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Discussion Starter · #1 ·
So my son's new car, 08.... is starting to piss me off. We have gone over and over this thing end to end...can not figure out why the AFR is going nuts.
Time line and things we have had to change so far..
  • Bought car from Arizona (we live in northern Colorado), drove home 13 hours straight. Car ran BEAUTIFULLY the whole time.
  • Car started missing, running like crap after about a week, major hesitation when you rev.
  • New NGK plugs, and bigger gap - old ones were heavily carboned/black
  • New tune by Apexpowered / Marc - removed the E85 tune for now, and improved the 91pump tune by about 100hp on the dyno.
  • Ran perfectly for THE DAY...limp mode on way home.
  • Barely idles, sputters, gotta hold it to the floor to start it.
  • AFR all over the charts.
  • New MAF
  • Re-gapped plugs with wider gap
  • Hooked mighty vac to multiple ports in the engine bay. 100% held vacuum in all cases. (Doesn't mean I didn't miss some connection some where...but confidence is high.)
  • New FIC injectors - my fault, ran bad test and fried two. Spendy lesson!
  • Cleaned and tested the O2 sensor, it passes test - brake clean method
  • New battery
  • Car starts much easier, has big cam, so to say it idles smooth is generous...but idles properly.
  • AFR all over the charts
  • I can't recall the S & L trim numbers, but they seemed good.
  • Scanner shows O2 only reads/registers when you give it gas.
Took it for an easy ride tonight after finishing up the tests. It does not behave like it's going lean. The spark plugs tell ME that it's running really rich. Started very slow, and eased our way into some light/medium pulls. Anytime you are into the gas pedal, the AFR calms down, and goes to the richer side. At one point we were pulling about 9.3:1. But if you are just cruising around it will jump from like 11:1 all the way up to 25:1 and "- - - -" when you let off. Reading up on that, the dashes indicate that it is completely cutting fuel (emergency). I would expect the engine to die when that happens, but the idle is steady.
All in all my gut and butt feeling is that the car is back on track, and either the wide band is on crack, or the gauge is bad. But knowing what can happen if it really is running lean, I have to get to the bottom of it.

I see a ton of topics on line that are "similar" to what we are seeing, but in the end they seem to be a result of one of the things we have already replaced.

Any guidance is greatly appreciated.
 

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Do you have any way to measure fuel pressure (or logging it would be even better)? You mentioned a dual fuel pump setup in your other post so I'm wondering how that's set up. Some setups (like the Buschur Double Pump) use a reed switch to activate the second pump under boost. So if your primary pump is having issues it could clear up under boost when the second pump kicks on.
 

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Discussion Starter · #3 ·
Tried to look into that last night actually. Not real sure of the set up. Was told it has a secondary that kicks in under boost...yes. Took out the back seat expecting to see something out of the ordinary...again, this is all new to me.
But (under seat) driver's side definitely has an aftermarket set up, and passenger side looks to just be maybe the sending unit, or some other form of sensor. This is why I don't like to buy something someone else built. Trying to figure out what they did, how they did it, is it right, is it a hack...? Meant to find the brand on the one unit before buttoning it up for research...but while I was putting the sensor back in, he put the seat back together. Laughed at the markings on the top of it though. The feed port was labelled "send it". Not being familiar with the dual pump setups though...I don't know if a single "unit" with two pumps replaces the original factory setup, or if there is a secondary in line pump some where. I need to start at the regulator and back track the lines. Also not sure why it will never read more than 3/4 full, even when properly topped off. Odd.
He has a fuel pressure gauge that says he is at 41psi (if I recall). But what I was watching more, was it's stability while driving, and it's stable.
One thing on the setup I don't like, is the wide band sensor is mounted about 30" from the turbo. (should be less than 18), as well as it's supposed to be at an angle, and it's flat/level.
 

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If it's getting fuel under boost and the pressure is stable, I think I'd have someone take another look at the tune for the conditions you're having issues with. If the car was just in for a power tune and they didn't mess with the other maps that could be the problem.
 

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If afrs are all over the place the tuner should be able to look into. I would contact him before anything. He has/should know why or at least point you in the right direction. The fuel pump is back seat driver side. Take like 10min or less to take fuel pump out but if it also goes up down to 9 something I doubt the fuel pump is the issue. Could have a bad o2 for the gauge that is possible too. When you get on it do you notice a lot of black smoke? That will also kinda tell you if it’s rich or not. Mine is tuned rich and looks like a diesel truck when you get on it
 

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Get the tuner to look at their tune, and let them know if something was done between the tune and when the troubles started.

Could be a bad tune, could be end of service life on parts. Everything mentioned, the tuner can easily find, test, or troubleshoot while on the dyno and should warranty their work if they're found at fault.

Maybe get tuned for less power and more economic. Hearing that a tune gave 100 more WHP without additional mods seems like getting an aggressive tune to push numbers. Taking this with a grain of salt cause all dynos read different so the +100 is maybe just a difference in dyno machines.
 

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Discussion Starter · #8 ·
Well, not here to bash. Tuner doesn't answer his phone, and is horrible about responding to voicemails. More than an hour away with a car that runs questionable.... Not a good combo.
 

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Yeah, pick up an AccessPort and work with an eTuner. I listed a couple of reputable guys below. I'm sure others will chime in with more.
 

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Discussion Starter · #12 ·
Thanks for all the input. No offense, but not a huge fan of etunes. Especially at these power levels. A lot riding on assumptions in my mind... Would personally prefer a hands on shop. Having said that, does anyone have any recommendations for a good Evo tuner in Colorado? My son mentioned a couple that seem to have closed up shop. So it's a little harder to find than you would expect.
 

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Discussion Starter · #13 ·
We went ahead and replaced the wide band sensor. That was the culprit. Took it out for some testing, and now cruising it holds nice and steady right around 14+/-.

Just a heads up to anyone shopping to get a replacement wide band...I found a bosch 30-0300 direct replacement on Amazon for almost half the price averaging out over three performance shops on line. Plus their shipping is much faster, AND with prime, shipping is free. Something to think about.

Thanks for all the input!
 
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