Monday, May 02, 2005

The new injectors and O2 sensors are IN!

Last week I did something very strange: I wrenched on my own car! As strange as that sounds, I am severly 'mechanically challenged' and usually all my alterations/modfications/new parts are done by my mechanic. But even with most of the parts being bought not at retail prices (forums, ebay, friends, etc) it gets expensive quickly. So some simpler things, I've wanted to do myself.

So last thursday, right after work (5pm) I put my car up on ramps and jack it up on a side, and slide myself underneath, looking for the front oxygen sensors. Not only I was able to find them, but I ended up exchanging them almost entirely by myself! Granted, due to them being there for almost 80k miles everything was quite fused together with heat (they're up there, right after header flanges and before catalytic converters) so it took multiple takes of PB Blaster and some other rusty bolt removing spray thingy (can't think of the name right now) to get them to budge. That combined with the fact that I only had an adjustable wrench, and not a real 7/8 open end one, made this a long affair. What I was told was a 15 minute swap, took me 4hrs. But it fired up on first try, and after they warmed up, started oscillating quickly, which I could actually verify by looking at the HPTuners scanner. I was very happy, and proceeded to go get drunk in celebration with my neighbours and a friend that have been my peanut gallery laughing at my grease monkey skills (or rather the lack thereof).

Saturday was injectors day. As per previous posts, on a day with 'good air' I hit 109% duty cycle on stock 26.4 lb/hr injectors, which made me rather scared. I've picked up some Ford SVO 30lb/hr injectors, as I figured that at one point I will need them. And what do you know, that moment finally came.

So a guy I've known for a long time told me to come over and we'll do them. We started at 2pm, and took out the LGMotorsports 3point strut tower brace (which is a bitch, unless you have the suspension completely unloaded) as it was completely in the way. Bunch of other stuff was in the way too, throttle line, all the cabling going to IAT/MAF sensors, and a bunch of things I don't even know what they're called. Once everything was out of the way, we let out the fuel rail pressure, took out the clips holding the injectors, and disconnected the electric harnesses. Few more bolts, and the entire fuel rail was loose, so we lifted it and flipped it around. Once on it's back, we took out the first injector and got sprayed with gas. Lovely, that's exactly why I don't like wrenching. There was a decent amount of gas still left in the rail and injectors, so we spent quite some time letting it leak out on some rags. Then we popped out all the injectors and o-rings left in the injector seats. Cleaning the new injectors was next, we checked to see if there aren't any visible clogs/damage on them. I wish I had the time to send them out for real flow test and a cleaning, but this whole 'out of injectors' situation sneaked up on me from nowhere, and I have a trackday to do in about a month, so I needed to get this stuff done ASAP.
Once the injectors were in, everything went in fairly smoothly, and we mounted it all up without major hassles.
The funny moment came of course once it was all done and ready for the first 'fire in the whole' test, as early on we decided to cool the engine down faster by turning on all the engine fans, but running it entirely off the battery. At one moment the fans just went out, and I though it was some automatic precaution of draining the battery. No such luck as 'timeout' for fans apparently, the battery was dead. So we fired it up from a gigantic charger, and it seemed to work ok, but the idle was surging and hunting, as we didn't flash the PCM with the new IFR tables yet, as we just wanted to see if it works (and waited a bit for the battery to charge up, as we didn't want it to die half way through flashing the PCM). Then the new calibration went in, and the car idled perfect right away. We took it for a spin, and top of second gear at 6300rpm yielded somewhere around 75% duty cycle, while on stock injectors earlier that day it would be closer to 96% (the air wasn't as good as the 109% day). So I can now finally start safely proceed with more tuning and not be afraid of going lean because of injectors not being up to a task.

The amazing part happened on the way back home. I was in MAF mode, logging for all my usual stuff, and the car ran perfect, with ZERO other alterations. That's what happens when it's all calibrated right folks. None of that old school 'lets calibrate AFR with IFR multiplications and MAF shifting' crap pseudo-science.

The only thing right now that's a bit off that I just noticed going through logs are the values of oxygen sensors at WOT. They consistanly average between 820-830mV for Bank1 and 835-855mV for Bank2. I should be at 12.2AFR, so shouldn't that be closer to 900-910mV?
Something's off about PE, but now that I have the hardware in place, I can finally go play with PE/WOT/Open loop mode.

That's probably gonna be another story though...


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