DuffmasterFresh

My 2009 2.4L CVT Lancer has 45K miles on it and it's 6 years old. I had my CVT replaced in October last year because it was making a humming noise at 40MPH. No more noise. But now a new problem has appeared. I accelerate slowly and I drive the speed limit. When accelerating slowly, my RPMs will suddenly drop by about 500-750 and then instantly pick back up again. This doesn't seem to happen if I floor it from a stand still or if I use manual mode. This problem happens more often than not, especially with the AC on. The CVT is supposed to maintain RPMs (About 2K-2.5K) all the way through acceleration but mine has that dip. This happens only at low speed and only when accelerating from 0. Ideas?

I took it to the dealership a few months ago for an oil change and told them about it and they insisted that an injector service and TB cleaning would "90% likely fix the problem" and it didn't. I know those are BS services, but I paid to see if it would actually do something. But to be honest, I doubt they actually performed the service. Lastly, is it normal for my halogen headlights to dim when I'm parked and roll my windows up or down? Thanks for any feedback you can give me!

Veronica

iTrader: (2)

Yes, the headlights can dim when rolling up (or down) all four windows. Especially at idle (least output from the alternator) and when they reach the limit of travel and the current draw goes up until the limit is reached so the computer cuts power to the window motors.


Any other load on the power system (a/c or headlights) would also exacerbate the dimming.


Summary: Not a problem!

DuffmasterFresh

Thank you for the reply, Veronica! I had HIDs forever and never had dimming because they had a lower power consumption so I guess when I switched back to Halogens I got a little paranoid. I also don't remember the dimming occurring when the car was new, but that was 6 years ago so I can't count that haha.

Any feedback on my RPM issue? I also posted on Project Lancer and have had no responses at all. After 9gLancers went down, I feel like there are no more active forums these days for our cars.

CamShaft

In my opinion, the issues that I have heard about RPM's dropping when A/C is on may be due to the throttle body or the ECM itself. The engine control unit should compensate for the load on the engine when the a/c compressor kicks in. If the throttle body is a bit gummed up this could delay that response time. I would think it would log a fault, but every manufacturer is different. I would clean the throttle body or just replace, depending on the price.

I have 120000 Kms on mine and the PVC lets almost no oil into the intake. The only thing may be when in some conditions the vacuum of the intake may get some sprayback of fuel onto the throttle body from the backside.

DuffmasterFresh

Thanks for the reply! The issue occurs randomly. The last two days it never happened once, but today it happened 4 times. It happens even with the AC off and they recently cleaned my TB.

If they just looked at my TB, I hope that the TB isn't the problem. Before and after the TB cleaning it was doing this. Do you have any troubleshooting tips I can try to get to the bottom of this?

DuffmasterFresh

*BUMP*
I reset the ECU by disconnecting the battery over night. It seemed to fix the issue for all a good half hour and then it started to return. It could have just been a placebo effect.

Any ideas of what could be wrong or what I can test? The nearest dealership is an hour away and I don't want to bring it in just to do a test drive and be unable to duplicate the problem at that moment (happens often enough to me -___-)

Or at the very least, does anyone know any active forums for 08+ Lancers that I can join? Once 9GLancers went down I haven't found a forum that has any activity on it and it's really disheartening making a post an having no response when you really need some help.

CamShaft

replace the throttle body

DuffmasterFresh

I'm finally getting around to trying to diagnose my issue. It's intermittent and hard to track down because one day I could have a drop in RPM during acceleration, and then the next day it works perfectly. I've even tried to video record the problem but when I whip out my phone, it behaves.

I know that you can use a standard ohm meter to test a switch and combination type throttle position sensor and a volt-meter to test a throttle position sensor that uses a potentiometer. Do any of you know which system we use and how I can test the throttle body?

Also, do you know the acceptable resistance of the accelerator pedal positions? I want to compare the values. Thanks a bunch!

DuffmasterFresh

Also, could it be possible that it is the CVT belt slipping?

DuffmasterFresh

I just got back from the dealership. It's an hour drive away, so the car has plenty of time to warm up, which is exactly what I DON'T want. So to remedy this, I waited at the dealership for 3 and a half hours to let the car cool down. I had a tech hook up to the OBD port as I drove it around. The vehicle dropped the RPMs 3 times, however the drops were smaller than usual and the tech said that this was normal, that it was just the CVT shift points. I don't think it's normal at all to drop and then recover. I decided to get a rental and leave my car overnight so it's nice and cold in the morning for them to test drive it. I was told that they no longer provide rentals, even for warranty related services.

I took this video this morning down the street from my house as I was on the way to the dealership, It was 8:30AM, and I was at a complete stop. I was beginning a right-hand turn onto a busy main street. At the 7 second mark in the video, you can see the RPMs drop for a split second and then recover. My foot did not change positions of the pedal when this occurred. You can hear the engine change pitch. This happens to me all the time when the vehicle is cold or has been sitting for a long time. Once it has warmed up, it happens a lot less. Watch the video a few times so you can catch the action and listen to the change in pitch.


Here is a video from a while ago which was when I was going uphill. If you're accelerating up a steep hill, why would the RPMs drop and then recover? They shouldn't drop because it needs the power to go up the hill. My old transmission never did this. If it dropped RPMs, it did it very subtly, very smooth.

I'm starting to feel like I'm crazy. That this is completely normal CVT behavior, or that I'm doing something wrong. I emailed Mitsubishi Corporate last week and have had no response from them. I'm tired of driving an hour to the dealership to try and find a solution only for them to find nothing. This has been going on for over a year now. My transmission was replaced back in April of 2013 and this replacement transmission only has 17K miles on it.

The tech said he thinks it could be the transmission control unit, the coil packs not igniting one or more of the spark plugs (misfire), or the CVT is slipping.

**UPDATE: They called me this morning and said they drove the car and they noticed the RPM drops, but they said it's completely normal and that those are just the shift points. I'm going to go in on Friday morning when the service manager arrives and drive it with him. This was not the normal when I got the car, I can't believe this would be normal at all.

Is this normal? Should I accept this as normal? Or should I keep fighting?

eric0113

Well since I'm already logged in here looking for some tips: my 2011 Lancer has been doing that since new..... since it was the first CVT car I had I always thought it was just like that, even thought I thought it wouldn't do "shift points" and be a much smoother transmission. It does it more frequent when its cold and mostly goes away when its warmed up. Could be maybe the next transmission is programmed differently??? But I doubt it, but I'm not sure how they work. Mine currently has 82K miles on it, with regular service done on it.

CamShaft

have we tried replacing the throttle body as I said?

ChristPuncher

I think I've cracked it .it's most likely down to one of your speed sensor connectors on your front tires, or speed sensor for the transmission. Your car is hitting limp mode on account of a faulty sensor. Happened to me pulling on the highway, infront of a transport truck, at 40kmh... And then again when my girlfriend got t-boned losing power trying to make it through a yellow. She now drives an Audi, cause f*** japan.

DuffmasterFresh

If it's the speed sensor, then I would assume my issue would happen randomly anytime day or night, but it doesn't. It only happens the first 15 minutes or so of driving and then the transmission behaves normally from that point forward. If I let it sit again, the problem will come back. There is only a 5% chance that the issue will happen after I've been driving the car for a long time.