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Erratic Idle - faulty injectors or something else?

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Old May 24, 2011, 08:15 AM
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Exclamation Erratic Idle - faulty injectors or something else?

I drive an EVO X MR.

After recently installing my FP Green / Kelford 214-A cams / ID1000 injectors I have been experiencing occasional erratic idle.

It doesn’t happen all time but normally occurs when I am at full stop (e.g. traffic lights). The revs bounce all over the place from 800rpm down to 200rpm and sometimes causes the car to stall.

When I see this erratic idle about to happen, I normally give the car a bit of gas to prevent the stall (and embarrassment!). Have tried driving with /without aircon and changing the plugs but no difference. Have also been watching battery voltage (I use a small Odyssey battery) but no significant correlation to speak of.

Recently I have been monitoring my A/F gauge and noticed that the erratic idle is normally accompanied by very lean readings (e.g. 17+ or “****” on the AEM gauge). When my A/F is 15 +/- the idle is perfect.

This got me thinking that there might be a problem with my fuelling and/or injectors. I presume the fuelling should be covered by the tune which I have confidence in, so that leaves me with suspecting the injectors are faulty.

Was considering changing out the injectors for another set but before I incur that expense was wondering if anyone has similar problems / or possible solutions.

I am still running a stock fuel rail and fuel pump, but don’t think that would cause problems when at idle.

Btw, I have noticed my car spits out an abnormal amount of fuel. After hard driving at the track, my boot has turned brown from an abnormally thick layer of fuel, oil and soot (need to use Mr Muscle to remove it from paintwork...). In addition, every couple of weeks the car has trouble starting and I need to depress the accelerator (instead of just the brake) while cranking before the engine fires up.

If it helps, my mod list is:
  • FP Green
  • Kelford cams 214-A
  • Injector Dynamics 1000 injectors (with stock fuel rail and stock fuel pump)
  • Odyssey battery
  • Okada coils
  • GruppeM intake
  • HKS GT Extension kit
  • Test pipe
  • Greddy / Trust PE2 exhaust
  • HKS intercooler and piping
  • Koyorad radiator + Samco hoses
Old May 24, 2011, 09:32 AM
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change the tuner,not the mods...
Old May 24, 2011, 09:34 AM
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Has the scaling and latency been properly adjusted for those injectors?
Old May 24, 2011, 09:44 AM
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Have you checked your fuel pressure regulator hose to see if it popped off?
Old May 24, 2011, 10:16 AM
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Sounds like you're heatsoaked. It can be tuned out just have it happen while youre logging. This is one of benefits of a road tune
Old May 24, 2011, 04:36 PM
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Your tuner needs to dial in the injector latencies at the lower voltages in that table. I'm with the electrical load of fans kicking on and off, your battery voltage drops. So he needs to fine tune the 11.73V latencies. If car is going lean, ofcourse he needs to add more latency. I just dealt with exact same thing on another local evo I tuned.
Old May 24, 2011, 06:26 PM
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I've neve heard of ID's failing(my tuner recomends to all n they work fine) get your fuel trims right & she will be good to go!
Old Dec 6, 2011, 11:06 AM
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Same issue I'm having to the TEE. Any resolution to this yet? Did your tuner solve this for you?

Same injectors however running ams rail and walbro kit
Old Dec 10, 2011, 04:34 PM
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Bump anything?
Old Dec 10, 2011, 04:37 PM
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Interesting - I'm having a similar issue tuned out but my AFR's go rich when it happens. It's like the car forgets to breathe for a second and then gives itself more revs or something. I've got FIC 1050ccs (not a X though)
Old Dec 10, 2011, 04:39 PM
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Bleh -_- isn't it annoying lol
Old Dec 10, 2011, 06:04 PM
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yeah I don't think it's injectors though. It's been much improved as its been getting tuned out
Old Dec 12, 2011, 12:26 AM
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Are you just missing with the latency with the injectors? Did you consider heatsoaked as one member mentioned above, any idea on what that is and how to adjust it?
Old Dec 12, 2011, 09:49 AM
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Originally Posted by phishy
Are you just missing with the latency with the injectors? Did you consider heatsoaked as one member mentioned above, any idea on what that is and how to adjust it?
no idea, tuner's taking care of it
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