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Zetec engine running lean?
pekwah1 - 14/7/14 at 05:26 PM

Hi guys,

Have been having some running issues with my 2.0 blacktop.

Specs:
Standard ECU and ignition
"Log" style intake with standard throttle body and come filter
4 to 1 exhaust (obviously)

I have gone into limp mode recently with a PO171 error code.
I've looked this up which reckons I'm running lean.

Checked for air leaks but can't find any.
Got a high pressure fuel pump, smallest point of fuel return is about 6mm.
Not sure if my fuel pressure might be too low?

Also don't know if it's related but car reliably pops out of the exhaust on deceleration.

Anyway, sorry for the long post, if you have any bright ideas of what I should look for please reply!

Regards
Andy

AndyW - 14/7/14 at 06:18 PM

I had the same fault code which was a faulty O2 sensor. Turns out my wiring was wrong when I first wired it in, new sensor cured it.

Mine pops nicely on deceleration. Running standard ecu too

There is a way of checking the o2 sensor rather than just buying a new one, but I cant find the reference to it. If I do I will ping it to you.

Happy hunting


Andy

pekwah1 - 14/7/14 at 06:24 PM

I've seen something about testing O2 sensors before.
I'll have a google and see what I find!

Shorty - 14/7/14 at 06:43 PM

Do you have the speed sensor connected?
I believe the ecu cuts the fuel on deceleration.

pekwah1 - 14/7/14 at 07:14 PM

ahhh, no VSS so maybe that's why i spit

Shorty - 14/7/14 at 07:29 PM

I have no idea if that's connected to your problem.
Could the extra fuel in the exhaust system do damage to o2 sensors??

zetec - 15/7/14 at 06:54 AM

With mine set to cut the fuel on over run, cuts when revs drop below 1500 with no throttle, plenty of pops and bangs. Maybe get you friendly local MOT tester to check emissions. I've got an emissions tester but you would have to remove your sensor to instal it which defeats the object a bit.

pekwah1 - 15/7/14 at 07:09 AM

Cheers guys,

Other thing I forgot is that my MPG seems terrible.
Managed 100 miles from 21 litres, by my calculations that's only low 20MPG.

Not actually bothered about fuel consumption but was still expecting more than that!

whitestu - 15/7/14 at 09:58 AM

Must be running rich if your MPG is poor. My Blacktop get 38+ cruising. I've got carbs though.

Stu

Paul Turner - 15/7/14 at 12:12 PM

quote:
Originally posted by whitestu
My Blacktop get 38+ cruising. I've got carbs though.

Stu


Dream on.

My Blacktop on correctly mapped fuel injection is currently doing about 32 mpg in mixed use. Since I fitted the engine 5 years ago its averaged about 30.5 mpg.

When I had a Silvertop in the car on Webers it did about 26 mpg on a very good day.

whitestu - 15/7/14 at 03:29 PM

quote:
Originally posted by whitestu
My Blacktop get 38+ cruising. I've got carbs though.

Stu


Dream on.

My Blacktop on correctly mapped fuel injection is currently doing about 32 mpg in mixed use. Since I fitted the engine 5 years ago its averaged about 30.5 mpg.

When I had a Silvertop in the car on Webers it did about 26 mpg on a very good day.
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Why do you say that? 38 isn't exactly a lot for a light car. I've checked it brim to brim when I used to work up the M40 and that's about what it did. The Blacktop is also a bit different to a silvertop.


I think you need to get your money back from the mappers, or buy some carbs!

Paul Turner - 15/7/14 at 04:22 PM

quote:
Originally posted by whitestu
38 isn't exactly a lot for a light car.


May be light but any seven has the aerodynamics of a brick. Put my engine in a more aerodynamic body and I would expect more.

quote:
Originally posted by whitestu
The Blacktop is also a bit different to a silvertop.


The differences are minimal (slightly larger inlet valves, slightly lighter pistons, longer rods, slightly different cam profile) and will make 1/2 of sod all to the fuel consumption.

Having had sevens for 25 years now I know that 32 mpg is a very good figure form a 2 litre motor and that 38 mpg is unobtainable from a Zetec. Owners don't get that from a 1.6 K on a single TB.

whitestu - 15/7/14 at 07:27 PM

What can I say! It does what it does.

Paul Turner - 15/10/14 at 12:26 PM

Further to my previous posts on the thread a few more comments now I have done a bit more checking.

As I said earlier my mpg for the first 5 years of having the Blacktop in was 30.5 mpg. Happy with that, best I have had from a Seven.

This year the mpg appeared better and now having had a summers use out of the car I can confirm its been doing 32.5 mpg. It appeared to be running perfectly but I checked the fuelling and it was spot on so no worries there thus the reason for the increase must be elsewhere.

The only mods I made to the car last winter was to service the rear calipers and fit new pads and I fitted brand new HiSpec Billet 4 front calipers, disc and obviously new pads. Pushing the car about on the drive is so much easier now thus I can only assume the old calipers were allowing the brakes to drag a little. If that is the case the new calipers etc should pay for themselves in about 50,000 miles or with my use 25 years.

One other thing I did this year was on one long trip I used the Garmin sat nav to measure the distance covered. Have done this in our other cars in the past, BMW over read by about 1%, Ford was spot on, Seat over reads by about 1% and the wifes Kia under reads by about 3.5%. Have checked the Garmin against AA AutoRoute distances and the motorway markers and its spot on.

In the Seven the odometer under read by 6.5%. Its a VDO with the correct gears etc. At 70 the speedo is spot on and at 30 it over reads about 2 mph so no issue there.

So if I add the 6.5% to my 32.5 mpg its means I am actually getting 34.6 mpg which is better than I used to get out of a Ford Puma and Cooper S.

Even happier now. And another advantage, I can actually do a true 2130 miles on my 2000 mile insurance policy since they take the reading off the speedo.

jeffw - 15/10/14 at 12:36 PM

I can get my Zetec well into single figures on track 20-25MPG on the road though.