RPM drops when the gas pedal off - Toyota Nation Forum : Toyota Car and Truck Forums

FSADIGHIAN · 03-05-2011, 06:12 PM

Hi,
I have a 1997 v6 Camry. I’m experiencing big RPM drops when I let the gas pedal off! For example when I drive 80KM (60MPH) RPM is about 2300. As I leave the gas pedal, RPM drops to 1500 and it makes annoying engine brake.
I washed throttle body and idle control valve but it still does the same thing.
It starts just after I replaced one of injectors. engine working smoth and has no weakness. So I’m wondering if I did a mistake.
I appreciate any guide.
Thanks

***fenixus*** · 03-05-2011, 06:32 PM

to me it sounds like transmission (automatic?) not shifting to overdrive or something among those lines.

pmesfun · 03-05-2011, 06:35 PM

Finally someone else who has this problem. subscribed.

carpetguy00 · 03-05-2011, 09:31 PM

ive noticed mine doing this. and you dont have to completely let off the gas. it is irritating. and my iac, tb, maf is clean as hell.

pmesfun · 03-05-2011, 09:42 PM

Feels good not be alone.

Same here everything is clean as a whistle. Intake manifold, plenum, throttle body, junkyard iacv is mirror finish clean.

I definitely think something needs adjustment. hmmm I will mention this to my auto tech instructor on Monday.

Here is a video I made a while back, if you guys are talking about the same problem.

Skip to 1:25 to see when it happens:

You Tube

carpetguy00 · 03-06-2011, 08:45 AM

that is exactly what mine does! tho i dont think the rpms fall that far that quickly. are u driving a v6? cuz mine takes much more power to take off.

Maybe the car was driven fast the 90k before i had it. If you get on the pedal taking off, it revs much higher and seems to shift smoother. But if u drive gently like i do, does seem to shift harder. I have noticed after a good run of the freeway, the shift smooths out. still scratching my head.

FSADIGHIAN · 03-06-2011, 09:29 AM

I have auto transmission. The gear changes is ok while acceleration. But I feel jerking as the RPM drops, it may does a gear down, because when I hit the gas pedal again I feel a little shock like when it change the gear. Is the any way to monitor the engaged gear while driving?
My understanding is Idle air valve compensate the throttle while cold start. Does it handle drive cycles too? Is there any other valve to be able change the RPM while drive? I thought maybe one of those stucked?

pmesfun · 03-06-2011, 11:05 AM

Quote:

Originally Posted by carpetguy00

that is exactly what mine does! tho i dont think the rpms fall that far that quickly. are u driving a v6? cuz mine takes much more power to take off.

Maybe the car was driven fast the 90k before i had it. If you get on the pedal taking off, it revs much higher and seems to shift smoother. But if u drive gently like i do, does seem to shift harder. I have noticed after a good run of the freeway, the shift smooths out. still scratching my head.

Yeah its the V6. The transmission used to shift a little rough at higher rpms but after fluid changes it is very smooth in every gear.
I don't know what is causing it, something to do with the throttle wire or kick down cable. I think its something in the throttle body area.

Quote:

Originally Posted by FSADIGHIAN

have auto transmission. The gear changes is ok while acceleration. But I feel jerking as the RPM drops, it may does a gear down, because when I hit the gas pedal again I feel a little shock like when it change the gear. Is the any way to monitor the engaged gear while driving?
My understanding is Idle air valve compensate the throttle while cold start. Does it handle drive cycles too? Is there any other valve to be able change the RPM while drive? I thought maybe one of those stucked?

I feel a pull back when letting off the gas, when driving on the highway. This rpm drop only happens at 45 mph or above. It even happens when the engine is cold and I'm driving 45mph or above, but it will happen in 3rd and surge between 2200 and 1800rpm. I am clueless as to what the problem is.

***Silent Runner*** · 03-06-2011, 04:48 PM

Auuurrrrrg!

I believe this one was just thrashed a month or so ago by 71'Corrolla and many others. I think this is normal for the car with an auto transmission. I has a very loose (high stall) torque converter. (around 2000-2200rpm stall). In higher gears, when the lockup in not engaged, but is close to doing so, the rpm can slop around alot from "on throttle" to "off throttle". If you are experiencing alot of drivetrain shock from this, it may be because the transaxle shock absorber is shot. I don't know why it does'nt seem to do this in 1st and 2nd gear, though. Perhaps fluid pressures are maintained at higher levels and the converter slips less, or maybe the clutch system is different in 3rd and 4th gear. All I know for sure is that I have a relatively new, actually new transmission replaced in 2008, with 40K Km. on it now that does the same thing.

71Corolla · 03-06-2011, 05:11 PM

Quote:

Originally Posted by Silent Runner

All I know for sure is that I have a relatively new, actually new teransmission replaced in 2008, with 40K Km. on it now that does the same thing.

Did the tranny show this behaviour when new? But yea we hashed this out pretty good, I tried all kinds of things but nothing made even the slightest difference (except a bad TPS which amplified things).

I have found that this is engine temperature related, if the engine is not fully warm, doesn't happen. So that leads me to believe it is a programming "issue" and not strictly mechanical.

pmesfun · 03-06-2011, 05:43 PM

I will ask my teacher and see what he thinks. I know for a fact this isn't normal, because this started happening recently. Even my dad noticed it when he drove it one day.