Hi! I recently purchased an 07 Nissan Altima 2.5 S, from a private owner. The car ran great for about the first month and a half, but after that, when I would go on long trips, it would randomly decelerate. And still does. I've replaced the catalytic converter to see if that would help, but it is still giving me the same issue. It will run fine for about 1 1/2 to 2 hours going 75-85 mph but after a certain amount of hours/miles, especially uphill, it's like the car completely loses power. Any thoughts of what it could be?
I forgot to mention that the car started doing this (losing power) recently. I'm not sure the iridium plugs have ever been replaced, honestly. And nothing came up from my sensor data. I've taken it to several different mechanics, all suggesting a different answer, none of which are write. If I keep the mph at around 60-65 the whole trip, it doesn't lose power though. I did stop every hour just to be on the safe side though.
The car started doing "it" around 158,000 miles. And when it does start decelerating, if I wait to let it sit for too long, it won't hardly accelerate at all if I'm at a stop. The car also has a rotten egg/sulfuric smell about it. And it seems to consume an unusually large amount of gas. I filled it up yesterday and it's already at half tank today, no leaks though. I've heard there are two catalytic converters on Nissan Altimas, and like I said, I did replace the manifold and converter. I did reset the computer the one time it started acting up and it seemed to help, but I also let the car sit for about a half hour.
Sounds like it is running rich contaminating the cats, which are getting bodaciously hot as you drive. Diagnostics are in order and would confirm this. Besides, you don't want to get in a cycle of replacing cats when those are not the root cause.
could the atmosphere effect what you think it might be? It was in the 90s over the weekend and the problem started within an hour of me being on the highway.
Yes, on your question. But, I'm not sure I've been much help. Sorry.
There are things I would have done to try to diagnose and isolate the car (study the scan data - if you have that from a real-time run you could post it here or even if you have that from a static car-off capture you could post it here - focusing on the O2 data and FTRMs; replaced the plugs IF in doubt as to them ever having been changed now being 158k - with NGK and same type per OM; checked my CVT fluid for condition and full - supposed to be flushed every 30k miles ... and even then they're going out - huge #s of CVTs are being replaced; checked coil wires for snug; checked for vacuum leaks; etc.)
There are other guys on the forum who may have encountered this.
I'm going to get it scanned tomorrow. There are not check engine lights on so I wasn't sure if a scan would be any help but it's worth a shot. I'll post what it reads on here, if it reads anything.
Bad news! The scan didn't read any faults whatsoever. Everything was good according to them. I honestly don't know what the next step would be. Any ideas? I'll replace the iridium plugs but it's hard to tell what's helping since the problem doesn't pop up unless I've been driving awhile or unless it's extremely warm outside.
Another thing, when the problem starts, at one point, I can press the gas as much as I want and although it won't accelerate, my RPMs still go up like they normally would if I were to accelerate quickly and my engine will rev up, but it won't go any faster. One person had said that Nissan Altimas don't have a transmission coolers and he had to get one installed because his car was experiencing the same issue
That would be surprising if that were true/accurate.
Again, diagnostics of the ECU data parameter set would help us help you. Have someone scan (all) those values - preferably when the car is running and producing the symptoms, upload it to/for you, and then post here.
<I can press the gas as much as I want and although it won't accelerate, my RPMs still go up like they normally would if I were to accelerate quickly and my engine will rev up, but it won't go any faster. One person had said that Nissan Altimas don't have a transmission coolers and he had to get one installed because his car was experiencing the same issue>
Engine running, but CVT is not.
Your car DOES have the CVT cooling lines. You should see 2 rubber hoses from the CVT to the bottom of the the radiator. One is output hot CVT fluid NS-2 flowing to the radiator for cooling, and the other is the return hose back with the NS-2 slightly lower temp.
Again, Nissan is replacing CVTs by the thousands ... if not tens of thousands ...
Nissan extended the warranties on many of the cars.
It had been 5 years/60k miles. It was extended to 10 years/120k miles.
They know about the issues.
They even have a dedicated phone in center just to handle the CVT issues.
With your engine revving and you not getting the power output through the tranny, that would include anything from the torque converter all the way through the CVT to the diff.
Check your records to see if Nissan Customer Satisfaction mailed you the letter for the extended warranty for your car. There was a small tear-off sticker/card in the lower right of the letter to keep with the car for the eventualities.
Also, I'm getting it rescanned. ECU scan this time. I'll post what that reads when it's done.
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