206 GTI (RFN) diagnostics - fuel trims advice sought

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Stuey

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Howdy,

I didn't want to post this in my other thread because it might not be seen by the smart people who have given up on my rantings there. :)

I ran some diagnostics with my Foxwell NT204 and got the following relevant results:

FROM COLD-ISH, IDLING CIRCA 850 RPM

FUELSYS1 = CL (I know this means closed loop, so OK)
LOADPCT = 3.5
SHRTFT1(%) = around 0, fluctuation up and down to circa 8% either way (+/-)
LONGFT1 (%) = >+30 up to around 40 (indicating lean I believe)
MAP(kPa) = 37
O2B1S1(V) = around 0.7
SHRTFTB1S1(%) = around 0.8 fluctuating (not sure what this should be)
02B1S2(V) = 0.4 to 0.8 fluctuating
SHRTFTB1S2 (%) = N/A

AT CIRCA 2,000 RPM

FUELSYS1 = CL
LOADPCT = 5.1
SHRTFT1(%) = around +48, fluctuation up and down a little
LONGFT1 (%) = around 0 fluctuating up to -7
MAP(kPa) = 24
O2B1S1(V) = around 0.8
SHRTFTB1S1(%) = around +48 fluctuating
02B1S2(V) = Didn't record this...oops.
SHRTFTB1S2 (%) = N/A

DROPPED BACK TO IDLE AND SETTLED

SHRTFT1(%) = around -6 to -10
LONGFT1(%) = +39

During the 2000 rpm stint, a code was stored; P0170 - Fuel Trim Bank 1. The Check Engine MIL was lit.

Freeze frame data was:

RPM = 1601 (note it is difficult to keep stable at 2000)
ECT = 60C (this is about right; it hadn't fully warmed)
FUELSYS1 = CL
LOADPCT = 5.9
SHRTFT1(%) = +48.4
MAP(kPa) = 34
SHRTFT3 (%) = -100
LONGFT1(%) = -7.8
LONGFT3 (%)= -100


OK, so firstly it seems the ECU is compensating for a lean condition. My first port of call is that I'm getting my son to take a fuel pressure gauge home from work and I'll check the rail pressure static and running, especially since the pump is makng a weird thump when priming first thing. I wouldn't think the filter is blocked but....? I'll replace it anyway in case.

My thinking is that the duty cycle is bumped up because the pressure is below spec and not as much fuel as required is passing through the injectors while open.

Secondly, my internet searches suggest the 'bank' 3 data from the freeze frame may be spurious data thrown up by a non manufacturer specific reader, but none of the three or four sources for this were reliable (ie. not a tech of some sort) so could be just repeated BS. But if not, what is bank 3? It only has two O2 sensors.

So, I'm thinking fuel pressure or a dodgy upstream O2 sensor, but the latter shouldn't affect starting should it? I think the O2 sensor voltages look OK, too.

Oh well, it's all a good learning experience!

I welcome any comments as this is all new to me.

Cheers

Stuey

Edit: I looked through the receipts and there's an invoice for a fuel filter in 2012 around 20,000km ago so (as long as it was done!) it's probably not this.
 
Last edited:
You seem to have a vac leak rule of thumb is add long and short together and you get a ballpark should really check them with the motor hot .
It’s not uncommon for this motor to leak at the manifold maybe time for a smoke machine


4008
Gone but not forgotten C5 x7 3008 206 GTI 180 306 XR SED 405 MI16 x2 xzara VTS 406 SV 206 XT Berlingo 2011 (best car ever) 306 HDI 307 XSE HDI touring
Fix it right the first time
 
Cheers, yeah, I did wonder about the plastic manifold as I mentioned in the other thread. Does it split at a seam, or just leak at the gaskets to the head/throttle body?

I checked them hot yesterday (fan was cycling on and off) and they were similar but I hadn't written them down so I quickly did it again today so I could post them up here.
 
They can go anywhere I normally see the gasket to the head or the pipe fittings underneath


4008
Gone but not forgotten C5 x7 3008 206 GTI 180 306 XR SED 405 MI16 x2 xzara VTS 406 SV 206 XT Berlingo 2011 (best car ever) 306 HDI 307 XSE HDI touring
Fix it right the first time
 
That's not so funny after all Garth...I've just seen Youtube vids of people using cheap disco fog machines for smoke machines to check vac leaks. Sounds like a plan!
 
Before there were smoke machines we used LP gas from a plumber's torch, opened a crack and played around the manifold joints which are suction pressure on the engine side of the butterfly while idling. If it gets sucked in the revs rise.
 
Yeah, see my other thread - I tried a propane torch - and following DMC's advice that it's probably a vacuum leak, tried carby cleaner which is another trick on the same principle (but easier to pinpoint due to being able to see where it's applied). But no vacuum leaks were indicated, although I couldn't get good access to the underside of the manifold.

So until I could get some smoke...I borrowed a fuel pressure tester and I think found the issue. The fuel pressure spec is circa 3.1 bar but I'm getting around 1 bar on KOEO and as soon as the pump stops priming, it drops to zero. So I'm assuming the in tank regulator is kaput because if it was just the pump it'd hold 1 bar; same if it was a blocked filter.

This might explain the key-on thump in the tank that started when this problem did.

Now am I right in saying that the regulator can't be bought separately? Are Peugeot again going to upset me?

According to receipts, a pump was put in the car a few years before I bought it, so about 5 years ago.

Arrgh, it's a tank out job too.

Anyway, it's all fun and learning!
 
You can do a pump without dropping the tank access hole under rear seats


4008
Gone but not forgotten C5 x7 3008 206 GTI 180 306 XR SED 405 MI16 x2 xzara VTS 406 SV 206 XT Berlingo 2011 (best car ever) 306 HDI 307 XSE HDI touring
Fix it right the first time
 
Cheers, yeah, I know about the hole; I've worked on the pump before without removing it, but I thought it was very difficult to get it sealed if you have to remove the ring...is that wrong? I read your comments about not leaving the ring off too long.

Geez I hate wasting a working pump just to get the regulator.
 
Check what pressure you are getting close to the tank. I have now had 2 hoses collapse internally on Pugs. :)
 
The 206 has hard plastic single layer pipes throughout (with click fittings), so they shouldn't collapse like rubber ones.
 
You just need to replace the seal every time and use the right tool like this

https://rover.ebay.com/rover/0/0/0?mpre=https://www.ebay.com.au/ulk/itm/264347726917

I would lend you one of mine but it’s cheaper than both way postage’s


4008
Gone but not forgotten C5 x7 3008 206 GTI 180 306 XR SED 405 MI16 x2 xzara VTS 406 SV 206 XT Berlingo 2011 (best car ever) 306 HDI 307 XSE HDI touring
Fix it right the first time
 
Yep, wouldn't dream of reusing the o-ring. It smells a bit as it is, so at least I can sort that out.

I was looking at a similar tool with two prongs going down but that looks better. The two prong job would tilt under pressure.

ANNND! The books came today thank you! They're really good, especially the Marelli one. I've learned stuff already just from flicking through.

I'll need to get you to PM me some details so I can pay.

Thanks again for everything.
 
dmccurtayne said:
You can do a pump without dropping the tank access hole under rear seats
Click to expand...

True, but I did a fuel pump on a 206GTi. It was a PITA to get the ring on, hard to tighten given the restricted access and it leaked badly every time the tank was filled.
I then dropped the tank, removed and refitted the pump again and all was good.
So much easier to get the ring lined up correctly and screwed in with the tank on the ground and plenty space to work.

Admittedly, I did not have the correct tool, just a home made version.

Dropping the tank was remarkably easy, compared to other vehicles I've worked on. Took about 30 minutes to remove, same to replace.
 
Done a bucket load of them but yes have seen people have trouble.


4008
Gone but not forgotten C5 x7 3008 206 GTI 180 306 XR SED 405 MI16 x2 xzara VTS 406 SV 206 XT Berlingo 2011 (best car ever) 306 HDI 307 XSE HDI touring
Fix it right the first time
 
Anyone....am I being too hasty in saying it's the pressure regulator?

I'll pull the unit out on Saturday, but was just wondering if the symptoms could be anything else (symptoms; low static pressure and instant drop to zero at end of prime). I've blown into the regulator inlet (return) on the pump by mouth using a pipe and it resists air, but does leak down a little. Obviously I can't puff at 50 psi though.

I don't want to fork out a few hun on a pump module and find it was something else! I'm hoping there's just something on the reg displaced. It looks to be an el cheapo pump that was fitted before I got the car though, with no writing or numbers on it at all. It's in the receipts from a local euro independent.

I note the fuel filter has a 2013 date code and appears unrestricted when I did a few impromptu flow tests of no scientific value whatsoever... Ha ha ha. (I will renew this anyway).
 
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