shadyonedeath

iTrader: (10)

PROBLEM FIXED - see posts below





-Automatic trans


When I'm cruising, say at about 2500 rpm @ 40 mph, if i let go of the gas pedal, the RPM needle drops to 500 rpm and bounces back up.

Is this normal? The engine doesnt shutter or anything, it just drops the needle quickly and then it idles normally.

Shift_Nismo

iTrader: (9)

Mine does something similar, but only when idling for a little while, like while at a light. It will drop to about 450-400rpm, then pop right back up to normal. It only does it for a quick second, and I do feel a little vibration when it does, and then the vibration goes away when the idle returns to normal.

shadyonedeath

iTrader: (10)

that's not my situation.

FallenOne

iTrader: (17)

eh? Sounds awfully strange. Do you feel it kicking out of gear when this happens?

On Decel your tranny might drop gear and It could go close to Idle.

My RPM's take a serious Dip on Decel when im really braking hard, or when I tap the brake and coast.

mahanddeem

My previous 97 auto did the same thing all the time...I made a thread about it and didn't get an answer for it at that time.....Man I miss my 4th gen.

ImmaSquashYou

iTrader: (7)

mine did the same thing after my mechanic swapped a used tranny after mine was done. Not sure why it does it I sold the car to a buddy and she is still driving it. been like that for like 3 years.

jas1203

The only time mine drops that low is during heavy braking, otherwise it tends to idle a little under 800 RPMS.

I sometimes see it under 1000 while driving, if it kicks into OD at low speeds for instance. I wonder if anyone else has an auto that is as eager to go into overdrive as mine? I guess that helps my gas mileage anyway.

j-dawg

So what you're saying is, the needle drops, but the revs don't.

ImmaSquashYou

iTrader: (7)

if the op symptons were the same as mine. It happens at around 35-40 mph going from a dead stop only. Once you reach 35-40 mph, the rpm needles and engine rev drop to about 500 rpm, after a second or two, comes back up to where the rpm and mph match (ie. 35 mph should be like 2k) Its kind of like pushing in the clutch at 35-40, and then letting it back out. doesn't do anything, don't feel anything but you know thats what happened.

To the OP, i had previously told my mechanic when he changed out my tranny and said that there wasn't anything that was really wrong and he didn't know why either (he's a trusty mechanic and won't screw ppl over). the used tranny has now seen over 38k and is still running strong.

shadyonedeath

iTrader: (10)

No.

yes. similar. Maybe has something to do with low trans fluid? vacuum leak?

cashoit

Any codes? Any TCM codes?

Could be VSS, or bad connection in the instrument cluster.

shadyonedeath

iTrader: (10)

Negative. Code free, and O/D light doesn't do anything strange on startup besides flash once.


Ill get a video of it up tonight

DBear

Mine does something similar. Sometimes when I'm going downhill at freeway speeds, it will drop into neutral. The idle drops to 1000 or less, and if I give it gas I can feel it kick back into gear, so I know the tach is reading the engine speed correctly. Mine will also drop out of OD into 3d at inappropriate times, like with a light throttle going up a slight incline (and sometimes it will bounce back and forth). It's only an issue with OD, and I've taken to driving with OD off, which eliminates the problem.

My assumption has been that it has something to do with the torque converter, but I'm not going to replace that until the tranny goes. And I've had this problem for 6 or 7 years now. I'd love to find out that it's some sort of sensor, but I've replaced the TPS, which didn't help, and I'm not willing to drop a couple hundred bucks on a solenoid pack without some assurance that it will fix it.

maxed_out_99

Is your tb and iacv nice and squeaky clean

5150pa

Happened to me today, But I think our situations might have been different.

When it occured to me, I was acting a fool.

Were you OP?

maxfever1987

iTrader: (93)

this is been going on in my car for about 3 years, cleaning the tb and iacv is not the gonna do a thing, i changed over iacv and still the same thing going on, at arounf 40 mph you let go of the gas pedal and the car still runs proerly but the rpm will go to 4-500rpm and bounce back, i never understood why this happens

shadyonedeath

iTrader: (10)

Lower your volume.

Notes:
-Starts at acceleration from a stop
-Pedal is released when rpm's dip to 500rpm
-When RPM climbs to 1000, pedal is still released and the ECU/engine/whatever is picking itself up.
-Second acceleration is while moving
-Only happens city driving, not highway.

FallenOne

iTrader: (17)

Its kicking out of gear like its supposed to. Usually about a second after you drop throttle.

shadyonedeath

iTrader: (10)

So i have nothing to worry about.

maxed_out_99

I never even checked if my car does this I'm going to check it out on my way to work tomorrow

FallenOne

iTrader: (17)

Nope.

I can't recall where I found this but there was something posted on here with all of the Normal operating functions of the Auto Trans. I'm sure its in the FSM.

I will say, I do think its a bit strange that yours drops so harshly. But I know that when I am braking heavily for a moment Mine will do the same thing, I think its vacuum related?

cashoit

do any of u guys experience hard shiftin? Do u think its a bad DR?

Either that or shift solenoids.

defiance

iTrader: (1)

RPM's are most defiantly dropping to quick, it should be nice even and slow rpm drop when pedal is let go. Still your problem isnt as severe as mine was, not nearly.

Your IACV is either getting old (higher mileage) or its dirty and clogged, OR both. Might be time to replace it.

iDuty

If you were accelerating from a stop with OD turned on, then at 35mph the transmission is still in 3rd gear, and in 3rd gear with OD on it is allowed to overrun when you let off the throttle, effectively acting like it is in neutral. So like others wrote, the engine speed dropped a bit too low before the computer used the IACV to bring it back to normal.

maxed_out_99

Ok so as I stated before I think your IACV is dirty I was on my way home today and from a dead stop to 40 mph slight throttle pressure to absolutely no throttle my needle does NOT move the max decelerates but the rpms stay the same

maxed_out_99

Usually bad DR would cause a o/d light
If I were you I would change my fluid

shadyonedeath

iTrader: (10)

my IACV is not dirty, it has less than 2000 miles installed. Thanks for the advice, ill have to check for vacuum leaks first before replacing anything.

FallenOne

iTrader: (17)

Well, for starters.. Do you flog and beat your tranny daily? Have you Ever changed the fluid? What color is it. Does it smell sweet? Does your battery give a good 12V and your Alt A good 14?

BTW their are updated shift solenoids available via Nissan.

Sounds reasonable.

Could be A vacuum leak I suppose..

Actually.. Heres an Idea..

Rev her up to 2K like you did in the Video and drop her into Neutral. See how low she can go.

maxed_out_99

is your thottlebody clean?

vqmaxman

I have been having the same issue as the most of you guys are as soon as I installed my new tranny, I had the p 1336 code and the knock sensor code I took care of that problem and thank god. I don't have a SES light since than so far, I have been noticing the RPMS are shooting up in the 2000 rpms when I am in the 60 MPH and going faster the RPMS are climbing up and stay up there in the 2500-3000 rpms that's when I am doing 60+. If I am slowing down to 40-35 MPH the RPMS will hover at the 1000-550 RPMS. I noticed my old trans had the VB mod one of the vavles were removed so the flow will be stronger into the VB. I used to be at the 1500 RPMS when I was 35-40 MPH and going up to 60 MPH+ speeds my car was constently at the 1500 RPMS. I think this has alot to do with the vb mods and If theres any doubt I think we should check IF the ECU are shot by the chance and the same for the shifting points on the TCM.

maxed_out_99

do you have any shifting concerns? hard shifting long shifts slipping?
if not your torque converter is prolly toast

shadyonedeath

iTrader: (10)

Problem was a vacuum leak in my oil catch can barb fittings. I used plumbers teflon tape instead of gas-line teflon, and it came loose/leaked.

Problem solved. No longer have cold starts, powers back to normal, no more dips.

defiance

iTrader: (1)

Oil catch can ?? I don't think I ever seen one of those ? What does this thing look like ..where is it located ?

iDuty

In this situation the transmission was in 4th gear and the torque converter clutch was engaged (TCC lock-up). In our transmission programming, in 4th gear the TCC remains engaged when you let off the throttle, so the engine speed does not drop, and you get engine braking. If you hit the brake pedal, however, the TCC disengages and engine speed drops.

As a side note, the TCC is not activated until the transmission warms up. This can take a few miles of driving, especially in cold weather.

madhat311

can you take a few pictures , i have a 07 and i have the exact same problem. i could use all the help i can get in resolving this

JvG

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