Overfuelling - Can't Undersatnd Why.

[brian j 32]

Hi,

 

I've swapped my engine out for a rebuilt unit from SPGTi.

 

Got it in and started last night (first turn of the key, and no oil or water leaks. woohoo!) but it is overfuelling. (black/grey smoke and stinks of petrol)

 

The odd thing is that the engine was absolutely fine in Steve's car (I know, I was driven round in it and gave it a good going over) and I have swapped the enitre lot into mine (Engine, dizzy, AFM, inlet and injectors)

 

Now in my car it starts on the button, shows good power, sort of idles (chuggs a bit but I haven't tried to set it up really yet) but kicks out clouds of black/grey smoke when revved and stinks of fuel.

 

I have tried swapping the AFM and CTS for the units from my old engine (which were also fine when in situ) which hasn't resolved the issue.

 

I am running my original Throttle body because it has the tapping for the A/C idle speed valve in it and my original ECU but both engines are D6B's so I thought it wouldn't cause a problem. I have also removed the brown multiplug and replaced it with heatseal crimp butt-joints, for reliability, but I haven't touched anything else.

 

I have searched and found some comments about the wiring to the AFM or the tachymetric relay being possible causes. Has anyone got any suggestions for the best logical order to tackle any further fault-finding in? Or is there something obvious I've missed?

Edited March 20, 2009 by brian j

[Tom Fenton 1,542]

I'd bell out the wiring from the coolant temp sensor back to the ECU. Your symptoms do sound like this is not working properly, so if you have replaced it with a known good one then it is possible that it is a wiring problem, especially as you have just disturbed it all changing the engine.

[GLPoomobile 958]

As a 10 second check, try unplugging the ECU temp sensor with it running and see what happens. If nothing happens at all, and it carries on running exactly as before, same idle speed etc, then I'd continue looking there, either for a faulty sensor, pins dislodged in the plug, or duff wiring from the sensor. And make sure you have the blue plug on the ECU temp sensor, and not the black plug that goes to the SAD.

[brian j 32]

As a 10 second check, try unplugging the ECU temp sensor with it running and see what happens. If nothing happens at all, and it carries on running exactly as before, same idle speed etc, then I'd continue looking there, either for a faulty sensor, pins dislodged in the plug, or duff wiring from the sensor. And make sure you have the blue plug on the ECU temp sensor, and not the black plug that goes to the SAD.

 

Thanks for that tip. I have got the plugs on the right way round. I was anal about labelling everything that I took off and checking colour coding etc.

 

I know Tom may well be right, I just don't want him to be, because removing enough stuff to get back to that point on the loom would be a bit pants!

 

I'll start looking at the CTS wiring when I get home from work.

Edited March 20, 2009 by brian j

[GLPoomobile 958]

I don't know what belling out means, but I'd have thought you just need to (initially) take readings at the sensor end and at the ECU end, so no need to take the loom apart. If it is a broken wire in the loom, then of course you will need to start unwrapping it all and tracing the wiring back.

[steve@cornwall 100]

As it stays running whilst smoking, my bet is that the wiring to the AFM has popped out of the back of the multiplug ( IIRC it was the white one on my CTi).

As it was ok in the other car and doesn't overfuel enough to flood, I would be surprised if it was the temp. sender

[brian j 32]

OK,

 

Got back to it from work, and now it won't start at all. It sounds like it's flooding, because it turns, catches for a fraction then dies. If you try to start it immediately it won't fire, but if you wait 10 mins or so it goes through the turn-catch-die routine again. The AFM plug and wiring all look fine, although I was worried when I saw only 4 wires in the plug, till I checked the wiring diagram. I think Tom is right and it's a CTS wiring issue. (The CTS itself is showing around 3500 Ohms)

 

I'm off out with my mutimeter to try and trace it.

 

As I understand the Haynes wiring diagram, one pin of the CTS goes to the ecu (wire 10) and the other is earthed. Is that correct?

 

If anyone knows the colour and/or pin position of the CTS wire on the ECU plug then I will be in your debt!

[EdCherry 34 1 Cars]

I seem to remember when my engine was flooding, bit of full throttle would get it started atleast, even if it was poorly. These CTS jobbies seem to be the route of all evil.

[brian j 32]

OK,

 

I've been out and checked the wiring from the AFM and the CTS back to the ECU and it is all fine.

 

The car still won't start at all.

 

If I unplug the injectors and crank it, it will fire very briefly, leading me to believe that it is definitely fuelling related.

 

Any ideas where to go from here?

Edited March 21, 2009 by brian j

[GLPoomobile 958]

Check the AFM flap is closed, that it moves freely, and that it has a strong spring action to it. When my Mi did this it was because the flap had jammed fully open. The AFM was fubar after that.

[mhyphenl 10 1 Cars]

Check the AFM flap is closed, that it moves freely, and that it has a strong spring action to it. When my Mi did this it was because the flap had jammed fully open. The AFM was fubar after that.

 

 

I seem to have exactly the same problem. I didn't even change an engine or any components, just the loom that connects the heating, door equipment and ignition barrel together, the loom seemed to be identical but all i've been left with is a brief hickup when cranking, won't run at all!! Got to be wiring for me as thats all i've touched but will keep you posted if i find an obvious problem!

[brian j 32]

Check the AFM flap is closed, that it moves freely, and that it has a strong spring action to it. When my Mi did this it was because the flap had jammed fully open. The AFM was fubar after that.

 

I have 4 AFMs, 3 of which are known to have worked perfectly when last (recently) used, all look perfect and all 3 show the same symptoms.

 

I am pretty convinced that it is not the AFM

[brian j 32]

Right,

 

I have now got it running again after cleaning up the plugs (which were properly sooted up). I have so far changed:

 

Coolant Temperature sensor,

AFM (3x)

Fuel pressure regulator,

Injectors

Tachymetric relay

for units which worked fine.

The wiring from AFM and CTS to ECU has been checked and it is all fine.

 

It is still overfuelling (i.e. rev it and you dissappear in a cloud of grey/black smoke and stinks of fuel)

 

What is left to check?

 

Could it be the ECU itself that's gone faulty? (it was fine before the engine swap, and hadn't been disturbed until after the symptoms showed)

 

I've got to the end of my knowledge now and I need to get it running properly.

[GLPoomobile 958]

Could it be the ECU itself that's gone faulty? (it was fine before the engine swap, and hadn't been disturbed until after the symptoms showed)

 

Well there's only one way to find out. Luckily they are easy enough to swap, IF you have a known good one available.

 

205s have this fantastic sense of humour though. They love to throw a fault at you and it'll usually be the very thing that you least suspect, because "it was working fine before I did xyz" . Something always stops working after you've done a job, so you think it must be something to do with what you've done, but oh no, the cheeky little f***ers like to spring something random on us, just to keep us on our toes. Bloody attention seekers, I tell you!

[brian j 32]

Well there's only one way to find out. Luckily they are easy enough to swap, IF you have a known good one available.

 

205s have this fantastic sense of humour though. They love to throw a fault at you and it'll usually be the very thing that you least suspect, because "it was working fine before I did xyz" . Something always stops working after you've done a job, so you think it must be something to do with what you've done, but oh no, the cheeky little f***ers like to spring something random on us, just to keep us on our toes. Bloody attention seekers, I tell you!

 

I call it lack of gratitude myself! I mean, you buy a 205 from a nice but mechanically naive owner, treat it to a new engine, headlights, indicators, sort the bolsters on the seats, fix the oil leak, clean and paint the engine bay, de-chav the stereo, and generally love it and what does it do? Play up. I swear all 205s are female!

 

On a serious note, does anyone in the Northampton/Milton Keynes area have a KNOWN good 1.9 8v ECU that I could borrow to see if that eliminates the fault?

[brian j 32]

I have now changed the set:

 

Coolant Temperature sensor (x3, 1 brand new, 2 known good),

AFM (3x)

Fuel pressure regulator,

Injectors rail etc.

Tachymetric relay

ECU

for units which worked fine.

The wiring from AFM and CTS to ECU has been checked and it is all fine.

 

Guess what? It still overfuels.

 

With all the messing around the oil is full of petrol too.

 

Is there anyone local to Milton Keynes / Northampton who you'd recommend to look at it? Even with an oil change (which I'm going to do) I don't want to drive it too far, because I think that it will go the same way again pretty quickly and I don't want to do damage.

[steve@cornwall 100]

The way I found the broken wire on mine was to have 2 cars side by side and compare the voltages at the ecu pins, when running, not running and under throttle. I didn't even need to understand which was which and why it did what it did, the difference was that obvious on mine ( Can't remember enough to be more spacific, I'm afraid) and although I wrote downhow eachone should behave, it's long lost

[Tom Fenton 1,542]

I know what you haven't checked

 

The fuel pressure. If for some reason this is way too high the car will overfuel even if all the ECU injectors AFM etc are healthy.

[steve@cornwall 100]

I know what you haven't checked

 

The fuel pressure. If for some reason this is way too high the car will overfuel even if all the ECU injectors AFM etc are healthy.

 

 

 

Good point!

Possibly caused by the fuel return pipe being damaged when installing the engine?

[brian j 32]

I know what you haven't checked

 

The fuel pressure. If for some reason this is way too high the car will overfuel even if all the ECU injectors AFM etc are healthy.

 

Interesting theory Tom.

 

I have swapped the FPR, but I suppose a blocked fuel return might cause it? As I understand it, it's probably not worth buying a fuel pressure gauge, I should book it in somewhere to look at it.

 

If I want to do a quick and dirty check the fuel return, should I be able to disconnect it from the FPR and blow through it fairly easily? (cue petrol in the mouth...)

[Tom Fenton 1,542]

Should be about 3 bar if I remember rightly? As steve says could be caused by a blocked return to tank (this should be a free flow, to test you should be able to easily blow through it) or it could be that your fuel pressure reg is u/s.

[brian j 32]

I THINK IT'S SORTED!!!!!!!!!!!!!!!!!!!!!!!!!!!!

 

I checked that the Return hose was clear and it was fine. I haven't checked fuel presssure yet, but have bought a guage to measure fuel pressure.

I found that one of my AFM's had more range on the idle mixture screw than the others. Fitted it, the new ecu, new CTS and did a mini service (oil+filter, plugs, leads)

Adjusted the idle mixture to the leanest and the car is a lot better.

 

It still smells of petrol when idling, but no more black or grey smoke.

 

Starts fine, goes fine, I have even almost got it to idle!

 

I don't think that it was any one thing, but a lot of little bits.

 

So I went for a blast down the back roads to celebrate.

 

I still need to get it on an exhasut ags analyser to see if it is ok now.