lexus-is2

So my check engine light came on again after random sluggishness in power.

Usually what happens is the car performs perfectly, and then about 45mins into journey i will get power lag when i try to move off.

Eventually this led to the engine light to come on, so I plugged in a code reader and it read P0127 - Intake Air Temperature Too High

I thought maybe its MAF issue so cleaned the MAF with CRC MAF cleaner but when cleaning it, I couldn't tell if it was dirty, it looked quite clean to me. So I cleaned it anyway and then had to disconnect battery to reset the ECU. Will wait and see if this has helped when driving to work tomorrow.

Anyone know what this error code actually means?

knguyenk

A quick Google search of the code pulled up a good read.

lexus-is2

I did read that, the IS250's MAF sensor also incorporates the intake ambient air temperature sensor. So i also gave that a good spray with the CRC. So, i guess I will just have to see how it drives tomorrow.

The sluggish lag symptoms that i experienced last week, does sound like it could be the air temperature related, because it would randomly appear only after i've been driving for a while, and it was random.

Joshohoho

Just curious do you have an aftermarket Intake?

lexus-is2

Yes, i have Joe-Z intake and i've had it for 3 years without any issues. Issues only started last week.

lexus-is2

The problem seems to have come back. The check engine light hasnt come on yet, this usually takes a few days of driving before it comes. But I drove the car a few times since i did the MAF and TB clean and it drove fine without the lag symptoms but unfortunately this morning the symptom has come back. 50minutes into my journey the car started lagging and responding slowly. So, i doubt the problem was with the MAF in the first place. The power lag starts to happen only when the car has really warmed up and so far when i'm driving harsh.

Also the code P0127 seems to be a Generic Code and not something that is documented in the Lexus DTC document

I am really confused now. Taking it to the dealer wont really help much because they will find it impossible to replicate the problem.

Anyone have any suggestions or advice?

knguyenk

What kind of temperatures where you experiencing when this issue occurred?

Also, trying to cover all bases, is your air filter to your Joe-Z intake clean and free of restricting elements?

minato

iTrader: (1)

^^what he said^^^
plus you can also put your stock intake back in , and try that out for a while

lexus-is2

next time the issue happens i will measure what the intake and ambient temperature and see what that is. i've just changed the Air Filter, it looked a bit dirty. No other obstacles.

One other thing that i noticed is that the MAF connector loom, has this plastic backplate adaptor thing (not the connector itself) this plastic bit seems to clip onto the connector itself and to me it looks very loose and comes off very easily. I've attached a photo below of the bit i am referring to. But this plastic just seems like some kind of cover to protect the wires and doesnt seem like it serves any other purpose. I really doubt this will cause any issue because its just a plastic cover that seems to be removable.

lexus-is2

So this morning the problem didnt arise. As the problem seems to be very intermittent, it's very hard to replicate. So i did some data logging via OBD in the beginning of my journey and at the end of my 1hr 15mins journey. On a cold start i got the following readings:

Intake Temperature: 41°F
Intake Ambient Temperature: 34°F

LAMBDA: 1.0 (in the middle between lean and rich - so not rich and not lean - in the green zone)

When i got to my destination, i checked the reading again and the readings were:

Intake Temperature: 105°F
Intake Ambient Temperature: 50°F

Coolant Temperature: 187°F


Would like to see what the reading is when the problem occurs next. So just waiting for this problem to come up again so I can read the data.

Just wondering if anyone knows what would be considered a high Intake Temperature reading?

Also, as my air filter looked a little dirty, decided to replace it.

lexus-is2

So this morning the symptom came back. But no check engine light yet. It seems that when this problem occurs, when i try to pull off quickly the car seems to not want to go above 2k rpm but then you push it harder then eventually it goes above it and works fine. The problem is very intermittent and occurs occasionally after a while into the journey. But then when the problem occurs, it stays for the rest of the journey until you turn off the car and drive it a little later and it becomes normal after that.

So i checked the sensor readings via the OBD port and they were pretty much the same as when everything was working correctly yesterday. Here is the readings I got:

Intake Temperature: 95°F
Intake Ambient Temperature: 39°F

LAMBDA: 1.0 (In green zone, not lean or rich)

BST/VAC: -10.8psi (The higher the rev, the higher this number goes but in negative)

So based on these readings, it doesnt seem like the MAF sensor is malfanctioning or giving incorrect readings or anything, yet the car still hesitates before it lets me rev above the 2k-rpm. It's a bit like being in snow mode

Any help guys?