I Threw Gasoline On The Fire And Now I Have Stumps For Arms And No Eyebrows
but here's the latest issue I'm having...
This all started after my alternator failed, it did so in a way that allowed huge 17+ voltage spikes. My boost solenoid seems to have been vicitim of it, and my TPS signal has become very unstable as well, it was never perfect, but it's worse now.
I started noticing after I replaced the alt, my idle was getting unstable. I had just loaded new firmware that required retuning my PID code, but I was unable to tune out some oscillation. I reverted back to an older firmware with a known good map and the same thing occured.
Fooling around I found that if I idle rich, it's very smooth and pulls a lot of vacuum, notice the pulse width. This is with '01 240cc injectors, I pulled my 460s in an effort to maybe rulle them out. Same thing was happening on them.
Once I lean it up just a little, I go from a solid 33kPa to around 35kPa and the idle becomes slightly unstable, enough to notice a slight oscillation. I can only really tell becuase of the exhaust drone.
In the video I select my entire idle VE table and strat reducing fuel, the value is which it's fueling off of remains fairly steady. Any amounts of fine tuning the VE table are to no avail.
So as soon I bring it nearly 14.0:1 the vacuum starts going crazy between 33-38Kpa and I can't maintain a smooth idle no matter what I do, the only thing that solves it is runnig rich agian.
This didn't used to be the case with my car and I'm unable to figure out what the cause is. I cannot find any vacuum leaks, and the only other guess is the HG, but there's no real evidence of it.
Note: the crazy blip at 1:01 is my TPS enrichments causing havok, my TPS signal is very unclean.
I kinda hope that's the deal. I'm starting to just think that too. The only reason I don't is because I've been idling at 15:1 for the past few months without issues. And When I first went seq. fuel last March, I could even idle at like 16:1 if I wanted to, only then is where I'd start having this same issue. I've more or less idled at 14.5:1 for the last 4 years on MSI, MSII and MSIII. If it wasn't for that I wouldn't think there was a problem really.
Only thing is, I do notice my PWs are more or less the same as before. High 1.699, low 1.7XX, but the AFRs are now richer, so I'm wondering if my sensor was off. Last time I dynoed in Nov, my tune was crazy rich according to the dyno's wbo2 and the large amounts of black smoke, where I thought it was 12.0:1 in boost.
It could also make sense that in spots where I tuned for 16.0:1 it's very hesistent now, where it wasn't before, if it was always richer than indicated.
I had recalibrated my sensor, and I just went as far as swapping it out for my old spare one this weekend to double check the AFRs are correct, unless the LC-1 unit itself is failing.
I even went out and installed an adjustable FPR, dropped the pressure down to like 20psi at idle so I could increase the pulse widths to make sure it wasn't the injectors being driven too fast. then I swapped in the 240cc injectors to completely rule them out.
Only other thing I could thing is a vacuum leak or HG failure. I've pressure tested the cooling system, and it can hold 20psi over an extended perioud of time without loss. When idling at temp, there is no loss and no flickering of the needle when revving the motor. I do seem to have a slight loss of coolant over time according to the levels in my overflow over the last 4 weeks.
The only other thing I cant think is a small leak at the coolant ports on the IM flange and it's only leaking between that and a runner, allowing water to get into the motor, but no leaks anywhere else. But I'd think I'd see that on my coolant pressure test. All pistons when looking through the spark plug holes appear dirty and non-steam cleaned.
I've sprayed highly flammable brake cleaner all over the intake manifold trying to find a leak. all bolts are tight. It's hard to get up under and spray the bottom of the flange, but I'd expect to hear some suckage. Even if I get the must minute amount of cleaner in my BOV at idle, the engine stumbles, so im sure I would have found a leak by now.
TB is correct. Double checked it. Even made sure the piston was actually at TDC when indicated on my crank pulley.
So I'm either left with this is normal, you can't idle stoich, or I'm missing something else.
The stock injectors are not terribly good either. My car tends to whack out if I try to idle at 16:1. On the other hand, a customer's built 1.6 on 650cc EV14 injectors idles at 17-18:1 like it was born that way.
I would buy EV14 660cc injectors if I knew that would solve the issue. That's why I tossed in y8s injectors to see how lean I could idle them. They reacted the exact same, as soon as I tried to brin git up past 14.0:1 or so, it gets very unstable. No matter the ign timing I lock it at or engine speed. So long as I keep the AFRs below 13.5:1 the vacuum increases and stays solid.
Reverant has my log, he can post it. I cant from here.
C16 is your basic input filter and is needed for stability, I've seen weird things happening with it either missing (it happens to the best of us, which is why I check 35 different things on each ECU I build) or crapped out. C17 helps with transient response.
yeah, reading over at msextra.com there is a correlation between voltage spikes and losing those. One guy said his ran but had missing issues. Kinda sounds like mine (it does miss every now and again at idle). I'll give it a check.
Ive experienced this while tuning other cars, Ive alwasy assumed it was due to difefernt brands of injectors.
Basically, some engines Ive gotten to idle way lean, like 15-16 AFR, rock solid, no lope, no missing. Then there are others that refuse to idle well with anything less than ~13:1
My buddy Tw34k who used to post on here occasionally had his civic running in the 16s at idle with RC 550cc injectors.
I think I have a video of it starting up and idling on my youtube account, Ill see if I can find it.
Also, ignition timing does play a roll, but the exact nature of the relationship is not clear to me still. It usually just requires trial and error to see what will allow you to lean it out.