306 Hdi Engine Management Light

[hexhamstu 9]

I've searched and read, and the outcome is get it diagnostic checked in some way or another. But I was wondering weather the fact it has been limited to around 2200RPM makes any difference?

 

(Background: Driving on the motorway seemed to lose power a couple of times but came back straight away, then it went but it only dropped back to 62ish miles an hour, and 2200 RPM. So I managed to get home like this.

Cheers!

[welshpug 1,627]

sounds like limp home mode!

 

is it smoking badly or just very underpowered?

 

start ok?

[hexhamstu 9]

No smoke, idles fine, starts fine, drives fine. It's just very slow.

[welshpug 1,627]

time to get it plugged in then

[hexhamstu 9]

Will a normal back street garage be able to do this?

[welshpug 1,627]

Most have something like a Snapon Solus or a Modis these days, many of the smaller cheaper units wont do it afaik as its too old (i.e pre obd2, diesels were 2005 IIRC) especially if it throws some specific codes up.

[hexhamstu 9]

Cheers mei!

[sport1901966 8]

I have an ELM327 OBD II reader I got from eBay that I have used to read codes/sensor data on my HDI. Only about £20 I believe so may be worth investing in as thats less than what it typically costs to get someone else to read it.

 

I have experienced limp home mode, only cut in when under full acceleration. Turned out to be bits of a perished seal that had found its way into the high pressure pump restricting fuel flow. Cleaning out the pump sorted it.

 

Good luck sorting it

Edited June 14, 2011 by sport1901966

[pug_ham 242 3 Cars]

If it's in limp mode (certainly sounds like it is), don't attempt to many hills, god they are painful when you do & the car is in limp.

 

I've got a obd2 reader off ebay for about £20 & it works fine on my 306 along with a mates passatt.

 

g.

[dcc 855]

do these run with a cat? saw similar symptoms on a 307 with a fubar cat :|

[pug_ham 242 3 Cars]

They have a cat but no lambda etc, they can be safely decatted according to my MOT tester which is why I got a stainless front pipe to backbox made.

 

g.

[lukesaddy 0]

i had a similar problem to this on my 8V 306 XSi - it was dying up the revs and losing power. The problem turned out to be the cold air feed pipe going from the slam panel to the air box compressing around the flexible part - its worth checking the daft things like this, in case you have serviced it recently or something

[hexhamstu 9]

More to add to this, the codes turned out to be refering to the MAF and the glow plugs. Both of these I've replaced and it's stil kaput. Same symptoms (not sure about codes as I got them read at the garage but I imagine atleast one of them is still on there. Tried disconnecting the cold air and air filter to see if it would rev up. It wouldn't.

 

Do the faults need reseting? I've unplugged the ECU etc, and the light does go off on start up and then instantly back on again.

 

The garage seemed to think the turbo was dead because it wouldn't rev up. Would the engine know the turbo is goosed and put the K-light on and then tell me the MAF and glow plugs are dead? Surely not? and it's only got 88k on it.

 

[Anthony 1,000]

If it starts and runs, I think that you can rule glow plugs out as being an issue.

 

MAF would make sense, but remember that the ECU will only give you a clue as to what it thinks is wrong. The MAF itself might be working fine (and if you've replaced it, probably is) but it could be that there's broken wiring so the ECU doesn't get a signal from it, or it could be that there's another problem that means that the signal from the MAF isn't what the ECU expects to see and thus thinks the MAF is faulty. Something like a boost pipe that's come off for example, meaning that there's very little airflow through the MAF for a given engine speed/load.

 

If you unplug the MAF completely, does it run/behave any differently? If it does, that suggests that the MAF is working atleast to a point.

 

You say that if you unplug the ECU to clear codes, and then start the engine, the engine check light is initially not on. If you just leave it idling, does the light come on, or is it only when you try to drive it and where the turbo would normally be boosting? If it comes on when idling then it's probably nothing to do with the turbo.

 

The other thing with error codes is that some of them could be old and have never been cleared, and others could be related to completely unrelated problems - in your case, I'd suspect the glow plug related code is nothing to do with the current running problem.

[hexhamstu 9]

If it starts and runs, I think that you can rule glow plugs out as being an issue.

 

MAF would make sense, but remember that the ECU will only give you a clue as to what it thinks is wrong. The MAF itself might be working fine (and if you've replaced it, probably is) but it could be that there's broken wiring so the ECU doesn't get a signal from it, or it could be that there's another problem that means that the signal from the MAF isn't what the ECU expects to see and thus thinks the MAF is faulty. Something like a boost pipe that's come off for example, meaning that there's very little airflow through the MAF for a given engine speed/load.

 

If you unplug the MAF completely, does it run/behave any differently? If it does, that suggests that the MAF is working atleast to a point.

 

You say that if you unplug the ECU to clear codes, and then start the engine, the engine check light is initially not on. If you just leave it idling, does the light come on, or is it only when you try to drive it and where the turbo would normally be boosting? If it comes on when idling then it's probably nothing to do with the turbo.

 

The other thing with error codes is that some of them could be old and have never been cleared, and others could be related to completely unrelated problems - in your case, I'd suspect the glow plug related code is nothing to do with the current running problem.

 

Unplugging the MAF does nothing, I actually drove it home from the garage without it plugged in by accident. It behaved exactly the same. I'll have a check along the MAF wiring tomorrow (unless the this torrential rain continues) , I'm guessing that is where I should start. The light goes off, then half a second later comes back on again, basically just flashes off for a second.

 

Cheers for the help everyone!

[Anthony 1,000]

If I get chance tomorrow and the rain holds off, I'll unplug the MAF on mine and see if it gives the same symptoms that you're getting

[Anthony 1,000]

I had to pop out in the car briefly earlier, so I quickly tested this for you and got the exact same symptoms:

 

• Unplugged the MAF, started the engine, CEL went out for a moment and came back on, and the engine wouldn't rev above 2200rpm.
  
• Switch off, plug MAF back in, start engine, CEL still illuminated but the engine now behaves properly and full revs/boost.
  
• Switching off and starting the engine further times makes no difference to the CEL - it's still illuminated.
  
• Unplug ECU for a couple of minutes, start engine, CEL goes out and stays out.

So I'd say something relating to the MAF is what's causing the issue - just be warned that the CEL won't go out without an ECU reset even if you fix the issue!

[hcmini1989 16]

Id seriously doubt it would be a turbo without it having any other symptoms.Id start by as anothony says checking splits in boost hoses or if any have come off just look for oily resadue on them .Then id look into vacuam hoses being split or little knicks in.Im not sure but if these run a MAP sensor aswell then id be looking into that aswell.Did you put the MAF the right way round? some have a direction of flow on them.

 

Other than that find someone with a more in depth computer peugeot planet etc because it sounds definatly more electrical than mechanical .But rule the above out first

[hexhamstu 9]

Cheers for doing that anthony! So basically it's more than likely the wiring to the MAF. This makes much more sense than the broken turbo the garage claimed.

[hexhamstu 9]

Anyone got a haynes manual or wiring diagram for these that can tell me which pins on the MAF plug relate to which pins in the ECU plug so I can test for continuity?

 

Cheers

[welshpug 1,627]

ecu pin 13 -

 

engine idling - 2v

ignition on - 0.5v

 

ecu pin 22 - earth.

 

MAF pin 6+3 connected to 22 (IAT incorporated)

 

MAF pin 5 connected to ecu pin 13.

 

ecu pin 11 - ignition on - 2.4v @ 18 degrees

 

ecu pin 11 and 69 connected to MAF 1+2

[hexhamstu 9]

ecu pin 11 and 13 are both 10v with ignition on.

 

Maf pin 3+6 to pin 22 on ecu is fine.

 

maf pin 5 and ecu pin 13 showing seemingly varying resistance.

 

Rain started came inside

[pug_ham 242 3 Cars]

iirc there was a problem with the MAF earths a while ago but I've also run my car with the MAF unplugged when it was runing like a dog before the hp fuel pump was replaced.

 

I think I havce a wiring diagram somewhere.

 

Will post it up once I find it.

 

g

[TT205 42]

I'm not familiar with the Hdi but does it have an EGR valve? - I had very similar symptoms in my Saab when this was capput - turbo wouldn't spool, wouldn't rev, no power etc

[pug_ham 242 3 Cars]

Dave, the hdi does have an egr, mine is blanked off / removed without issue so I wouldn't expect it to cause a problem such as this, mine jsut caused masses of black smoke when it stuck open.

 

I found the wiring diagram I had but forgot to post it unitl now after being reminded by Rob_turbo's topic for his hdi problem.

 

 

g