Ideas and suggestions to my X5 issue

[upallnight]

You can take a compression gauge and remove the pre-cat 02 sensor and screw in the gauge and see what type of back pressure therre is.

Here's a video on on testing the cat with a pressure gauge, go to 4:00 into the video.

https://www.youtube.com/watch?v=9TlygJMxTps

You was probably burning rich for the CAT to overheat and glow red. Take a look at the long term term fuel trim and the short term fuel trim. Could be a bad MAF, check what the airflow through the maf is. Flow should be in Grams per second.

[tmv]

Originally Posted by upallnight

You can take a compression gauge and remove the pre-cat 02 sensor and screw in the gauge and see what type of back pressure therre is.

Here's a video on on testing the cat with a pressure gauge, go to 4:00 into the video.

https://www.youtube.com/watch?v=9TlygJMxTps

You was probably burning rich for the CAT to overheat and glow red. <-Would this throw a SES code? Take a look at the long term term fuel trim and the short term fuel trim. Could be a bad MAF, check what the airflow through the maf is. Flow should be in Grams per second.

Very helpful upallnight. Thank you. I'll check them and report back.

[SlickGT1]

Have you tried giving it a solid rip. Make it move, get the flow going. Maybe someone did stuff some shit in your exhaust.

[tmv]

It seems to run just fine now. I gave it a few good revs.
http://vid300.photobucket.com/albums...pslzixvsok.mp4

MAF seems to have no affect on engine. It must be bad. Engine idle perfectly 695-715 rpm with or without the MAF plugged in.

upallnight, I read the Mass air flow with GT1/DIS. It's 27.2 kg/h or 7.556 g/sec

[SlickGT1]

Well a shot maf will mess with your fuel. Which will mess with the cats.

How is the fuel mileage by the way?

And I still suggest you get it moving, and give it a few pulls to red line. Get it warmed up and see what happens after to those cats.

I also had a similar problem with my Lexus GS430 when I had a piggy back ECU for my intake. My maf died, but no check engine. The software that was in that piggy back ECU was hiding and over riding the maf error. I had a bitch of a time figuring it out. Same issue like you. Cats got stupid hot. Once I removed the ECU and went to factory intake, the maf code came up. Maybe the dinan stuff is doing something similar?

[upallnight]

Was the engine in "Closed Loop" when you took this snap shot? By closed loop I mean was the engine warm up?



It appears that the engine is in "Open Loop", so the 02 sensors are not controlling the mixture, in open loop a default set of parameters are controlling the mixture.

[upallnight]

I would hook up a scanner and view live stream data for the 02 sensors. You should be able to see voltages that the sensors are generating as inputs to the DME.


OXYGEN SENSOR DIAGNOSIS

O2 sensors are amazingly rugged considering the operating environment they live in. But O2 sensors do wear out and eventually have to be replaced.

The performance of the O2 sensor tends to diminish with age as contaminants accumulate on the sensor tip and gradually reduce its ability to produce voltage. This kind of deterioration can be caused by a variety of substances that find their way into the exhaust such as lead, silicone, sulfur, oil ash and even some fuel additives. The sensor can also be damaged by environmental factors such as water, splash from road salt, oil and dirt.

As the sensor ages and becomes sluggish, the time it takes to react to changes in the air/fuel mixture slows down which causes emissions to go up. This happens because the flip-flopping of the fuel mixture is slowed down which reduces converter efficiency. The effect is more noticeable on engines with multiport fuel injection (MFI) than electronic carburetion or throttle body injection because the fuel ratio changes much more rapidly on MFI applications.

If the sensor dies altogether, the result can be a fixed, rich fuel mixture. Default on most fuel injected applications is mid-range after three minutes. This causes a big jump in fuel consumption as well as emissions. And if the converter overheats because of the rich mixture, it may suffer damage.

[tmv]

Here is a screen shot from a video last night. Both pre-cat O2 sensor heater is jumping back and forth from "not active" to "Active". The pre-cat O2 sensor readiness is ready.

[upallnight]

Since the 02 sensor appears to be working I would look at the long term and short term fuel trim.

[tmv]

Did I look at the right place?