Ok, this is going to be kind of long, but I REALLY need some help!

Last week, I brought my 2K2 into the dealer to finally have the clutch replaced. They did so, and the new clutch is great. (As a side note, they put in the wrong viscosity and grade gear lube which I just replaced with Amsoil).

When I got the car back it felt like I didn't have nearly the same power and the engine is running really different than before. Here's a list of what changed:

1. Lumpy/rough idle is almost completely gone. Engine idles much smoother than before.
2. Low end torque is weak up to about 3K.
3. I don't get the same, very noticable, power increase at around 4K when the variable intake is supposed to kick in.
4. Top end power also seems less than before.
5. Fuel economy slightly improved.
6. Engine seems smoother throughout the RPM range despite less power.
7. Problem is very noticable when running at 55-60 mph in 6th gear - the pick-up is horrible (before it used to be really good with gobs of torque between idle and 1500 rpm now it feels like a dead spot). Also very noticable in 2nd gear at low speed, like 2-3 mph.
8. Engine used to make a kind of "vibrating" sound under full throttle at around 4K when the variable intake opened up, that sound is completely gone now.

Here is what I have performed as per the ESM (Followed the manual procedure since I do not have a Consult II):

1. Checked the ignition timing by using the "timing loop wire" with the engine at operating temperature and at idle. It appears that base timing is greater than 15 degrees before TDC, more like 17/18 degrees (this is still in spec, but I don't know if it should be dead on 15 degrees).
2. Verified idle rpm in spec. Always idles around 600-625 rpms.
3. Performed Accelerator Pedal Release Position learning.
4. Performed Throttle Valve Closed Position learning.
5. Performed Idle Air Volume Learning.
6. Performed sequence 2-4 three times.

These procedures seemed to help a little, but the engine is still running really sluggishly.

I checked to make sure all the sensors are connected, etc. and everything looks good.

Here are my hypothesis as to what might have happened:

1. Mechanic may have reversed the camshaft sensor with the crankshaft sensor upon reassembly.
2. MAF may have been damaged when intake was removed by mechanic and new sensor was re-installed but ECU was not fully reset. Two Torx head bolts holding the MAF sensor in the plastic tube look like they have recently been unscrewed/screwed.
3. I had mentioned to service rep that some people were advancing the base timing to 18 degrees BTDC. It is possible that they may have alterred this parameter in my computer. The service rep says they did not do this.

My engine is completely stock, including the intake. I would like to follow the ECU reset process, but don't know if I can do so without the Consult II. I don't have time to leave the ECU unplugged for 24 hours.

Any help/suggestions would be appreciated. Thanks!

 

Haha.. Sounds like the dealer switched your Vacume lines on your variable intake manifold. There are two little lines, one connects to the butterfly valve and the other one just goes into the manifold. The one that goes into the manifod should have a little white square at the end of the vacume line facing the sky. Check to see if that hose has the white square on it.




The only catch to this theory is I dont understand why the manifold would be touched with a tranny install. I know teh air box adn MAFS is removed but..

 

I had the plastic engine cover off a couple of days ago, to check the timing, and I saw the black plastic vacuum collector on top of the engine with two tubes going into it. I also saw the computer controlled vacuum switch, and I also saw the vacuum operated actuator and arm for the variable intake. Is this the system that you are referring to?

If so, could you confirm for me, I should be looking for a white square, which is screen printed, on the vacuum hose that goes directly into the manifold? I think I'll print out the appropriate pages from the ESM and confirm that ALL these hoses are routed properly.

Would this also cause a low end torque problem though?

If this is my problem, it could be that the dealer did this intentionally to recoupe some of the time/money spent swapping out the clutch. I think Nissan only allows the dealer to charge 4 hours of labor, but the job probably took 6-8 hours . . .

 

Latest update. Last night I pulled off the plastic engine cover, confirmed that the vacuum lines for the VAIS system were plumbed correctly (as per the ESM) and then I tested it's operation with a friend. With the engine at 2000 RPM, the VIAS system is fully opening the butterfly valves. I am assuming that the butterfly valves should be operating at between 4-5K RPM.

Any ideas what could be causing this failure? I am guessing it could be an item from my last post, or it could just be a bad VIAS vacuum switch. The only thing is, what could have caused this switch to go bad . . .

Any input would be appreciated.

 

Ok, trying to figure out why the butterfly valves are opening at 2K instead of 4K (interesting to note that the variance is approximately 2x different). Anyway, I tested to see if the vacuum plunger (which controls the butterfly valves) was always getting vacuum (i.e. a faulty vacuum switch) and the answer was no . . .

The computer is definitely controlling the vacuum getting to the plunger. So, what would cause the computer to decide to open the butterflys 2K rpm's early? I wonder if the dealer accidentally (or intentionally) switched the Crank sensor with the Cam sensor? Since these engines are 4 stroke, I would guess that the Cams rotate 2x for every one revolution of the Crank . . .

Any ideas how I could test this theory?

 

Are the sensors that similar that they could be swaped?
And If so could you swap the plugs on them?
Lastly can you get a part# off of either of them?


Do either of you know where I can get an ESM without breaking the bank? Thanks

 

Very good questions. The sensors are physically in different locations, so I doubt the wiring harness would allow the plugs to be interchanged, but I think they look very similar overall. I have already located the CAM sensor, but I have yet to crawl under the car to look at the CRANK sensor and to confirm its size, etc. I have not looked that closely, but I might be able to find the part numbers.

Also, you have PM.

 

I've read at least one posting on here where a dyno was able to prove the performance degradation. I realize it costs money to do this but it would certainly help validate your conclusions. I realize you don't necessarily have a baseline but you should be able to use any of the posted ones (I have a 02 stock 6speed you can have) to demonstrate the issue.

 

Well if your 100% sure the lines are indeed on correctly then hmm.. My car was swithing around at like 1.5-2.0K too. Reason my car was doing this was becuase I istalled my Butterfly valve with the gasket improperly mounted. I doubt this is your problem though. I recommend you take your car back to the dealer and have them worry about it.

 

Are there any wires or connectors over or under the trans or by the clutch lines? There could be a loose connection there. If not then I'm with emax, take it back to the dealer.

You have a PM also.

 

ajahearn,

You have an excellent idea. I am bringing the car into a second dealer Saturday, so I will keep my fingers crossed that they can find the problem. If they deny any problem, then I will follow your recommendation and dyno the car to prove the problem. If it comes to that, I would definitely appreciate the stock dyno chart from you.

emax95

Interesting, how did the gasket interfere with they butterfly in your example? I am beginning to wonder if the dealer did something intentionally to the engine just to get more warranty work to offset the time lost on the clutch swap. It probably wouldn't be that difficult to pull off the intake and mess with the butterfly valves . . .

maximaman777

There is a cluster of wires over by the transmission shift cable input and more sensors on the same side of the head. There is a temp sensor, the cam sensor, etc. I haven't found anything loose, cut or disconnected, but I could easily have missed something. I wanted to pull the whole intake out to get a better view, because it looks like the mass of wires is right under that big plastic box that connects to the breather tube from the engine.

Something else I noticed the day I picked up the car is that the assist on the brakes feels greater than before. Is there anything that could be increasing the vacuum in the intake? I was considering the possibility that a cloth or towel might even have been stuffed into the MAF or an intake tube.

I can't describe how frustrated I am with this situation. The engine should not have been touched in the least just to swap the clutch.

 

ABS there is such a volume of air that goes thru the intake that if something was in there I would highly doubt the car would even run and if it did you would have valve damage by now. My thought on the vacuum & brake assist is that if the VI isn't opening up correctly that the negitive manifold pressure is going up as the engine is scavenging for air. Thus increasing the vacuum to all accessorties. This sould easily be seen on a ConsultII, but what is causing the VAIS to malfunction? This could be a nightmare to diagnose. I would take it back to the sane dealer the 1st time, if they truely f'ed someting up they should be able to fix it and you'll know never to use them again.

Please keep us up to date whit what happens at the dealer. This is a very interesting problem. I have wondered what kind of symptoms a car would have if the VAIS wasn't working right. Think about it. The only thing that controls engine speed & power is the amount of air (o2) the engine can get. If the VAIS is a POS, why don't the Z or G35 have it, then emax is on the right track with his manifold swap. If this is truely your problem we should put this it the stickies.

 

I appreciate your feedback. I tend to agree with you regarding something in the intake - this is very unlikely. However, something is clearly out of sorts. The car goes into a different dealer tomorrow to try and diagnose this engine problem. I also have a Monday appointment setup with the original dealer who did the clutch work. My hope is to have this resolved tomorrow and for it to be something obvious.

The worst case is that nothing shows as wrong, but that the engine keeps running this way, then I will have to dyno and fight to have whatever the problem is, fixed.

I'll keep everyone posted. If necessary, we should make this a "sticky" but it is probably premature to make that call.

 

The latest update is that I finally pulled of my intake and checked out all the wiring and connections. The only think I can find that looks like it might be wrong is crankshaft sensor could have been switched one of the camshaft sensors, or that the two camshaft sensors were reversed. I can only guess what the impact of this might be . . .

Anyway, I just posted an urgent note here:

Need Sensor Info

To see if anyone could verify the location of these sensors for me. My car is in pieces right now and I will have to re-assemble before tomorrow morning. But I would like to resolve this issue if at all possible tonight.

Thanks in advance to anyone who could help!

 

Status Updated:

Spent 5 hours today at a dealership here in Queens. After waiting about 4 hours, they finally took my car in and hooked it up to the Consult II. Guess what? They gave me a tech with limited knowledge of both the ECM and the Consult II. I knew more about the ECM than he did. Long story short, between the tech's lack of knowledge, their claim that they did not have an ESM, no DTC's and all sensors looking normal, I was told that nothing was wrong with the car.

I asked if they could at least reset the RAM buffer in the ECM, but the tech had no idea what I was talking about. Then I asked if they could run through the throttle, idle air and timing calibration sequence with the Consult II, since I didn't have one and wasn't sure if I was doing it right, and the tech also didn't know how to perform this basic procedure.

I was given the standard party line: "The computer is supposed to reset itself. If you want, you could call our shop foreman on Monday, if he doesn't know it, then nobody will . . ." Blah, blah, blah.

So, I am out of luck with this for the moment. I think I am going to try to reset the ECM myself using the manual procedure spelled out in the ESM. Does anyone have any knowledge/experience about this process . . .

 

Ok, here's my latest (and hopefully last) update to this thread. I believe I resolved my problem myself. Here's what I did:

(1) I disconnected the battery for about 25 hours, ESM states that the ECM has a backup battery that will last 24 hours, so I played it safe by waiting an extra hour.
(2) After reconnecting the battery, I started the engine and let it idle until it reached operating temperature.
(3) Then I checked the base timing using a timing light connected to the "loop wire" held inside the hard plastic casing over the passenger side of the engine and sticking out of the thick wiring harness there.
(4) Then I proceeded to follow the instructions in the ESM for the following ECU calibrations:

Accelerator Released Position Learning
Throttle Valve Closed Position Learning
Idle Air Volume Learning

(5) ESM states that the computer should then come into spec for timing and idle speed. If it doesn't come into spec then the calibrations are supposed to be repeated, in sequence until they do.

(6) I did not need to recalibrate. The base idle rpm shows as 600 on my tach and the base timing looks to be exactly on at 15 degrees BTDC.

(7) I took the car out for a test drive and it feels to be pulling harder from 1000-2500 rpms which is the range where I had been experiencing the problems.

(8) I called the dealer, cancelled my appointment and decided to wait a few days to see how this goes. If I am not satisfied with the change, I may choose to bring the car back to the dealer then. I am hoping this will not be necessary.

Thanks for everyone's input and help with this . . .

 

It looks like it worked if it's accelerating correctly. I hope it lasts. The ESM sounds like it has some very useful info in it.