Help with 2004 Sentra

[svgmuc]

Hi,

I've been searching the forum and I haven't found any similar topic posted.

My Sentra has been doing fine for years, only now it keeps coming up with some troubles.
I am talking about a 2004 Sentra 1.8S with stick shift at about 120,000 miles. My assumption is that something is wrong with the clutch but I would like some expert opinions on that.

Here is a list of the symptoms.

1. 1st gear and reverse are difficult to get into. Normally I would shift into another gear and then to 1st or reverse and it would work. Now, it takes me several attempts, sometimes up to 2 minutes.

2. The engine output is limited. Depending on the gear, the engine stalls(?) at 4000-5000 rpm, i.e. it does not slow down, but the is no more than that possible. 1st and 2nd gear would go up to 5000, 3rd ends at about 4500 and 4th and 5th even lower. When I reach the max, the service engine light would turn on. I haven't been able to run diagnostics yet, had to order a new cipher cable. However, the light turned off again, even though I didn't disconnect the battery.

3. Fuel intake has increased. I had the catalytic converter and both oxygen sensors replaced after which fuel mileage had increased, but now it went down again.

4. Sometimes, I would hear a metallic clank from the engine compartment when shifting. That wasn't the case before.

5. Shifting has become rougher, sometimes I wouldn't get the new gear in with the normal hand movement and the 2nd attempt would need a little more force.

That's all I can think of right now. I would appreciate any input. Please also ask for more information if you need.

Thanks in advance
Sven

[PapaSmurf2k3]

Welcome to NICO Sven, we'll see if we can answer some of your questions here.
From what you've described, your clutch sounds fine. The only real problem a clutch can give you is if it starts slipping (like the engine revs up but you don't go anywhere until you let off the throttle... kinda like spinning tires).

Now- as far as your shifting problems go. It sounds like you are either low on gear oil in the trans, the incorrect weight gear oil is in there, or the gear oil is SUPER old. At 120k, if you've never changed it, you've gone twice as long as you are supposed to.
To help out temporarily, try "double-clutching" to get into first and reverse. That is, shift into neutral, let the clutch out, then hit the clutch again and try to go into the gear you want.
4&5 seem to be related. You could have a worn bushing or something in your shift linkage.

Engine output is a separate issue than the transmission. How long ago was the catalytic converter replaced? I've had one go bad on me (and heard of others going bad) where they clog up, which would cause a severe lack in power, especially in the higher RPM range. Definitely check your engine codes and get back to us.

[svgmuc]

Hello PapaSmurf,

thanks for the quick response. Indeed, the gear oil was never renewed. I will have that done very soon.

As for the catalytic converter, it was replaced somewhat recently, 3 months ago and about 3000 miles. If it was already clogged, I would be tempted to bonk my mechanic on the head with it.

The O2-Sensors had been replaced about a month before that.
The RPM limitation only started to show some time after the catalytic converter was replaced.

I will follow up with the trouble codes as soon as I have the cable.

[PapaSmurf2k3]

Mine clogged after about 3k as well. Don't blame your mechanic haha, its more of a "bad part" issue. Sometimes they just clog/implode.... but if that is indeed the problem, I'd raise hell for a warranty part.

An easy way to tell would be to unbolt the exhaust prior to the cat, support the exhaust system, and take it for a drive (or just rev it up while sitting still).

[svgmuc]

Hi everyone

I've just had my gear oil changed and it's a huge difference already. My mechanic said it might take some time to creep all over the gears but it's noticeable just a few minutes afterwards. Thanks a lot for the advice.

He also checked the exhaust system and we ran the car with no catalytic converter. The effect is the same - no more than 5k RPM in 1st gear.

I do understand, that I rarely ever need that high RPM, but a side effect is that it just doesn't pull anymore when it comes up to 3000-4000. And if you slow down just because you're going uphill, that's sort of annoying.

I am still waiting for the cable. Will follow up as soon as I have new information.

[PapaSmurf2k3]

Interesting. Not sure if its adjustable here, but have you checked ignition timing? I wonder if your valve timing could have gotten off...

[svgmuc]

I have gotten my Cipher cable today and checked out the ECU.

The only error code I got was O2-Sensor related:

P1278,A/F Sensor Slow response (Bank 1 Sensor 1)

Now, I have the impression that it could be a remnant of my last O2-Sensor incident and I cleared the ECU trouble codes.

I have taken the car on the road and logged everything for about 10 miles. Nothing odd, just the RPM-limit and the low output if it comes close to the limit. But no SES light coming on.

When I took her to the expressway, I tested the RPM limits:

1st - 4850 RPM
2nd - 4600 RPM
3rd - 4250 RPM
4th - 4050 RPM
5th - 3800 RPM

After that limit, the engine keeps running, but there is no more increase possible.

It looks very much like a load factor that decreases the max RPM value.

Is there any way I could test the valve timings? Or do I have to bring it in for service?
My mechanic also speculated, that the clutch may be running hot. Any experiences with this?

I am cross-posting this to another Sentra-specific forum. Please PM me for a link.

[PapaSmurf2k3]

Clutch running hot? wtf?
If he meant slipping, then no, he's wrong. Your RPMs would increase but you wouldn't accelerate... it would be almost like hitting the clutch and the gas at the same time.

Has your mechanic driven the car?

[svgmuc]

In and out the shop, probably... other than that, he only took a quit ride with me driving.
He's no no Nissan specialist, though.

It sounded somewhat plausible to me, that I lose power when the clutch runs hot at higher RPMs.. but then I would also expect the engine to run higher than the measured limits.

[PapaSmurf2k3]

Yeah a clutch running "hot" really won't stop the engine from running. It'll smell bad, and eventually won't grab anymore. At that point, your clutch will "slip" and you'd be having the exact opposite problem you're having now. Engine revving to the high heavens, but you won't be going anywhere. It'd be like you're in neutral all the time unless you really baby the throttle. Let me see if I can get you some help in this thread.

[svgmuc]

Hi,

I have some new info. I took her out on a ride today and the SES light came back on.
I got the trouble codes 1278 and 1279, both A/F sensor slow response.

Reasons could be the harness connector, the A/F sensor or its heater, fuel pressure or fuel injection, PCV or MAFS.

I rule out the A/F sensor itself for now, because I had it exchanged about 5 months ago. It's been used for about 3k miles. I have checked the harness connector, looks for from my perspective. (I am no car mechanic, but I know physics and electronics.)
I have notice one peculiar thing about my gas pedal today, which might indicate to an issue with the fuel system. Flooring the gas pedal yields less engine output than a slight bit before hitting the floor (~1/4"). I have no idea if this is normal, I wouldn't expect it though. Any ideas?

Further research also brought this up:

http://www.nissan-techinfo.com/TSB/TSB_ ... modelyear=

How are those handled? Does any mechanic do them or do you have to go to a Nissan dealer?

Cheers and thanks for all the time and effort.
Sven

[PapaSmurf2k3]

TSBs are issued through dealerships, and also alldata. They should be pretty readily available for a 2004. I THINK NICO was trying to get our hands an all the older TSBs, but I'm not sure.

I doubt an O2 sensor could be causing all the problems you're experiencing. MAF sensor on the other hand, yes.

[svgmuc]

Just to update this for anyone else who has problems like this:

I found out that my mechanic is a slacker. Whenever I brought my car to him for a checkup, he did oil change and oil filter, but nothing else. Little did I know, until I found out that my spark plugs were at least 45.000 miles old, and the air intake filter probably the same.
I replaced both and the output of the engine increased dramatically.

The next issue is a worn clutch and, assumably, a broken flywheel. I haven't gone to fix this, yet. The afore-mentioned mechanic wants to charge me $1000 on the clutch replacement alone and I felt that was too much. I think, he has seen me for the last time, anyway. So, I am trying to find someone whose garage and lift or ramp I can use, a fix it with the help of a friend. If the flywheel turns out broken, it'll be replaced. Still hoping to find a way to tell for sure if it's broken or not. Don't want to invest $200 for nothing.

[06_blkout]

Where are you located? Maybe someone close to you can point you in the direction of a good mechanic

[svgmuc]

That would be cool. I am in Orlando, FL. So, if anyone can recommend a good mechanic, who's not trying to massage my wallet too much, I would appreciate it a lot.

Thanks!

[speedeast]

I'm a good mechanic.

Give me a call.
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