weird boost issue

[cypher0117]

Here is a fun highway cruise for you. IAM goes bat$h1t crazy

[cypher0117]

had to break the file into 2

log0012-1.csv

log0012-2.csv

[iNVAR]

I see in your first log you did a pull, but why is your Throttle Opening Angle only at 83%? Didn't go all out WOT?

 

Anyway, from your log, you are knocking HARD, and it may be due to your AF trims. You are subtractinging 8-9% of fuel under moderate to hard throttle, which is likely causing you to go lean and induce knock.

 

Whatever's causing your AF trim to dip is the problem... usual suspects are boost leak (are you SURE you checked everything?), leaky manifold gasket, bad MAF, bad fuel pump... and there's a lot more I'm sure that could be possible.

[cypher0117]

I'll look again for a boost leak. My manifold gaskets are only about a year old as I replaced those then I replaced my inlet. I'll recheck the torque on the manifold bolts. Fuel pump I don't think it would be that, this had the same behavior when I had my dw65c in there. I should have some time tonight to dig into things and look for boost leak again.

 

I've never replaced the maf, only clean it about every 10k miles. Do they go bad after ~103k miles?

 

Thanks iNVAR

[cypher0117]

upon further investigation..... Looks like my stock bpv is not holding pressure. I pressure tested everything post turbo and got to like 10ish psi and started hearing leaking air into the inlet. I took the bpv off and plugged the hole with a pingpong ball and my hand. pressure tested everything again up to ~27psi and no hissing anywhere.

 

would this explain the lean conditions/knock/bad fuel trims?

[cypher0117]

New bpv. Boost builds/holds a lot better than before. Still knocking.... Would you guys say this is a tune related issue now? Or maybe is there something in the logs I'm not seeing?

log0004.csv

[PtPixel]

An LV screenshot will show if you're knocking. Your log has both feedback knock correction and knock sum logged. Since the FBKC log shows 0 the entire way through your log then your LV screenshot should look clean, i.e. no knock.

 

The knock sensor which logs in the knock sum will always pick up random background noise from the engine/car/anything, hence why the sum goes from 0-4 throughout the log. On most 15min drives you would see the sum go from about 0-20 from background noise. Sometimes even a heatsheild rattling will trigger the knock sensor.

 

Looks like your tune is fine to me know that your boost is sorted.

[cypher0117]

It's knocking. From what I don't know. Fuel trims seem to be fixed though

[iNVAR]

I'm glad that it seems like you've solved your leak problem!

 

That knock is concerning and I'm inclined to say it's a tune related issue. To find out if that's the case, you can pull timing in those cells. About 3 degrees in the exact location, and 1-2 degrees in the neighboring ones. Reflash the new rom, get back to IAM 1, and relog and see if it improves.

 

Unfortunately, I don't think you're going to get much (if any) help from Infamous from what I've seen is going on in other threads.

 

What sort of weather was your tune done in, and what is the weather like currently?

[cypher0117]

I think my ecu forgot how to car. I was literally just cruising and not doing anything and my IAM shot to 0. I haven't made any tune changes yet, this was driving home for Thanksgiving

smallsample.csv

[iNVAR]

you file appears to be zip compressed, and when i grab it and extract, there's stuff in there that's not the log. might want to edit and reup the correct file.

[cypher0117]

well, here is another try with the file. Sorry about that

highway.csv

[iNVAR]

Pull another LV, but your fuel trims still seem to be off. IAM dropped down to 0 because of the large amount of knock you were experiencing. Also check for anything loose in the engine bay and/or near the knock sensor.

 

You seemed to have just been cruising in 5th at that point around 2300 RPM and about 20% throttle. Were you going uphill? If so, you may have been bogging the engine down and maybe should've downshifted.

[cypher0117]

Here is my current LV. And it seems as though the bogging may have caused that. It did a very similar thing on the same hill on the way back from relatives this weekend. Why would bogging the engine cause it to knock so badly?

[iNVAR]

Well for starters, you are pulling a lot of fuel. 6% upwards to 8.3% of fuel is a substantial amount. Plus, bogging yourself down in 5th is not good. If you want to accelerate, you should strongly consider downshifting to 4th...

 

Anyway, I'm still concerned about the amount of fuel you're pulling, but I'm sort of out of ideas. Again, there are a lot of places you can be leaking from, and many of them are hard to track down and fix.... intake manifold gaskets, for example, would sort of suck.

[cypher0117]

some food for thought: The second time my IAM dropped to 0 I had 93 octane in my car. Car is tuned for 91, which is the octane I had the first time. So the extra octane didn't help at all. For my stage2 Infamous also never tuned my fuel with a wideband. So it could just be off I guess?

[iNVAR]

2 points of octane isn't going to help if you're subtracting 8% fuel.

[cypher0117]

I looked for more/any leaks tonight again. Didn't find any, but I did look down by the knock sensor. There was a bunch of small pebbles (probably 5-6) chilling out next to the knock sensor. Sucked them out with my shopvac and will see if that helps anything. That wouldn't help the fuel issue at all but, maybe it caused some of the knock?

[iNVAR]

Could be.

[cypher0117]

after I broke up the pebble party around my knock sensor, My LV has been nearly identical to the one I posted in post #33. But my fuel trims are 0.4... -6.3.... -8.8 .... -6.2.

 

Weather has been going between 50 and 15 F a lot in the last few weeks. Can that do it? Could an exhaust leak cause this? like in the manifold before the o2 sensor (airs leaking out enriching the exhaust)?

[cypher0117]

IAM has been at 1 until my way home tonight about 10 minutes ago. My tactrix cut out so I don't have a log, but my boost gauge showed ~20psi peak and now my IAM is at .875. Is it possible that I'm overboosting and that is causing the lean conditions?

[ehsnils]

It's possible - check that the wastegate isn't stuck and that the wastegate control works.

[iNVAR]

That's not how it works and you likely spiked a bit due to colder temperatures but not enough to trip a CEL apparently. It was cold out tonight, right?

 

Overboost doesn't cause you to go lean. If you look at your fueling map, you'd understand better.Your AFR isn't determined by boost directly. It's determined by engine load. If boost goes up, MAF goes up, and correspondingly, engine load should go up, which would shift your fueling rightwards in the fuel table.

 

If your fueling tables are dialed in appropriately, and so is timing, and boost, then a small spike of 1-2 psi won't really induce knock.

 

In a nutshell, for a given engine load, you are limited to a set amount of boost and timing. When you run a certain amount of timing, you have to reduce boost. If you run less boost, you can run more timing. There's a balance between the two to produce power. There will be times where it's better to reduce boost and instead add timing, and you'll end up with more power, and vice versa.

 

Stuff that causes you to go lean is UNmetered air. Overboost/boost spike is metered air.

 

Anyways, bad time for the tactrix to go out.... log would've been very handy.

[cypher0117]

I've only looked at my tune once or twice and I was kind of overwhelmed with all the different tables. I have lots more reading to do about actual tuning (which is why I went with someone recommended by these forums). BUT, for knowledge sake... I'm guessing there is a point where the fuel tables run out and you've reached that last column to increase fuel. Theoretically if you overboost enough (not saying that is my situation), the ecu can no longer compensate by adding more fuel. Is that thinking right or wrong? 1-2psi should in no way be pulling in that much extra air to do that but I'm curious.

 

I probably won't have a chance to check for boost leak again until the weekend but I'll look again. This has to be between the turbo and cylinders somewhere right? if it was post maf/pre turbo it would be adding fuel then.

 

If I can't find a leak I'm going to try replacing my front o2 sensor. After that, then probably the maf.

[iNVAR]

No, you're mistaken. Fueling is done by a combination of injector flow scaling and a targetted AFR.

 

If you run out of columns on the right on your fueling table, say it's only scaled for up to 2.75 load max, and let's say at 3KRPM your fueling table targets 10.9 AFR, and say you overboost a lot and instead at 3KRPM you are at 3.5 load max, it will STILL target 10.9 AFR.

 

The quantity of fuel delivered to achieve that 10.9 AFR is calculated through use of the injector scaling.

 

So if your injectors are scaled to 520 or whatever stock is (I forgot) the ECU knows, based on this scaling, how much voltage and how long it needs to apply that voltage to your injectors to get a certain amount of fuel to get a certain AFR for a certain RPM and certain load.

 

You're not specifying the quantity of fuel to deliver - you're specifying the AFR you want, and the ECU figures out the quantity of fuel necessary and supplies it by activating the injectors.