Car pulls in waves between 170 and 220Kmph

[mituc]

Hello everyone,

A few days ago I noticed a very strange behaviour on the german autobahn (somewhere between Salzburg and Munich): at full throttle in 5th but mostly in 6th gear the car pulls in waves. In 5th gear it happens between 180 and 190Kmph and in 6th I could see it between 170-180 and 220Kmph.
I noticed the same behaviour last year but because I didn't have the aftermarket intake and intercooler the problem was barely noticeable (I even thought it was because of the bumpy highway).

Looking at my dashdaq while this was happening I was able to see that the boost was going up and down between 13PSI and 18PSI, and while this was happening (boost going up and down) I could hear a quite distinctive and periodic "psshhh" which I'm not sure where was it coming from (stock BPV or wastegate?).

This doesn't happen in any of the other gears, 1-4, so apparently there are no leaks (and if there were I think I wouldn't be able to see any boost value higher than, say, 10-12PSI). Maybe it's just because in the lower gears the effort on the turbo is less, while in 6th gear the turbo gets a bit hotter while pushing air continuously for a longer period of time?

I don't think it's a clutch slip, the car was moving accordingly to the RPM values.

While keeping the foot on throttle the problem disapears around 220Kmph. Does anyone have any idea what could cause this?

My list of mods includes:
- Cobb SRI;
- Cobb turbo inlet;
- Street unit top-mounter intercooler;
- Street Unit boost tubes;
- Denso Iridium ITV22 sparks;
- SU RMM (soft bushings).
Everything else (ECU maps, BPV, turbo, exhaust) is left stock. However, since this seems to have been happening even before I think that the aftermarket mods only amplify the effect.

So what could it be?
If there is not enough information right now for someone to figure this out, what parameters should I set my dashdaq to log if I'm going to reproduce the phenomenon again? I'm currently logging: rpm, iat, bat, ect, boost, afr, frp, load, speed, throttle position, cat temp, sparkadv, knock retard.

[darth vader]

I'd be up for checking for boost leaks, making a cardboard block off plate for the BPV to isolate that and making sure your DI fuel pressure is over 1660 all the time you're WOT.

[speedms6]

get a new blow off valve, form the intercooler your bost gos up 1-2 psi the stock bov supposedly leaks at stock boost sometimes, just a thought

[phillyb]

fuel pump

[mituc]

The fuel pressure is around 1700PSI (1690-1750) all the time while this happens, the fuel pump I have seems to perform just great, it holds fuel pressure over 1650PSI up to 6300-6400rpm and doesn't drop pressure even for a reading (never tested above these RPM values).

I also thought about the boost increase due to the new intercooler, however since this was happening also before (not that horrifying though, actually hardly noticeable) it means that the stock BPV has been a liability all this time?

I also thought about boost leaks but they can happen only between the turbo and the intercooler, there are exactly two silicone tubes there which have been changed when I changed the IC. So you guys think it's probably the stock BPV, right? That's relieving... since I already have a turbosmart BPV on the shelf which I never installed thinking that stock is fine (I have both springs for the turbosmart, I'll leave the softer one in place since I'm kind of stock).

I was also thinking about the wastegate as possibly causing this. Is there any chance to be the case?

[Zak]

It's because of the Cobb SRI!!

Friends of mine have same issue when they put the Cobb.

[rodrigo]

^^^^ gtfo clown.


check boost leaks, first and always on turbo cars. and post some logs of different prameters

[Zak]

Originally Posted by lenny127 ^^^^ gtfo clown. check boost leaks, first and always on turbo cars. and post some logs of different prameters

Lol

If he had boost leak, he should have problem in 1-4 gears!

@mituc, put back the stock airbox or another intake and you'll be fine.

[reddeerspeed3]

it sounds like your stock BPV is a peice of shit just like mine was. as soon as i installed my sri/tip my BPV started to leak at ~14psi. if you were driving next to me under WOT you could actually hear the valve flutter. i installed a Forge BPV and picked up 2psi without touching anything else. if you have a aftermarket valve already i would install it and see if it helps.

[ChrisK]

Originally Posted by Zak Lol If he had boost leak, he should have problem in 1-4 gears! @mituc, put back the stock airbox or another intake and you'll be fine.

If you're car does this with an intake (especially Cobb or CPE) Then you have other issues.

Those intakes will not cause that.

More than likely, it's a boost leak. Probably the stock BPV, just like others have said.

[burntRice]

Mazda Service Bulletin ROUGH IDLE, LACK OF POWER, AND/OR MIL ON WITH DTC P2177/P2187 (FUEL SYSTEM LEAN) Ebooks Download | Acrobat PDF Files


read it...power surges from the fuel high pressure side of the fuel pump needing a software update....bring it to the dealer they should be able to do it no problem

[mituc]

BurntRice, thank you for that link, however I don't think it's the case because it happens only at WOT in my case and only when boost is high. And when that happens the fuel pressure is good (1650PSI or more), the AFR is also fine (12 or less), and so on.

I replaced the stock BPV yesterday and the problem is still there, if it's a leak then it must be somewhere else. I'll try to tighten even harder the screws from the clamps and see what's the situation after I do that.

What are the spots I should look for leaks in this case? The two intercooler boost tubes? IC cold pipe?
Is there any consistent way of locating these leaks?

[Zak]

As I said, there's 2 guys here in Switzerland who's got same issue as yours. And both had Cobb SRI. We've already checked everything (AFR, Fuel pressure, etc,...) and everything was Ok except boost was going up and down in higher speed like yours (170km/h for one guy and +200km/h for another). When they changed intake, issue was gone.

[mituc]

Zak, thanks for the heads up!
This summer I was about to go to Germany to QAS to tune the car a bit more and they've recommended Cobb SRI (I would have taken the CP-E SRI). I'll do no change to the car so I will not visit QAS anytime soon, so I'll have to deal with this myself.
So what's the new intake your friends got? And did they figure out what the problem actually is? Is it the MAF position, the filter (I have both the original Cobb/green filter and a KN one), something else?

I also found a clamp between the turbine and the intercooler which was moving easily, by pushing with the fingers. I have tighten that clamp a bit more as well as some others, I just hope it's not the SRI even though from what you've told me it's still quite possible considering the behavior and the fact that from the ECU settings point of view our cars are identical (when stock).

Later edit: after fixing the loose clamp the problem did not disappear.

[mituc]

The only thing I did not check yet is the link between the IC and the cold pipe. I wanted to wait until I have a spare gasket, as far as I remember that link is a weak point and the problem always was the gasket in between, is that right?

All the clamps are now tighten and that's the only thing between the turbo and the intake manifold that I didn't check so far and I will when I'll have that gasket at reach - is my approach correct?

[mituc]

Is it possible that this wavy pull in 5th and 6th gear between 3500-4000 and 5000rpm to be caused by a dirty spark plug?

[BrianZX10R]

I think that Because 5th and 6th gear have a much higher load its causing you to Hit the boost limit for the stock ECU and its boost cutting on you. I think stock limit is 18psi. I would bet money this has everything to do with the stock tune. When u added the TMIC id reduced pressure drop and made your boost increase in the manifold. You will need a Cobb Acessport now so it does not do this anymore. The boost cut limit will be like 22 psi with one and should solve ur problem. I had same issue when i tried running fully bolted with no Acessport.

[mituc]

I was afraid of such an answer and it finally came. I thought about this as well but I didn't know what I was hitting first, +18PSI of boost or the wavy pull/crazy stock BPV recirc/anything else.
Looks like sometimes I hit 19.5-20PSI and load of 92-93.7 which I believe triggers the boost cut.

Ok, so until the ECU tune I should tune my right foot and make it lighter, right?

[BrianZX10R]

pretty much.

[mituc]

Ok, how dangerous and bad for the engine is to hit the boost cut? I'd say it's far from being as bad as hitting the rev limiter when the engine still spins very fast but the fuel is cut, thus rev variation putting a lot of stress on the internals, but let's hear someone who knows better.

[mituc]

Also, would a manual boost controller help in this case considering that I don't want to mess with the ECU just yet?

[darth vader]

Originally Posted by mituc I was afraid of such an answer and it finally came. I thought about this as well but I didn't know what I was hitting first, +18PSI of boost or the wavy pull/crazy stock BPV recirc/anything else. Looks like sometimes I hit 19.5-20PSI and load of 92-93.7 which I believe triggers the boost cut. Ok, so until the ECU tune I should tune my right foot and make it lighter, right?

You are definitely boost cutting and the ECM is closing the throttle plate at over 19 in high gears. You also need to measure ABSOLUTE load, which exceeds 100%. The load you are measuring tells you nothing about the load on the engine as, wot will always be ~ 100%. Load cap hits ~180%.

[mituc]

Originally Posted by mituc Also, would a manual boost controller help in this case considering that I don't want to mess with the ECU just yet?

I intend to get a turbosmart MBC (boost tee), is it suitable for what I need to do (limit the boost to 18PSI)?
Has anyone else tried it? Does it work fine?

[darth vader]

Very difficult to tune out boost creep like you're describing, given the small turbo we have. The environment you are running is is a perfect scenario to create boost creep, max load, long duration, high gear.

I was able to calm it down enough for my North American acceleration-based driving using the Boost T but, it's really a mechanical issue with the wastegate and the exhaust side being too small on the turbo. You could put a catalytic converter back in to reign it in, that extra restriction slows the wheel and prevents overspeeding, which is you boost creep.

[mituc]

I have both cats, my exhaust is stock.

[Tobyboom]

I've had this problem since day one of installing the Cobb SRI. I posted about it a year ago, and no one seemed to know what would be causing it. My car is 100% stock other than the SRI, and it didnt do this from the factory...

Could it perhaps be too much turbulence reaching the MAF due to the short run from filter to MAF? I encountered similar problems on my boosted Focus, and moving the MAF further away from the air intake cured it completely.

[darth vader]

Anything's possible...the Cobb is tuned for the North American acceleration-crazed market. It delivers on that front with a pretty explosive bottom end. This is due to the velocity stack design of the thing. The V stack, however, can only be tuned to an optimal length for a particular amount of airflow so, it's possible some weirdness could ensue if it's used under extreme airflow demands like long autobahn burns.

[mituc]

Ok, then how do I know it's not a boost cut (even though it looks like this) but some crazy MAF malfunctioning because of the Cobb SRI? This SRI still has that air flow straightener which is known to do its job AFAIK. But if this SRI has any issue I'm willing to burn it in front of my house and get a new different one right now.
After I changed the stock BPV (which I thought was leaking) with the turbosmart BPV which holds pressure better this I get this wavy pull in 5th and 6th anywhere above 3500rpm at WOT (I don/t WOT so early, I just tested to get these figures), while with the stock BPV I was getting it in 5th above 5000rpm (180-190Kmph) and in 6th above 170Kmph. So it still looks like a boost cut though... and the stock BPV was recirculating earlier and keeping the engine a bit farther from this issue, but not completely away.

Someone else (Zak) mentioned some weird behaviour with the Cobb SRI somewhere earlier in this thread, but still it looks like a boost cut since it happens only at high load: WOT, only 5th and 6th gear, boost around or above 18PSI, calculated load above 90-92%.
As a side note, I started to monitor the absolute load (didn't know which one is the one I should log) from some time but I never got closer to this behaviour because I'm not sure how dangerous or harmless this is as long as the AFR vary sometimes with 1 at WOT (it jumps from, say, 11.2 to 11.9 or even 12-12.2, then gets back to 11 and it does that over and over again when the boost builds up).

It's not a fuel cut, the FRP stays above 1650 (usually around or above 1700) when this happens. Only boost goes up and down.

[mituc]

Guys, is anyone willing to help me analyse this log and tell me what's wrong except that I don't have a tune yet? I just want to make sure it's not something else before I get a tune, because if I get it and I have some other weakened parts the possibility to blow increases more than I would like.

I stepped on it harder at line #140 (timestamp 2010-06-20 16:57:52.424) and shortly after that I've got that wavy pull sensation and the surge sound. Most of the action was in 5th gear, so probably there's no need to analyse anything further.

The moment is pretty much this one (don't look at the timestamp recorded by the DVR, my dashdaq had the time misconfigured):

YouTube- 5th pull

YouTube- 5th pull

[FreeFlyFreak]

Your problem sounds very similar to what was happening to me the other day.

Car was pulling in waves at high rpm and load.
It did that all day.

Larter something failed on my car, I do not know what yet, but I am guessing it is the wastegate actuator.

When I get my car fixed and know what the cause was of my symptom which eventually lead to a failure I will be sure to post and let you know.

I should know by the end of the month.

[mituc]

FreeFly, I just read about your problem last night. Since I don't get this problem in any other gear than 5th and 6th, is still possible for my actuator to be jammed into a partially open position, but more close to the closed position?
I understand that there are a few people with a similar setup (intake + IC, no dp/tp, no tune) and still no one complained about such behaviour.
My MAF was cleaned up so that doesn't seem to be causing the issue, maybe I should ask for an actuator check when I'll return to the dealer for a strut bearing problem - do you think it may be the case?

[FreeFlyFreak]

Probably a different problem, but you could always have it checked.

[SJP0tato]

Originally Posted by mituc Guys, is anyone willing to help me analyse this log and tell me what's wrong except that I don't have a tune yet? I just want to make sure it's not something else before I get a tune, because if I get it and I have some other weakened parts the possibility to blow increases more than I would like.

It looks like your boost is jumping all over the place during your pull between 57:52 -> 57:56. It spikes to 19.4psi, then down to 18.4, then way down to 15.2, back up to 18.2, back down in steps to 14.69, back up to 18.2. I would think that would cause a wavy pulling sensation with the change in power.

It also looks like your MAF isn't calibrated with your mods (impossible to do without an aftermarket ecu), your LTFT for the entire pull is +11.7. That means your ECU is having to add an additional 11.7% fuel which means your stock maps aren't able to keep up with your mods. I'm not sure what aftermarket ecu solutions you have, but it might be a good idea to see what's available.

[mituc]

Indeed, I identified the boost variation as cause of the wavy pulling, but I couldn't figure out the cause of the boost variation itself. If it's just the MAF calibration then I should be fine once I get a tune (probably some EcuTek solution which should be a lot more flexible then the other option I have - Piasini, just like a Cobb AP I think).
As far as you can tell, apart from the MAF is there anything else? I guess that when boost jumps above 18-18.5PSI I also get a static boost cut - or not necessarily? I'm not sure what the stock abs load limit is, but I believe it's about 160 or so, and even when the boost varies the abs load stays at 157.something in my log.

Thanks a lot for your help, I feel a bit better now that it becomes more and more obvious that the only thing I need is just a ECU tune.

[SJP0tato]

Not sure if the MAF calibration would cause it, but the MAF is the primary sensor used in most calculations.

I think fuel cut is around 18-18.5 psi stock, it's possible you're brushing up against that. The stock MS3 ecu 07-08 MS3 according to cobb is 2.0, which means after temp corrections/other factors it might be 1.6-1.75, it's hard to say.

It might be a good idea to double check/replace the vacuum hoses for the wastegate and others in the area just to make sure that's not causing issues.

When you get the aftermarket ecu let us know how it helps.

[shpankey]

Wow, it's so good to finally hear from someone who has the same issue!

First, I did three basic power mods: intake (Cobb SRI), bpv (Turbosmart) and a race pipe (SU). The car ran this way for about 6 to 7 months and pulled like an absolute BEAST. I was so freaking happy with the car.

Then in December, I decided to do some more power mods. Added a Cobb TIP and HPFP internals and wow did my car's performance drop off substantially! It also started with (as u describe it) the "wavy pulling". I've had many people in my car and showed them the problem and it's very noticeable.

I checked my compression > 180psi all cylrs. fuel pump (aftermarket internals) is always over 1730, usually higher, at wot, so it's good.

It all comes back to the cobb TIP. I broke the small piece where the boost controller plugs in to the stock TIP, so I can't put it back on now to test. But it's pretty clear to me, the TIP took it over the top on what the stock tune can adjust for. Looking at my LTFT's, I'm at +10.7 now at WOT. So it's way off. Also, I clean my MAF, MAP and EGR several times. The MAF a lot. lol. Car is an 09 GT with now 19k. But issue started at 12k miles.

I'm betting a Hypertech tune would fix the issue for me, as it tunes your MAF for your intake, but I'm not tuning till the warranty is gone. So I think you can go too far with mods without tuning and lose performance, as I have. I so wish I had a stock TIP to try out.

If anyone would be willing to loan me theirs, for testing, I would pay for shipping to and fro. All I have is my word. But my word is my bond, as grandpa used to say!

[shpankey]

Any more word on this yet? This weekend I re-cleaned my maf, air filter; re-oiled my BPV and re-tightened all hoses to get rid of any possible boost leak. The car feels better, but the surge, or as you put it, wavy pulling, is still there. In 5th gear it is dramatic!

Any help on this issue would be greatly appreciated!

OP, have you figured anything out on the surging? Or are you still in the same boat?

p.s. on the fuel pressure issue, my car stays above 1730 at WOT at all times, usually between 1750 and 1850 with spikes up to 2000. This is with my HPFP internals. So I don't think it's related to that. My mods btw...

2009 MS3 GT
COBB SRI, TIP
Turbosmart BPV
SU Test Pipe
KMD V2.1 High Pressure Fuel Pump internals

I should say, this problem started when I installed the COBB TIP (already had the SRI and Test Pipe and BPV on) and HPFP internals. I've since fairly confidently ruled out the fuel pump, as it performs as advertised. Which leads me back to the COBB Turbo Inlet Pipe to the mix. That's when this surging/wavy pulling began. I should also note I've changed the plugs twice after this problem began. First to Denso's then now to stock NGK Iridiums (what I still have on). So it's definitely not a plug issue.

[FreeFlyFreak]

Originally Posted by shpankey I should say, this problem started when I installed the COBB TIP (already had the SRI and Test Pipe and BPV on) and HPFP internals.

So...........
put stock TIP back on and see if the problem goes away.

[shpankey]

A friend of mine was over and he dropped the stock TIP and it broke the little nozzle off where the boost controller hose plugs into it. So I can't. Believe me, I've been asking around the forums to borrow a stock TIP to test. lol

Correct. No tune either. Mine didn't exhibit this problem when I had the Cobb SRI, TS BPV and SU TP on. But when I added these things...

HPFP Internals
Cobb TIP
Denso step colder plugs (ITV22)
CP-E RMM

Since then, I took off the RMM and put the stock plugs back in. My HPFP tests fine. Though I should probably get a DH to get you all some proper logs. Right now I just have a scan tool... which lets me look at "Live" data, but that's it.

Anyhow, last night, I put the stock intake back on (left the Cobb TIP on of course cause I had to) and am learning new trims now. I should be able to test it soon to see if this fixes it. I'm with the OP, I don't want to mod any more until I figure this out, for sure. If it's just a tune issue, then np, I'll get a Hypertech now as an intermediate step, finish modding and then do a custom dyno tuned Cobb AP since they're not to far from where I live. But I have to figure this out, for sure, first.

[shpankey]

Ok, I put the stock Intake back on. But I left the CObb TIP, Turbosmart BPV and Street Unit TP on it. Drove a few days and got almost 300 miles on it for it to learn the new trims (LTFT's are now, idle = 0, pt= -4.2, pt= -6.4, wot= 0 btw).

I can tell you, the wavy pulling is completely gone in 5th and 6th gears now. So there is something going on with the intake or the tune of the maf on the Cobb SRI & TIP combo.