FX37: Not revving over 3500rpm

B

Bottie

Member
Location
Aalter
Name
Bram
Hi All,

After a few months of worry-free driving, I have again some issues :at-wits-end:

It started last week, not revving over 3500 rpm and lack of power, shortly followed by a Engine Warning Light. Readout says error P0340. The next day, it was very hard to start the engine and again followed by a festival of warning-lights ... When finally started, driving is almost impossible, the gearbox isn't changing gears when i should be and such, untill the engine has warmed up a little and when I stop the engine, get out, close the doors and get back in. After this, only the Engine Warning Light and driving almost normal, except not possible to revv up fast. When driving like an 80-year-old, it keeps up :)

Today, I changed both the camshaft-sensors and all is much better. Car starts perfect, no warning-lights but ... still the revv-block at 3500rpm ... Also, I have loud ticks coming from the engine, which I suspect to be the timing chain(tensioners)



Any idea?


thanks!
 
Check your spark plugs. Closed or worn out spark plug gaps wont let rpms go up past 3k. Low fuel pressure. Or just as mentioned clogged converters. You can try removing the upper o2 sendors and taking it for a spin with them out to see if its the converters.
 
Themechanic said:
Check your spark plugs. Closed or worn out spark plug gaps wont let rpms go up past 3k. Low fuel pressure. Or just as mentioned clogged converters. You can try removing the upper o2 sendors and taking it for a spin with them out to see if its the converters.
Click to expand...

Sparkplugs are replaced a few months ago, so I think we can exclude them :)
 
I'm guessing MAF if you can't rev over 3500. I don't think it's your cats clogging up, and that happens very rarely unless you're heavily modded. Stock cats last a long time.
 
Obsedian said:
So you already had a code for the cats! [emoji19]


Obsedian
Click to expand...


Must be almost 2 months ago since the last code for the cats.

Just did a small test-drive (about 80km). Since I have 2 fuel-systems (petrol and LPG) I filled the tank with LPG too:

- Cold start: same issue, hard to start. after 7 attempts, finally a running engine but rpm fluctuating between 8-1500rpm and stable at 1200 after 2 minutes and at 7-800 a minute later
- Driving: Not good, humping and bumping. Stop the engine, get out, close the door. Wait 30 seconds, get back in, start en drive without a problem
- Revving up to 3500rpm. Bang, rpm down.
- Switching to LPG (which is programmed to add Petrol at 4000rpm, building up from 3500rpm): same issue
- ODB-readout while driving: Cat-temp: 524°C, O2-senser: N/A
- When revving up below 3500rpm: Engine sounds 'heavy', less power than normal
- No warning-lights at all, that's a change compared to the situation before changing the Camshaft-Position-Sensors.

ODB-Diagnostics:

0 stored codes
1 pending codes found: P0340 ... there it comes again

Readiness monitor:

5 complete
1 incomplete: Oxygen-Sensor

about the readiness monitor. I'm about 99% sure this used to be 6 complete and 0 incomplete ...

ECU has been reset after I changed to CP-sensors, no warning-lights since the reset
 
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Bottie, I am not positive about what is going on, but here is what I would do so you wouldn't damage your transmission, don't drive on high rpm keep it down as much as you can until you figure out what is going on. Second if you happen to have a muffler shop that you deal with, they probably can help to figure this out, I don't believe it will cost that much to chop the cat temporarily for the duration that you would drive your vehicle around the block and you will be able to see if it help or not! Obviously if it helped then you would need to change the cats, if not then they can weld them back in place! By doing this you didn't spend the money on the cats for no reason and in the mean time you would know that your transmission is not in danger


Obsedian
 
Please don't cut off your catalytic converter. Your symptoms sound like limp mode which is why you can't rev over 3500. You can try to unplug your MAF and see if it changes anything, if it doesn't, MAF is bad. Maybe you got another bad cam sensor, it happens.

Your cat code could be related to your O2 readiness issue. Sensor could be failing and intermittently throwing codes. But I don't think your cat is the cause of your issues. If you really want to be sure, you can unbolt it and do a visual inspection. It's really easy to see if your cat has failed or not, the material is easily visible. Modern O2 sensors are very good though, if your cat had clogged, they would have thrown a lot more than one code.

If your transmission was truly failing, it would throw it's own codes. I think it went into limp mode the first time when your car went into limp mode (the transmission does have it's own limp mode where it locks into gear to prevent further damage). It doesn't mean anything is broken with the transmission, it just can just be electrical.

I don't know how LPG use impacts the sensors or operation. But based on the symptoms changing when you get out and restart the car as well as it changing when it warms up leads me to believe MAF. Can you take it to a shop to diagnose?
 
shadow191 said:
Please don't cut off your catalytic converter. Your symptoms sound like limp mode which is why you can't rev over 3500. You can try to unplug your MAF and see if it changes anything, if it doesn't, MAF is bad. Maybe you got another bad cam sensor, it happens.
Click to expand...

I replaced 2 cam-sensors, is there another one? :rotfl:


shadow191 said:
I don't know how LPG use impacts the sensors or operation. But based on the symptoms changing when you get out and restart the car as well as it changing when it warms up leads me to believe MAF. Can you take it to a shop to diagnose?
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Car drives perfect on LPG (before these problems started ;) ). I put it on LPG to see if it's a fuel-pump issue. Bit since the system is programmed to add petrol from 3500rpm this stays the same. Like I feel it, and my knowledge to cars is not that much, it feels like a bad sensor or something like that. It just feels like the engine "can't breath" or the exhaust is blocked ...

Is there a way of testing a MAF? I already paid 282€ for 2 camshaft-position-sensors, 1 MAF is about 200€ ...

---------- Post added at 09:03 AM ---------- Previous post was at 07:56 AM ----------

This morning, same situation as before changing the cam-sensors. Hard to start the engine ... and back to the P0340-code (Camshaft Position Sensor Circuit Bank 1)... 282€ down the drain
 
No, it's just the 2 cam sensors. But there's a chance a replacement one is bad or maybe the wiring/connection is having an issue. So have the wiring checked.

For the MAF, you can unplug it and see what happens. If your symptoms remain the same, the MAF is likely bad. It doesn't always throw a code.

My opinion still is that it is something electrical vs. mechanical.
 
shadow191 said:
No, it's just the 2 cam sensors. But there's a chance a replacement one is bad or maybe the wiring/connection is having an issue. So have the wiring checked.

For the MAF, you can unplug it and see what happens. If your symptoms remain the same, the MAF is likely bad. It doesn't always throw a code.

My opinion still is that it is something electrical vs. mechanical.
Click to expand...

When I start the engine with both MAF unplugged, the rpm goes up and down between 8 and 1200rpm and a get an errorcode and the MAF
 
That means the MAF is still working. So I think next step is to chase down the P0340 code. Start checking wiring and such. If you search that error code on this site, you get people with similar symptoms to you. Maybe not the specific 3500 rpm issue, but other driveability issues. I think there is another member on the forum who uses LPG as well, maybe "Case Holland"? Maybe he would have more insight into whether the LPG has any impact on your problems.
 
shadow191 said:
That means the MAF is still working. So I think next step is to chase down the P0340 code. Start checking wiring and such. If you search that error code on this site, you get people with similar symptoms to you. Maybe not the specific 3500 rpm issue, but other driveability issues. I think there is another member on the forum who uses LPG as well, maybe "Case Holland"? Maybe he would have more insight into whether the LPG has any impact on your problems.
Click to expand...

That's something I'll do tomorrow. The Nissan-dealer also said to check the connectors at the ECU (anybody knows where that one is located?). I also disconnected the battery for the night, just te make sure the ECU is reset.


Anyhow, thanks all for thinking with me :good::good:
 
shadow191 said:
That means the MAF is still working. So I think next step is to chase down the P0340 code. Start checking wiring and such. If you search that error code on this site, you get people with similar symptoms to you. Maybe not the specific 3500 rpm issue, but other driveability issues. I think there is another member on the forum who uses LPG as well, maybe "Case Holland"? Maybe he would have more insight into whether the LPG has any impact on your problems.
Click to expand...


The sage continues ...

We had a cold night last night, car didn't start this morning. I opened the hood and placed a hot air fan in the enginebay ... after 15 minutes of warm air, back in the car ... push the button and engine started like a charm :eek.:

---------- Post added at 08:27 PM ---------- Previous post was at 12:51 PM ----------

Did a test-run today:

Run1:

Distance: 2.5km

Engine:

Max RPM: 2900
Average Value: 1216

MAF:

Max: 386.55 gr/sec
Average: 17.60 gr /sec




Run1:

Distance: 2.7km

Engine:

Max RPM: 3215
Average Value: 1056

MAF:

Max: 74.78 gr/sec
Average: 17.08 gr /sec


Quite a diffirence at the MAX-value for the MAF, driving style the same, on the same road
 
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