1999 Mitsubishi Eclipse Engine missing, check engine light

Tiny
QUENTIN24
  • MEMBER
  • 1999 MITSUBISHI ECLIPSE
  • 4 CYL
  • 2WD
  • MANUAL
  • 238,000 MILES
99 mitsubishi eclipse, 2.0, non-turbo, manual transmission, 238,000 miles, have owned it since new and taken very good care of it. Intermittent missing problem. Sometimes the check engine light flashes on and off, but I feel no engine miss at all. Other times it misses badly, but then stops after I pull over. Sometimes the check engine light stays on, other times it does not. I have changed the plugs and wires twice. A shop replaced the coil twice. I was told it might be the ECM. I bought a used ECM and put it in myself, but the problem immediately continued. I've never changed the rings or head gasket. Trying to decide if it's worth it to keep spending money, or bail to a new car. Thanks!
Do you
have the same problem?
Yes
No
Tuesday, June 3rd, 2008 AT 9:42 AM

5 Replies

Tiny
KHLOW2008
  • EXPERT
Hi quentin24,

If the check light flashes, then there should be some code stored in the ECU. Have you done a diagnostic check on it? If none is found, get the diagnostic done after the check flashes without stopping the engine. Some codes are not stored in memory after the ignition is switched off.

Don't think is anything to do with the rings or head gasket.
Was this
answer
helpful?
Yes
No
Tuesday, June 3rd, 2008 AT 10:52 AM
Tiny
QUENTIN24
  • MEMBER
Hi there. Yes, I forgot some information. I have had the codes checked, and it has generically pointed to misfiring on cylinder 3. My mechanic did some wire switching to make sure it wasn't a plug or wire, but the second occurence was also cylinder 3. At this point, he was fairly convinced it was the ECM because of how good the car ran when it was "not" missing. Also, he was driving it during one of the "cel flashing" episodes, and concluded that at that moment the car was running perfect - not missing at all. Of course, at other times it does miss - badly.

I should also mention that about 8 months ago, or slightly more, I had an O2 sensor fail and replaced it. That one was properly diagnosed with the engine light code.
Was this
answer
helpful?
Yes
No
Tuesday, June 3rd, 2008 AT 11:20 AM
Tiny
KHLOW2008
  • EXPERT
Hi quentin24,

Since it is an intermittent problem, The ECU could be faulty but a loose or insecure wire connector or internally broken wires can cause the problem.
Was this
answer
helpful?
Yes
No
Wednesday, June 4th, 2008 AT 8:48 AM
Tiny
QUENTIN24
  • MEMBER
Thank you. Since I've already replaced the ECU, I guess it's on to the wires now? I'm, unfortunately, very inexperienced in this area. Am I right in saying that I'd need to replace the wiring harness next? Is this a job that a semi-amateur like myself could attempt? Am I even saying any of this correctly? :)

thanks!
Was this
answer
helpful?
Yes
No
Wednesday, June 4th, 2008 AT 4:16 PM
Tiny
KHLOW2008
  • EXPERT
Hi quentin24,

It is not necessary to have the whole harness replaced unless you can see bad damages at many places.

Since the misfiring is from the 3rd cyliinder, then you need to check the wire from the ECU to the coil.

If you understand the basic principles of electrical circuit, it is possible to DIY but might be quite tedious.

Just start from the coil and check backwards to the ECM.

Having a wiring diagram would be much easier.
Was this
answer
helpful?
Yes
No
Thursday, June 5th, 2008 AT 6:20 AM

Please login or register to post a reply.

Related Check Engine Light Content

Is it Safe to Drive Check Engine Light
VIDEO

Recommended Guides