Car is a 1993 240 with automatic transmission. New problem: in sub-freezing temps, when braking hard from cruising speed toward stop sign, after coming to stop the engine majorly lopes/surges for at least 5 seconds before slow idle levels out. Kind of like punching the accelerator while slamming the brake pedal every second or so. Anybody else living in cold climate (like Minnesota has) ever experienced this? What might be going on thats causing this?

Thanks all for the good suggestions. TB has been cleaned within past year, but not the IAC. Will take care of this and see if it makes a difference. Marty, my car generates the same hissing as yours.....but I had assumed it may have been originating from the braking system. Your diagnosis seems much more logical, i.e. a vacuum leak. I have also noted a slight hiss when depressing the heat and defrost buttons. So, could well be there is one or more vacuum leaks behind the dash causing problems...but, they will have to wait until the weather warms again (June!) and I have some extra time to pull the dash apart. Once in there, may as well be proactive and go further by replacing the blower and heater core, too.....not that they need it yet, but at 166K it may not be long before they do.

A year between TB cleanings may be too long it just depends on the car. Also check for proper operation and setting for the throttle position switch.
A quick and easy TB cleaning is to wipe the TB bore with a rag and TB cleaner. Not the best way but you can tell if it is good or bad.

Dan

Thanks Dan. Will give it a fresh cleaning and see if it makes a difference. In the past, I've managed to get along fine for a much longer period before cleaning, but it's not a difficult job to do more often. Have you any information to share on the possibility of leaking vacuum lines being to blame for the loping problem after sharp braking and coming to a stop?

Hi again Daryl,

Not to argue with you but I wouldn't make a project out of the heater core and blower motor until I have to - and I have had to. Never done the heater core, however, but the blower motor isn't something I'd recommend replacing pro-actively.

I bet our prob is a leak in the vacuum system. The only thing I would like to have answered would be in what way does the vacuum system influence the throttle, where a leak in the ventilation actuators (under the dash somewhere) is the likely cause.

Hope you understand what I'm asking. I barely do!

Marty

Hey Marty,
After getting lost in the mail, my new tan carpet finally arrived this week! It was ordered in August!! Anyway, the 245 interior has been completely stripped out for some time(seats, old carpet, plastic panels, front of dash), with only a couple more hours at most to remove the remaining dash parts. Being that close already, it seems to me I may as well go for it. We had a cold snap of -15F about a month ago, at which time the blower was squealing until the inside temp was up to 50F. So, it probably won't be all that much longer anyway before I'd be forced to do the job.

I've done a heater control a couple of years back. Now, that was one miserable undertaking, as most everything was in the way of getting it back up in place, to mention getting it out too. Lying upside down, feet over seatback, head jammed between floorboard and underside of dash for three hours.....haven't had that many bloody knuckles at one time, ever. With that contortionistic episode to compare with, doing the blower and core can't possibly be much worse. Actually, with the dash out of the way, it might be easier.

Yep, we need to hear from another forum member who has some more experience with the vacuum lines backside of the dash. You may well be correct in assuming they may be the cause of the loping after hard braking.

Daryl

A frequent cause of vacuum hissing under the dash is a bad vacuum check valve, located at top of intake manifold. It's white nylon with black rubber fittings.

One guy posting here fixed his by cleaning it.
I replaced mine with one from a junker.

--
Sven: '89 245 NA, 951 ECU, expanded air dam, forward belly pan reaches oem belly pan, airbox heater upgraded, E-fan, 205/65-15 at 50 psi, IPD sways, no a/c-p/s belt, E-Codes, amber front corner reflectors, aero front face, quad horns, tach, small clock.

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Hi Daryl,

My green 93 w/ 151K runs very well, but exhibits the same symptoms you've indicated. With hard braking, the idle fluctuates from about 500 to 1200 rpm for about 5 sec before it smooths out. It almost seems like the car might stall, but it never does. It only happens when I drive the car, with some hard braking since my wife drives like a LOL. Car doesn't do this any other time and I had cleaned the IAC and throttle body last Feb about 10K ago.

However, I do hear a slight whistle from under the instrument cluster during this hard braking, so I presume there must be a vacuum leak creating this prob that I need to investigate.

Marty

I agree with cleaning the throttle body as a great place to start. My 1992 240 had similar idle symptoms last month. I cleaned the throttle body and the problem was resolved.

Best wishes.

13

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This one may be out there a bit, but a co-worker's Toyota experienced this problem. Turned out to be a crack in the flex pipe between the TB and the AMM.

Beyond that, try squirting a bit of cleaner/lube into the IAC valve see if that helps. From there, how about a TB cleaning.

jorrell

--
92 245 250K miles, IPD'd to the hilt, 06 XC70, 00 Eclipse custom Turbo setup...currently taking names and kicking reputations!

I would clean the IAC valve with the TB. The gunk in the IAC may be sticking at cold temps. Of course I'm in FL and don't care about cold. Except next week it is predicted to be in the 30's. Dan

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