C5 misfiring under light load

C5Norman · Unread post by **C5Norman** » 06 Apr 2006, 10:51

I have a C5 HPi petrol NOT diesel - its a great car to drive but has an annoying misfire when in slow traffic and you barely have acceleration on - it misfires. A friend did a Diagnostic test gave a code of P1294 "Fuel pressure regulator flow". Unfortunately he works for Peugeot so does not have the software to go further. (I got the code from a Lexia forum) Took it to an expert on fuel injection and they suggetsed the coil pack - as their tests showed no fuel probs. So £116 later and a new coil pack it IS performing better BUT still misfires! The other thing is it seems to be weather dependant being worse below 13degrees C and esp if its raining.
A main dealer told me it was the pump and it would cost £500 but refused to give me codes print out so I am a little reticent to go that way.

If anyone can help or refer me to someone who has the proper Lexia gear to diagnose I'd be v grateful. I live in Newcastle area

wheeler · Unread post by **wheeler** » 06 Apr 2006, 18:55

have you changed the spark plugs ? i know the high pressure pumps are very common on these engines.

AndersDK · Unread post by **AndersDK** » 06 Apr 2006, 20:52

I'm with wheeler - check you get the correct spec plugs for a HPI (which indeed is a special petrol creature).

Those readers not knowing what a HPI petrol is :
High Pressure direct Injection petrol engine - which have the fuel injected directly into the cylinder (like a diesel).
The common petrol injection engines are NOT direct injection. I.e. the fuel is injected to the intake.

C5Norman · Unread post by **C5Norman** » 06 Apr 2006, 22:13

Thanks for the replies. The plugs are Bosch Platina ZR8 TPP15 . (£8 each!) They are supposed to last 40000 miles. They were the first thing I changed when it started to play up so they've only been in about a couple of months. BUT the first Citroen specialist I called on said that they "don't like Bosch plugs". He reckoned I should get NGK equivalents, but I have not had any luck in getting them. Also, once I got this fault code for the fuel regulation I kind of got stuck on that line.
So if you have any other ideas?? Could it be the pump or maybe a fuel pressure solenoid? Apparantly there's 2. I've had an email from a guy in Australia and he reckons it could be the manifold pressure sensor on the blink?????
If you can suggest NGK equivalent I'll give it a try.
Wheeler - do you mean the HP Pump is unreliable? Please clarify.
I used to have a Renualt Laguna Mk1 2.2 Diesel which I wrote off in a crash. I sure do miss it........................
Norman

C5Norman · Unread post by **C5Norman** » 06 Apr 2006, 22:55

I forgot to mention earlier..........If the misfiring is particularly bad at low speed eg 15 to 20 mph it will just konk out and the service light and engine light comes on with the dash info saying "Antipollution fault". This has happened only 3 times. Sometimes it wont start for 5 minutes. The yellow lights stay on but they go out the next day. It will then run OK for a few hours and then the trouble gradually comes back. No probs if you give it lots of accel....goes like a rocket! Hope this helps a bit more.
C5 Norman

AndersDK · Unread post by **AndersDK** » 07 Apr 2006, 17:23

Must be a MAP or ATS sensor fault - or related cabling.

C5Norman · Unread post by **C5Norman** » 07 Apr 2006, 21:02

Anders thanks but can you tell me what MAP and ATS stand for. It would help.

If anyone reads this who can help with the diagnostics please contact me.
Norman
Gettin desperate!

AndersDK · Unread post by **AndersDK** » 07 Apr 2006, 21:18

Manifold Absolute Air Pressure = MAP
(intake) Air Temperature Sensor = ATS

Donno how the HPI is equipped with sensors, but its got to have some means of monitoring the intake air flow & temp to control fuel volume by the injectors. Cant be different from other petrol species in that aspect ...

IMHO the symptom you have is like false air or a dodgy MAP sensor. If you think back on the old timer carburettor engines with the wellknown problem symptoms - you can still apply these symptoms as a pointer. Its just another means of regulating air & fuel to the engine ...

C5Norman · Unread post by **C5Norman** » 07 Apr 2006, 22:00

Many thanks Anders. I'll try changing those sensors and see what happens. My Peugeot pal will probably be able to help with that.

I'll post a reply to let u know how it goes.
I have friends in Herning where are u in DK??

AndersDK · Unread post by **AndersDK** » 08 Apr 2006, 12:28

Cheers Norman -

X-ing fingers for your faultfinding. I am 1 Hours drive south-east to Herning

wheeler · Unread post by **wheeler** » 08 Apr 2006, 13:31

C5Norman wrote:Thanks
Wheeler - do you mean the HP Pump is unreliable? Please clarify.

Yes, they are known to be very unreliable.
If your looking for the MAP sensor on this car it's located on the brake servo which is unusual for a citroen.