AiToR51

I rebuilt a 200 block last months and I first started it last week and today I've installed a boost pressure gauge and a wideband lambda to check how it runs.

The car is on stock injectors, turbo and ecu. Only differences are 92,5mm wossners, WRC head gasket, long studs and a little more CR due to head and block machining

On cold start, it show me around an AFR of 16:1.

when hot, it has an idle of around 15,5-16:1, on cruise light pedal near the same. When pressing a little more to atmospheric pressure but without boost it goes to 14,5-15:1 and then when boost come it downs to 13-14:1

Boost spike is 0,9bar and then it goes to 0,6 aprox.


is the first time I own a cosworth but I found it very lean. I was hoping to see around 11,5-12:1 on boost.

what do you think?

AiToR51

more info:

yesterday I installed a new set of Denso IK27 spark plugs and they show at this way now:




just after 4 mi of driving. the one in the left is cyl 4 and the one in the right is number 1

it looks that cyl 3 is running really lean. I will do a injector clean during week.



I checked the WB controller on another engine I've with a WB since 4 years and in that car shows the correct AFR's, so it should not be fooling on the YB

costina

iTrader: (1)

Have you tried trimming the co pot on the ecu if L6 or L8? Imo you should be looking at around 11.2 on boost to be safe. Decrease the boost to gain that figure. Also check your fuel pressure and regulator are working correctly. Also as with any cosworth the fuel pump wiring can be a issue not giving enough voltage hence running lean.

AiToR51

Ecu is L8, I didn't tried the co pot. I will leave this for the end as the car was supposed to run well before the rebuild, at least old spars were very black (but it has been off the road for 8 months).

I've checked fuel pump voltage and is not very good. It had 11.5v when running engine battery showed around 13,1v. I will redo the wiring with new fuse and relay.

I will try to install a fuel pressure gauge to check all is correct, is common for those to fail?

costina

iTrader: (1)

Yes they can fail. Also has the fuel filter been changed?

AiToR51

Ok, I've a friend who is going to lend me a fuel pressure gauge for testing.
I didn't changed the filter but I'm going to change it also. I've just ordered a Motorcraft one in local ford

AiToR51

Changed fuel filter, rewired pump (and gained 0,6v at pump), checked fuel pressure:

2.8bar at idle with vac
3,5bar at idle without vac
Boost increases fuel pressure 1:1
So is ok

None changes at this stage in terms of afr

Checked also co pot. I've to put it full clockwise (2 turns), less than 1.3 turns and afr at idle went to 16,17 and it failed a lot. According to afr it should be around 1.5 turns.

Now it improved a little, but just a little. Gained only around 0.5 afr on all situations. So 12.9-13.2 on max boost.. No good anyway

Checked with an oscilloscope all 4 injector connectors and all seem to have the same signal.

Now I'm going to bench test injectors to check all inject the same

I measured from ecu pinouts ohms in coolant and air sensors and coolant is ok. Found a problem in first instance with air temp sensor, but no changes in fuelling