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I’ve searched the forum and haven’t been able to find any posts that resemble the issue I’m having.
On March 30th, I drove down to Florida and I’m still here, returning at the end of the month. The drive down overall was ok, but I developed an issue whereby every time I had to get off the I75 to fill up for gas and stop at a stop sign or stop light. Upon light acceleration (I drive like a Grandma) I experience an intermittent and random drop in RPM when I reach speeds between 30 – 60 kmph (20-40 mph) . As I lightly accelerate from a stop the RPM gradually increase to over 2k, as it reaches it’s peak normally the rpm slowly decreases to between 1K-2K, but on some occasions, it just completely drops to idle, 600 RPM for a 1-2 seconds, almost feels like kit wants to stall but never does and then pops right back up to normal RPM. It’s not consistent, sometimes it does it, sometimes it doesn’t.
It happens more often when its hot outside, but I’m not able to force to happen. I even tried driving while holding my phone in video mode over the steering wheel, to record the event, but every time I pull out my phone, she’s fine. The moment I put my phone away, it’ll happen at some point.
Since I really don’t want this issue to get worse on the drive home later this month, I took it to a local Nissan Dealer to check out. They took the car in promptly at 9:00 a.m. and the mechanic had it until 4:00p.m. I described the issues and stressed that it only happens during light acceleration. If I accelerate moderately, its fine, if I accelerate more aggressively it’s fine, it’s only under light acceleration. He first checked to see if there were any codes and there was one for the CVT, P0868 – Fluid Pressure Low. He cleared the code then took the car for several test drives, he was out for almost an hour one time. Ater each test drive, no more codes, all clear. I’m of the opinion that the P0868 was generated when I had the transmission oil changed by y local dealer at home in February before making the trip and the tech didn’t clear the code at the time.
In short the dealer down here couldn’t duplicate the problem, nor generate the same code again. Their recommendation is the replace the CVT. But I’m 99.99% sure its not the CVT, because it functions perfectly fine under moderate acceleration or aggressive acceleration. I’m thinking it might be some sensor malfunctioning but don’t know what. It seems to happen on really hot and humid days.
I thought it might be the MAF sensor. Bought a can of MAF cleaner and cleaned it a few times, it seemed like it made a difference but after a few days, the issue came back. So then I visited the Parts department of the same dealer and bought a new MAF sensor. It seemed to work fine, but after a few days, the problem returned.
So I’m wondering if anyone has experienced this type of issue before and if so, what was the root cause and how did you fix it? I’m kinda limited as to what I can personally do, since I’m on vacation down here and don’t have my tools with me.
A pretty common source if an air leak is on the hose running along the back of the fkrewall on the passengers side to the pcv valve. This, or another intake leak, is where I would look first.
A pretty common source if an air leak is on the hose running along the back of the fkrewall on the passengers side to the pcv valve. This, or another intake leak, is where I would look first.
I popped the hood and looked k to see if I could find any hose that looked and/or felt deteriorated/cracked, couldn't find anything. I wanted to remove the engine cover, but like I said I didn't have any tools, then I remembered I had a very small Husky Allen Key set in my road bike pouch, so I grabbed it and lucky for me it had the right size Allen key 5mm. Once the cover was off, I visually examined and felt the underside of several hose pieces and some felt rough and/or fatigued where they connect. Then saw this one below.
I could probably buy some hose at a local Advanced Auto Parts and replace it myself, but I 'm wondering if it's worthwhile calling the dealer I brought the car to the 1st time to perform a vacuum test and not only replace the aforementioned hose, but detect it there are others.
I'll let you know how it goes. Hole in the vacuum hose.
Well, visited the dealer. they wanted $185.00 to perform the vacuum test. I decided to hold off on the test and just replace the cracked hose for now. Visited the Parts Dept and was told I'd have to buy the whole roll for $125.00, forget that. Visited Advance Auto Parts, they don't carry the right, size. Popped into Harbor Freight, but they don't carry hose period. So for the time being, I pulled off the cracked hose from the broke end, tore off the last inch were it was cracked and reinserted the hose, there was enough slack to do that. Temporary fix until I can find the right sized vacuum hose somewhere.
Do you or does anyone know what the I.D. and O.D. is by any chance?
While I was at it, I noticed I'm going to need to replace the top engine/vibration mount, It's cracked and explains the period vibration and clunking sound I here.
I was finally able to locate some vacuum hoser at O’Reilly’s Auto Parts. They seem to be the only ones to have the right size in stock (5/32”). Once I got back to where I was staying, I started to replace some fatigued pieces. Hose #1 in the pic below was the 1st piece I replaced. But once I took the new hose out of the package, I noticed it’s much softer to pinch than the OEM hose. I’m not sure if that is going to create any issues. I noticed the bottom end of the long tube easily slid off the port it connects to, so put a zip tie on it. I’m not too happy with this new hose for that reason. So, I took the OEM long hose I removed and cut it into the necessary lengths to replace #2, #3 and #4. All the other hoses looked ok. Took it for a test drive and although it’s too early to tell, car seems to run smoother, quieter. Or maybe its just in my head. The true test is going to be when I drive back to Canada at the end of the month. I’m post an update then if not sooner
I thought I’d provide an update. After replacing some hoses with the new hose I purchased from O’Reilly’s in Florida, I noticed a difference while there and on the drive back home to Canada. The issue still intermittently occurred but was notably less severe. When it happens, the RPMs doesn’t drop as fast as before, it’s a bit more subtle and no longer drops to 600rpm, it drops to 900-1000rpm. So, I think we’re on the right track with the vacuum system being the root cause.
Once I returned home, I took my Maxima to my dealer to have the oil changed, I also mentioned the issue and asked them to perform a vacuum test. They were hesitant and wanted to perform a diagnostic instead, but I told them it’s intermittent and they likely won’t experience it when they take the car for a test drive. Long story short, they weren’t able to experience the issue and therefore didn’t charge for the diagnostic. They were adamant that if there was a vacuum leak, it would throw a code. I know it didn’t in my case because the dealer in Ft. Lauderdale didn’t see any codes and that was before I changed the hose with the hole in it.
I wasn’t too happy with the O’Reilly hose I purchased in Florida, so I inquired with the Nissan parts dept. as to how much replacement hoses would cost. Unlike the US where I would have to buy the whole role for 125.00 USD, here in Canada they sell each vacuum piece separately. The price for the short 4” pieces (for which there are 4) was $176.15 EACH! Freaking ridiculous! So, I purchased some new vacuum hose from Amazon, one that had a thicker wall, closer to that of the OEM and it was offered in colors, so I said what the hey…
I replaced all the 5/32” I.D. lines, including one just inside the rad at the bottom which went into some kind of canister. Again, these new lines made a notable difference, the issue still exists, but it’s very subtle. Unless you’re use to hearing/feeling it, someone sitting in the car wouldn’t likely notice. So, the fact these new lines made another improvement tells me we’re still on the right track. Now I’m looking into how to perform my own Vacuum Smoke test.
Been watching several DIY Vacuum Smoke Test videos on YouTube, but the vids are on different vehicles, so I don’t know where to insert the hose to perform the test? Can someone tell me where the vacuum port is so I can insert the hose to perform a vacuum smoke test?
Thanks
After finding a couple more YouTube videos, I learned where the vacuum port was. The guy in the video I watched said to remove the valve insert from the port, then insert your hose from your smoke machine. I was unable to remove the valve insert, so I removed the ½” hose going into the port housing and connected my smoke tube directly to the inlet of the vacuum port housing.
I started pushing smoke but didn’t see any leaks anywhere. I wanted to be sure pushing smoke through this port was working properly so I disconnected one vacuum hose, see illustration below, expecting to see smoke come out, but nothing. So, as it stands now, I still can’t confirm that I’m leak free, if I can’t see the smoke traverse the system?
Does anyone know if it matters what direction I push the smoke? I was pushing it in toward the vacuum port, maybe I should push it the other way? Does it matter?
I also found a YouTube video that illustrated how to test the two solenoids, they tested ok.
Anyone have experience with Vacuum testing?
Last edited by smeegle; 06-18-2024 at 10:17 AM.
Reason: typo's
Another Update:
I have yet to be able to test for vacuum leaks myself. Reason being, from what I gather online, in order to successfully perform the test, the Vacuum Valve in the Vapor Cannister needs to be closed when performing the test becuase its usually in a open position. From that I understand, some diagnostics tools can trigger it closed, but I don't that those expensive tools. Having said that, I also read that, that valve will open/close depending on the driving condition, I came across a procedure which listed step by step on how to test it, unfortunately I didn't save the link and now can't find it. But in essence I was supposed to drive the car for 10 minutes up to 60km/h with multiple stops in between, then drive on the HWY @ 90 km/h for another 10 minutes. I did this while I had my car connected to the diagnostics software I have to monitor the EVAP system. Initially the status showed fail, but after driving the car as described, the status changed to PASS, so I felt better, but would still like to perform a smoke test if I could.
A few days, later, I was driving up the HWY and got off at an exit, as I pulled to a stop at the lights, all of a sudden, loss of power, dashboard lights lit up like a Christmas tree. Car felt like it was in limp mode, couldn't drive more than 10 kmh. I pulled off the road and turned off the ignition. I waited a few minutes and then when I tried to start the car, it was completely dead, had to have it towed to my dealer. Following day, they diagnosed that the alternator failed and it also killed my battery. I had the alternator replaced in 2021, it only had 35,000 km on it (hardly drove during Covid time), but given it was over the 1 year expiry, I was screwed. The alternator was the first part I replaced that was "Nissan Refurbished", it was cheaper and carried the same warranty, so I said what the hey and went with it. Lesson learned, this time brand new OEM Nissan Alternator and fortunately for me, the battery was still under warranty, so it was replaced free of charge.
I thought the failing alternator may have contributed to my Intermittent and Random RPM drop issue, but it's been almost 3 weeks now and the condition is still there, albeit much less severe. So I'm still at odds as to what the root cause is. If I come across anything new, I'll be sure to post another update.
Only other thing to check is to look for the "green crusties" on your electrical connections/grounds. These can cause intermittent issues as well (sorry i didnt have you check this before but I read Ft Lauderdale and missed Canada.) We dont see much green corrosion here in Fl but it is very prevalent up north where salt is used on the roads.
Thanks for the reply LTLeary, Yes, green crusty connections was one of the things I looked for. I always make sure my battery terminals are clean and rust proof the everywhere almost every year. So that's in check.
I'm experimenting with the diagnostic tool I have, trying to configure the logging with parameters that might shed more light on the issue, I'm not a mechanic so I'm purely guessing what to capture so when it happens again, the data might help, Although this means I'll have to have my laptop setup in the car on days when I think the hot humid weather might trigger another occurrence.
05-13-2024, 04:34 AM
