4age 16v running roughly - diagnostics shows unknown code
09-28-2020, 09:53 AM
Post: #1
4age 16v running roughly - diagnostics shows unknown code
Hello,
I seek help understanding in 4age self diagnostics what means 2 quick pulses (check engine light) followed by pause and after that 8 pulses follow and it repeats. The error code is not in the 4age manual. Anyone having some experience what such code means? My ae86 with unmodified 4age 16v was running fine until recently now it idles roughly i can write in detail lot about it but what i would like to find more about is this error code maybe it has somethig to do about the issue i am experiencing.
Thank you.

85' AE86 GT coupe lifetime project since 2005
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09-28-2020, 11:34 AM
Post: #2
4age 16v running roughly - diagnostics shows unknown code
Easy.. code 2 and code 8...
So MAP sensor and IAT sensor troubles..all around the intake manifold.

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09-28-2020, 01:29 PM
Post: #3
4age 16v running roughly - diagnostics shows unknown code
Thank you Ivan i didn't know that the ECU show two symptoms by running diagnostics Big Grin

85' AE86 GT coupe lifetime project since 2005
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10-19-2020, 04:18 PM
Post: #4
4age 16v running roughly - diagnostics shows unknown code
Hello,
I would like to ask for your help as i am currently experiencing some issue with my AE86 and i was still not able to locate it. Maybe someone had already this issue and will point me in the right direction to solve it. I already mentioned the diagnostic error code but after it was cleared the engine still not running as it should be.
Actual sympthoms are that the car idles roughly and i was not able to locate the issue it warms up normally and the rough idle is all the way from cold to warm engine. The rpm from cold to warm engine goes normal. If i hit the accelerator it does not hesitate it responds quickly and by 2000 rpm i hear some knocking noise from top of the engine than after it goes above that rpm the sound vanishes and the engine idle stabilise and all seems running well from that point.
First time i noticed something wrong was after i was driving on highway at normal speed about 110km/h by overtaking some card i notices some weird sound from the engine for short time by accelerating. After i finished my 150km long journey and entered the city i noticed that from the light stop when i accelerated that by 2000rpm engine was making weird knocking noise. At higher rpm was everything normal. When i parked the car i noticed the idle is not normal.
The other day i went to test again and the idle was not correct still this noise by 2000rpm.
I spend whole day analyzing but did not come to some solution what can be wrong. Weird is that it warms normally it response normally on throttle. No overheating, Oil pressure is normal. Oil level between H-L markings. No significant Fuel consumption. Engine is not smoking. No oil losses. Engine coolant levels normal.
The engine is unmodified 4age 16v with AFM, catalytic converter and O2 sensor. It has now around 195 000km on the clock
What i already done was:
Checked spark plugs – all looked well still tried different set but no change.
Verified spark plugs wires tried different set but no change.
Checked distributor cap and rotor but all seems to be okay.
Inspected injectors sounds and cleaned all injectors and verified thay spray the fuel normally.
Diagnostics was first showing something wrong with MAP sensor and IAT sensor so i tried different AFM but no difference in idle only now there is no error from ECU.
Verified timing and timing belt all is correct.
The car starts normally without hesitation.

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10-21-2020, 01:50 AM
Post: #5
4age 16v running roughly - diagnostics shows unknown code
A "knocking", "pinging" or "rattling" sound is an indication that something is not happy in your engine.
There can be a number of causes and depending on the cause the sound will be different, and it will
occur under different operating conditions. Knock from worn or damaged bearings is usually a deeper
sound, like tapping on the block with a heavy hammer, and often occurs when the load on the engine
is relatively light and increasing or decreasing.

Spark or ignition knock (detonation) is mostly heard if the engine is struggling to accelerate under
heavy load at low rpm or when running WOT at high rpm. The sound is more like rapid tapping on the
block with a small hammer.

Rattling may also be produced by other causes. For example I once had a car where the cam belt idler
wore out and started to make a noise. It first started happening as the engine rpm dropped as I slowed
for a traffic light. After a while it was making a noise at idle as well, and even my mechanic thought
it was bad engine bearings until he investigated with a stethoscope.

Unless the engine has been pushed past its limits, bearing knock does not start suddenly. It creeps up
very gradually as parts wear and at first it is only heard faintly under certain conditions. Spark knock
mostly happens under high load conditions... accidentally trying to start in 3rd instead of 1st or towing
a heavy load uphill. It is easily reproduced and you will know what you did to make it knock Smile

You may want to check your fuel pressure to see if it is dropping low. A good workshop will be able to
test the pressure for you. If the pump is getting tired or if the filter has not been changed for a long
time the pressure may be dropping under load. Even a bad batch of fuel where the octane rating is too
low can cause spark knock. If you can narrow down the circumstances when the knocking sound is
heard (high load, low load, accelerating, decelerating, cruising etc) that will help make a diagnosis.

Cheers... jondee86

The reasonable man adapts himself to the world; the unreasonable one
persists in trying to adapt the world to himself. Therefore, all progress
depends on the unreasonable man.
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11-08-2020, 07:48 PM (This post was last modified: 11-09-2020 10:51 PM by banpei.)
Post: #6
4age 16v running roughly - diagnostics shows unknown code
Hello. I recorded video what is exactly my engine doing. I hope someone can point me in direction what should i be looking at next. I was still not able to locate the cause. I am replyiing a little late as i catch bad cold but now i am fine and can continue with the repairs. I can now smell more gas from the exhaust as before. Maybe because it is getting colder and i am repairing the car outside as garage is occupied by other car currently (not too happy about it Undecided as it is getting colder).

Thanks Jondee for taking your time to help with the analysis. I really really appreciate it :-)

What you mentioned i will try as next. I got fuel pressure gauge so i will need to hook it up as manual say and test the fuel pressure. My fuel filter was not changed for years i think at least from 2005 when i buyed the car i have not changed it but i buyed new one from toyota already as i wanted to do so this summer but got no time to do it perhaps now it is a good time :-) I remember that it occoured some months back while driving on highway the car suddenly started to hesitate to accelerate this occoured 2-3 times. I was thinking bad fuel as well that time so i changed the gas station and after that no more issues. But this time i was putting fuel there as well on different gas station maybe they got water inside the tank but i am not able to tell this only way to do that will be drain the tank and i am not sure if i will be able to unscrew the bolt on the bottom (still using the original tank).
I am always using 100 octane ( 98 ) fuel now (E5) as i dont want to put E10 fuel inside.

Link to the video:

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11-08-2020, 10:21 PM
Post: #7
4age 16v running roughly - diagnostics shows unknown code
From the video the ignition timing sounds too far advanced but the hollow knock is ominous. You could try retarding the ignition timing maybe 10° to see if anything improves.

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11-08-2020, 11:03 PM
Post: #8
4age 16v running roughly - diagnostics shows unknown code
Almost sounds like it is running on three cylinders. Try pulling the caps off the spark plugs
one at a time while the engine is running. If the cylinder is working the engine speed will drop
and the idle will get rougher. If taking the cap off makes no difference then the cylinder is not
working and you can investigate.

If all cylinders are working, but there is a big difference in the sound of the engine when you
take one of the caps off, there may be a mechanical problem with that cylinder.

Cheers... jondee86

The reasonable man adapts himself to the world; the unreasonable one
persists in trying to adapt the world to himself. Therefore, all progress
depends on the unreasonable man.
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11-09-2020, 10:51 AM
Post: #9
4age 16v running roughly - diagnostics shows unknown code
Plug leads in the wrong order?

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