When it's cold out, my car will only boost about 7 or 8 psi, but will eventually creep up to 10 or 11. The car is completely warmed up and seems to run the same as any other time. In anything above 40 degrees or so, it's completely normal. I have heard that some turbo cars will only allow a certain boost level when the temp is low, does the mr2 do this? Or might this be another sign telling me to get a new boost gauge? Thanks for the help!
It is normal. My MR2 is currently boosting at 7psi as well. Its called "Low-Boost mode" and its a protective measure the ECU triggers to prevent a Super Lean condition. When the Air temperature becomes cold the oxygen becomes more desnse, and to prevent a lean-out condition the ECU will trigger a VSV solenoid to open the waste gate a little bit to keep the turbo from boosting fully.
To not be in low boost mode a few conditions must be met: The coolant Temperature has to be above 168*F, The ambient Intake temperature I belive has to be 50*F or higher. If you have knocking occuring this will also cause Low boost mode.
Just wait till it gets warmer out, it will boost fine again.
You should always warm up the turbo before pushing it. Not only does the engine need to be warm , but the turbo itself will operate better after it gets hot. until then, it will be sluggish and operate in the low boost mode as ModifierMR stated.
Even in cold weather temperatures, once the turbo gets hot, it will operate even better due to colder intake and denser air. Just as an N/A engine does.
However, Even with the engine completley warm this doesnt mean that it will boost a full 10-14 psi every time.
You could still be stuck in low boost mode if its cold enough. Up north where I live, it is cold enough to trigger low boost mode between november and april. I have only hit high boost levels twice with my engine scince I installed it. And those were on days where it was 60*F out.
If your cooling system is doing its job, chances are in 40*F weather and at road or highway speeds the cold air is super cooling the radiator and keeping the coolant under 168*F, and the AFM is only seeing air of about 40-50*F so one if not both conditions are not being met so that the ECU can trigger full boost mode.
Agreed,
Normally , colder denser air yields alitlle more power and better performance-to a noticable degree. But that IS limited. And having temp sensing sensors will limit that even further. As compared to the old school V8's that loved the cooler denser air. Humidity can also play a factor.
Of course, we don't get nearly as cold down here as you do up there. Cold here is in the 30's. The coldest I've EVER seen it here is 5 degrees. Which is very rare.And of course here, it usually means we have ice and/or snow. In which case I wouldn't even consider driving my 2.
I like winter, But I'm glad it doesn't get as cold here as it does in you area of the country.. I can still drive the 2 90% of the winter here.
lol I drove my MR2 all through the winter. I didnt want to because I wanted to use a daily driver and spare the MR2 a winter season, but I was forced to drive the MR2 around because i had no money for anything else.
I will tell you tho, Its not that bad driving a car with a power to weight of 0.1 around in the snow, you just gotta take it easy. The one thing that sucked is that for most of the winter I didnt have any heat, So during the coldest months of the year when it was 10*F all day, I was driving in my MR2 and freezing to death (I have a ton of air leaks in the windows).
What would cause it to eventually creep up to 11 psi, though? If for instace, I'm in 3rd gear and step on it, it will jump to 7 right away, then by the time I'm ready to shift, it's up at 11. Low boost mode keeps it at 7 the whole time, right?
I'm thinking the problem might be with my boost gauge. I have that crappy plastic tubing running from the intake manifold all the way to the gauge. I think maybe there is a small kink in it that only obstructs the air when it's pretty cold out. Then, pushing more air through might open it up all the way. Does that sound possible? Thanks for the info, you guys.
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