1G [4g67] combustion failure while cruising

vicore · Sep 24, 2014

It's not a 1g but similar since it is a 6bolt with only a smaller bore and same stroke...

Since a couple of weeks a got the problem that the combustion stops for some seconds.

I do not call it ignition failure because my wideband is reading 17+ in that case until the engine runs normal again. If there would be only a failure in ignition the wideband should read fat mixture not lean as mentioned, right?

Before and after that behaviour everything runs fine. Lambda is jumping up and down - everthing alright.

Most of the time, that failure ends automatically within 1 or 2 seconds, if not it helps to push the pedal to the metal. It even occurs with MAF is disconnected and the ecu runs in limp mode.

Currently there is the C53 ECU in the car but it's the same with my evo8 ecu. I dont have another spare ecu to test, just a 2g N/A ecu - how far are the differences regarding the pinouts between evo8 and 2g FL?

Temp sensors look fine so far and no code saved in the ecu

Hope you have some more ideas, it is annoying meanwhile and i cannot figure it out myself - Thanx

Derail20T · Sep 24, 2014

Sounds like the ignition is cutting out. Start by checking the gap on your spark plugs and inspecting the plug wires. I had the same thing happen before and I had a bad spark plug wire. After changing it, my problem was fixed!
It would with the diagnosis if you filled out a dsm profile so people could see your setup...

ervin00 · Sep 24, 2014

Have you done your maintenance? New spark plugs, o2 sensor, wires and also do a boost leak test. A small boost leak can also give you the symptoms you are describing.

vicore · Sep 25, 2014

Profile updated. (sry that I haven't done it before)
Spark plugs are new and cables are OEM and just two years old.
It is N/A but the rubber hose from the air filter is fine and vacuum hoses are new as well.
The O2 is not a new one, but the symptoms occur even if it is unplugged.

v8srslo · Sep 25, 2014

open up the ecu and look for any melted solders, or any circuit damage. if u can swap/borrow with know good ecu. check cas, coils and power transistor. but they might check fine while not under electrical load.

vicore · Oct 6, 2014

CAS wires seem fine, could not detect any failure. All the time continuity is fine while bending them.

spark plugs and wires are both new now and another ecu has been tested as well - problem still occurs.

But I could narrow it a bit, it is only occurring between 1900-2400 rpm - how does a dying CAS feel or behave like?

vicore · Oct 9, 2014

Transistor, Coils, Cables and Plugs are new/changed meanwhile. Problem still occurs. When I had the malfunction in idle I pulled;pushed;moved;bended all the cables in the engine bay without changing anything. Unplugged the coolant temp sensor (signal jumped to -59°C) but the behaviour didn't change. No matter which ignition cable I pulled the engine died. Currently testing with another (told good) ecu but it is exactly the same!

Here's a link to some logs:
http://www.file-upload.net/gal-108150/yytgv4/1.html

the time at the end of the file name indicates the "beginning" of the malfunction. Sometimes timing goes badly wrong - don't know why. In the file with ..._499s.csv fo example, the timing starts to behave strange beginning at ~160s.... Fuel is still coming. InjPulseWidth is increasing, I think due to Lambda-regulation since the lambda detects more O2 and interpretes the mixture as lean and tries to compensate that....

vicore · Oct 24, 2014

Meanwhile:
CAS, MAF and another ECU been tested... no change

Yesterday after starting the engine it went fine for a minute... then it started again

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Here's a video of it:

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Any ideas?

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1G [4g67] combustion failure while cruising

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Derail20T

ervin00

vicore

v8srslo

vicore

vicore

vicore

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