1999 Dodge Intrepid Intrepid is Possessed

Tiny
HEWAD
  • MEMBER
  • 1999 DODGE INTREPID
  • 6 CYL
  • FWD
  • AUTOMATIC
  • 200,000 MILES
I have a 99 Dodge Intrepid, currently with a 3.2L engine. It started life as a sludgey 2.7 that I had to switch out. For the past two years, if the temperature drops below 40F, it will die once and can usually be restarted. When it does this some very strange things occur. The tach bounces wildly like it's possessed. You can audibly hear every fuel injector being fired like crazy and the purge valve is being activated in unison with the fuel injectors. Sometimes it blows one of the fuses but at this point I'm not sure which one. All this will be happening if you leave the ignition in the run position. After you turn the key to the off position you have to wait a couple of minutes as the engine will be locked up from raw fuel in the cylinders. After it restarts, it runs perfectly fine again, until the next cold morning. I live in Houston, TX so this only happens a few times a year. My daughter now drives the car and I don't want her driving it like this.
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Wednesday, November 25th, 2009 AT 11:13 AM

4 Replies

Tiny
MERLIN2021
  • EXPERT
Sounds like a PCM problem, check PCM grounds, If OK it may need a trip to Chrysler to do a reflash!
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Wednesday, November 25th, 2009 AT 3:03 PM
Tiny
HEWAD
  • MEMBER
I really doubt it. I'm using the same PCM as was in the 2.7L. I never had this problem until I switched out the engine. There have literally been thousands of folks who have done this swap and use the exisiting 2.7L PCM without issue. There is some sensor on the 3.2L engine that is malfunctioning. What's your best guess as to which one?

Some additional information that I didn't include. It only does this after it's warmed up for a couple of minutes. It happens at the same engine temperature every time. I know because it will almost always die in front of a Starbucks on the way to the kids school. Given that I take the same route and have similar traffic flows, the engine temperature should be consistent. It seems to happen when switching from open to closed fuel injection emissions control.
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Wednesday, November 25th, 2009 AT 3:30 PM
Tiny
MERLIN2021
  • EXPERT
Just so you know, 2.7 and 3.5 engenes may run on the same PCM, but they have different calibrations and different parameters, PCM reflashing is COMMON to fix drivability issues, even on cars that have NOT had engine swaps! If MIL is on, have the codes read with a scantool, Autozone does it free. PCM Controls more on Chryslers than on other makes. Charging system for one! One problem that does come to mind is it sounds like it happens when the PCM goes from closed loop(cold operation) to open loop(warm operation) This is when the 02 sensors come online, if you swapped engines because of a blown head gasket, it may have a bad 02 sensor or two, here's why:
All types of O2 sensors can also be contaminated by silicone from coolant leaks inside the engine (blown head gasket or cracked head), and by phosphorus from burning oil (worn valve guides, rings & cylinders).
If you suspect an O2 sensor problem, the first thing you should do is check for any codes that would implicate the sensor circuit. A code by itself doesn't necessarily mean the O2 sensor is bad, however. It might be a wiring problem or something else. So always check the operation of the sensor to see if is is functioning properly before you replace it. If there are no codes, that doesn't necessarily mean the O2 sensor is okay. In many instances, a sluggish O2 sensor may not be bad enough to set a fault code but will still cause an emissions or drivability problem. According to one California study, 70% of all fuel-injectedvehicles that failed the state's emissions test failed because they had bad O2 sensors. Yet few of these vehicles had check engine lights or fault codes that indicated a faulty O2 sensor.
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Thursday, November 26th, 2009 AT 4:54 AM
Tiny
HEWAD
  • MEMBER
Thanks Merlin2021,

It passed emissions just two months ago with almost perfect readings. It throws no codes. I have an ELM327 hooked to my laptop. It gives real time readout of all sensors. All are within specs for new sensors. That's why I'm asking the question. Unless somebody actually has dealt with this before, diagnostics aren't going to help. I hate just throwing parts at something but I may be in that boat. I understand about PCM reflashing but this really isn't a driveability issue like poor performance or stalling at a light. After an episode it runs perfectly. Thanks for your time and input.
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Thursday, November 26th, 2009 AT 8:53 PM

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