1991 Chrysler New Yorker Second Mile stalling

Tiny
INTERNET
  • MEMBER
  • 1991 CHRYSLER NEW YORKER
  • 130,000 MILES
The car starts fine.
After it starts to warm up, after about 2 miles it begins to buck, back fire, idle very rough, tries to stall.
As I continue, after another mile and it is fully warmed, it runs great.
If I shut down and wait several hours the same routine happens.
Most sensors and items that affect fuel/air mixture have been replaced.
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Tuesday, October 29th, 2013 AT 3:21 PM

3 Replies

Tiny
CARADIODOC
  • EXPERT
Really need to know the engine size when discussing an engine running problem. For this model the 3.3L was the most common one. Backfiring under acceleration was a common problem caused by the original spark plug wires. Replace those if they haven't been already. The MAP sensor has the biggest say in how much fuel enters the engine. Typically they fail within a day resulting in a no-start condition, but at first they can report the wrong vacuum reading resulting in a lean condition and misfires. Check for cracks or other leaks in the vacuum hose going to that sensor.

The 3.3L uses a crankshaft position sensor that has a critical air gap. If it is removed, a paper spacer is needed to set the gap when it is reinstalled. The wrong gap can cause backfiring, intermittent stalling, or a no-start condition. The same symptoms can occur when it is starting to fail, although they most commonly fail by becoming heat-sensitive. The typical complaint is the engine runs fine until it is stopped, then it won't restart minutes later. That's due to "hot-soak" where the engine heat migrates up to the sensor. It will work again and the engine will start after it has cooled down for an hour.

The first thing to do is check for diagnostic fault codes. Chrysler makes that real easy to do yourself. Cycle the ignition switch from "off" to "run" three times within five seconds without cranking the engine, leave it in "run", then count the flashes of the Check Engine light. The first group of flashes is for the first digit, then there's a short pause, then the flashes for the second digit. Additional codes will flash the same way after a longer pause. If you miscount, turn the ignition switch off and back on once to start the sequence over. The last code will be "55" meaning "end of message".

If there are no diagnostic fault codes you might suspect a plugged pickup screen in the gas tank. Driving with a fuel pressure gauge connected will show an excessive drop in pressure, typically during coasting when the largest volume of fuel has to go through that screen.

Another approach is to connect a scanner to view live data on a test drive. That will allow you to see what the various sensors are reporting when the problem occurs.
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Tuesday, October 29th, 2013 AT 4:24 PM
Tiny
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It's a 3.3L V6 engine.
Spark plug wires are newly replaced.
The MAP sensor is being replaced tomorrow. It was replaced several years ago.
The crankshaft sensor was replaced a couple of weeks ago.
The oxygen sensor was replaced last week.
The fault codes are: 35 62

Most of the work on my car is done by a trusted mechanic who has been stumped by this for a long time.

Several weeks ago my local Chrysler dealer had it for two weeks trying to figure it out and they replaced the crankshaft sensor.

If the MAP sensor doesn't cure it we will go for a new computer which it had a couple of years ago.

Most mechanics don't catch what I am saying in that the PROBLEM ONLY OCCURS WHEN THE ENGINE IS PARTIALLY WARMED! NOT WHEN COLD AND NOT WHEN HOT!

I have been dealing with this problem for a couple of years on and off, mostly on. It is dangerous to leave home and go straight to the open highway. I have to let it have it's fit on side roads first. Once it passes you can run all day long without any problem.

Do you have a solution?
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Tuesday, October 29th, 2013 AT 5:04 PM
Tiny
CARADIODOC
  • EXPERT
Another approach is to connect a scanner to view live data on a test drive. That will allow you to see what the various sensors are reporting when the problem occurs. Most scanners have a record function that allows a few seconds of sensor data to be recorded. You drive with it connected, then push the button when the problem occurs. Because that data passes through the scanner's memory, the recording actually starts a couple of seconds before you pressed the button. You can replay that data later to see frame by frame what each sensor reported to get a clue of where to start looking.

The Engine Computer is definitely the very last thing to even think about until every other possible cause is eliminated. Chrysler had almost no problems with theirs in the early to mid '90s. Everyone likes to jump on the computer when they don't know what else to do and they need something to blame.

35 - Radiator fan control relay circuit, open or short detected.
62 - EMR mileage not stored.

Neither of these codes refer to something that can cause stalling or backfiring. Code 35 usually is set by a mechanic unplugging something while the ignition switch is on. Code 62 refers to the emissions maintenance reminder light. That code shouldn't even be able to set on a car. It's is related to truck emissions systems which included minivans. It's possible you have the wrong computer in your car. The 3.3L was used in minivans starting in '89. In '92 they began using a Body Computer that knew the vehicle's mileage and sent that information to the Engine Computer so it would know when to turn on the "Maintenance Required" light on the dash. If you have a '92 minivan computer, it would be waiting to learn the mileage, and it set code 62 when that information isn't showing up. Neither of those codes should turn on the Check Engine light because they don't relate to something that could adversely affect emissions.

If you still haven't found any clues by this point, the cause is very likely related to the fuel supply system. That is not monitored so there's no related fault codes, but if a problem gets bad enough you could get a code as a result of a pressure problem. Typically that would be "running lean too long. That plugged screen in the gas tank could do that. I've been driving for over a year with a fuel gauge strapped to my radio antenna on my daily driver '88 Grand Caravan. I was chasing an intermittent problem that only acted up on real hot days. It turned out to be an overheated terminal on the fuel pump motor, AND the plugged screen, for the second time in that van's life. This system runs around 45 to 50 pounds of pressure. When the problem occurred, usually when pulling a really big tandem axle enclosed trailer, the engine still ran fine as low as 20 pounds. At 15 pounds it finally started to sputter and stall. Some GM engines won't even start if the fuel pressure is five pounds low. One big reason I'm leaning toward a fuel supply problem is a sensor or computer that is failing will not take a year to do so. They can fail intermittently at first under always the same conditions, coolant temperature in your case, but eventually it will become a hard failure which is easier to find. A plugged pickup screen CAN continue to present the same symptoms for a long time. They don't usually really become plugged. They collapse from the force of the fuel being drawn through them and that blocks the opening in the supply tube. They cause stalling typically after 5 to 15 minutes of driving, and it shows up when the largest volume of fuel is being pumped, which is during coasting, but the symptoms don't go away if you keep on driving. That's the only thing you described that doesn't fit with my pickup screen story.
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Monday, November 4th, 2013 AT 1:24 AM

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