Lose power as engine heats up

[sonicgrounds]

Is it my car or is this the way the turbo engines work, because I'm coming from an e39 M5 and this is beginning to bother me. The car pulls like a train until the engine reaches it's full operating temp and as it gets there the power goes down (not by a lot but noticable amount), or rather the peak TQ rpm goes up, meaning it only starts to pull at 4-5k rmp as oppsed to 2-3k rmp. Is this normal?

[coco_m3]

Mine did that when my HPFP was going out.
Still does it a little.
Is it cool in the mornings there in MD?

[modbargains]

You shouldn't be wrecking the throttle when warming up either way. Because the engine is cold and still warming up its still going to be in the high RPM range, that is a given.

[coco_m3]

Yeah i wouldnt redline mine, but i did notice there was not as much lag as when it was warmed up, not beating the crap out of it while its warming up in a givin.

[sonicgrounds]

Obviously I don't floor it while it's warming... but the power is noticably THERE in low rpm's while warming up, but less as it gets hotter.

[sonicgrounds]

it is a bit cooler in the mornings 60's as oppsed to 90's during the day, and what is HPFP btw?

[sonicgrounds]

Originally Posted by **********s

You shouldn't be wrecking the throttle when warming up either way. Because the engine is cold and still warming up its still going to be in the high RPM range, that is a given.

I've been driving beamers for 15 years now (all M cars, this is my first non M), and I'm well aware of letting the engine warm up before putting the pedal to metal . even otherweise you misread my post. I'm saying while it's warming up it's in low rpm range (meaning you get all TQ at low rpm) and after it's fully warmed up it's in high rpm range.

[clivem2]

This is exactly one of the symptoms the 335i owners on E90POST have been complaining about. The lag was introduced by V29.2 software which operates the wastegates differently at low revs vs earlier s/w - the lag seems ok when cold but is apparent when the engine is up to working temp/

The post is 60 pages!!!!
http://www.e90post.com/forums/showth...147781&page=60

[mistermojorizin]

Originally Posted by sonicgrounds

Is it my car or is this the way the turbo engines work, because I'm coming from an e39 M5 and this is beginning to bother me. The car pulls like a train until the engine reaches it's full operating temp and as it gets there the power goes down (not by a lot but noticable amount), or rather the peak TQ rpm goes up, meaning it only starts to pull at 4-5k rmp as oppsed to 2-3k rmp. Is this normal?

on e90, some of the people who report the post 29.2 turbo lag, say that there is no lag b4 the car warms up, after it warms up, then there's lag below 3,000rpm.

my car has the lag, no matter if its warm or cold. (cold here is like 70 degrees in the morning).

[Swift135]

Mine is the opposite, the car feels more responsive and has full power around 115 degrees C. more torque than it has around 95-100 degrees.

[eunosracr]

Time for a big front mount intercooler!!!!

[sonicgrounds]

that sucks!
i'm sure this has been covered in another post, but is there a quick way to check which software version I have?

[mistermojorizin]

Originally Posted by sonicgrounds

that sucks!
i'm sure this has been covered in another post, but is there a quick way to check which software version I have?

no, but if you were built in march or later (check driver's door jam) you probably have the potentially laggy s/w (you definitely have the v81 hardware).

[RoninWheels]

Heat Soak.

Getting a larger front mount will drop the psi from the start but hold it there... so hypothetically; if you lose 3-4+ psi in heat soak the larger intercooler will drop say 1psi 'off the bat' but not go any lower during heat soak

[Papito135]

Yep its call Heat Soak. It happen to all high performance cars. My GTO is famous for heat soak. Had to invent a home made way to over come the heat soak.

[stylinexpat]

Getting rid of the pan beneath the engine helps get rid of some of the heat soaks:biggrin: The intercooler upgrade helps as well.

[twinturbo135i]

any person who owns (or has owned) a turbo car knows that heat is it's worst enemy, period. I use to own two '87 Buick Grand Nationals. one was a daily driver and the other was a race/show car. both of my GNs would run awesome as long as the weather was under 80 degrees or less.

unfortunately though, we get too damn many 90+ degree days here in central FL which means my 1/4 racing days only happened in the Jan to Feb periods of the year. otherwise I'm just killing the engine(s) with the ridiculous heat and humidity from living in FL.

by the way, my 135i is the same exact way. it runs very strong early in the morning but I can definitely tell the difference in 5PM rush hour traffic.

[raolc]

From what I understand, when the car is running hotter it has a little bit less power than when its running cold. A friend explained it to me, forgot his reasoning, but it made sence when hew as explaining it. He was mainly talking about how it was easier to get power out of the older engines that ran cooler but now engines have to run hotter because of emissions so its harder to get the power. What do you guys think? Is that why his car may feel faster when its colder? Anyone know what my friend is talking about and can add to it, or may be that doesn't apply to these engines...

[Viral@ActiveAutowerke]

I wouldn't rule out the dreaded 29.2/81 lag issue. Heat soak can also contribute to this. A hotter engine bay will lead to hotter air entering the engine. Hotter air is less dense, less density leads to less efficient combustion, less efficient combustion leads to lower horsepower output.

[and 1]

Originally Posted by raolc

From what I understand, when the car is running hotter it has a little bit less power than when its running cold. A friend explained it to me, forgot his reasoning, but it made sence when hew as explaining it. He was mainly talking about how it was easier to get power out of the older engines that ran cooler but now engines have to run hotter because of emissions so its harder to get the power. What do you guys think? Is that why his car may feel faster when its colder? Anyone know what my friend is talking about and can add to it, or may be that doesn't apply to these engines...

air density decreases as temperature goes up, aka cool air is more dense than warm air. this has 2 major benefits that i know of:

- you can pack "more" air into the cylinders and hence more fuel, leading to a bigger explosion upon combustion
- there's a bigger temp difference between the air intake charge and the burning fuel, making the combustion process more efficient

anyone else wanna chime in on this?

[and 1]

Originally Posted by Kirk@ActiveAutowerke

I wouldn't rule out the dreaded 29.2/81 lag issue. Heat soak can also contribute to this. A hotter engine bay will lead to hotter air entering the engine. Hotter air is less dense, less density leads to less efficient combustion, less efficient combustion leads to lower horsepower output.

crap, this guy beat me to it...

[raolc]

Originally Posted by and 1

air density decreases as temperature goes up, aka cool air is more dense than warm air. this has 2 major benefits that i know of:

- you can pack "more" air into the cylinders and hence more fuel, leading to a bigger explosion upon combustion
- there's a bigger temp difference between the air intake charge and the burning fuel, making the combustion process more efficient

anyone else wanna chime in on this?

That seems to be just about what my friend said in different words! Great explanation. I'm not too familiar with the 29.2 issue and such, going to have to put an hour aside and do sone research about it on the forums later.