SwedeSpeed - Volvo Performance Forum banner
1 - 20 of 20 Posts

·
Registered
Joined
·
298 Posts
Discussion Starter · #1 ·
I'm still chasing the cause of my variable boost pressure. I've posted about this a few times but I'm wondering if maybe somebody can help me find the cause with some more information. My T5 had virtually no boost when I bought it, but after replacing some split hoses on the TCV and patching a crack on the charge air pipe I immediately saw spikes to 18 psi (awesome by the way) and then steady a 14+ on the gauge. Eventually, the very high spikes went away but it still built to 14+ right away and stayed there. Then seemingly overnight the boost dropped to 12 to 13 psi and the car seemed much less responsive. The boost seemed to build more slowly too. I replaced a bad clutch switch, replaced the TCV, changed the plugs (which were loose, one even finger tight), and patched the charge air pipe again but the car behaved exactly the same. Then a couple of weeks ago, suddenly the boost was back to 14 psi and the car was much more lively again. I can't figure out what is happening and why it keeps changing.

I know that the boost I'm seeing is within what I should expect with this car but the performance should be consistent. The main thing that makes me wonder what is going on is how the responsiveness of thee engine seems to change. When the car is running right, it seems like the engine responds instantly to the throttle, revving immediately and pulling hard. It's actually tough to keep the tires from spinning in 1st through 3rd. But when the boost is off the engine is much less eager too. There are no codes coming up, and the car runs fine at steady speed and idles great. The turbo is quiet and looks to have been replaced, the car uses about 3/4 of a quart of oil between changes at 5,000 miles. Could this be something related to the ETM? This car had the ETM replaced under warranty before I bought it, but that was a while ago. I believe the replacement ETM it has maybe 45,000 miles on it. The car has just under 178,000 miles on it now.

I apologize if my repeated posting on this issue is tiresome, but the performance of this thing when it is running right is fantastic and I would love it if I could have it run that way all the time.
 

·
Registered
Joined
·
505 Posts
I have an 01' T5, have noticed this at times. There are a number of things that could potentially leak under pressure and cause fluctuations in boost across the board.

Have you pressure tested the wastegate or cbv? Doesn't take more than 5psi or so and then just put a stopwatch to it, see if they leak down over several minutes. You can also smoke test or get a pressure tester to find pinhole leaks in charge piping that could also be robbing performance.

If you've noted any big changes in weather recently it could also be the car adjusting to a temperature change.

For example, last weekend my car was running like a raped ape and we had daytime temps in the upper 50's. It's dropped about 20F the last few days and I've noticed it needing much more heat before it'll boost properly. Just make sure you're not only testing boost figures in 1st and 2nd gear. 3rd gear WOT is where you want to measure boost figures.
 

·
Registered
Joined
·
298 Posts
Discussion Starter · #3 ·
We've had nothing but temperature changes here. Fifty-five degrees last week, twenty yesterday, now close to forty today. I would think cold air temps would make this thing rip.

I did do a smoke test on the intake when I did the plugs and patched the charge pipe but found nothing. I'll test the wastegate and cbv and see if anything is wrong there.

Regarding boost pressures in 1st and 2nd, when it's running right I see full boost in 2nd but I'm only seeing 12psi in 2nd and 3rd right now. No sure about 1st because I'm feathering the throttle to keep traction plus it's not in 1st long enough to see what it hits. Is the boost limited in 1st and 2nd with a manual transmission?
 

·
Registered
Joined
·
505 Posts
Boost shouldn't be limited in a manual in 1st and 2nd, 3rd gear just seems to give the most accurate representation of the boost pressure i believe. When my boost is right where i want it in 3rd, 1st and 2nd are usually good also.
 

·
Registered
Joined
·
298 Posts
Discussion Starter · #5 ·
Gotcha. That does seem to be where the car is able to spend some time pulling hard from 3,000 rpm. Second goes by quick and forth gets you into serious fine territory in a hurry.
 

·
Registered
Joined
·
5,373 Posts
Boost isn't limited in 1st and 2nd due to programming, but due to the fact that the lower gears do not load the engine enough to allow for full boost production.

Lower ambient temps and high atmospheric pressure will result in lower boost. Does this mean the engine is producing less torque? No. If you want to see if engine torque is down then what I would do is in VIDA make a few graphs in varying conditions plotting ENGINE TORQUE, BOOST PRESSURE, MAF, RPM, and IAT to see what the ECU is doing.

Quite sure you can plot graphs in VIDA showing requested boost pressure vs. actual boost pressure to see if it's hardware or software that is playing with your max boost numbers.

Example:
Here in Toronto it's 2*C and 102.8kPA (or 14.9psi) I'd expect boost to be down due to colder denser air.
 

·
Registered
Joined
·
505 Posts
Boost isn't limited in 1st and 2nd due to programming, but due to the fact that the lower gears do not load the engine enough to allow for full boost production.

Lower ambient temps and high atmospheric pressure will result in lower boost. Does this mean the engine is producing less torque? No. If you want to see if engine torque is down then what I would do is in VIDA make a few graphs in varying conditions plotting ENGINE TORQUE, BOOST PRESSURE, MAF, RPM, and IAT to see what the ECU is doing.

Quite sure you can plot graphs in VIDA showing requested boost pressure vs. actual boost pressure to see if it's hardware or software that is playing with your max boost numbers.

Example:
Here in Toronto it's 2*C and 102.8kPA (or 14.9psi) I'd expect boost to be down due to colder denser air.
This is spot on.

Today the temp avg. has been 45F and pressure is at 30.08in/hg and falling and car was boosting very well this morning. Yesterday avg temp was 36F and pressure was 30.40in/hg and steady. Either way, more boost today to create same torque, didn't need as much boost to make same torque yesterday due to colder more dense air. So basically, outside of our differences in setup and mapping, atmospherically Antherzoll and i had similar atmospheric conditions yesterday. 36F vs 2C (35.6F), and 30.40inhg vs. 102.8kpa (30.36inhg) so either car should have seen slightly less boost across the board unless otherwise requested through throttle input (WOT = max torque request).



Antherzoll, have you mapped any of those plots you mentioned?
 

·
Registered
Joined
·
5,373 Posts
Not in ages, and not since I've had my Hilton tune because I've not any reason to worry about it ;). I do have spreadsheets from datalogs during the tuning process with Hilton (I'd share, but that private information) and everything looks tight.

Here's a VIDA graph with my previous ARD tune. Forgot the ambient condition, and for this run the tune was behaving itself.


 

·
Registered
Joined
·
7,614 Posts
Since you've already found cracked hoses, I'd start by replacing every single intake tube and hose and vacuum hose under the hood. I hate to say it but I think until you've done that you'll be chasing ghosts.

I'm in a similar boat, I'm at 176K and I see hard and cracking hoses all over my engine bay, but so far it pulls like new, so I've had no reason to dig in there. Not excited about the day I do.
 

·
Registered
Joined
·
298 Posts
Discussion Starter · #10 ·
I would agree that it might be cracked hoses except that the performance seems to vary all the time. Late last week, it didn't have anywhere near the power that it does when it's running right. This morning, it pulled as hard as it ever does. It's not necessarily that I want to see the same boost value every time I get in the car, it's that I would expect the car to rev as eagerly, pull as strongly and generally feel as responsive all the time. There is a very noticeable difference in power from this engine between when it is running at tit's best and when it isn't. I don't have VIDA but I can read data from the engine with my autocom and graph it as well. I can also use Torque on my phone to get a general idea of variations in acceleration to prove I'm not crazy.
 

·
Registered
Joined
·
5,373 Posts
How does the LTFT and STFT look? If there is a leak they would be off.

Are you still operating on the stock intercooler? Boost/timing can be pulled due to high IATs. Since the BPS (boost pressure sensor) PID is not available through OBDII I'd assume IAT is also not available as they are integrated into the same sensor.

What fuel are you using? Should be at least 91 if you're driving it hard. If the ECM detects knock it will pull timing and boost to keep it under control.
 

·
Registered
Joined
·
357 Posts
I have an auto T5 but I've noticed these issues sometimes on mine and it's almost always some air pipe. On mine the usual suspects was the charged air pipes and almost always the throttle clamp slipping or the hard ote pipe to rubber intercooler inlet pipe.

There have been times when I give it the beans and i hear a POOOOF and it's one of the pipes i mentioned already. So far it's because I didn't clean up the oily pipes well enough when I spill or clean up from something.
 

·
Registered
Joined
·
260 Posts
Is it possible the car has a crappy tune? This basically sounds exactly like what I was going though when troubleshooting my tune for the first time.
 

·
Registered
Joined
·
505 Posts
And he mentioned the car seeing well over 10psi. Which sounds like someone cranked down the waste gate tighter, and now it's possibly having trouble holding. Outside of what everyone posted regarding vac/boost hoses and tubes, the obvious other checks are cbv and wastegate.

Sent from my HTC6525LVW using Tapatalk
 

·
Registered
Joined
·
5,373 Posts
That is true. The ECM is very sensitive to WGA preload and will trip a P2281 or ECM-640C, but It's still possible that it's set to tight and the ECM I trying to keep boost under control.
 

·
Registered
Joined
·
505 Posts
That is true. The ECM is very sensitive to WGA preload and will trip a P2281 or ECM-640C, but It's still possible that it's set to tight and the ECM I trying to keep boost under control.
I know you mentioned looking at logs. Something that you noted that is important to remember on these also is that ETM cars, really all ME7 cars work on a torque-request basis. So what you'd really want to compare i would think is throttle angle/TPS along with MAF, IAT, BOOST etc.

If the torque request is low, everything else will be also. So both the boost and the torque are right foot dependent. Could be a number of things that were discussed like aging vac/boost hoses and evap hoses, or it could be the right foot not as aggressive.
 

·
Registered
Joined
·
298 Posts
Discussion Starter · #18 · (Edited)
This car has new plugs, a smoke test showed no leaks, there are no codes and when the thing is on, the throttle response is instantaneous and it rips. Like traction-control-kicking-in-when-the-boost-comes-all-in-while-hammering-it-on-the-highway-in-third-if-it's-wet rips. My little triangle friend gets a real workout. Then some days throttle response is lazy and it feels like someone siphoned off 50 horse power. I run 93 octane gas, and haven't touched the wastegate setting although that shouldn't matter as the ECM controls the maximum boost through the tcv, doesn't it? My understanding is that changing the wastegate settings affects the rate at which the turbo spools up but doesn't change max boost pressure. As for max boost in a T5, this seems to be a constant point of contention. Here's a post from another forum:

Re: On a S60 T5 what is the stock boost pressure?
Postby jimmy57 » 09 Jan 2011, 04:25

The base setting of wastegate influences the max boost as does the boost pressure sensor.
The spec for boost in the data book from Volvo lists normal as 82 Kpa(11.7 psi) and max as 93 kPa (13.3 psi).
Your car may have a low biased boost pressure sensor or may have a base wastegate setting that is on the high side.
The ECM on ME 7.0 engine management uses the boost pressure sensor for feedback but does have a little "wiggle" room in the program.
Those values are actually given as absolute pressures of 182 and 193 so higher altitude would read higher on your gauge if it is zeroed at an altitude having less than 100 kPa of atmospheric pressure


With my autocomm, I am seeing around 196 kPa when the car is running right which is a little higher than this but I really like it. For the past few days it has been running great. And my right foot is as aggressive as ever. Maybe I need to cut a hole in the footwell so I can push the pedal "to 11."

By the way, looks like me and Legtayor have the same "issue."
 

·
Registered
Joined
·
260 Posts
This car has new plugs, a smoke test showed no leaks, there are no codes and when the thing is on, the throttle response is instantaneous and it rips. Like traction-control-kicking-in-when-the-boost-comes-all-in-while-hammering-it-on-the-highway-in-third-if-it's-wet rips. My little triangle friend gets a real workout. Then some days throttle response is lazy and it feels like someone siphoned off 50 horse power. I run 93 octane gas, and haven't touched the wastegate setting although that shouldn't matter as the ECM controls the maximum boost through the tcv, doesn't it? My understanding is that changing the wastegate settings affects the rate at which the turbo spools up but doesn't change max boost pressure. As for max boost in a T5, this seems to be a constant point of contention. Here's a post from another forum:

Re: On a S60 T5 what is the stock boost pressure?
Postby jimmy57 » 09 Jan 2011, 04:25

The base setting of wastegate influences the max boost as does the boost pressure sensor.
The spec for boost in the data book from Volvo lists normal as 82 Kpa(11.7 psi) and max as 93 kPa (13.3 psi).
Your car may have a low biased boost pressure sensor or may have a base wastegate setting that is on the high side.
The ECM on ME 7.0 engine management uses the boost pressure sensor for feedback but does have a little "wiggle" room in the program.
Those values are actually given as absolute pressures of 182 and 193 so higher altitude would read higher on your gauge if it is zeroed at an altitude having less than 100 kPa of atmospheric pressure


With my autocomm, I am seeing around 196 kPa when the car is running right which is a little higher than this but I really like it. For the past few days it has been running great. And my right foot is as aggressive as ever. Maybe I need to cut a hole in the footwell so I can push the pedal "to 11."

By the way, looks like me and Legtayor have the same "issue."
Not anymore, and mine was software related. My car was going into limp mode because some parameters were set too tight or something.
 

·
Registered
Joined
·
505 Posts
a smoke test showed no leaks
But did you pressure test the system? A smoke test may reveal holes or cracks, but a pressure test would show whether or not a clamp is tight enough or not to handle boost pressure.
 
1 - 20 of 20 Posts
Top