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Discussion Starter · #1 ·
My 2.2 i-CTDi with DPF is behaving strangely since some time. When i check the boost pressure during full throttle acceleration, there is always a "spike", followed by a significant drop of pressure, which can be felt as a momentary reduction in acceleration (e.g. as if you would slightly release the accelerator pedal for a second or two from full to 3/4). The clutch is not slipping.

It is especially bad if you start at about 2000-2500 rpm, when you begin at low revs (1400-1500) it is a little bit better, but there still is a reduction in boost pressure between slightly above 2000 rpm until after 2500 rpm.

The boost reduction is always more or less the same, only the effect it has on acceleration varies with outside air temperature - the warmer it gets (less air density) the worse it gets.

There are no errors stored in the ECU, no check engine light. I am unsure if this indicates a mechanical problem, or if this could be some software "trick" of Honda to save the clutch or cut down emmissions, since they are at least trying to find a way to flash my ECU to an older firmware version (the one the car came with, has been updated since then) to see if it gets better.

Has anyone out there with a 2.2i-CTDi with DPF (ideally MY 2007) the possibility to record a log of boost pressure vs. RPM via OBD in 3rd/4th gear at full throttle? Perhaps even done so, or experienced something like me? Or even looked inside the original ECU map?

There are not many Civics in my region, and the few which exist are either petrols, or MY 2006 without DPF, which might not be a valid comparison. I know the boost logs of Relic, i compared them to mine and found that i am constantly below his curve, which represents very well what the car feels like - somewhat strangled of air and not performing as well as it could. There is a lack of midrange torque, and rough estimations derived from achieved maximum speeds reached on german autobahns (compared to what was possible earlier, when the car was new) it feels like some 10 BHP are missing at the top end too. And the acceleration to top speed seems to take more time, although i do not have data to back this up, it is more a general feeling that it takes too much time, compared to what i was used to.

As im am out of warranty (94.000 km, car is 4 years old), i would hate to spend money investigating mechanical problems if it is a software thing which could only be solved by a firmware downgrade or, if this does not work, a remap. Has anyone experienced degraded performance after a software update form Honda?
 

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Have you got a datalog you can post up with
MAP MAF IAT RPM ?

Could be something as simple as a loose connection / split pipe & resultant boost leak..
..to stuck EGR as FAHAD said..clogged VNT ..or even an issue with the MAF over reading (exceeding limits) so the boost is cut back.

Whats the smoke like at full load ?
 

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Discussion Starter · #8 ·
Here in Austria the Civic has been delivered with DPF since 2007 - there was an extra tax to pay when you bought a car without DPF then. Car manufacturers who did not have DPFs ready would even pay the tax for you, so that you dont look somewhere else (a couple hundred euros)!

I have some logs with MAF, MAP and IAT, even some wih EGR - i will post them shortly (have them on my other computer).

I did them at different temperatures, and they always look more or less the same. It is perhaps a little bit better in freezing weather when the EGR is always at 4.7% regardless of RPM or throttle position (do the UK Civics also do that?).

I myself suspect some problem with the VNT vanes, like they have a tight spot somewhere which makes it impossible to set the correct amount of boost. Sometimes when accelerating at about 1/3 - 1/2 throttle in second gear, acceleration does not increase smoothly with RPM. Instead, there is a jerk at about 2500 - 2700 RPM, like when you suddenly press harder on the accelerator, although i did not change its position. It feels like something sticking in that situation.

The higher the RPM, the less the drop in boost, although it is even there above 3000 RPM (but much shorter in duration then), and the final boost reached seems to be a little bit on the low side.

What has been done so far (all on warranty / goodwill of Honda):

.) MAF and MAP sensors replaced - did not really help

.) Looked over my own recordings - found to be "within tolerances"

.) Checked for stored faults - nothing found
.) Actuator tests with the HDS (boost control solenoid, injectors) - no faults (dont't remember for sure if EGR or swirl control valve was checked)

.) Boost test with the car in neutral gear - looks o.K. according to the technician, although i find the method of testing boost without any load on the engine somewhat useless, as you would never reach full boost before you hit the rev limiter.

.) ECM replaced in an attempt to restore the old ECU software - new ECM has the same software on it as before (now they try to find some other way)

Next will be a comparison with an identical car on the road (with HDS / OBD-adapter attached), to see if there are any differences which could help pinpoint wether there is some mechanical problem or if it is a (DPF specific?) software thing, or a combination of both.
 

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Discussion Starter · #9 ·
Whats the smoke like at full load ?
That is the hard part in diagnosis when you have a DPF - you do not see any smoke, especially the black smoke which you get when there is not enough air to burn the fuel.

A check of soot levels in the exhaust gas , as it is done for the MOT here, did not reveal anything unusual. In fact, my readings where excellent (absorption number 0,01 - our Peugeot 307 SW HDi with DPF ha 0,30).

Bad that you cannot simply remove the DPF temporarily to check for smoke...
 

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I drive my Mistress...
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Maybe need DPF regen, have had this problem in the past and that sorted the problem.


Sctrpop used Tapatalk to post this!!
 

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Discussion Starter · #11 ·
Maybe need DPF regen, have had this problem in the past and that sorted the problem.
!
DPF has been regenerated with the HDS twice (although there were no indications that this was needed, no warning message, just to rule this out) - both times the procedure failed because of "time out" (maximum permitted time exceeded before procedure was complete).

This was regarded as "nothing unusual" by the Honda technician, they often seem to get that kind of incomplete regeneration, and there is nothing to worry about if it works while driving.

In fact, i do not have problems with the regeneration process during driving, it comes up around every 350 - 400 km in summer and 700-800 km in winter, taking about 8-12 minutes to complete under normal conditions.

The HDS (Honda Diagnostic System) however does not regard a failure of regeneration as "normal: I got a snapshot with my mobile phone of the HDS screen, which suggested the following probable causes:

1) Catalyst
2) EGT Sensor 1
3) EGT Sensor 2 (did not go above about 520°C during regeneration)
4) Injector fault (injectors found to be working normal, at least according to the test with the HDS)
5) MAF not measured correctly / plumbing in relation to intake air temperature (hole/leak)

According to what my logs show (see attachment), the most probable cause seems to be an induction leak, as i get higher airlflow values than Relic for the same or even less boost (although i do not know if this could also be caused by the increased exhaust back pressure in a DPF equipped car). Strangely, no such leak was found when Honda did a test.
 

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I drive my Mistress...
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Do you have the stock intercooler on? Have you checked the intercooler piping, especially connecting to the turbo? Maybe it is a leak in that system.


Sctrpop used Tapatalk to post this!!
 

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Theres 4 leak points assuming the Intercooler isnt cracked and the gaskets arent leaking on the inlet manifold.
1. Swirl valave.
2. Intercooler.
3. Turbo to the pipe under the engine.

Those clips arent always on tight.
Im about to compare the OP against mine OEM.
Might be more revealing about where the problem is.
Give me a couple of hours.
 

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I have attached a typical datalog of 4 WOT runs for your use.
Not sure where your other data comes from.

Ideally you need IAT MAF MAP and RPM.
This is the only way you can calculate Ve and volume flow rate of the engine.
This will tell you how the engines doing and if eveything is OK.

You are at 500m above sea level....Im about 15m so atmospheric pressure should be much lower.
I idle at 990-1000 mbar MAP.
So you would expect a difference between the two.

MAF is also extremely dependant on inlet air temperature.
So its pointless comparing without this.

Looking at the log you have a lot of MAF (airflow) for less MAP (boost).
The main point of interest is 1600-1800 rpm where you get a boost spike.
So I would say that the high MAF readings are cutting boost.
But that spike at that rpm isnt right IMHO.
Maybe 2000rpm yes....but not that rpm.
Question is why.

Need IAT at WOT also to compare volume flow rate.
Just to rule out altitude.

You say the MAF and MAP sensors have been swapped and the IAT is in the MAF sensor too.
Assuming the MAF sensor is fine the turbo is pulling through air into the turbo fine...so airbox to turbo is OK.
So if anything the low pressure between turbo and engine would indicate a boost leak in pipe or gasket.
The engine not receiving the air indicated by the MAF sensor.

I assume the EGT will go high and the engine will cut fuel as a consequence.
 

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Discussion Starter · #15 ·
It feels like the engine could give power (enough air going in), but is for some reason not allowed to do so. Unfortunately the EGT cannot be seen via standard OBD, but this might be a good point for the planned comparison with an identical car with the HDS.

I will record another log with IAT, MAF, MAP, RPM and maybee EGR position tomorrow.

Perhaps some EGT limit is reached during hard acceleration, which would also explain why this problem gets worse in warm weather (higher IAT=higher EGT, plus less air density which would lead to a richer mixture which also increases EGT).

The pipes should be ok, at least when assuming that the check by the mechanic was performed properly. But i habe once read (in think it was a VW) that someone had an EGR valve which was forced open at high boost, which led to all the nice pressurized air to escape into the exhaust.

The boost spike happens every time when i accelerate hard, regardless of RPM (it gets better above 3000 rpm, the worst is around 2200 - 2400 rpm). When i accelerate more gently, boost goes up to about 2 bar (sometimes 2.2) and stays there without fluctuations, but when i then press the pedal down further, it suddenly drops to 1.7 - 1.8 bar, there is a momentary change in induction noise, and there is a small jerk.

Fuel economy also seems a little bit to low, i do not get much below 7.0 liters / km at the moment.
 

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Discussion Starter · #16 · (Edited)
Here is an actual datalog, recorded last evening in wet 8°C weather at about 550 m altitude. MAP at idle is 95 kPa (0.95 bar).

In 3rd/4th gear, the boost spike between 2000-2200 rpm, then comes the drop (both MAP and MAF go down simultaneously), boost and MAF recover at about 2700 rpm.

In 5th gear the spike comes somewhat earlier.

If there is a boost leak - shouldn't MAF stay up, and only boost drop / not rise to specified value?

For me, it seems more like boost is actually commanded to go down - wether this happens because it is programmed in the ECU that way, or because the VNT acts up, is another matter.
 

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If its a loose joint...it will normally hold so much pressure fine.
When you go over a certain threshold the boost will suddenly drop.
The Maf will go high as it suddenly flows more air.

But the ecu will see the boost dropping and close the VNT to increase boost back to where it should be unless the MAF hits the target.
So generally MAP will drop and MAF will appear at the limit.

With a blockage you need much more MAP to get the required MAF.
In this case MAP will limit the airflow.

Thats the way I understand it anyway.
Hotter air temps = lower MAF generally

Sure your clutch aint slipping ???
It normally does at peak torque 2k and slips until 2.5k
It will shoot to 2.5k and then hang or drop slightly until the car catches up.

MAF and MAP will drop if load suddenly drops.
VSA will also cut power.
 

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Id suggest stripping and cleaning the EGR and Swirl valves (I only ever found load vs rpm for EGR and am not aware of airtemp modifiers).
Suck on the vacuum pipes to the diaphragms too..(ideally with a vacuum gauge with constant vacuum) to make sure the diaphragms aint leaking.
Check the vacuum tubes are airtight too.

You cant do nothing with the VNT...but you can rule these out if it makes no difference.

Anyway... Now you got the IAT I'll plug them in tommorrow morning.
Genrate some Volume airflow and efficiency tables.
Working tonight and the laptops at work Im afraid.
:(
 

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Discussion Starter · #19 ·
Sure your clutch aint slipping ???
It normally does at peak torque 2k and slips until 2.5k
It will shoot to 2.5k and then hang or drop slightly until the car catches up.
@Relic: Thanks for your hints and help. I really appreciate this.

Clutch is definitely not slipping - RPM goes up smoothly as speed goes up - no sudden rise at all.

I will now see what i can do myself to check the EGR / swirl - just have to look what i can use as a vacuum pump, perhaps a syringe (without the needle) would do for a quick check? Could i move the diaphragms that way? In the DPF version of the i-CTDi, there is also an ISV (intake shutter valve), which is some kind of a throttle plate - maybee this one could also need some attention.

Vacuum with the enginge running was tested, it is stable at -0.7 bar.
 
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