Some of you may know that I've been having issues with my car since the dealer installed a new clutch for me. I was thinking about how my engine has been running and I have a new idea of what the problem might be. The engine is missing a lot of low end torque, below 2500-3000 rpm's, but pulls very hard all the way to redline. When it was stock, the engine would "bottom out" by around 6000 rpms and feel flat to redline. Also, the engine is idling smoother.

I would like feedback on what everyone thinks about my new idea.

The steps I have already taken to resolve my issue are in this thread:

2K2 Engine Problem

The engine has a crankshaft position sensor which operates based upon the signal generated as the "signal plate" which is mounted to the flywheel passes by the sensor. The signal plate is magnetic and the ESM says not to ever remove it from the flywheel. I suspect that one or more of the following things occured when the dealer installed the new flywheel: 1 - the new flywheel did not come with its own signal plate, so the old signal plate was re-used which may have caused some type of issue, or 2 - the dealer mounted the flywheel, with either the new or old signal plate, without taking note of the position of the original signal plate relative to the new one. I suspect the result of this situation is that the computer will perform all of its calculations for timing and valve advancement based upon an incorrect crankshaft reading. In effect, when the ECM thinks any given cylinder is at TDC or BDC, it will be wrong since it's only way of noting the position is through the crankshaft position sensor.

This could explain why the power band feels as though it has been shifted up by over 1500 rpms couldn't it?

The only weird thing about this is that when I check the timing with my timing light, it appears to be set properly.

 

That would only make sense if the CPS when bad on its own. They were working on the other side of the engine and would had had no reason to mess with the CPS at all.

BTW is your FTP server up yet?

 

Maximaman,

Thanks for the response. I haven't forgotten about you. The FTP server is nearly up, I finally got the server to my house. Now I have to buy a new router, and configure the ports.

BTW, the dealer did have to mess with the CPS in two ways: first, they had to remove the sensor in order to pull the tranny and second, they replaced the flywheel which includes the signal plate that actually tells the CPS the position of the crankshaft. It's also possible that the dealer re-used the old signal plate by removing it from the old flywheel and installing it on the new flywheel. My guess is that the CPS is working just fine, but that either the flywheel or the signal plate was installed a number of degrees off (relative to actual crankshaft position). I suspect that this would result in the CPS sending its signal to the ECM at the wrong time, either early or late. I think my idea could be tested by verifying that the signal plate is lined up with the CPS when piston 1 is at TDC (or something like that) . . . The ESM doesn't go into much detail on aligning the signal plate with the CPS. It's also possible that the plate is offset by exactly 180 degrees, i.e. the plate is calibrated for the exhaust stroke and not the intake stroke of the 4 cycle engine . . . Either way, I think a problem with the signal plate position would cause timing errors for overall engine timing advance/retard and also for IVT. Since the CPS is operating normally, no DTC would be set . . .

Would you agree? The more I drive the car, the more I realize that the power band has been shifted "up" meaning I'm getting more top end and less bottom end power . . . I'm not noticing any more flat spot at high rpms before redline - it's pulling harder to redline. But I am noticing a BIG drop in low end output. This is definitely very different than stock . . .

 

Wow I did not know they had to do that much work to your car, I thought it was just a clutch replacement. It's very possible that this was the 1st time the tech at that dealer had to do that kind of job to this new engine. If so there's no telling what he F'd up and it would all have to be taken apart to verify this. This is where a FSM would be handy. Now I'm with you about taking it to a new dealer if you haven't already.

This is what I know. The crank has to make 2 revs to complete a firing sequence and on the 3rd it starts a new fire on cyls 1,3&5 and completes the exhaust for 2,4,&6. If the plate was on the flywheel 180 deg from spec wouldn't the ECU be trying to fire the cyls in the exhaust sequence? (unless it was set at TDC for cyl 1 by the tech) At best you would get an SES light because of higher emissions. Now if the sensor is out of whack or the plate is off slightly (Is there a sensor at the flywheel or is it just on the front of the crank) Then ECU would show it in the spark advance since it has found the right combo at higher RPM. And you need to find out what the initial advance is set at. See this thread Advanced my timing on my 2k2 maybe it's just off to start with. Either way the ECU is learning but it doesn't learn the initial advance (or retard) this is set, hence no power at lower RPM's. If your getting the run around from the dealers then get the car dyno'd.

 

Maximaman,

Thanks for the info, I didn't know the firing order of the engine, but what you wrote seems right. When I check base timing, it appears to be set correctly at 15 degrees BTDC on the crank pulley. But this is only the base timing. It is completely possible that the crank sensor doesn't come into play until higher rpms are reached, but I really don't know for sure. What I do know is that the signal plate is mounted on the flywheel and the CPS is mounted on the front of the engine where the tranny connects to the engine. The sensor is magnetically operated and "listens" for the signal plate to pass by it . . . when the signal plate passes by it, the sensor detects the change in magnetic field it sends it's reading to the ECM.

I agree with you regarding the signal plate being off by 180 degrees, this would cause combustion on the exhaust stroke and big problems. I don't think that is what's happening. What I do think is that the signal plate might be offset by 5-10 degrees . . . and this might yield the problems I described above. Unfortunately, the ESM is very vague regarding installation of the flywheel.

I've been trying to figure out how to test my theory. I think it will be necessary to confirm that the signal plate is either "aligned" or not "aligned" with the CPS sensor. The only way I can think of to do this is by determining actual crank position as it relates to TDC for piston 1 on the compression stroke. Unfortunately, I doubt the CPS will produce a reading unless the engine is actually rotating/running. I think the dealer should be able to monitor the CPS with the Consult II, but I can't figure out how he will know when cylinder 1 piston is physically at TDC with the engine running.

Ultimately the issue is that the dealer is going to try to deny any wrong doing. Without a test to confirm my idea, the dealer is probably not going to agree to spending another 2 days of labor to pull the tranny and recalibrate the signal plate.

 

All I can say is keep pressuring the dealer and or get a dyno done.
With the dealer you can try to let him drive your car hard then have him drive one of the managers cars or one that has some miles on it thats on the lot. Because the only other options are having someone else check it out or trading it in, with either one it's money out of your pocket.

On a side note if the base timing at idle is 15 deg BTDC wouldn't that mean that the plate is aligned correctly? And the problem may be somewhere else?

 

Maximaman,

I am planning to have the tech drive another 6 speed (assuming they even have one) back to back with my car so he can see the difference. I'd rather not drop the cash on the dyno, if it can be avoided, but I will do so if I have no other choice. My appointment with the dealer is coming up this Monday.

It did occur to me that since the base timing at idle appears to be correctly set at 15 deg BTDC that the problem could be somewhere else . . . the only problem is that I don't know which inputs the computer uses to set base timing? It might rely on the camshaft sensors and not crankshaft sensor to set base timing? I'm not really too sure. It could also be that the signal plate has some kind of marker on it that can be used by the computer to help set dwell. So maybe what's happened is that the computer automatically corrects timing based upon the camshaft sensor, but under full throttle the timing advance/retard or dwell changes are not happening correctly because the required "marker" is offset . . .

It also may be that the base timing is not supposed to be exactly 15 degrees, don't forget that the spec calls for 15 degrees +/- 5 degrees. It appears that my timing fluctuates from about 13 or 14 degrees up to 15 degrees at idle.

Someone on the .ORG just posted a link showing that the flywheel does require "alignment" when mounted to the crankshaft check out the Clutch TSB near the bottom of this list, page 2 shows a dowel used to align the flywheel.

Clutch TSB

Here is the orignal post on .Org from Afty:

?Afty's .ORG post

As a side note, I've discovered something really weird, when I place the inductive pickup for my timing light on the wiring to coil number one, it seems to "skip" every so often (the timing light flashes regularly for a while and then it flashes kind of irregularly and then it flashes regularly again). Alternatively, when I place the pickup on the "timing loop wire" I don't see this problem. However, when using the "timing loop wire", if I flip the inductor from the timing light upside down, it shows that I have a lot of advance (like 40 degrees BTDC) . . . I have NEVER seen a timing light do this before. It shouldn't matter which way I install the inductor should it?

 

Also note that some people are seeing more power down low from changing the timimg advance. I'm sure you have seen this post but if not here it is. Advanced my timing on my 2k2 actually there are several posts here is the serch page Thread Results




I believe this is do to Nissans "High performance coils" The connector on the timing light is probably losing the signal occasionally when connected to #1. With the timing loop wire your getting a better signal through the wire but it may be getting all 6 clys or 3 firing every rev. 3x15=45 + or - a few deg I dunno I've never hooked up a timing light to a distributor less car schit I haven't even used one on a 90's or newer car.

 

Maximaman777,

I think I finally got that server up and running. I'll PM you some info. Test it and let me know if it's working ok . . . I haven't been able to check for myself . . . thanks!

 

I was unable to connect this morning.

 

Sorry man, I'm trying to get this damned router setup right. I don't think the issue is my fault. I can hit the server on the LAN side just not from the WAN side . . . I may have to get a different router . . .

 

Maximaman777,

Try it again . . . I made some configuration changes. Same IP.

 

Here's the latest update to the ongoing saga. Finally brought the car into the original Nissan dealer who did the clutch install. (I had to reschedule twice due to my own scheduling conflicts.) The dealer made no physical changes to the car, I watched them the whole time. Although the did not admit to it, I saw them get into the car with the Consult II for a little while. Took the car off the lot when they were done and the engine is running MUCH better. All of a sudden I've got more low end torque, the engine is whining less and the brake pedal feels harder. These changes were immediately noticable.

Also, I confronted the mechanic, with the Service Rep and the Service Manager there and he flat out denied any possibility of a problem with the flywheel mounting. He claims to have marked the fly wheels and to have used the required alignment dowel during the install.

I still don't feel like it's running right, but it's way better than it's been for the last couple of thousand miles.

I also had my Bose HU replaced and now I've got new issues, which are undeniably the result of tinkering with the system. Windows open when I'm out of the car and the dome light and ignition key light are coming on intermittently while driving.

I really hate this dealer. At this point, there is no question that they are screwing with me. And, just as I suspected before, it is probably due to there need to recover money for the time they spent working on the clutch.

I won't be bringing the car back to them ever again, unless nobody else can fix the new problems . . .