C5 HPI Est 2002 Emissions

birstall · Unread post by **birstall** » 18 Jan 2008, 20:15

Car passed MOT last year without too much of a problem.

This year there is a problem with the emissions.

My local indie mechanic has run a diagnostic and can't find any obvious fault.

Suggests that it might be a faulty sensor wire - but says that the ECU "makes up a number" sometimes if the wire gets damaged. So may not show if wires are damaged. Hmmmm.

HC reading way up. O2 reading low (below minimum). CO reading high but within maximum.

Last year we pulled off a connector on the manifold to get the O2 reading down. O2 was 2.3 with sensor on and 1.3 with sensor off. Other figures were well within the maximum both with and without the connector on.

This year makes little difference to reading - O2 still low either way.

Mechanic has checked and found that the Lamba sensor is sending a high voltage to the ECU indicating that it wants to increase the air volume but for some reason the fuel mixture is still too rich.

Anybody got any ideas?

I have been getting an anti pollution fault but this sometimes disappears, but I got this last year also - so probably not connected to the emissions problem.

Cat appears to be OK.

There are a couple of sensors going to a canister type thing that comes after the manifold but before the CAT. Is this an anti pollution filter and could this be connected to the problem? The sensor readings don't seem to appear on the diagnostic.

I also heard that that there is a sensor on the fuel inlet which can sometimes cause an anti pollution warning unless it gets recalibrated? Anyone know anything about this? Again, probably not connected to the emissions problem.

Car has done approx 51,000 miles. Can't afford any higher mileage due to cost of petrol/insurance!

Unread post by **CitroJim** » 19 Jan 2008, 14:17

Generally, high HC means poor combustion resulting in unburned fuel going out of the exhaust. First thing to do is to check/replace the service items; plugs and air filer. High HC can also be caused by a misfire, it can be so insignificant as to be almost undectectable so another possibility is your coil pack or HT leads.

Cats don't works correctly unless the mixture is dead right so low O2 suggests, as you say, it's running a little rich.

The Lambda sensor looks suspect as it's voltage output should cycle from low to high to low over a period of a few seconds as the ECU constantly corrects the mixture.

Is the lambda sensor heater wiring intact?

Unless done, change air filter and plugs and then change the lambda sensor. If the lambda sensor output remains wrong, then another sensor is playing up. The Coolant Temperatutre Sensor my be a bit iffy, believing the engine always to be cold, keeping the mixture rich and not allowing the ECU to enter "closed loop" lambda mode.

Other than that, the airflow sensor may be a bit unhappy. Not sure on these wether they use a MAP sensor or Mass Airflow Meter (AFM).

It's a Citroen so do check all wiring and connectors

Also check for inlet manifold leaks as these can seriously confuse mass air sensors especially.

birstall · Unread post by **birstall** » 19 Jan 2008, 16:24

Jim

Thanks for your comments.

I'll pass these on to my mechanic.

The coolant temperature sensor sounds like a prime suspect from what you say. I'll ask him to check that first. Would this show up on the diagnostic check?

Changed the air filter and it did make a very slight improvement.

I thought that the plugs were long life type? - but these were checked and seemed OK. I seem to remember someone recommending a specific brand somewhere?

I'll keep you posted.

Thanks again.

birstall · Unread post by **birstall** » 28 Jan 2008, 20:09

Car passed emissions test this morning (Monday).
I had seen a Citroen specialist last Friday, but we couldn't find anything wrong with the car and planned to do some more investigative work this week. I only put it in for a retest this morning because the test station had agreed to do a partial retest up to 11.30am for free, so I thought might as well for nothing.
On Saturday I put some "Emission Control" in the petrol as well as r@d@x so that might have helped.
I think that something may still be wrong. The emission figures are far different from last years.

Emission figures:

-----------------------CO-------------HC------------Lambda---------CO Natural idle test
Pass figures------<0.30%-----<200ppm------0.970-2.050-----<0.3%
2007 (1)---- minus0.004%------23ppm---------2.652(F)-------0.000%
2007 (2)------------0.016%------19ppm---------1.007------------0.003%
2008 (3)------------1.7%(F)------94ppm---------0.95(F)----------1.57%(F)
2008 (4)------------0.12%--------14ppm---------0.998------------0.19%

(1)--Failed initial test due to high lambda (not unusual for this vehicle, I hear).
(2)--Retested with air sensor disconnected to bring down lambda (Passed).
(3)--Failed initial test due to high CO and low lambda.
(4)--Passed but much lower lambda than (1) and (2) for previous year.

Looks suspiciously like something to do with the Air Flow Sensor (or is it an MAP sensor?). However, I don't think this came up as a fault on the Lexia test on Friday - I'll have to double check this and report further. Or are these figures OK - is it just a quirk of the Engine Management System? Anybody got any clues?

wheeler · Unread post by **wheeler** » 28 Jan 2008, 23:20

birstall wrote:Looks suspiciously like something to do with the Air Flow Sensor (or is it an MAP sensor?).

These engines have a MAP sensor,its located in the pipe at the brake servo though. what pressure reading were you getting from the map sensor at idle ?

birstall · Unread post by **birstall** » 29 Jan 2008, 19:07

Wheeler

Unfortunately I didn't get a print out and I didn't note the figures.

However there has been a new development today following my discussions with a local Citroen dealer. As a result of this, they are going to do a free software upgrade (yes free,

you can pick yourself up off the floor now). The car should have had this done under a recall but it missed out. So they will do it for me at Citroen's expense.

So the plan will be to get a print out from them of the new readings and also hopefully to tap them for any information that I can about the problem. Anybody else needing any information about this particular model, let me know and I'll try to get the information when I take the car in (next Tuesday).

By the way, does anybody out there still drive an HPI? I don't see many about. I'd be interested to hear of others experiences with it. I understand that they were only made for an 18 month period. I heard that they had a lot of problems with the engine. Anyone know anything about this?

Personally, I love the car, although it's a bit larger than I really need anymore. But the engine is a bit of an enigma and not as frugal on petrol as you might expect.

birstall · Unread post by **birstall** » 29 Jan 2008, 19:45

Having said all that, for a large estate vehicle, it does return better mileage than the missus petrol Xsara and surprisingly costs less to tax.

_kid_ · Unread post by **_kid_** » 31 Jan 2008, 09:10

i dont think HJ members rate it - see below

http://www.honestjohn.co.uk/forum/post/ ... =2&t=59574

alos do a seach for past posts, i recall both the 406 and c5 his had problems.

birstall · Unread post by **birstall** » 31 Jan 2008, 18:11

Hi kid

I've been driving the car for 2 years now. This year it's been driving fine - had it serviced last January, then not needed anything until December when new section of exhaust needed for about £70. I still love the car.

If I'd been better advised at the time, I would probably have forked out the extra for a diesel. But when I took the car for a test drive it was superb - I had to have it!

I'll let you know how I get on with the Citroen dealer next Tuesday.

birstall · Unread post by **birstall** » 30 Mar 2008, 15:26

An update:

My mechanic has been off sick, so bought an Elm 327 EOBD (OBD II) USB scanner off Ebay for $12.83 + $25.99 p&p (= £19.59). Thought it was worth a try for less than £20. You need a laptop with a USB connection to use the device.

See Ebay Item http://cgi.ebay.com/ebaymotors/ELM327-U ... 0218305171

If you're interested, go for the one listed in US dollars because it works out cheaper than the one listed in UK £ (ships from China but arrived in less than a week). You may need a Paypal account to buy the one listed in dollars.

I can now confirm that this works with the HPI petrol engine (2002 model), so I was able to reset the fault codes (4 in total). Note that this unit is unlikely to work with early diesel models, so I wouldn't bother trying anything earlier than 2004 in a diesel unless you're willing to risk £20. Anyway, I've noted the fault codes and I'm planning to run the car for a bit to see which one comes comes back first (if at all).

One problem I may have already fixed: there are two electrical connecting plugs in the engine compartment near the top front of the engine. I found that when I pressed lightly on these I could make the engine speed rev up and down, depending on the amount of pressure applied.

After cleaning the connecting pins inside, this wierd effect seems to have disappeared. I can press on both connectors without causing any variation in engine speed.

So the initial problem may have been partly due to bad connections in these plugs.

I'll let you know how things progress, but car going in to body repair shop tomorrow for some work under insurance so might be a few days before I get it back.

I also suspect the downstream O2 sensor, since the mechanic who previously looked after the car mentioned that he had to renew the upstream sensor about 2 years ago, but presumably didn't renew the downstream one and the car has now done over 50,000 miles.

Chow for now.

Unread post by **CitroJim** » 30 Mar 2008, 16:33

Excellent news

Citroen wiring strikes again!!!

It is good to know the ELM 327 at least works on one Citroen

and that it is properly OBDII compliant.

All petrol cars made after 2001 had to be but this did not apply to diesels until 2004 so what you say about it working on earlier diesels is most likely correct

wheeler · Unread post by **wheeler** » 30 Mar 2008, 20:00

birstall wrote:One problem I may have already fixed: there are two electrical connecting plugs in the engine compartment near the top front of the engine. I found that when I pressed lightly on these I could make the engine speed rev up and down, depending on the amount of pressure applied.

After cleaning the connecting pins inside, this wierd effect seems to have disappeared. I can press on both connectors without causing any variation in engine speed.

So the initial problem may have been partly due to bad connections in these plugs.

What connectors was it out of interest ? do you have pics of them if you dont know what they are ?

DaiRees · Unread post by **DaiRees** » 21 Apr 2008, 20:43

Hiya guys, newbie here so be nice.

I've got a 406 with the HPi 2.0l engine, been having misfire problems to varying degrees over the last year or two. Changing the (£47 a set!!!!

) spark plugs seems to cure the misfire, at least temporarily, but there's still a bit of hesitation at low revs. I was wondering if it might be a dodgy MAF, and my search for info brought me to this fine site and indeed this very thread, so I'd also be very interested to know more about the MAP sensor and whether you guys think this could be contributing to my car's symptoms.

Many Thanks
Dai

birstall · Unread post by **birstall** » 24 Apr 2008, 21:04

Hi - I'm back at last. My computer has been destroyed by a virus, but at last I'm just about back up and running.

Here's the photo of the connectors:

The fault codes that I got were:

P0400 Exhaust Gas Recirculation Flow
P0403 Exhaust Gas Recirculation Control Circuit

Still getting the same symptoms: about 5-10 minutes into the journey sudden loss of power for about 1 second then back up to normal again.

DaiRees:

Glad to know that I'm not the last person in the country driving a car with one of these engines! and welcome to the forum.

If you can get hold of a laptop with a USB connection, I recommend you also get hold of one of the devices I mention earlier in the post. At £20 it is much cheaper than going to a dealer, although you won't have access to as much information as they do on their Lexia software.

Waiting to see if the fault codes mean anything to anyone, so if this sorts me out may well be worth it.

Recirculating exhaust gas???

This used to be something you only did when you were very depressed!

Bit of a new concept to me. Can anyone help?

Unread post by **CitroJim** » 24 Apr 2008, 21:20

Exhaust gas Recirculation (EGR) is a method used to reduce peak combustion temperature by introducing a small volume of exhaust gas into the inlet tract under controlled conditions. The reason is to reduce NOx (Oxides of Nitrogen) emissions. NOx emissions are directly related to combustion temperature so, if you cool the combustion, the NOx goes down.

It was/is extensively used on diesel engines as their NOx emissions are worse than petrol engines due to the nature of diesel combustion. The HPi engine is a petrol engine with diesel overtones.

NOx is not an MOT requirement and in our older diesels, the EGR valve can be rendered inoperative with no ill effects; actually positive ones. Older pertrol engines can have their EGR systems rendered inoperative by blocking off the system but in the HPi I'm sure the ECU would bitch about it.

Your EGR valve will be electrically operated and as they operate in a harsh enviromnet (exhaust manifold) they don't live long and get sticky in operation. My guess is that the EGR valve is getting bad and needs replacing. It might be worth having it out and giving it a good clean in carb cleaner. The faults indicate the ECU is unable to set and confirm the EGR valve position it desires and logs a fault.

An EGR valve that sticks open slightly will have a rather detrimental effect on engine performance as it is diluting the incoming fresh charge with useless and incombustible exhaust gas.

If you live near me, I could try running a diagnostic for you with my box of diagnostic tricks. It should work on your engine and it may be able to exercise the EGR valve.