Help me AEU86, you're my only hope

[totta Crolla]

The ecu is quite power sensitive and by running low voltages you may be forcing the injector latency off of the scale and that might explain the AFR fluctuation. A decent battery is important for electronic fuel injection. Indeed the Freedom ecu not only constantly monitors +V but it also measures battery temperature. l have no idea how if does that

[jondee86]

WOW!!! This thread is getting really interesting

As shown by Jeremy Ross in his article the ECU has a correction table to
adjust the injection duration to compensate for low system voltage. His last
comment in particular is relevant to the current investigation.



Now, what happens when the jumper battery is disconnected ? I suspect
that with the jumper battery connected the alternator sense wire is seeing
the voltage of the fully charged jumper battery. The alternator will ramp
down its output current and cause less load on the engine.

When the jumper battery is disconnected the sense wire will see the lower
voltage of the discharged battery and ramp up its charging output. This will
certainly increase the load on the engine, and very possibly cause the
system voltage to drop slightly. Check the voltage across the battery to
confirm of deny this theory

Cheers... jondee86

[Nakilad]

(03-29-2021 09:52 PM)totta Crolla Wrote:  The ecu is quite power sensitive and by running low voltages you may be forcing the injector latency off of the scale and that might explain the AFR fluctuation. A decent battery is important for electronic fuel injection. Indeed the Freedom ecu not only constantly monitors +V but it also measures battery temperature. l have no idea how if does that

Sorry, maybe I wasn't clear. Battery voltage with motor running is constantly above 14 volts, drops to 13.5 or so when the electric fans kick in, so there should be no problem on that side. A broken cell in the battery though, could make for some weird stuff. I guess we will see in a few days.

[jondee86]

Just been looking at the latest video clips. In the "Air Leak Test" the screw
that you are adjusting down the tube at the side of the throttlebody is the
Idle Air Bypass screw. This adjusts the amount of air that is allowed to
bypass the closed throttle plate to set the idle speed.

When the engine died you were raising up a tube attached to one of the
vacuum ports on top of the throttlebody. If moving the tube or blocking it
with your finger stalled the engine, that tube must be supplying at least
some of the idle air. If I am correct about this then capping/blocking that
port and opening the idle air bypass screw should enable the engine to idle.

Cheers... jondee86

[jondee86]

Also I was looking at the way the AFR gauge behaves with the crankcase
breather blocked or venting to atmosphere.

Because of the much higher sensitivity of the narrow band sensor near
stoich, the gauge needle will always be much more active when he AFR is
near stoich. Conversely, when the mixture is very rich or very lean the
sensor is at the extreme end of its range and insensitive to small changes in
the mixture. In your case the needle moves further into the rich zone and
becomes steady which is in line with the mixture becoming richer when you
block the breather.

From what I read you should expect a narrow band gauge to have the
needle "twitching" as shown in your video with the crankcase breather NOT
blocked. That means that it is actually reacting to the minor changes in AFR
due to low V.E. and exhaust gas reversion that commonly occur at idle. My
wide band gauge always jumped around between 14:1 and 15:1 at idle.

That is what causes the unevenness you can hear in my video below. Bear
in mind this engine had cams so that exaggerated the rough idle.
https://i.imgur.com/JsnZvRJ.mp4

Cheers... jondee86

[Nakilad]

(03-30-2021 04:50 AM)jondee86 Wrote:  Also I was looking at the way the AFR gauge behaves with the crankcase
breather blocked or venting to atmosphere.

Because of the much higher sensitivity of the narrow band sensor near
stoich, the gauge needle will always be much more active when he AFR is
near stoich. Conversely, when the mixture is very rich or very lean the
sensor is at the extreme end of its range and insensitive to small changes in
the mixture. In your case the needle moves further into the rich zone and
becomes steady which is in line with the mixture becoming richer when you
block the breather.

From what I read you should expect a narrow band gauge to have the
needle "twitching" as shown in your video with the crankcase breather NOT
blocked. That means that it is actually reacting to the minor changes in AFR
due to low V.E. and exhaust gas reversion that commonly occur at idle. My
wide band gauge always jumped around between 14:1 and 15:1 at idle.

That is what causes the unevenness you can hear in my video below. Bear
in mind this engine had cams so that exaggerated the rough idle.
https://i.imgur.com/JsnZvRJ.mp4

Cheers... jondee86

That exhaust note sounds pretty sweet there Jondee, nice!

I think I understand what you mean regarding the jumping of the needle, its just that it goes from 'rich' to nothing and then back again. See below for my next planned steps.

Idle bypass was completely closed, that is one of my points of the video, to show the bypass closed. You can also block the input to the idle up and it does not affect the idle speed when hot (it does when cold).

The tube above the throttle body is attached to the idle up solenoid. It opens when the lights are on, or the blower fan, and you can hear the change in idle speed.

Apologies for not updating this in the last week or so, its been Easter (and my birthday) and we had some snow this week so I haven't been really tempted to go to the carport in the last days!

Small update, I swapped out the battery for a known good one, and switched to RWD throttle body number 2. Result, idle was higher than before, and didn't really stall as easily when blocking the intake. Note, the idle up was swapped from RWD throttle body 1 to 2.

So, plan for tomorrow / sunday. I have taken RWD throttle body no. 1, blocked the port from the idle up (where the water goes through) where it reenters the input behind the throttle plate, as well as blocking the inlet port to the idle up. This should mean no airflow whatsoever through the idle up, which will make it a bitch to start when it is cold but at least should eliminate any possibility of air getting past the plate that way. The only air bypassing the throttle plate should be then through the idle speed screw. Then, its throw a battery in it from another car and drive it somewhere. I will do my best to get a recording of the gauges as I drive around, and add that to the playlist.

[jondee86]

I can't speak for engines with EGR but for the UK spec (no O2 sensor)
engines I owned the items affecting idle air were these...

1. IDLE AIR BYPASS SCREW used to set the correct idle speed when the
engine was up to temp.
2. AUXILIARY AIR VALVE heated by coolant and wide open when engine cold.
Raises idle to approx 2200rpm and then tapers down to 850-900rpm
as the engine comes up to temp and valve fully closes. If cold start idle
does not act like this the AAV water circuit is likely blocked with crud.
3. IDLE-UP SOLENOID controlled (ON/OFF) by the Idle-Up computer to
compensate for extra electrical load. I believe (as stated) that this valve
is also activated by the ECU on cold start.
4. THROTTLE PLATE SETTING which controls the amount of air that leaks
past the closed plate. This is set by adjusting the throttle stop using feeler
gauges and monitoring the action of the IDL switch in the TPS.
5. VACUUM LEAKS that allow air to enter any part of the intake after the
throttle plate will raise the idle speed.

While I am sure that you are aware of these items it does not hurt to
check them off your list one at a time. Many idle speed issues are caused
by partial blockages in the AAV itself or the small water tubes and hoses.
If the AAV does not get hot enough it will not close fully and you end up
with a permanently high idle. Same effect as a vacuum leak.

Cheers... jondee86

[totta Crolla]

Just checking. You are using a TVIS inlet manifold and not a smallport to RWD conversion?

[Nakilad]

(04-10-2021 11:15 AM)totta Crolla Wrote:  Just checking. You are using a TVIS inlet manifold and not a smallport to RWD conversion?

Correct, everything is big port + tvis.

(04-10-2021 12:06 AM)jondee86 Wrote:  I can't speak for engines with EGR but for the UK spec (no O2 sensor)
engines I owned the items affecting idle air were these...

1. IDLE AIR BYPASS SCREW used to set the correct idle speed when the
engine was up to temp.
2. AUXILIARY AIR VALVE heated by coolant and wide open when engine cold.
Raises idle to approx 2200rpm and then tapers down to 850-900rpm
as the engine comes up to temp and valve fully closes. If cold start idle
does not act like this the AAV water circuit is likely blocked with crud.
3. IDLE-UP SOLENOID controlled (ON/OFF) by the Idle-Up computer to
compensate for extra electrical load. I believe (as stated) that this valve
is also activated by the ECU on cold start.
4. THROTTLE PLATE SETTING which controls the amount of air that leaks
past the closed plate. This is set by adjusting the throttle stop using feeler
gauges and monitoring the action of the IDL switch in the TPS.
5. VACUUM LEAKS that allow air to enter any part of the intake after the
throttle plate will raise the idle speed.

While I am sure that you are aware of these items it does not hurt to
check them off your list one at a time. Many idle speed issues are caused
by partial blockages in the AAV itself or the small water tubes and hoses.
If the AAV does not get hot enough it will not close fully and you end up
with a permanently high idle. Same effect as a vacuum leak.

Cheers... jondee86

Yeah, I am aware, doesn't hurt to go over them again though. Gotta admit, sometimes when I write these posts its getting a bit late in the night so sometimes I don't write as clearly as perhaps I should.

In that last video we spoke about, the Idle Air Bypass Screw is completely closed, blocking the intake to the Auxiliary Air Valve with a finger has no effect or rpm when the motor is hot, meaning the valve is completely closed. RPM increases (and air / fuel reading drops to 0) when turning on lamps or heater fan, meaning the idle up Solenoid is working. This also happens when removing the hose from the throttle body itself, meaning the valve itself is not leaking. The Throttle plate has been adjusted so that it is just above the 'gripping' point (not sure how to describe this proceedure very well), and therefore is as closed as possible. Putting the hand over the intake to block air flow is designed to show there are not loeaks after the throttle plate.

I swapped over the throttle bodys again today, with the procedure I described yesterday. Can't go for a drive yet as the tyres are all quite flat! I'll try to sort that tomorrow and am charging up the apeman so I will hopefully have something tomorrow.