My car "lunges" forward at stop lights???
 

So this has been happening for a while now and I really don't know what's going on. When i'm stopped at a stop light, my car lunges forward, or the engine feels like it it shifting forward for a split second. Has this happened to anyone before? It is really quick, and it is annoying. Could it be the tensioner the recall is for? A bad motor mount? Please help.

is ur ac on when it does it?

Hey man that happens to me too. I have a 03 tl type s. But only when the air is on. Its the compresser kicking on and off.

what tensioner recall? the certain 03 timing belt ones?

The dropping pedal is usually the ac kicks on - causing momentary drop in vac pressure to the brake booster unit. Does it still hold the car stopped .. is the question!
Try it without the AC to confirm

If thats not it, and the pedal makes a gradual descent to the floor- think bad brake master cylinder
Many gen2s are old enough to need caliper overhaul or replacement - new master cyl- and of course my favorite- new brake fluid every year

hmm.. i never thought about the AC. is that just normal with the AC then? it is so annoying.

every car with power assist brakes does it- there is supposed to be a mechanical or computer slight rise in rpm when ac kicks on, so it compensates for the extra load and keeps the amount of vacuum right, then the vac powered brake booster works

^ Yeah ... the A/C is notorious to kick in/out and you feel the 'surge' when you're stopped at a light. That's "normal" but follow the advice 01tl4tl has provided. (He is a great wealth of info!) :thumbsup:

Yes, as 01tl4tl has said, when the AC kicks off, load on the motor decreases, vacuum increases and the pedal drops since it works off of vacuum.

Ideally, the computer is supposed to kick up the throttle the instant the compressor kicks on and lower the throttle the second it kicks off so you will never notice a fluctuation in the rpms but the timing of the two usually isn't so seamless.

My car willl actually rev slightly a split second before the compressor engages because the computer adds throttle just a hair before the compressor clutch engages.

I notice that too when I first got my car, I thought it was something wrong with the AC pump or something, and the car didn't expect that much of a drop in power. But ya say its normal then eh?

One other thing i notices, maybe its just me, but the car to seem to feel different with the AC on, and not shift as smooth either. Once again it feels like the car didn't take in account of the AC drawing some power away from engine, and over or under reving between shifts? Anyone else know what i mean? Only when the AC is on.

Any feedback on this?

I don't think it's the MC. I guess i'll just have to live with the 'surge'.

I plan on changing my pads and bleed the brakes this week. my pads are almost metal.

thanks guys.

I've got a similar problem. It's not the AC. Mine does it when it is cold out (below say 50 degrees or so) and only in the first 15 minutes of driving. When I'm at a stop and in Drive, it will give a little "surge" forward almost like you've got one foot on the brake, and one foot on the accelerator. I haven't figured out what it is yet and I've cleaned the egr, replaced the whole throttle body and IAC, spark plugs, etc.

Someone on an Odyssey forum mentioned they had the exact same problem and they replaced the speed sensor in the tranny. I have no idea how to test that sensor (ohm readings or something like that) since I don't have a real shop manual. Since it's all honda, I figure the Odyssey folks might be on to something.

I think this problem might be related: When i'm pulling away from a stop sometimes the car will simply stop reving up. I have my foot on the accelerator, but the car acts as if my foot is off the accelerator. If I push the accelerator down, the car will stumble and then jerk forward as the rpm's come back up quickly. If I keep my foot steady on the accelerator (neither pushing down or letting up) after 1 to 2 seconds the engine rpm's come back up and the car jerks ahead. Like I said, I don't have an Acura shop manual so I don't know how to test everything.

Anyway, there are a couple of other people on here that have the same problem, but nobody seems to have a solution. The AC jerking you forward is different than this issue. Good luck, and if you figure it out, please post the solution.

I've experienced the same sensations with my '03 TL-S and attributed it to the AC kicking on...never really thought there was an underlying problem, still don't...can't remember experiencing it any time the AC wasn't on...

Yeah, the AC jerk forward is different than the "surge" forward if Leo is having the same problem I am.

Your car actually moves forward?

Is stating the obvious - put more pressure on your brake pedal - to obvious?

If the brake pedal is sinking and keeps sinking- thats probably the Master Cylinder for the brakes has failed- its all just tiny orings holding the system together~
Failure to change the brake fluid can and does result in some expensive parts failing.

In cold temps you probably have the system on DEFROST- that turns the ac on!!!!~
As it dries the moisture inside the car from the air and takes the frost away,
It also causes the compressor to run and circulate its oil and fluid/gas process so it keeps itself lubricated during the off season....that protects ITS O rings seals and prevents leakage from the system :thumbsup:

since day one on my 2003!! USed to it now and always when A/C is on, not when off

acually the CL that I drive is the FIRST car that I have were it wants to lunge forward when the A/C kicks in..........I believe that it has to do with the ICV overcompensating for A/C drag.........

98 accord V6 never did it
94 accord I4 never did it
92 sables never did it
89 sables never did it


to keep the car from lunging forward apply MORE brake pressure after you come to a stop

I'm well aware of the AC jerk forward. Mine does that, too. The other lunge is different. I'm also well aware that the AC is on when defrost is on. I'm in MN, I spend half the year with the temperature hovering around freezing or well below and I spend a good amount of that time with defrost off.

For me, it only happens within the first 15 minutes or so of start up when the car is in Drive and it is at a stop. The brake pedal does not sink. For those of you familiar with RWD, the sensation is similar to one foot on the brake and one foot on the gas with the car in drive reving to race off the line. Other folks who have driven the car have commented on it, too. Since it doesn't throw a code, the Acura dealership couldn't figure it out.

I think it has to do with a part called the ELECTRONIC LOAD DETECTOR.
Check the amount of volts that the alternator is sending to the battery.
Hook up the volt meter semi permanently some where in the car so you can monitor, if there is any fluctuation in the voltage received by the battery. It should stay AROUND 14.5.

I think it has to do with a part called the ELECTRONIC LOAD DETECTOR.
Check the amount of volts that the alternator is sending to the battery.
Hook up the volt meter semi permanently some where in the car so you can monitor, if there is any fluctuation in the voltage received by the battery. It should stay AROUND 14.5.
My understanding of what this part does, is it senses a request for additional power e.g. in your case the fan in about to start the ELD is supposed to communicate this to the computer a little ahead of time, the computer will slowly increase engine rpm to compensate for this load.Now if this is not happening the alternator torque up to send the load causing the computer sense the load on the engine and and act accordingly.

I received my Helms Service Manual in the mail so I'll be going through everything with the ohm/volt-meter to make sure things are up to snuff. I'll keep everyone posted.

The same exact thing happens to my car acura tl 99. At first I thought it was the AC that was making it jerk forward. But since than the ac hasnt been on, and its still jerking and gotten worse. i havent drive the car since july 08. my brother who fixes cars, think its the transmission and said it needs to be replace for the second time. The transmission now was just replaced a year ago. how could it be????? HELP ME????

You guys are funny what what Montaigne problem is....is acutally the car idling high when it is cold your rpm is high because the car is cold and eventually by 15 mins when you are taking off your car warms up and rpm says low. The feel that you are getting is similar to what they are describing you should apply more pressure or warm up your car to the appropierate operating temperature