Made an interesting discovery today

[Dirk37]

I've been having issues where my car likes to almost die when I clutch in, so I did some investigating today and found something rather strange.

Whenever the clutch switch is activated, the ECU commands the injectors to like 3x the pulsewidth for a brief moment (the commanded AFR doesn't move at all though). It seems to be some sort of enrichment function.

I'm thinking it might be to accumulate fuel in preparation for a WOT condition.

 

[gmail]

Its extra programming to help keep the engine running as to not stall out. adding fuel can raise idle. Kindalike changing spark timing can effect idle.

When the clutch is it the understanding is the car will move soon or the engine will undergo load so extra fuel will aid in keeping it from stalling.

Not really a wot preperation. Mainly just to keep it from stalling.

My zx3 focus does the same thing and I promise its not for improving its 1/4 mile times

 

[Dirk37]

Ahh that makes good sense. Do you know if its adjustable?

 

[gmail]

In stock form I dont believe it is with tweecer but I could be wrong. . I use megasquirt so I could do anything I like with tuning

 

[Dirk37]

Ahh how I wish I would have gone that route!

I just worked around it by disabling the clutch switch in the ECU. No more dying engine on clutch in!

I'm really curious to know how other people with larger injectors solved this issue, but no one else seems to be having it.

 

[Toolman]

What parameters did you adjust for your injectors?

 

[Ishodu]

The clutch switch also increases timing to the engine. This helps the engine slow down for shifting. You will find it much more of a PITA with that disabled than you did with it enabled.

 

[Dirk37]

What parameters did you adjust for your injectors?

I have the yellow Accel 48lb injectors, the parameters I have set are:
Low Slope: 57
High Slope: 48
Breakpoint 3.999998
10 Volt offset: 1.1
12 Volt offset: 0.9
14 Volt offset: 0.9

I messed around with them to see if I could make it work normally, but it always wants to almost die.

The clutch switch also increases timing to the engine. This helps the engine slow down for shifting. You will find it much more of a PITA with that disabled than you did with it enabled.

The engine does bump up a few hundred rpm on clutch in now, but it's much more drivable than it dropping down to 300 rpm and stalling the car every time

 

[gmail]

Whats your fuel pressure

 

[Dirk37]

Fuel pressure is 44 KOEO and 30 KOER.

I just got my wide band installed yesterday and dialed in the injector offsets which really helped, I'll keep playing around with stuff and see if I can make the problem go away. I'm having a weird issue with half the engine running richer than the other too which may be contributing.

 

[Toolman]

Not enough.

 

[Dirk37]

What does it need to be? Supposedly it's within spec

 

[intimdatr]

I thought you wanted 60ish?

 

[shomethe$$$]

Not enough.

Agree with Toolman here, I only got those Accel's to run at 46psi only, so at idle the engine is 20-22 inches of vacuum (or -10psi), fuel pressure should read 36-38psi. Your reading 30, that's way low.

It would be helpful if you gave us a list of your add on's, what FPR are you using? What fuel pump are you running?

Your high slope is way off. Don't mess with the offset yet. Actually don't mess with anything else unless you know what your doing. Concentrate on the slopes. You need a vacuum gauge directly on the intake.

No issues with the clutch depressed, I bypassed the clutch safety so maybe that's why I didn't have it. Idle is solid. You have another issue, when did the clutch in problem start after the injector change, did you take out or change any other parts? specifically the IAC.

 

[Dirk37]

The only change I've made to the fuel system is the larger injectors, I'm saving up to buy the shonut FPR and a 255 lph fuel pump.

I got all of the numbers I'm using from this thread. I realize they are different injectors but I couldn't find any info on the ones I had and needed somewhere to start.

The clutch problem came immediately after the injector swap. Since I didn't have the right numbers for anything, I just kind of played around with them until I could get it to start and drive. Of course it doesn't run that great at all but it gets me around until I have time to play with it more.

I just put my wideband in the other day and I was able to get it to idle at the correct AFR by playing with the offsets, but it is definitely down on power.

 

[shomethe$$$]

your slopes are way different the thread you posted, with that low slope value your probably way rich, post a log. if your using the factory fpr then your pressure is way too low for those injectors, only way to fix that is get shonuts fpr or if your daring enough just get the 255 and that will raise your pressure by 10 psi if i recall. until you get the correct fuel pressure you'll go in circles trying to tune it.

 

[Dirk37]

Ok I had a dyslexic moment and mixed up the slopes, the high slope is 48 and the low is 57.

I'm getting the shonut fpr in a week or two so I guess I'll just have to wait until then.

 

[justin mccluske]

Are you guys talking about the two wire switch at the top of the clutch peddle? I re-routed those wires to a momentary switch and use it as a **** switch so that switch never sees a change of state except when I start my car.

 

[Dirk37]

Are you guys talking about the two wire switch at the top of the clutch peddle? I re-routed those wires to a momentary switch and use it as a **** switch so that switch never sees a change of state except when I start my car.

That's the one.

What do you mean by "use it as a **** switch"?

 

[justin mccluske]

That's the one.

What do you mean by "use it as a **** switch"?

That switch doesnt let the car start if the clutch is not pushed in so I re-routed the wires for that switch to a momentary button type switch and when I start my car I have to hold in the momentary button and use my key to turn over the motor. I did this in case someone gets past my alarm and this will stop them from driving off with my car.

So if I read the above comments right, this switch has something to do with the timing of the car?