2276cc fuel injection issue...

[Volky]

Good day,

Yesterday a friend called me to check out his EFI system which is installed in a buggy. When I got there it was a Fueltech FT350. I told him I have MS-2 but I could "sneak a peek" at the fueltech system.

The car idles roughhhh, unstable rpm's. In the little time sent playing around with the fueltech (6hours) I noticed it isn't that hard to manage. I believe ms-2 is more complex due to all its features.

What I know about the engine:
-2276cc n/a engine
-Comp. Ratio is unknown by the owner
-cam FK-he told me but I forgot, I'll get back with that...
-big valve heads unknown, too.
-injectors: 850cc at 55psi
-crank trigger with 60-2 wheel for wasted spark.

The settings in the system seemed to be "ok" since any alteration up or down worsened the car so we left it how it was. I told him that those injectors are to big for a n/a engine. Correct me if I'm wrong.

Last night I got home and downloaded the FT350 manual. It states it has two injector banks but he is only using Bank A they fire all at the same time. At least that is what I understand. Why can't he use bank A and B?

Another thing, why the 60-2 wheel?

The tooth away from the gap is 11 when the system states it should be 15.

The car runs but to me it's not all there.

That's all for now. If I remember anything else I'll post it later on.

Thanks...

[falcor]

Yes those injectors sound way to big, 250-300 cc/min should be enough depending on what hp he plans on extracting from it.

[Piledriver]

Max size depends largely on the injectors--- there are <2L turbos idling great on 1000cc injectors.
850s are a ~reasonable size if he wants to run E85.

Nothing wrong with a 60-2 wheel, very common.

Agreed both banks should be used, but before I would put any more effort into it, check out the mechanical basics
no efi system has the capability to make a whipped motor run well.

[volksbugly]

Injectors depend on the brand and what resolution they can run at. For example I have Injector Dynamics 725cc injectors that I ran fine on a stock 1600cc. Are you able to verify all the simple things like throtte position, ect...? What kind of logging capabilities does it have?

[jhoefer]

I think those injectors are probably at least twice as big as they should be. They'd only be running ~30% duty cycle at max power. At idle I'm sure they're deep into single digits and that's a bad place to try and run injectors. Injectors don't behave well at very low duty cycles. Fuel pressure is almost 30% higher than standard too. That's just pushing the idle duty cycle even lower.

A big, lumpy cam is going to further reduce idle smoothness.

Changing to semi-sequential from batch with the additional bank may help since each fuel pulse would need to be roughly doubled in length. That may help get the injectors out of their non-linear low pulsewidth region. I'd certainly try it first before buying a new set of injectors.

[miniman82]

Probably drowning in fuel with way too much cam. $10 says he put an FK-89 in it.

[Volky]

Hi to all,
mini: I just talked to the owner, he says it's a fk10.

pile, I did not mention, the engine is brand new even the block.

[Lo Cash John]

I'm no guru, just trying to help out. Has this combo ever run properly or is this a new build that's never been tuned?

[Volky]

Lo,
It's a new engine that never ran properly.

[Piledriver]

Drop the fuel pressure to ~42 psi, 30 if the injectors will work there.
Check the actual fuel pressure and look for funny readings in case pump is cavitating or such.
Check vacuum leaks, ideally injector flow balance, compression and leakdown, valve adjust etc.

If idle etc is very rich may have washed the ring seal out, compression/leakdown will tell the tale.

An engine with a lot of cam may want to idle at a higher RPM, sometimes 50-100 RPM makes a huge difference.

[Volky]

Pile, I will tell him go try that. Thanks

[miniman82]

The combination of big cam and huge injectors is what's causing the problem, though with an FK-10 it may never idle as smooth as you want it to even if you fix the mixture. What's the wideband have to say about AFR's at or near idle?

[Lo Cash John]

Where in PR are you?

[Volky]

Mini, his wideband is in lamba. It was showing I believe 1.05 or even more. I could not richen it up on idle because it starts to stall.

I forgot to mention his timing on idle is set to 17* Topping 30*.if I lower the idle it gets worse. I was thinking of taking it to 20* Or is it too much?

I plan changing it to map to see the effects since I did not see an unstable signal.

I told him to make a data log and see if it could be seen onboard since he doesn't have the cable nor software.

Lastly, randomly the car pops at cruising speeds. I think without a log we're blind.

If anyone can analyze the ecu, it's a ft-350. the instructions are at there site. I still have doubts on why the the ecu uses one bank for all the injectors used and fires them at once. That's what I understand.

In ms2 I use two banks in wasted spark config.

[Piledriver]

It looks like it has ~the EFI features of an ms1e +internal logging, and a fancy hand held lcd tuning unit for $1100.
Logging (or knock, or several other features) require adapters or additional boxes, but it looks like it has some onboard datalogging ability, need a canbus to usb adapter to get at it with a pc it seems.

How useful is the display? can it play back datalogs in any meaningful way?

The single bank use is not an issue, it doesn't appear to have semi-sequential capability even.

It may need to have idle cranked up to 1100+ rpm to get sorta stable.