Fuel Injector Timing In A Cammed Xr6 Turbos

[stee3]

I’m on leave at the moment and the wife is in Brizzy visiting her mum so I have some much deserved time to myself to play around with my car

I’ve had the car idling okay but wasn’t really that happy with it. After the recent failure and the rebuild I also played around the exhaust cam timing which has thrown out my idle quality just a little. Now I have managed to fix it again and it now idles better than did before, but I want to get it 100%.

I have been playing with Dashpot, Idle spark gain and Fuel and with the assistance of my data logger and the new LC1

which is the best thing ever I managed to get idling nicely. So far so good.

Here is where im stuck and I think maybe the toad hatter or Ralph might be able to help me. Its Fuel injector timing. Now with cams comes overlap and I can smell fuel when its on idle so I think the injectors may be firing just a little to late meaning some of the fuel is being sucked out due to exhaust cam overlap. The more overlap you have, the greater the chance for fuel to escape through the exhaust valve. Ideally, fuel is sprayed on top of the intake valve while it is closed.

I have Crow Cams (3231393) FORD BA-FG 6 Cyl DOHC Mild Inlet Cam are as follows inlet opens 10.5 deg BTDC.

If I can see what the factory inlet cam open at I can compare that to what my inlet cam opens at and make the adjustment.

Edited 30/12/12 09:22 AM by stee3

[stee3]

Okay found it BF inlet cam opens at 27.5º BTDC so the injector is firing at 332.5 in the SCT software. Now im confused how my cams opens 10.5 deg BTDC. I think a call to Crow cams is on the cards.

[Ralph Wiggum]

Are your afrs rich at idle?

[stee3]

Not anymore sorted all that out, wanted to see if changing the injector timing would improve idle any further. If the inlet cam opens earlier it would only make sense to have the injector fire earlier as well.

[IH8TOADS]

You can't change injector timing with SCT...the table you would be looking at in SCT is actually a repeat of the injector battery offset table, just presented and labelled differently/wrong. Change one and the other table changes with it.

[stee3]

You can't change injector timing with SCT...the table you would be looking at in SCT is actually a repeat of the injector battery offset table, just presented and labelled differently/wrong. Change one and the other table changes with it.

Sorry for the late reply just got back form Summernats and now just seen your reply. Strange becuase when I change the values in the table below it doesnt change any values in the injector battery offset table.

[IH8TOADS]

Whoopsy my bad....I got confused with global inj timing and individual inj pw! I have never touched that scalar TBH. Without knowing the algorithm it's difficult to make an educated decision with this one :-(

[IH8TOADS]

This seems to be a unique problem and for this reason it maybe something more simple. However some things to help the thought process:

1) What Injectors. At operating voltage the ID2000's have a battery offset of ~0.00085 seconds and therefore are a quicker reacting injector than the stock item (0.001047 sec). So in some way you have effectively advanced your injector timing buy simply changing injectors.

2) Logged Fuel Trims graphed against time would help to see if there is massive variances between firing cylinders.

3) Excessive EGR (have a play with the EGR tables)?

4) Ignition Timing. How stable is spark at idle? Use the 'Desired Idle Spark Drive' and 'Desired Idle Spark Neutral' to set your desired ignition timing (use the same values for each).

5) Are you using the factory speed density tables? With fixed gears you have a bit more freedom.

6) If you are going to play with the tables, start with 'Injector Timing vs ECT'. Although it is zero'd from factory doesn't mean its not active. Set all to 20 and see if you get any delay or visa/versa.

How did you go with the call to crow? Wouldn't you need to know the advertised duration of both crow and Ford Engineering to make a direct comparison?

The larger cam would think you're opening sooner and you're firing in the overlap period as you suggested. I know you would ideally time it to inject on a closed valve, but if this is indeed your problem it maybe better to retard the injector timing and have it injecting on the otherside of the overlap....at least that way its not being lost to the exhaust valve or being drawn back into the manifold by other firing cylinders?

[stee3]

This seems to be a unique problem and for this reason it maybe something more simple. However some things to help the thought process:

1) What Injectors. At operating voltage the ID2000's have a battery offset of ~0.00085 seconds and therefore are a quicker reacting injector than the stock item (0.001047 sec). So in some way you have effectively advanced your injector timing buy simply changing injectors.

2) Logged Fuel Trims graphed against time would help to see if there is massive variances between firing cylinders.

3) Excessive EGR (have a play with the EGR tables)?

4) Ignition Timing. How stable is spark at idle? Use the 'Desired Idle Spark Drive' and 'Desired Idle Spark Neutral' to set your desired ignition timing (use the same values for each).

5) Are you using the factory speed density tables? With fixed gears you have a bit more freedom.

6) If you are going to play with the tables, start with 'Injector Timing vs ECT'. Although it is zero'd from factory doesn't mean its not active. Set all to 20 and see if you get any delay or visa/versa.

How did you go with the call to crow? Wouldn't you need to know the advertised duration of both crow and Ford Engineering to make a direct comparison?

The larger cam would think you're opening sooner and you're firing in the overlap period as you suggested. I know you would ideally time it to inject on a closed valve, but if this is indeed your problem it maybe better to retard the injector timing and have it injecting on the otherside of the overlap....at least that way its not being lost to the exhaust valve or being drawn back into the manifold by other firing cylinders?

Got a hold of crow yesterday and the advertised duration I mentioned above was actually at 0.05" Anyways the factory cams open at 27.5deg BTDC and the Crow intake cam opens at 28deg BTDC so I’ll play around with that I don’t think it’s going to make much difference and the IDs firing quicker have probably given me that extra .5 degree anyways.

As for ignition timing I have that spot also changing the Idle spark gain from 1->0 has also smoothed out the idle a fair bit too.

EGR I have no idea!

I did tune it using speed density tables and have disabled VCT which made life a little earier as well.

Yestarday I had a talk to a tuner who also seems to know how to get around the TMAP sensor issue so im sending the car to him to tune. Ive gone too far with it to skimp on the tune. I like tinkering with sh*t but I think it’s time to get someone who does this for a living to tune it. So another 196KM before I change the oil and smash 30 pounds of boost into it with E85.

[welshy_89]

Who u getting to tune it?

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