NefMoto

Hi Folks,

I've been doing some logging recently and noticed that at high rpms (=> 5500 to be precise) the actual throttle angle is very jumpy.

I'll upload some logs after work tonight but was hoping for some ideas or some areas that I should be logging.

I've checked already :-

- EGT's - These appear to be not getting to high, no enrichment etc.
- IAT's - These rise up to 32*C at redline so don't think this is an issue
- Fuel - This is ok, I'm getting low 12's (checked with my wideband also)
- Boost - Actual is following desired pretty well
- Knock - I've pulled the timing so now I'm getting max 1.5* retard upon knock now (previously ~3/4 so thought this could be the cause)

I can't think of anything else that would pull the throttle, it's only a small amount, ~3% cut but it's very unstable.

I've been thinking a faulty N75, but that should show up with requested vs actual boost pressure shouldn't it?

Apart from this I'm thinking possibly a boost leak somewhere, or my wastegate is too tight (as turbo has been rebuilt a few months ago so it's been apart). Reason I think this is I put the standard map on and it overboosted and huge throttle cut at around the same rpm. It doesn't overboost on my mapped file though, maybe the turbo doesn't have enough in it to do so but something's wrong causing the erratic throttle angle?

As said, I'll upload logs later (new ones if anyone has any ideas as to what extra I should log), I also logged WGDC's but can't remember them off the top of my head, what should these roughly be at?

Thanks in advance!

Edit:- I'm running 22psi tailing to 17psi redline and is an LCR (BAM engine) K04 turbo.

Quick update for anyone looking/thinking

I've loosened the wastegate and retightened until it's just nipped up, few mm preload that's all. Was maybe 7/8mm too tight and the car feels much better!

Boost gauge fluctuates much faster and stuff so it must be better controlled, not done any more logging yet as it's hideous out right now (damn rain) and can't safely do 4th gear pulls.

Any ideas?

Don't think I should be at 95% duty cycle should I?

That is not throttle cut, and it is largely irrelevant.

Yes, I guess I believe it's not throttle cut in the sense of preventing boost deviation, but why it is so unstable?

I've checked it against the requested angle and it requests it. Albeit yes I probably can't feel it, it would be nice to know if there is an underlying problem, I just can't see/understand why it's happening?

You'll need to actually post the log.

http://nefariousmotorsports.com/forum/index.php?topic=5295.0title=

Apologies, I had to cut some down as it was too big to upload but should be all there.

Ignore the initial overboost, I'm tuning this out :)

Thanks in advance

Looks like you are at 100% WGDC.

That turbo is probably not going to be happy in the long run, unless you set your wg pretty soft and thats that.

BTW log is missing

1) timing
2) injector on time


Also, you have quite a bit of boost overshoot, you'll probably want to log the various PID variables.

Thanks Nyet.

Yea, I have a feeling I've made the wastegate too loose :/ it was previously around 70 IIRC. It's a k04-023 so I thought they'd easily do what I'm asking of it?

I have older logs with timing (it's fairly conservative I think with little to no knock)

I'll get another hopefully shortly with injector and timing.

Does the unstable throttle angle look like anything you've seen before?

Yup. Very common, especially on older throttle bodies (and old harnesses... that is the signal from the throttle plate angle sensor)

If you are paranoid, you can pull it and give it and the connector a good cleaning. Might help.

If you want it gone entirely, you may need a new TB.

Does it matter? No, probably not..

Awesome, that puts my mind at rest then! I was thinking it could be something like that but everyone's logs I looked through were 100% all the way up.

Found it a little odd that the car is requesting that throttle angle, not just the signal coming back. It's a 2003 leon so it's getting on a bit.

I'll tighten the wastegate a little and clean the TB then get another log, see if anythings changed :)

Thank you.

Uh, i confess I did not look that closely to notice that. That does actually seem odd.. Still, a few % isn't going to change much (or shouldn't)

Oh man :p

But no it's definitely not going to have any (noticeable) effect. Just wondering if there's an underlying issue somewhere.

I tried the standard map and it just overboosts (large TIP and exhaust) so I was going to try raising the limits (and keeping an eye on fuel) and seeing if the same thing happens.

Would confirm if it's a hardware issue I guess wouldn't it?

If you have messed with waste gate pretention / adjustment rod you might have the pretention way off. You need to hook up a hand pump with gauge and pump 4-5 psi to each WG. You have to watch the Wg arm and adjust it so the WG arm just starts to open ( cracked open ). The waste gate should be wide open at 6-7 psi . If you have every thing way off you will have one turbo doing a lot more work and boost spiking. It is very important that you get the adjustments within 1-2 psi other wise you will get boost spiking , lag , turbo over spool and burnt out N75.

Lee

The boost issues you are seeing have nothing to do with the throttle plate weirdness.. get your PID straight and your boost will be fine.

Sorry Nyet, I meant to see if the throttle angle still bounces around. I've managed to tame the overboost (I do need to tidy it though), but also the top end is unstable, assumedly it's possible to smooth this out?


Thanks Lee, the wastegate isn't too far out now, boosts around 4/5 psi (it should be ~6) with the N75 disconnected so needs to be tightened a little, previously it was 9! Hence my boost spikes and lag (previously) as you say. It's only been too loose for a few runs and will be tightened as soon as the weather dries up.

Definitely, once you get your wastegate tension set the way you want it. Also, make sure all of your inlet path is good and clean; ive seen a lot of boost issues from flexible inlet/intake pipes collapsing or kinking.

Cheers Nyet, just looked at an older log, wgdc is sat around 75-78 after 5k rpm, currently it's >95 so def. too loose

I've recently added a silicone inlet pipe, I also got an open cone filter but I was getting ~10g/s less and car felt a bit flatter, intake temp's were a ton higher too so waiting until I get a heat shield and feed for it before I fiddle again.

I'll get the boost nice and smooth and have a fiddle with some timing then come back to investigating the throttle workings another day, it's not worrying you so it must be alright!

Thanks all for chiming in :)

Another thing that can give you over boost issues is spark plug gap too lage and a very rich mixture. At times you will not a have a misfire but a large gap will cause unburnt fuel to collect in the turbine side ( turbo ) and then ignite. The ignition of the fuel will give you a boost spike and surging . The ignition inside the turbo will not make any noise ( back fire ) but it will over spool the turbo for a splitt second. I hope i am not sending you on a wild goose chase. I hope this helps you too.

Lee

Thanks for the suggestion Lee.

I actually thought about this and so changed my plugs and gapped them down, made no difference annoyingly :(

I need to tighten the wastegate again so should stop the dc being so high again, after that fiddle with the PID and see what I can get :)

Ok so I've been over the car pretty well now.

- I've adjusted the WG, at ~70% wgdc high rpm now so much better
- Gone over all vacuum/boost pipes and checked for any leaks
- Cleaned TB

I've also rescaled KFMIOP/KZWOP(2) and altered their values accordingly as I thought this could have an effect on the throttle oscillations up top.

Took it for a run and it's no better :( I disconnected the N75 which made no difference (apart from boost). When I disconnected the MAF however it requested a dead flat 100% throttle angle, with .3/4% throttle oscillations which I think is just signal noise.

I understand running without the MAF it defaults to predicted readings, so could this mean I possibly have a faulty MAF? Anyone know what things can intervene slightly with the throttle angle?

Looking here http://nyet.org/cars/info/Translated%20Funktionsrahmen%20Modules%20(10-01-2012).pdf I can see there's a few things, maybe cylinder charge maps?

I get these symptoms on both my mapped file and standard file so it's gotta be a hardware issue I think...

Again, although only 3% in the ideal world I'd at least know what it is so any ideas are appreciated :)

You'll have to dig through the FR (the actual one) and log the various variables in the DK path to know for sure.

Since it's in request I would say the potentiometer in your pedal is failing. There are 2 for plausibility diagnosis, I bet one is off. I have seen quite a few request 70-80 percent when failing and not cause codes. Your failure seems less likely, but possible.

Again, a couple percent is kinda irrelevant in the grand scheme of things, but it will not get better, only worse.

Agreed. Log pedal position.

That's what I thought... My pedal position stays on 100% in the first few logs I done of it, I've not bothered to log it anymore (me7 kept crashing for having too much going on), next logs I do I'll add it on.

I've noticed though sometimes when I start it the car has a little hiccup, almost like a misfire. I started it tonight and it almost stalled and EPC and traction light came on so I grabbed the codes fast.

Coincidentally they are P1544 (throttle signal too high) and P1172 (throttle signal too low). I've also got P1062 (power supply terminal 30: too low - intermittent).

I have a feeling it maybe something silly like a bad earth... I put a new engine in a few weeks ago so things have been apart. Sound reasonable?

Log both sensors, not just pedal position.

I shall do on the next log (tomorrow most likely), previously I logged pedal position and actual throttle angle, then later replaced pedal position with throttle and requested, I'll add it for completion purposes though.

Would these kind of symptoms appear if the TB wasn't calibrated? Not being calibrated as a result of some kind of power cut somewhere whilst cranking and starting the car before the TB can adapt/set. Just thinking aloud here... Apologies if I'm not making sense :)

Here's one of the first I made with pedal position and the throttle plate angle. Other things are much tidier now but throttle is still the same.

Wow. Very strange. Your load is also very noisy... but your RPM and MAF signals are not.

Hmm... Wonder what could be up.

How does the ignition timing look to you? Are those oscillations acceptable in your opinion?

I'll be checking the earths and all wires again tonight after work, see if I can uncover anything obvious.

No. Definitely not good IMO

I think some kind of noise is being picked up and ending up in your load signal... which is odd, since load is basically MAF/RPM, and both your MAF and RPM look good.

Perhaps there is some filtering of both that I dont know of in ME that the load calc doesn't get.

You mentioned before unplugging your MAF made it go away, I suspect a bad ground or wiring to the MAF, or a dying sensor?

Thanks for your thoughts Nyet.

Hmm, the car in general runs pretty well, but there is this 'hiccup' issue.

The wires should be good, I went over everything like that yesterday. Also cleaned the maf but nothing changed so it's not simply dirty.

Fingers crossed it's a silly bad earth or something. I've also got another ecu in the garage so if I don't find anything up with the earths I'll try that too.

I have to be honest, at first I thought you were being overly paranoid, but I have to say I think it would be a good idea to get to the bottom of this... Forget for a moment about the throttle and ignition swings.. having your actual load move around like that a lot is not a good thing for ME7....

Not to scare you or anything, but I think it is worth trying to fix.

I think that will most likely be the root cause of the throttle/ignition oscillations, hmmm. Got a busy weekend coming up I feel!

Shot in the dark: can you log your ambient pressure?

Also, do you have a spare ECU you can try?

Sure, I'll be able to take the car for some runs tomorrow day so will grab it then. Is there anything else I should add to look at in particular?

Which one is ambient pressure? pu_w or pus_w?

Also yes I do have another ECU spare, so I'll give that one a bash also. Rules it out if nothing else.

Ok so been fiddling with the car today, checked all MAF, MAP and earth wires, all look good.

Here's another log with all of the throttle sensors and ambient pressure.

Nothing's changing so I'm going to get my spare ECU fitted now and see what it does then.

Here's a log from the other ecu, it's in standard form, but there's still some throttle intervention up top.

It's looking like a hardware issue somewhere I think, maybe time for a new MAF.

Picking up a new MAF tonight, at £100 I'm hoping it'll be resolved after that!

My max MAF readings are ~200/210 so I'm thinking it maybe under reading a little anyway (signs of a dying sensor). Most of the guys with similar mods to me are seeing circa 220.

Will update later.

0 percent WGDC.
17psi boost at redline.

What's going on there?
Ignition angle looks normal to me (for a slow car with a shitload of samples).
Your AFR on the other hand......What's going on there?

Well the MAF has made a large difference, general throttle response is much better, but my boost has moved to lower than requested (previously it was a little more), also I saw very minimal throttle oscillations.

I was looking at your standard ecu log.

For anyone interested, changing the MAF has solved this, it must have been dying as my max g/s readings went up from ~200 to 210, oddly my actual boost moved around a lot so I've had to re-adjust for it but the car is running much better in itself. The throttle response has change dramatically at part load.

I still have some very slight reduced requested throttle angle sometimes but this is ~6.5k rpm and is ~1/2% max so I don't think this is anything to worry about really, it's almost at the limiter up there and will hardly ever be driven that high so will just keep an eye on it.

Thanks to all who helped out on this one!