What makes a car die every time you slow down? It restarts pretty quick but dies every single time.

Tiny
SKSILVER
  • 1999 CHRYSLER SEBRING
  • 158 MILES

The timing belt broke so had to have heads redone. Now runs good but every time I slow down, it dies. Went to Oreilly's to have scanner tool run on it, but car wouldn't read it so checked the fuses but they are all good.

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Monday, June 11th, 2012 AT 1:38 PM

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Tiny
WRENCHTECH
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First eliminate all vacuum or air leaks in the system. You may have a bad IAC ( idle air control) but try cleaning the throttle body first. Remove the intake snorkel, have someone hold the throttle wide open for you and scrub the back side of the throttle plate and surrounding bore with an old tooth brush and some carb cleaner. Be sure to spray some into the small holes next to the throttle plate. That should help stabilize the idle. If it still has a problem, replace the IAC

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Monday, June 11th, 2012 AT 1:56 PM
Tiny
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Thank you, I will try that.

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Monday, June 11th, 2012 AT 2:00 PM
Tiny
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Hey guys. Excuse me for butting in but there's an easy fix for this one. Most likely the battery was disconnected when replacing the timing belt. That means the Engine Computer lost its memory and has to relearn "minimum throttle" before it will know when it has to be in control of idle speed. Until that happens you also won't get the nice idle flare-up to 1500 rpm at engine start up.

To meet the conditions for the relearn to take place, drive at highway speed with the engine warmed up, then coast for at least seven seconds without touching the brake or gas pedals.

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Monday, June 11th, 2012 AT 9:01 PM
Tiny
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Okay I'll try that but I drove 40 highway miles yesterday and it still did it and let it sit for 3 hours then drove it again in town and it still did it.I'm getting ready to try it today.

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Monday, June 11th, 2012 AT 11:16 PM
Tiny
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"coast for at least seven seconds without touching the brake or gas pedals".

That is not a normal driving condition except for leaving the highway on a long exit ramp or coasting down a long hill. That's why it's often necessary to consciously do it.

What Wrenchtech suggested can happen any time. What I suggested is most likely to occur right after some other service was performed that required the battery to be disconnected.

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Monday, June 11th, 2012 AT 11:43 PM
Tiny
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Thank you for your advice, I will definitely try it.

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Tuesday, June 12th, 2012 AT 4:23 PM
Tiny
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Another possibility is that the belt is out of time too, depending on how good it runs the rest of the time.

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Tuesday, June 12th, 2012 AT 4:35 PM
Tiny
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It runs pretty good rest of the time, but sometimes it acts like it's missing out. Sometimes it restarts on first try and sometimes it takes 2 or 3 times and sputters. We changed the IAC sensor and that seemed to help a little. We're going to check the fuel filter to see if it's clogged.

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Wednesday, June 13th, 2012 AT 5:06 AM
Tiny
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We think it also could be the throttle position sensor so we're going to check that too.

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Wednesday, June 13th, 2012 AT 5:09 AM
Tiny
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Except for diesel trucks you will never solve a running problem on a Chrysler product by replacing the fuel filter.

Are you guessing at the throttle position sensor? That's the most expensive and least effective way to diagnose a problem. They typically cause a hesitation on acceleration but the momentary dropout in its signal will be detected and a fault code will set in the Engine Computer. That will turn on the Check Engine light.

Sputtering and intermittent hard starting but it does start eventually, then run okay suggests a fuel supply problem but that is not the way Chrysler fuel pumps generally fail. A much more effective way to diagnose this kind of problem is to drive it with a scanner connected that can display and record live data. You press the "record" button when the problem occurs, then the scanner records a few seconds of sensor data. Since that data passes through the scanner's memory, the recording actually starts a couple of seconds before you pressed the button. Later the data can be viewed slowly to see if the Engine Computer reacted to a glitch in a sensor's signal, and you can see which sensors reacted to a change in operating conditions. Experienced mechanics can diagnose a lot with that information. The rest of us are just shooting in the dark and guessing. Every time we do that and install another new part, we introduce another new variable that the computer has to learn.

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Wednesday, June 13th, 2012 AT 5:29 AM
Tiny
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Every time I take my foot off the gas pedal it acts like it's either clogged or missing out and then dies. Doesn't matter how fast or slow I'm going. The plugs were new 3 months ago. We changed the IAC and that seemed to help for a little while. It's got plenty of gas and has been driven on hiway over 60 miles and in town. Still the same. Going to try the tps. Or erg maybe?

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Wednesday, June 13th, 2012 AT 7:08 PM
Tiny
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Tried the coasting suggestion. Didn't work.

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Wednesday, June 13th, 2012 AT 7:08 PM
Tiny
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I'll try to find a scanner but when I took it to oreilly's their scanner wouldn't even read it. And also the check engine light that has always been on, for 2 days it went out completely and now it's back on and 2 days ago before it went out it was flashing. And I read in the haynes something about maybe it being the catalytic converter.

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Wednesday, June 13th, 2012 AT 7:10 PM
Tiny
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A flashing Check Engine light is serious. That means way too much raw fuel is entering the exhaust system and is going to overheat and destroy the catalytic converter. More than likely whatever is causing the over-fueling is related to the stalling and poor running. You have a lot more going on than a need for a simple relearn after a battery disconnect. Absolutely do not disconnect the battery now because that will erase whatever diagnostic fault codes are stored in the Engine Computer, then that valuable information will be lost.

The MAP sensor has the biggest say in how much fuel enters the engine. As long as its signal voltage remains within the acceptable range it won't set a fault code, but it could report a wrong reading within that range. Typically these sensors don't take more than a day or two between working properly and total failure.

A single cylinder misfire will send unburned fuel and air into the exhaust system where only the oxygen will be detected by the oxygen sensor. The computer will interpret that as the mixture is too lean and it will command more fuel to go with that air. No matter how much extra fuel it requests, there will still be that unburned oxygen being detected. That will result in way too much fuel but that shouldn't cause a flashing Check Engine light because the computer isn't aware there is too much fuel going in already. The additional clue is you would be feeling the misfire as rough running and low power.

If the engine is running relatively smoothly, without a constant misfire, the flashing Check Engine light suggests too much fuel is entering the engine for some reason beyond the computer's control. Fuel pressure that is too high or a leaking fuel injector are the first things that come to mind. Chrysler has had extremely little trouble with their pressure regulators. I've only read about that twice so far but that was on an older system with the regulator on the fuel rail on the engine. Yours is on top of the gas tank. A fuel injector stuck open is another possibility although that would cause all the excess fuel to enter just one cylinder and should cause a noticeable misfire. Another clue to that is it would bleed off fuel pressure right after you stopped the engine. That would result in a real long crank time to get the engine started the next time.

Given the expense of replacing one or two catalytic converters and the potential for causing damage to them before you figure out the cause of the problem, this is probably one of those times when it's more cost-effective to see a mechanic. It's easy to tell you what WAS happening once we learn of the fix. It can take a lot of searching, time, and wasted money with the trial and error method.

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Wednesday, June 13th, 2012 AT 7:59 PM
Tiny
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Keep in mind Wrenchtech's earlier suggestion about rechecking the timing belt, especially if the stalling problem appeared right after that service. At just one tooth off, the engine can run somewhat respectably but it will be down on power, up on emissions, and it won't respond properly to the computer controls. Be sure to share that recent history with the mechanic so he doesn't have to search all over in vain while overlooking something simple.

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Wednesday, June 13th, 2012 AT 8:03 PM
Tiny
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Thank you.I just printed off your last 2 comments and I will talk to the guy who replaced the timing belt after the heads were redone and I'm just not going to drive it anymore. I was just able to put the scan tool on it and got a reading of PO 175 (system adaptive fuel too rich - bank 2) and the P0108 (MAP sensor).I know how to replace the MAP sensor but is that what is causing the PO 175?

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Wednesday, June 13th, 2012 AT 8:27 PM
Tiny
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The P108 means the MAP sensor voltage is too high. That sensor is fed with 5.0 volts and 0.2 volts on the ground wire. Roughly speaking, the acceptable limits for its signal voltage is 0.5 to 4.5 volts. Anything above 4.5 volts is a defective state and will set that code. There's a number of ways for that voltage to go too high. The ground wire could be open, meaning broken. The sensor itself could be failing. Rather than being a simple mechanical sensor like a throttle position sensor, the MAP sensor has electronic circuitry inside that can fail resulting in that 5.0 volt signal. Finally, just unplugging the MAP sensor while the ignition switch is on will set that code. When it's unplugged, the signal voltage could "float" to some random value due to the Engine Computer circuitry it's connected to, and to prevent that, they use a real simple "pull-up" circuit to force the signal voltage to go to a defective condition so it will be detected. That pull-up circuit has no effect when the sensor is properly connected. The point is, you can disregard that code if someone was working under the hood and had to unplug that sensor, but given the history, I'd sooner suspect a wiring problem with that sensor.

A simple test is to turn on the ignition switch, then measure the voltages on the three MAP sensor wires while it's still plugged in. Only one should have 5.0 volts. If you find it on two, check the connector terminals for corrosion and to be sure they aren't stretched out. Your mechanic will get the same information with a scanner that displays live data. It will list the MAP voltage and corresponding vacuum reading. With the engine not running, that voltage will typically be near 4.2 volts and represents barometric pressure. Once the engine is running, that voltage should be somewhere near 1.0 volt to maybe 1.5 volts. If it stays closer to 4.2 volts, that represents wide-open-throttle and will result in a lot of fuel being dumped into the engine.

Besides just looking for the correct voltage readings, experienced engine performance mechanics observe how the MAP and oxygen sensors respond to other conditions they create such as a small vacuum leak. Things like that help them diagnose what's working properly and what needs further attention. To you and me the engine might seem to be running fine but they might pick up on things that are less than ideal.

One point of interest is that only one side of the engine is running too rich. A defective MAP sensor reading will affect both sides of the engine equally. That suggests something other than, (or in addition to), a sensor problem is occurring. There is a tuning valve in the intake manifold that changes the length of the passages under certain driving conditions for better performance. That valve can cause a vacuum leak to affect one side of the engine more than the other side. That might explain why just one bank is affected. A misfire on just one cylinder will also affect that side of the engine only. Misfires can be subtle enough that we don't really feel them but the incomplete burning of the mixture results in unburned oxygen being detected by the oxygen sensor, telling the computer more fuel is needed for that entire side of the engine. The computer can determine which cylinder is misfiring by knowing the position of the crankshaft when its rotational speed slows down just a little. It's that same slowdown that causes us to feel a misfire. Since there hasn't been a misfire fault code set, that could suggest incomplete combustion instead of simply no combustion taking place in one or multiple cylinders. The result is the same; unburned oxygen detected in the exhaust system on one side of the engine.

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Wednesday, June 13th, 2012 AT 9:55 PM
Tiny
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Wow, that's a lot of information. Thank you very much.I've printed off all of your suggestions and will give them to the person working on it tomorrow. Thank you again.

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Thursday, June 14th, 2012 AT 1:42 AM

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