It looks like you're new here. If you want to get involved, click one of these buttons!
Toyota Matrix Engine Questions
If you have been a member of any of the following forums: matrixowners.com, genvibe.com, corolland.com, toyotanation.com, then you may have already been made aware of an issue that has occurred in nearly 14% of Matrix/Vibe/Corolla owners (2003 model and up) according to my unscientific polls. Naturally 14% is an unrealistic high ratio since many owners without this problem are not members of internet forums or don't always vote in every poll they read. Nevertheless, hundreds of posts in several threads have been logged and since I stumbled across the EDMONDS forum by accident, I wanted to take the opportunity to invite any of the uninitiated here to be privileged with the information posted elsewhere.
So far we are 20 owners who all share the same 1800 cc engine, be it Matrix, Vibe, or Corolla, and have exactly the same symptom. In a nutshell, a very small number of these cars came off the assembly line during all of the last 3 years with some particular engine actuator or sensor which behaves in an unusual manner so that the engine computer slowly makes changes to the fuel tables or timing over the course of several days during the cold of winter.
The net result is that the engine idle speed which in a normal car is about 1800 rpm during the second minute following a cold start, becomes 2300 rpm in cars with this issue, and only in cars with manual transmissions. Reseting the computer makes the problem go away for a few days.
The excessively high rpms is probably due to the engine software having altered on purpose the amount of fuel, air and timing being admitted to the engine. But within the engine software appears to be a built in safety routine which independently decides that 2300 rpm is too fast a speed for the predicted amount of fuel and air, and the engine gets momentarily shut off until the rpms fall back into the safe zone which is below 1500 rpm. Once the engine is turned back on before stalling, it quickly revs back up to 2300 rpm, and the whole cycle repeats over and over 10 to 30 times during the second minute. The colder the weather, the more cycles. This cycling ends when the engine enters an new phase (probably when the heated oxygen sensors begin to function) and the idle then drops to a normal speed and all is stable.
Once this event has occurred at the start of the day, the computer never lets it happen again for the rest of the day. The car must sit outdoors overnight for the problem to repeat the next morning.
What does Toyota say? As you can imagine, it has been frustrating for many of us 20 owners because by the time we get the car to the dealer, the problem has disappeared for the day. However, I was able to leave the car overnight at my dealership's outdoor parking lot, and the blessed event got recorded on the dealership's scan tool.
This scan took place in January 2005 and following two failed attempts by my dealership to fix the problem, Toyota Canada, after some prodding, acknowledged the issue is so complex that that a solution would have to come from their engineering team in Japan. I was promised that research would start in the fall of 2005 (when it would be cold again) and any updates would be communicated through my dealership. Winter 2006 came and went without any notification or responses.
I should add that many mechanics across North America who have had to deal with this issue approached the problem with varying solutions, all without success. We have examples of changing the computer, the MAF sensor, the idle air valve, the O2 sensor, and it goes on and on.
Normally when there is an engine sensor that is grossly out of calibration, the engine computer generates a CEL warning and logs an error code. But should a defective sensor or actuator be just within the level of tolerance of the computer, then no error code will be generated, but the long term adaptive antipolution strategy might nevertheless be upset enough to unwittingly increase the cold idle rpms above a safe limit. For this reason I have to blame in part the engine software for not being more intelligent in monitoring when there is an instability occuring due to a slight mechanical defect in the engine. The problem is that the computer normally communicates using the OBD-II protocol and this protocol does not include a provision for such an instability. Engine software is assumed to be bug free.
I am providing the following link to one of the forum threads I set up elsewhere. You can listen to a MP3 audio recording of the engine during its unstable state and then judge for yourself if this issue applies to you. You can also link to similar threads at other forums where a comment can be posted or a vote can be cast for the vehicle (Matrix/Vibe/Corolla) which concerns you.
To hear the recording, you have to re-link to the Vibe forum where the recording is hosted.
I look forward to reading any comments posted in this thread or elsewhere.
Lastly, it surprises me that this issue has remained so invisible to organizations like the AAA and the like who would want to flag this issue as part of their reviews of second hand Matrix/Vibe/Corolla cars.
And even more surprising is that Toyota appears to be in no hurry to get to the bottom of this. I would have expected their engineers to have strapped a monitor on my car's computer so that they could gather all the data available in order to ensure that this problem is not carried into their next generation of engines.