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| EL__Fairmont |
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Had this problem for a while, basically at operating temp when the car is in drive/neutral/park at idle the engine will stumble at 1min 35sec intervals. The ISC then kicks in and picks up revs. Have used a stop watch and always exactly the same time.
Any idea's, i am thinking MAP sensor or ECU because they use timing circuits? Cheers.....
_________________ 97 EL Fairmont 4l OHC .Silver. Last edited by EL__Fairmont on Tue Aug 05, 2008 8:19 pm, edited 1 time in total. |
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| Masier |
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Purge from the fuel charcoal thingy??
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| EL__Fairmont |
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{USERNAME} wrote: Purge from the fuel charcoal thingy??
So this is normal to happen? All do i need to replace something. No petrol smells in cabin from a/c etc. So it must be working.
_________________ 97 EL Fairmont 4l OHC .Silver. |
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| s-tranzor |
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turn off your air conditioner?
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| Nigel |
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I think you'll find that the ECU is moving the engine into rich or lean territory, hence the stumbling. o2 Sensor, or Floating Earth would be normal problems. Also have you modified the engine at all?
Nigel |
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| EL__Fairmont |
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{USERNAME} wrote: I think you'll find that the ECU is moving the engine into rich or lean territory, hence the stumbling. o2 Sensor, or Floating Earth would be normal problems. Also have you modified the engine at all?
Nigel Yeah that actually makes sense! The engine internals are stock. Just got pacemakers, high flow cat, exhaust and intake mods. The 02 sensor was replaced about 40000km ago. It may have failed again? Although last time it failed the idle was really bad when coming too a stop, this is a bit different. Although similar. The engine at operating temp will idle perfect for about 1min 10secs then progressively get worse then stumble. ISC then picks up revs. And the process starts all over again. I have checked for vacuum leaks, tightened the bolts on the inlet manifold, checked the MAP sensor hose etc. What earths should I check- battery to block, engine to floor plan etc..? Cheers..
_________________ 97 EL Fairmont 4l OHC .Silver. |
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| Nigel |
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Id check all of them - battery to block, block to body, body to Battery.
And possibly also the ground for the ECU wherever it happens to be |
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| EL__Fairmont |
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Checked earths all good >1 ohm difference between block/battery and body/battery.
Ran error ecu code test. Engine on Test- Code 111 (All good) although the engine was stumbling Engine Off test- Memory Code 578 (ECU reference voltage low) What should I check, gregory's manual say it's to do with the auto box. Oxygen sensor is fine watching go from 0.8V-0.1V in the range. But just as the engine begins to stumble the oxygen sensor drops down to 0.1v and lower for about 10secs then the ISC cuts in, picks the engine revs up and it starts again at 0.85V and cycles through the range again. This repeats itself. So the ECU is switching from lean to rich mode. Any idea's Cheers
_________________ 97 EL Fairmont 4l OHC .Silver. |
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| EL__Fairmont |
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I have bumped up the base idle by 100rpm and replaced the fuel filter. It's now running sweet at idle. No more hickups.
New Post::: Bumping up the base idle was a bandaid solution, it's started too do it again a week later!! Cheers.........
_________________ 97 EL Fairmont 4l OHC .Silver. Last edited by EL__Fairmont on Sat Aug 02, 2008 9:54 pm, edited 1 time in total. |
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| EL__Fairmont |
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Started playing up again but it's now 2.10mins apart running 95 ron, injection cleaner and new spark plugs. Although the idle got worse at operating temp since fitting the new plugs. Any advise.......
Cheers..........
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| badkiwi |
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injection cleaner is crap, take it to a machanic an get injectors cleaned proper, a mate of mine had done same an it purrs now. cost abt $200 but worth it on many ways. response, fuel eco, quicker, an so on
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| EL__Fairmont |
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Problem is fixed. Found 3 loose bottom bolts on the pacemaker extractors. Tightened them up and the idle is good again and no more stumble.
Put a multimeter back on the oxygen sensor and it is switching between 0.1v-0.8v as per normal. Basically what happened is that unmetered air upstream of the oxygen sensor was making it show a lean reading and thus ecu was making adjustments to try to compensate.
_________________ 97 EL Fairmont 4l OHC .Silver. |
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