset and configurated some codes the car ran really nicely for 2 Days until it reverted back. Had it been the spark plugs causing the issue, it would not have helped, even for those 2 Days.
 
Cliffordski said:
Is it worth going back to that mechanic and seeing what has reverted back?
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I will end up calling the mechanic if Brian and/or John are unable to meet. I guess I am just sick of going through mechanics I think,a and it would be nice to meet some fellow forum members as well :)
 
I've had a look on the internet to see if there is a difference between an official HDS and a Chinese clone, and based on the sparse information out there, the only difference is that you should not use a Chinese clone to try to update the ECU software i.e. a Chinese clone has all the same abilities but it might lose sync over the OBD port (so reading data with a Chinese clone is ok).

Based on that, and ***uming that he had an official HDS, I can only think that he may have updated the engine ECU software, and the engine then went into "learn" mode. In effect this would have reset the fuel trims, which might have helped temporarily. Note that it is only possible to "calibrate" the injectors on the Accord diesel ... to properly check injectors on a petrol engine, they need to be removed. Furthermore, AFAIK, it is only possible to check an O2 sensor by connecting a good DVM or an oscilloscope to the sensor and observing the signal.

If it were me, I would have wanted to go for a test drive with the HDS connected to observe the actual fuel trims in operation. From the fuel trims you can see if the ECU is struggling to keep the mixture at Stoichiometry ....if it is struggling, then you need to remove things to look ....if it isn't struggling, then the issue is caused by something else

It is going to be very difficult to find a paid mechanic who is able to do anything other than visually check the following
1. the spark plugs
2. the injectors (to see if they need cleaning)
3. maybe, the fuel pressure
4. possibly, the MAF sensor (to see if it needs cleaning)
5. hopefully, the O2 sensors (either out of the car, or using a DVM with the engine running)
6. definitely the brake calipers (with an ***istant on the brake pedal)
7. finally, the VC's

All of that list will take time, and time costs money.
 
freddofrog said:
I've had a look on the internet to see if there is a difference between an official HDS and a Chinese clone, and based on the sparse information out there, the only difference is that you should not use a Chinese clone to try to update the ECU software i.e. a Chinese clone has all the same abilities but it might lose sync over the OBD port (so reading data with a Chinese clone is ok).

Based on that, and ***uming that he had an official HDS, I can only think that he may have updated the engine ECU software, and the engine then went into "learn" mode. In effect this would have reset the fuel trims, which might have helped temporarily. Note that it is only possible to "calibrate" the injectors on the Accord diesel ... to properly check injectors on a petrol engine, they need to be removed. Furthermore, AFAIK, it is only possible to check an O2 sensor by connecting a good DVM or an oscilloscope to the sensor and observing the signal.

If it were me, I would have wanted to go for a test drive with the HDS connected to observe the actual fuel trims in operation. From the fuel trims you can see if the ECU is struggling to keep the mixture at Stoichiometry ....if it is struggling, then you need to remove things to look ....if it isn't struggling, then the issue is caused by something else

It is going to be very difficult to find a paid mechanic who is able to do anything other than visually check the following
1. the spark plugs
2. the injectors (to see if they need cleaning)
3. maybe, the fuel pressure
4. possibly, the MAF sensor (to see if it needs cleaning)
5. hopefully, the O2 sensors (either out of the car, or using a DVM with the engine running)
6. definitely the brake calipers (with an ***istant on the brake pedal)
7. finally, the VC's

All of that list will take time, and time costs money.
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Thank you for looking into the HDS unit and for the detailed response. When the mechanic arrived, I specifically asked him to reset the ECU and he said not to bother as it's a waste of time.

I am not sure that all the things that you list necessarily need to be carried out as I think one of the codes that came up on his system is the issue. Once that is identified, I will probably then need to replace/clean that part and not bother with the reset/re-calibration. The fact that the diagnostic machine fixed the issue, even if only temporarily points to the problem being contained within one of those codes.
 
danny35 said:
Thank you for looking into the HDS unit and for the detailed response. When the mechanic arrived, I specifically asked him to reset the ECU and he said not to bother as it's a waste of time.

I am not sure that all the things that you list necessarily need to be carried out as I think one of the codes that came up on his system is the issue. Once that is identified, I will probably then need to replace/clean that part and not bother with the reset/re-calibration. The fact that the diagnostic machine fixed the issue, even if only temporarily points to the problem being contained within one of those codes.
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Any OBD reader will get codes. If there was a code, you must find out what it was. If he did not reset the ECU then I have no idea what he was doing for 90 minutes.

Cliffordski said:
IIRC disconnecting the battery resets the ECU and puts it in learn mode.
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I've heard that said before, but not in my experience.
 
I think he said it is resetting the codes to use the correct values. I don't know if that is considered an ECU reset. The car feels slightly underpowered compared to before, not rough so much.
 
danny35 said:
I think he said it is resetting the codes to use the correct values. I don't know if that is considered an ECU reset.
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No, "codes" are things that indicate issues, you just "clear" them, you don't need an HDS to do that.

Was the car stationary the whole time, or were you driving it at some point ?



Cliffordski said:
That sounds like a remap.
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You can't remap the 7th gen K24 ECU over the OBD port, but I reckon he did reset the fuel trims.
 
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