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541 Posts
Good morning all,
So, the day before the latest Mid-Atlantic meetup, my 2002 CVT started "misbehaving." It was subtle, and so I questioned whether or not something was actually different. A little more time in the car confirmed that something just wasn't right. I've got a few symptoms to throw out there, and some ideas... but I don't want to pollute the waters too much. When it comes to troubleshooting CVTs, I'm on the hairy edge of educated guessing, at best! Anyway, here are the symptoms.
1) The FIRST thing I noticed was while driving around on a usual route near my house. As I was pulling out from a complete stop, the engine seemed to "bog" down more than usual. It made the car vibrate just a bit. At first I thought that an engine mount might be going. After a while, I figured out that it just seems like the transmission is engaging too hard, or too soon, or is in too high a ratio. It's not unlike pulling away in a manual in too high a gear, with the accompanying vibration. I REALLY felt it yesterday, and was able to look at the RPM guage, and indeed, it was way lower than it normally would be, and stayed low for too long (like 2 bars, maybe about 200-250 RPM).
2) The second thing I noticed was while driving up to Columbia, MD for the meet. It was smooth "sailing as usual" while cruising, but when confronted with a steep climb that required the CVT to get into a lower ratio (lower gearing), the car would “pulse” at a cycle of about once per second(ish). I could REALLY get it to do it by climbing a hill and using the “sport” mode button to get the RPMs up. The car would accelerate, RPMs climbing smoothly, but then they would fall back down approximately 500 RPM, build back up 500, fall, build back up, fall… you get the picture. Every time the RPMs would drop by 500, the car would surge forward just a bit, just like you’d expect from the inertia of the engine pushing it ahead with a sudden, higher gearing. I haven’t felt the transmission make moves like this before. It’s always been very smooth and linear in it’s changes. If I held the accelerator in the same position while climbing the hill, sometimes the transmission would eventually “catch” and perform as expected.
To me, it was acting like it needed to build up more oil pressure to finish moving the pulleys inside and keep them where they needed to be. Again, I don’t want to muddy the waters here with my guessing.
3) Finally, and this symptom is a little harder for me to describe, the transmission seems to “coast out” just a bit… a tenth of a second… when I’m at moderat acceleration and then let off the gas. I can’t be 100% sure, but it seems that when I let off the gas, the RPMs drop more precipitously than expected, and I get that MOMENTARY surge forward. This symptom may simply be the same as the second one, just exhibited at a lower RPM/speed.
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OK, so in an effort to fix it, I’ve replaced the fluid and both filters in the transmission. As usual, the fluid looked great. The old filters were black, but in good shape. I was hoping that they had become restricted and it was a pressure issue because of that. However, after driving yesterday, the symptoms are still there. I can’t speak to the CVT service history before 58K miles, but from that point and beyond the longest interval for the fluid has been 30K, and that was between 58-88K. Since then it’s been done every 15-20K, and the car now has 150K on it. The manufacture date stamped on the larger filter that I removed was 99, and the one I replaced it with was 15, so I assume the old one was original. At any rate, it now has new fluid and filters, and still isn’t acting right.
I did a little research into the Honda Multimatic, and I see that it does have a pump, and some kind of proportioning valve system, as well as electronic controls and sensors. In fact, I woke up this morning and was excited to see that there are two pick-up assemblies (speed sensors, part# 28810-P7W-004), one for each pulley. Again, I don’t want to limit the troubleshooting here because of my guess work, but I’m thinking that maybe one or both of those sensors could be malfunctioning, and causing the transmission to not know what the rate of rotation is of the CVT pulleys.
I will be picking up my OBDII C&C from one of my buddies today, and I know that I can have it display CVT ratio… maybe there is more information that it can pull from the ECM/TCM?
Anyway, I GREATLY appreciate your input and suggestions. There are no weird sounds, no grinding, no clunking. The transmission works “fine” and cruises smooth. But something isn’t right. And I really love this car so I want it to work properly! I also don’t want to damage the transmission. I do have another vehicle that I can use for a while.
I took a little video of the RPM guage while it was bumbing back and forth between 3K-3.5K. I’ll see if I can link/post that somehow.
I haven’t really been able to find anything like what I’m experiencing on IC. How exciting… a problem all my own… ugh. ;-)
Thanks again!
John
So, the day before the latest Mid-Atlantic meetup, my 2002 CVT started "misbehaving." It was subtle, and so I questioned whether or not something was actually different. A little more time in the car confirmed that something just wasn't right. I've got a few symptoms to throw out there, and some ideas... but I don't want to pollute the waters too much. When it comes to troubleshooting CVTs, I'm on the hairy edge of educated guessing, at best! Anyway, here are the symptoms.
1) The FIRST thing I noticed was while driving around on a usual route near my house. As I was pulling out from a complete stop, the engine seemed to "bog" down more than usual. It made the car vibrate just a bit. At first I thought that an engine mount might be going. After a while, I figured out that it just seems like the transmission is engaging too hard, or too soon, or is in too high a ratio. It's not unlike pulling away in a manual in too high a gear, with the accompanying vibration. I REALLY felt it yesterday, and was able to look at the RPM guage, and indeed, it was way lower than it normally would be, and stayed low for too long (like 2 bars, maybe about 200-250 RPM).
2) The second thing I noticed was while driving up to Columbia, MD for the meet. It was smooth "sailing as usual" while cruising, but when confronted with a steep climb that required the CVT to get into a lower ratio (lower gearing), the car would “pulse” at a cycle of about once per second(ish). I could REALLY get it to do it by climbing a hill and using the “sport” mode button to get the RPMs up. The car would accelerate, RPMs climbing smoothly, but then they would fall back down approximately 500 RPM, build back up 500, fall, build back up, fall… you get the picture. Every time the RPMs would drop by 500, the car would surge forward just a bit, just like you’d expect from the inertia of the engine pushing it ahead with a sudden, higher gearing. I haven’t felt the transmission make moves like this before. It’s always been very smooth and linear in it’s changes. If I held the accelerator in the same position while climbing the hill, sometimes the transmission would eventually “catch” and perform as expected.
To me, it was acting like it needed to build up more oil pressure to finish moving the pulleys inside and keep them where they needed to be. Again, I don’t want to muddy the waters here with my guessing.
3) Finally, and this symptom is a little harder for me to describe, the transmission seems to “coast out” just a bit… a tenth of a second… when I’m at moderat acceleration and then let off the gas. I can’t be 100% sure, but it seems that when I let off the gas, the RPMs drop more precipitously than expected, and I get that MOMENTARY surge forward. This symptom may simply be the same as the second one, just exhibited at a lower RPM/speed.
---------
OK, so in an effort to fix it, I’ve replaced the fluid and both filters in the transmission. As usual, the fluid looked great. The old filters were black, but in good shape. I was hoping that they had become restricted and it was a pressure issue because of that. However, after driving yesterday, the symptoms are still there. I can’t speak to the CVT service history before 58K miles, but from that point and beyond the longest interval for the fluid has been 30K, and that was between 58-88K. Since then it’s been done every 15-20K, and the car now has 150K on it. The manufacture date stamped on the larger filter that I removed was 99, and the one I replaced it with was 15, so I assume the old one was original. At any rate, it now has new fluid and filters, and still isn’t acting right.
I did a little research into the Honda Multimatic, and I see that it does have a pump, and some kind of proportioning valve system, as well as electronic controls and sensors. In fact, I woke up this morning and was excited to see that there are two pick-up assemblies (speed sensors, part# 28810-P7W-004), one for each pulley. Again, I don’t want to limit the troubleshooting here because of my guess work, but I’m thinking that maybe one or both of those sensors could be malfunctioning, and causing the transmission to not know what the rate of rotation is of the CVT pulleys.
I will be picking up my OBDII C&C from one of my buddies today, and I know that I can have it display CVT ratio… maybe there is more information that it can pull from the ECM/TCM?
Anyway, I GREATLY appreciate your input and suggestions. There are no weird sounds, no grinding, no clunking. The transmission works “fine” and cruises smooth. But something isn’t right. And I really love this car so I want it to work properly! I also don’t want to damage the transmission. I do have another vehicle that I can use for a while.
I took a little video of the RPM guage while it was bumbing back and forth between 3K-3.5K. I’ll see if I can link/post that somehow.
I haven’t really been able to find anything like what I’m experiencing on IC. How exciting… a problem all my own… ugh. ;-)
Thanks again!
John
