2001 CE 1.8l - will fault then idle with lead removed from one coil pack

J

Jenna

New Member
I have a 2001 CE 1.8l sedan (4G93) that has just started to spit the dummy with an intermittent issue.

Cold or hot, after 5 metres or 500kms, the engine will lose power slightly, followed by the check engine light coming on. The engine will idle really roughly. Turn car off. Wait 60 seconds. Start car. Check engine light is gone, car idles perfectly. You can then drive either another kilometre or 500km, at some point, it will do it again.

To try to self-diagnose what was causing the issue, when it faulted and idled roughly, I tried disconnecting one of the coil pack leads - engine kept idling. Plugged coil pack lead back in and removed the lead off the other coil pack and engine stopped. Replaced the first coil pack with brand new one. Car faulted again. Repeated test, replaced other coil pack as well. Car still faulted intermittently.

Mechanic then discovered my alternator was operating at around 17.5v instead of around 14 (I hope that makes sense) so replaced the alternator with an aftermarket new one. Then we put scan tool on. Reported a fault with the ignition (I can't remember what it was) but he cleared the fault and it didn't come back. Tested every cylinder in isolation. Could not find an issue.

Next step we were thinking of replacing the engine ECU ? There are a few second hand ones on ebay but then will we have to reprogram it and then also reprogram the ignition/key etc? Can anyone thing of something that could be causing it? I am scratching my head and I love my car. Most of the time!
 
I think whoever you are taking it too isn't trying too hard to diagnose the problem.

From what you described and what you have replaced or tested already.

  • it sounds to me like it could be a faulty cam position sensor (sounds like a textbook fault to me) if it's an intermittent fault vs a failure then it will not show as a fault code on a scanner, depending on voltage being sent may be too weak to reg as fault.
  • Wouldn't be tps sensor as that is more when you put your foot down and engine cuts out for a second then you back off and it comes good again, this happened to my ch recently, no fault code showed up as was not sending enough voltage to reg as fault, replaced to, then back to normal.
  • I would not rule out the crank angle sensor as well, if that was faulty depending if failure or intermittent fault, but it would be hard to start, stalling rough idle etc.
  • Only other thing I could think off is a partially blocked fuel filter asembly/line, if it's blocked it can give symptoms similar to a faulty tps sensor.
  • Also make sure that not oil is leaking at seals on valve cover near spark plugs, check fo discolouration on the white ceramic insulator on your plugs looking for any arcing burn marks from oil seepage.
I'd try the cam position sensor first, it's hard to dianose something without actually seeing it first, but I think it may have an intemittent fault and is causing the problems you are having, my code reader is only a cheap one, just under a 1k, but sometimes not all intermittent faults will reg as code fault, people depend on code readers sometimes too much and don't think though the problem old school way, best to use both methods though for best results.
 
Last edited:
Jenna said:
I have a 2001 CE 1.8l sedan (4G93) that has just started to spit the dummy with an intermittent issue.

Cold or hot, after 5 metres or 500kms, the engine will lose power slightly, followed by the check engine light coming on. The engine will idle really roughly. Turn car off. Wait 60 seconds. Start car. Check engine light is gone, car idles perfectly. You can then drive either another kilometre or 500km, at some point, it will do it again.

To try to self-diagnose what was causing the issue, when it faulted and idled roughly, I tried disconnecting one of the coil pack leads - engine kept idling. Plugged coil pack lead back in and removed the lead off the other coil pack and engine stopped. Replaced the first coil pack with brand new one. Car faulted again. Repeated test, replaced other coil pack as well. Car still faulted intermittently.

Mechanic then discovered my alternator was operating at around 17.5v instead of around 14 (I hope that makes sense) so replaced the alternator with an aftermarket new one. Then we put scan tool on. Reported a fault with the ignition (I can't remember what it was) but he cleared the fault and it didn't come back. Tested every cylinder in isolation. Could not find an issue.

Next step we were thinking of replacing the engine ECU ? There are a few second hand ones on ebay but then will we have to reprogram it and then also reprogram the ignition/key etc? Can anyone thing of something that could be causing it? I am scratching my head and I love my car. Most of the time!
Click to expand...

No you wont need to re-program the new ecu as long as its another 1.8 lancer ecu.
Is the alternator still putting out 17.5v after putting in the new one?
On the 1.8 lancer the ecu controls the alternator voltage.
 
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