V1 Strange Idle Issue

[Rauq]

oh what I would give to be mentioned in the same breath as @Ross and @Gtstorey...

 

[Ross]

Rauq, I just added your great thread on Wiring Wideband O2 Sensors to my build thread & indexed it.
Nicely documented.

 

[Rauq]

Rauq, I just added your great thread on Wiring Wideband O2 Sensors to my build thread & indexed it.
Nicely documented.

I'm famous now!

Anyway back to OP's issue, if AFRs are whack, we can dive into that, if not, time to start looking for vacuum leaks. The only other thing I can foresee from this point is a bad injector or spark plug causing a misfire, but I don't think it'd be idling that well if that were the case.

 

[finazzoty]

I'm famous now!

Anyway back to OP's issue, if AFRs are whack, we can dive into that, if not, time to start looking for vacuum leaks. The only other thing I can foresee from this point is a bad injector or spark plug causing a misfire, but I don't think it'd be idling that well if that were the case.

Working on the issue as much as I can through out the day as work allows, but I believe your diagnosis of "pig rich" may in have been accurate. I'm gradually pulling the fuel pressure down lower and it seems to be running better. Stay tuned. Want to give it a few hours to cool off and will get back out there and crank it again.

 

[Rauq]

If you want to think things over, there's some general mental gymnastics calculations to be done on fuel pressure regulator settings and injector sizing. I have the Siemens 80# injectors, and they're rated at 80lb/hr at 43.5psi fuel pressure, then, assuming the tune is set up for 80lb injectors, you will need to set the regulator to 43.5psi with the engine not running. Then the system will work correctly for the reduced fuel pressure at idle, which should be about 35psi.

Again, you may have that particular topic completely squared away, but I've also been sitting at my desk at work and thought to myself, I could have completely overlooked that, but did I? And I'm still not 100% sure... feel free to tell me if that doesn't make any sense!

 

[Gtstorey]

Or unplug the vacuum line.

 

[Rauq]

Or unplug the vacuum line.

That should increase fuel pressure which pushes the system back towards pig rich, unfortunately.

@finazzoty you have a cat, right? If you didn't have one, I'd have a better expectation that you would be able to smell pig rich. With a cat, though, that odor is probably reduced at least a good bit.

 

[Gtstorey]

I was talking about setting/checking base pressure.

 

[Gtstorey]

Why are you leaning so much toward rich? It should have shown up on the narrow band either rich or lean when ZZP reviewed it?

 

[Rauq]

I was talking about setting/checking base pressure.

I guess you could do that to set base pressure, but while you're doing that, the injectors are going to be getting ~20% more pressure than they should, and @finazzoty indicated pulling the vacuum line to the regulator kills the engine currently. Pretty sure when the engine dies the fuel pump relay turns off.

Why are you leaning so much toward rich? It should have shown up on the narrow band either rich or lean when ZZP reviewed it?

If @finazzoty is just now getting to installing a wideband, Al with ZZP may not have seen anything more than a narrowband O2 reading of 1v or whatever narrowband rich is. Still would have been helpful IMO to indicate that as the issue rather than "the fuel is not making it from the fuel rail to the intake port in the correct amounts."

 

[Gtstorey]

I would guess he is seeing a narrowband lean of less than 200mv and probably a very wide injector pulse to indicate that the ECM has tried to push it richer but can't go any wider. Of course this is a guess without seeing the data log.

 

[finazzoty]

I would guess he is seeing a narrowband lean of less than 200mv and probably a very wide injector pulse to indicate that the ECM has tried to push it richer but can't go any wider. Of course this is a guess without seeing the data log.

Here is the most recent scan I sent them. I will pull another one later today after I (hopefully) get the wideband installed that will should be more informative.

 

[Gtstorey]

Looks lean to me, except it is misfiring quite a bit, which makes it seem leaner than it is. What I can't tell, is it running lean causing a misfire or is it dumping so much fuel that it misfires causing it to look lean? I would guess Al is experienced enough to tell the difference.

How are you measuring fuel pressure?

 

[Rauq]

womp womp... I will bow out of log analysis

that's on me, I'm unwilling to update my HP Tuners suite

For the sake of a productive comment, how sure are you that your tank of E85 is E85 and not like E50 or worse? That'd throw your fueling way off... in the rich direction.

 

[Gtstorey]

I run the newer version of the scanner on my old laptop although I'm not sure if there are any real problems the newer scanner causes.

The actual ethanol content crossed my mind too.

 

[Sluggonaut]

For the sake of a productive comment, how sure are you that your tank of E85 is E85 and not like E50 or worse? That'd throw your fueling way off... in the rich direction.

I can confirm running even a little bit of gas with your E85 will cause the idle to be pretty rough.

 

[finazzoty]

I went ahead and ordered a fuel test kit off Amazon as I have suspected this may be an issue as well - I listen to the ZZP podcast and they frequently cite E85 impurity as a source of issues, such as what I am experiencing here. The idle issue definitely seems to be resolved (still a tiny bit rough, but no more crazy surging). However, this has now been replaced by incredibly difficult startup - turn it over, it lights, then dies - repeat about 10-15 times and it will stay lit finally. This morning when I went to look at the fuel pressure gauge, it had completely dropped to 0 over night, which would be expected as it is a return style system. This leads me to believe that the fuel pump needs to prime the fuel rail for a longer period of time, prior to turning the engine over. Is that sound logic?? And is there a way to adjust this in the tune?

On another note:
I was just getting around to working on the wideband today and as luck would have it, the rain came with a vengeance just as I got all of the tools out. I did want to ask though, does anyone have any pictures of how this would be set up from a wiring standpoint? I have an HP Tuners Prolink if that makes things any easier.

 

[Gtstorey]

Even with a pro link you should probably just use the ac pressure input .

 

[finazzoty]

@Gtstorey So as far as the wires coming from the gauge/controller, these are my assumptions - can you confirm that this is correct?:

Red (power) - splice this into a 5 or 10 amp fuse. Any suggestions on which one?

White (signal) - splice into AC pressure input. What color is this wire? Assuming that this would be one of the wires that runs to the connector that was previously plugged into the AC compressor. Correct?

Black (ground) - ground it wherever.

Rest of the wires coming from the gauge/controller - tape/cap them off, correct? What would these be used for otherwise?

 

[Gtstorey]

What does the instructions for the gauge say for wire colors and hook up for the gauge side? And I don’t have wire diagrams for your model to confirm ac wire colors. I posted a link to write up on these forums within the last week that went into detail that probably covers your model.
I will say that you probably have a gauge output ground that should probably go to the ac sensor ground or low reference.