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hesitent acceleration and poor mpg

R

randalf

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Location
Manchester
Car
Accord 2.2 i-CDTI EX
Hi

I've noticed a few issues with my Accord Diesel recently and was hoping you guys could offer some suggestions as to possible reasons.

Up until about three months ago I was doing regular long runs on the motorway and was averaging in the mid to high 40's to the gallon, due to a job change my driving profile changed and I am now doing predominantly short journies, with a bit of urban and a couple of miles on fast roads.

The mpg has dropped to less than 40, which even given the change in distance/roads is more of a drop than I expected.

Around the same time I noticed that the car seemed hesitent in the 50mph - 70mph band (something I've always thought Diesels were particularly fast in) with the engine sounding as if it's pumping the power out but that it doesn't seem to be translating to immediate acceleration.

Also starting has been slightly problematic a couple of times (twice in the last three months) where it's taken a few attempts to start the car when it's been stood for a few hours (not overnight though), which I'm thinking could be an issue with the glow plugs.

The car has just about done 50k miles on an 07 plate.

I've no idea if the above is connected in some way or if it's a coincidence.

Any ideas where I should be looking guys??
 
I don't have a diesel, but the common response here seems to be:

When was the fuel filter last changed and did you use a Genuine Honda one? (you must). Also the oil must be 0w30

Diesel fans - how am I doing? :)
 
jayok said:
I don't have a diesel, but the common response here seems to be:

When was the fuel filter last changed and did you use a Genuine Honda one? (you must). Also the oil must be 0w30

Diesel fans - how am I doing? :)
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Very good - I can see how you became an advanced member. You should have probably have hinted at the EGR valve as well.
 
Jon_G said:
Very good - I can see how you became an advanced member. You should have probably have hinted at the EGR valve as well.
Click to expand...

:lol: - Ah yes, the EGR, becomes clogged with soot, it might need a clean.
 
Hi Alan
it could well be the glow plugs but another culprit could be a sticking EGR valve which seems to be quite common on Accord diesels. Unfortunately the EGR valves on these cannot be cleaned.

Fahad (F6HAD) on this site can offer a solution in the form of a remap that can remove the operation of the EGR valve completely. As well as that he can up the power of the car too, I currently have this on my car. Its called a Stage 1 EGR delete and completely transforms the car. Maybe have a chat with him to discuss further. There is a section on the home page called Premier Tuning which is him company and covers the aspects of remaps as well feedback from members who currently have the map.
 
Shabz said:
Hi Alan
it could well be the glow plugs but another culprit could be a sticking EGR valve which seems to be quite common on Accord diesels. Unfortunately the EGR valves on these cannot be cleaned.

Fahad (F6HAD) on this site can offer a solution in the form of a remap that can remove the operation of the EGR valve completely. As well as that he can up the power of the car too, I currently have this on my car. Its called a Stage 1 EGR delete and completely transforms the car. Maybe have a chat with him to discuss further. There is a section on the home page called Premier Tuning which is him company and covers the aspects of remaps as well feedback from members who currently have the map.
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OK taking it in turn

The fuel filter was replaced by Holdcroft back in 2010, while I never saw the filter I have absolutely no reason to doubt they used anything other than Honda parts.

Last oil change was in Nov 2011, the mechanic knows Accord diesels and has one himself. I'm sure that a good oil was used, next time i'm in the area I'll ask him what the grade was - what exactly is the issue with the other grades of oil? Surprisingly enough my Accord doesn't have particularly bad oil consumption, I've not had to top the levels up between services yet.

How can I tell if there is an issue with the EGR valve?
 
Randalf said:
Around the same time I noticed that the car seemed hesitent in the 50mph - 70mph band (something I've always thought Diesels were particularly fast in) with the engine sounding as if it's pumping the power out but that it doesn't seem to be translating to immediate acceleration.
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Are the revs rising when this happens? So the revs rise and the car eventually catches up with them?
 
HuskyMan said:
Are the revs rising when this happens? So the revs rise and the car eventually catches up with them?
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Yep.

I hear the revs rising and see that reflected in the rev counter.

A few moments later the car seems to realise that the engine is outputting more power and that it needs to do something about it.
 
If its slipping clutch, its unlikely to do it in the first 3-4 gears, or at least it wont be very noticable. The best bet is to find a straight road and put it in 5th/6th gear and put your foot down flat at about 1.5k-2k rpm, if the revs rise and the speed doesnt pick up much and then the revs drop again or stay constant then the clutch is probably slipping.

What mileage has yours done and has it had a clutch before?
 
NESH said:
If its slipping clutch, its unlikely to do it in the first 3-4 gears, or at least it wont be very noticable. The best bet is to find a straight road and put it in 5th/6th gear and put your foot down flat at about 1.5k-2k rpm, if the revs rise and the speed doesnt pick up much and then the revs drop again or stay constant then the clutch is probably slipping.

What mileage has yours done and has it had a clutch before?
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It's just shy of 50k miles and I believe it's on the first clutch.
 
I also had mild hesitation earlier this year and the fuel filter was replaced with a genuine one in august 2010, at the time I thought the issue was sticking rear calliper which when fixed improved mpg and hesitation but as part of my annual service regiment I have treated the car to a course of BG244 diesel injector cleaner which has made a big difference to both starting and mpg.

Although I now plan to replace the fuel filter again in the next few months to be sure as I have done 40k since it was last done. my injectors were replaced under warranty in late 2010 and I use only premium diesel VPD most of the time.

Even so, I think the i-cdti fuelling can be sensitive so the usual list of things things to improve performance are:

  • check and replace: all filters ( air filter could also be responsible for drop in mpg and is the easiest job to check and replace yourself)
  • run a course of BG244 through at least once a year if not every 9 k (trust me no other fuel cleaner is better in my experiance try powerenhancer.com or flea bay)
  • Must be 0w30 and changed with new filter every 8- 10k (rule no. 1 of Accord i-cdti ownership)
  • use the best fuel you can VPD preferably or premium diesel (the improved mpg and fuel system benefits offsets the higher price completely)

  • also as I mentioned earlier check rear brakes as the results of early seizing rear callipers feel similar to your issue and can cause a drop in initial power and mpg and are a known issue on accord 7 gens after 5 or so years.

finally if after doing all this your still unhappy, it very probably is the Egr issue ( Loads of threads on this issue in the forum)

I should mention i have a 2004 pre-facelift i-cdti with 125+k and i do mainly motorway miles about 80 minimum a day.
I'm also on original clutch no slipping and stock engine map,
hope this helps.
 
Randalf said:
Yep.

I hear the revs rising and see that reflected in the rev counter.

A few moments later the car seems to realise that the engine is outputting more power and that it needs to do something about it.
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Certainly sounds like clutch in that case. :( more expensive than proper hesitation. Reason I suspected is cos hesitation usually happens in low gears at lower speed.
 
HuskyMan said:
Certainly sounds like clutch in that case. :( more expensive than proper hesitation. Reason I suspected is cos hesitation usually happens in low gears at lower speed.
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What's the Honda Happiness price for a new clutch these days?
 
Sounds like a slipping clutch, but a 2 year old fuel filter won't be helping.

Sticking EGR valve is also a likely culprit.

I offer a Honda diagnostics service too if interested. I can perform some tests on the engine.
 
CJM said:
Alan,

Worth giving HH a call, didn't you get the car from them ?
Click to expand...

I think I will give HH a call as I did get the car from them but ultimately clutches are a consumable item and the car is out of warranty so I don't know how much they can do at this stage.
 
Randalf said:
I think I will give HH a call as I did get the car from them but ultimately clutches are a consumable item and the car is out of warranty so I don't know how much they can do at this stage.
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Right

I've had some thoughts about this.

I was originally considering changing the Accord at the back end of this year or early next year, which does tend to make me think I don't fancy spending too much money on things.

But taking the worst case scenario if I change the Air filter, Fuel filter, flush the engine, get F6had's EGR/Remap and have the clutch changed at HH.

Without going through the exact figures I'd expect that to cost the thick end of £1250, but that is every possible reason for the hesitation/fuel economy (apart from my right foot and urban driving) issue yes?

If I were to go down that route what other likely essential bits of work would be needed on a 50k six year old CDTI over 18 months?

I'm just trying to run through the financial implications of holding on for another 18 months compared with getting a 2 YO Accord.
 
Randalf said:
Right

I've had some thoughts about this.

I was originally considering changing the Accord at the back end of this year or early next year, which does tend to make me think I don't fancy spending too much money on things.

But taking the worst case scenario if I change the Air filter, Fuel filter, flush the engine, get F6had's EGR/Remap and have the clutch changed at HH.

Without going through the exact figures I'd expect that to cost the thick end of £1250, but that is every possible reason for the hesitation/fuel economy (apart from my right foot and urban driving) issue yes?

If I were to go down that route what other likely essential bits of work would be needed on a 50k six year old CDTI over 18 months?



I'm just trying to run through the financial implications of holding on for another 18 months compared with getting a 2 YO Accord.
Click to expand...


Going off what has been mentioned so far it does sound like the clutch is slipping.
A slipping clutch in the Accord is quite refined and can last for quite a long time before becoming an real issue to physical driving, however of course the engine is revving more and requiring more fuel etc to maintain the same momentum etc that would have been achieved with a fully functional clutch, thus being a strong possibility for the drop in fuel consumption.

As with any car, there can be no guarantees of everything being ok, although there is plenty of evidence on here of many trouble free miles. ***uming that it is the clutch then I wouldn't expect you to need any further maintenance on the car other than the normal service and maybe wear and tear on brake pads etc. If you keep the current Accord, personally I'd avoid flushing the engine, just ensure the correct grade oil is used and maybe have it changed more towards 6 to 8K rather than per the service schedule, which will help keep the engine in good condition.
When I mentioned ringing HH it was to see whether they could move a little on the Clutch cost considering you bought the car from them and a member from here etc.

On the other hand, if you have the means to consider a 2 YO Accord, you can get some good deals and it maybe worth just PX 'ing the current Accord "as is"
If it were me I would inquire on PX values and have a few test drives, before you finally make you mind up.
I imagine it will also depend on you reasoning for wanting to change the Accord at the end of the year, is it because of current issues or you just want a general change, if it is the latter, then I'd take the younger Accord option as the urge to change the car may come back a further 6 months down the line.
 
Mate if you're going to spend the money and you're looking at remapping, I'd just go for an uprated clutch from CG Motorsport. I believe they now do a non paddle uprated version.

The Honda clutches (even the revised ones) slip after 30k miles or so.

Are you sure it's the clutch? bring it over to Halifax this weekend, i'll run some diagnostics on it for you first.
 
On the subject of oil changes - looking at it cynically, you're not doing much mileage so why change the oil more often than recommended?

Over 2 years you might be looking at brake disks & pads and tyres but (if you're doing clutch now) there shouldn't be any other consumables. That just leaves suspension bushes/links and wheel bearings to worry about.
 
800jimbo said:
On the subject of oil changes - looking at it cynically, you're not doing much mileage so why change the oil more often than recommended?
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Depends on the journey type, diesels are most efficient when really warm, so loads of short journeys just fills the oil up with crud really quickly. I do mine every 3k cos I only normally do 10-15 min journeys throughout the week.
 
HuskyMan said:
Depends on the journey type, diesels are most efficient when really warm, so loads of short journeys just fills the oil up with crud really quickly. I do mine every 3k cos I only normally do 10-15 min journeys throughout the week.
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Well f6had made a generous offer to run a diagnostic on the car, and as he's only an hour up the motorway I thought it would be a nice run out and might answer a few nagging queries.

He didn't think the clutch was slipping significantly, although I will certainly be keeping an eye on it especially as I got F6had to do some work while I was there.

To cut a long story short I was convinced to have the stage 1 remap and EGR done while I was there and as it seemed to pass every diagnostic i think I will keep the Accord until the back end of next year.

I had a great blast back and despite it being early days the stage 1 does transform the car with more power and improved economy (admittedly because I don't need to push the pedal as hard)

Thank you F6had
 
No probs Alan, that was one of the nicest examples of Accord I've seen in a very long time. Pristine in fact.

Enjoy!!
 
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