S1 Rebuild(s)

[Dave Adams]

some pics of the rebuild process,

the top trailing arm bracket is broke......

the diff is sloping back a little (looking up) so that will need sorting.......

As you can see there isn't a lot of bracing in an S1 chassis, that will be sorted.

[James Doulton]

I have a feeling that the lambda sensor is only used when cruising and even then only when the cold start fuel enrichment has finished. I think that if it was used at other times then it would be fighting with the other 'modes'. This is particularly true if it is a narrow band sensor, as I think most factory systems are. So it not working properly should not affect wide open throttle driving (unless it puts you into 'limp home mode').

If it is a transient effect when opening the throttle, then it could be that the injector positions are different to the Ford manifold, which would change the wall effect and alter the enrichment profile. But I have a feeling that they were fitted into the head, not the manifold, so that should be the same.

Is there a throttle position sensor in the system or is it just MAF?

[Big Vern]

You'd be surprised James, the Lambda sensor is used most of the time. The cold start, High load fuel enrichment and cat protection model are the only places its not used (open loop fuelling) unless there is a fault. IIRC the hego kicks in above 60degrees C coolant temp on 60 pin and 140degrees f cylinder head temp on 104 pin (Zetec and DOHC - not sure about others) the warm up allows the sensor heater to heat the lambda sensor up. High load fuel enrichment starts at 2000rpm at eecloads typically above 0.7 and riches the mixture from stoich to 13:1 afr. Cat protection model for 60&104 pin is test bed and vehicle modelled and typically kicks in about 5000rpm and richens the fuelling up to 10:1 afr to keep the catalyst within its temperature limits, this rich mixture can also have a regenerating effect on the catalyst by purging the substrate of retained oxygen (oxygen storage). Later systems use an EGT and have an active cat protection model. The only other situation where the hego sensor is not used is in LOS mode.

[James Doulton]

Interesting detail there BV.

That is sort of what I was saying - not used during warm-up and not used at high load, which seemed to be where Dave had issues. In the case of my cars, that is the only way I drive them - either warming up or WOT, or both!

I have never heard of CAT protection mode. Does it enter that mode when driving?

[James Doulton]

If the car goes well at the top end, when the fuel demand is much higher, then I doubt that it is the fuel pump or pressure regulator. The need for an extra squirt as the throttle is snapped open at 2000 rpm is unlikely to require a greater fuel supply than full throttle at 6000 rpm.

[Dave Adams]

I am going to get a fuel pressure test gauge today....I also have a Bluetooth OBD reader and Torque on my phone (along with 3 other similar apps) .

These should give me all the fuel trims to get to the route of the issues.

[Dave Adams]

The O2 sensor forms part of a closed loop. After a period of warming.  It uses the feed back to adjust injector puse width to weaken or richer fuel.

[Dave Adams]

MAF replaced.......no effect.
TPS also seems OK

fuel pressure is 2.9 to 3 bar when running.....but only 1 bar on prime (when i turn on the key)
STFT (short term fuel trim) 0+/-1 at tick over
LTFT over 25%! but it will drop to about 8% when revved hard.....odd that the ECU hasn't given me a fault code for this..

the ecu gives me a fault code for the O2 sensor (heater inop).....but when warm it goes into closed loop ?

so.......fuel pump seems OK, might be an air leak to inlet manifold but i would have thought that the STFT would be all wrong at tick over if i have an air leak

i do have a 4-1 and weed burner exhaust fitted (41mm primaries and 50mm tail) and an inlet plenum with short equal length inlet runners.......could the engine be delivering more power from standard? therefore needing uprated injectors? i would expect the STFT to be low at tickover and the LTFT to be high if this were the case but do i have that right?

so........

i added redex injector cleaner to my car fuel tank and run it up.......almost immediately it coughed and spluttered and cut out.

so out came the fuel pump........and lo and behold empty fuel tank 180 miles and 10 gallon!

now i suspected it was running rich but 18mpg rich!

[Dave Adams]

oh and my new fuel gauge doesn't work........it reads full when empty........

it seems it works inversely to the gauge.......(Full when empty empty when full)

may need to look at bodging an after market sender onto the ford fuel pump assy.....

[Steve and Matt Pegrum]

We have that reverse fuel situation on the Phaeton (ford tank Peugeot/Citroen guage). I wish I was a bit more of an electronics designer as I'm positive it would be easy to reverse the sensor  input to the gauge with a simple 1 transistor circuit

[Dave Adams]

i am looking into reversing the output.....

[Steve and Matt Pegrum]

That - could be even simpler 

[James Doulton]

I wonder whether it might be that it needs to be fitted in parallel rather than in series, or vice versa?