1jz E36 BMW frankensteining

Nightstalker1993

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When cooling fan kicked in with A/C system on, the rev will drop to the 500 rpm and 12.1 V. If i turn of the A/C, and fan is not kicked in, the volt will at 13.6 v

Thanks,
Ken
So the cooling fan turn on, causing the alternator load to increase, which pulls the engine RPM down, causing the voltage to drop, or do you suspect the voltage drop from the fan turning on is causing the engine RPM to drop? :emoji_thinking:

Your engine running on stock ecu right. And the idle control valve working?

ECU does not compensate?
ECU only controls the idle valve when the fan turns on to compensate for the increase alternator load
 

vr2turbo

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When there is high draw of current, idling speed do drop. Just like when we switch on the head lights, idling speed dips a little.....
 

Mitevo7

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So the cooling fan turn on, causing the alternator load to increase, which pulls the engine RPM down, causing the voltage to drop, or do you suspect the voltage drop from the fan turning on is causing the engine RPM to drop? :emoji_thinking:

Your engine running on stock ecu right. And the idle control valve working?


ECU only controls the idle valve when the fan turns on to compensate for the increase alternator load
Yup idle control valve works perfectly fine, the RPM drop is enough till the level of stalling the engine though.
 

Mitevo7

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When there is high draw of current, idling speed do drop. Just like when we switch on the head lights, idling speed dips a little.....
That is exactly what happened. Latest experiment, i drove the car without A/C for full trip, the RPM is very stable and alive, except when the cooling fan kicked in again and the RPM dips lower, causing the voltage to drop. Would really like to try the pulley first and feedback here.

Some other 1JZ converted E46 uses aftermarket fan instead of original fan, they do not face this kind of issues.

Thanks,
Ken
 

Nightstalker1993

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Is your cooling fan controlled by ECU or is it a seperate switch? Maybe you can try pasang an FICD which turns on following the fan, to prevent your engine RPM from stalling due to the increased load placed by the alternator. If you were to undersize the alternator pulley, the load on the engine placed by the alternator will be EVEN greater. You are using E46 original fan or 1jz fan?
 

vr2turbo

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Is your cooling fan controlled by ECU or is it a seperate switch? Maybe you can try pasang an FICD which turns on following the fan, to prevent your engine RPM from stalling due to the increased load placed by the alternator. If you were to undersize the alternator pulley, the load on the engine placed by the alternator will be EVEN greater. You are using E46 original fan or 1jz fan?
Wow! then need one FICD for air con and another for the fan......
 

Nightstalker1993

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Wow! then need one FICD for air con and another for the fan......
Yeah that's what I'm thinking. I am not sure, but it is quite common for these euro cars to have a damn powerful radiator fan, but with a variable speed controller as well, which is controlled directly by the ECU. On idle they rarely go up to high speed, and usually they turn on for awhile then shut off. Once you swapped out the engine and ECU, I suspect they might be running the fan direct power, meaning max speed at all times, and those fans really are quite huge and eats up loads of amps, which might be what is causing the alternator load to be so high until the engine at idle is not producing enough power to actually run the alternator at that load.
 

Mitevo7

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Is your cooling fan controlled by ECU or is it a seperate switch? Maybe you can try pasang an FICD which turns on following the fan, to prevent your engine RPM from stalling due to the increased load placed by the alternator. If you were to undersize the alternator pulley, the load on the engine placed by the alternator will be EVEN greater. You are using E46 original fan or 1jz fan?
Using E46 original fan, which has high and low speed fan mode. My problem is not with idling, the car's voltage is normal with A/C off and fan is not kicked in. If i turn both on (fan and A/C), both accessories drain a lots of juice from the alternator, especially when i am in D gear and waiting by the traffic. Driving without both A/C has no signs of voltage drop or what so ever, in fact, voltage is at optimum level, 13.7.

Thanks,
Ken
 

Mitevo7

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Yeah that's what I'm thinking. I am not sure, but it is quite common for these euro cars to have a damn powerful radiator fan, but with a variable speed controller as well, which is controlled directly by the ECU. On idle they rarely go up to high speed, and usually they turn on for awhile then shut off. Once you swapped out the engine and ECU, I suspect they might be running the fan direct power, meaning max speed at all times, and those fans really are quite huge and eats up loads of amps, which might be what is causing the alternator load to be so high until the engine at idle is not producing enough power to actually run the alternator at that load.
How does the FICD helps with my situation, from what i know so far, it supposed to bypass the throttle or operates the throttle butterfly directly. My issue right now is not engine stalled at idle with all accessories turned on, its actually the RPM cluster kill itself when voltage drops near 12v. As per experimented, driving without accessories on shown the RPM cluster works perfectly.

Thanks,
Ken
 

vr2turbo

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Yeah that's what I'm thinking. I am not sure, but it is quite common for these euro cars to have a damn powerful radiator fan, but with a variable speed controller as well, which is controlled directly by the ECU. On idle they rarely go up to high speed, and usually they turn on for awhile then shut off. Once you swapped out the engine and ECU, I suspect they might be running the fan direct power, meaning max speed at all times, and those fans really are quite huge and eats up loads of amps, which might be what is causing the alternator load to be so high until the engine at idle is not producing enough power to actually run the alternator at that load.
Ah! reminds me of my ex colleagues Citreon ZX, twin fans, twin speed. Hot time really wheeeeee sound when both fans at high speed.....
 

^pomen_GTR^

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Yeah that's what I'm thinking. I am not sure, but it is quite common for these euro cars to have a damn powerful radiator fan, but with a variable speed controller as well, which is controlled directly by the ECU. On idle they rarely go up to high speed, and usually they turn on for awhile then shut off. Once you swapped out the engine and ECU, I suspect they might be running the fan direct power, meaning max speed at all times, and those fans really are quite huge and eats up loads of amps, which might be what is causing the alternator load to be so high until the engine at idle is not producing enough power to actually run the alternator at that load.
yeah..agree on this




Using E46 original fan, which has high and low speed fan mode. My problem is not with idling, the car's voltage is normal with A/C off and fan is not kicked in. If i turn both on (fan and A/C), both accessories drain a lots of juice from the alternator, especially when i am in D gear and waiting by the traffic. Driving without both A/C has no signs of voltage drop or what so ever, in fact, voltage is at optimum level, 13.7.

Thanks,
Ken
maybe u can ask your wireman to swap fan wiring... low speed for ac control, then high speed for water temp control...
 

Nightstalker1993

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Using E46 original fan, which has high and low speed fan mode. My problem is not with idling, the car's voltage is normal with A/C off and fan is not kicked in. If i turn both on (fan and A/C), both accessories drain a lots of juice from the alternator, especially when i am in D gear and waiting by the traffic. Driving without both A/C has no signs of voltage drop or what so ever, in fact, voltage is at optimum level, 13.7.

Thanks,
Ken
Yes, when the radiator fan kicks in, it draws Alot of current, which the alternator tries to compensate by increasing the actual mechanical load placed on he engine. Your alternator have a regulator which also affects the alternator 'load' on the engine. And it seems like there are 2 things that are happening now.

1. When your fan kicks in, it draws damn alot of current, creates a voltage drop which the alternator tries to compensate by increasing the mechanical loads placed on the engine
2. When the mechanical load from the alternator increase, your engine itself is not ready for it, the ecu does not expects a sudden increase in load and thus your idle drops as it cannot sustain the excess load from the alternator. The drop in rpm, causes the voltage to drop EVEN lower, below the threshold of what your meter requires to operate at probably.

When you are driving this is a non issue as the engine is already at a higher rpm and relatively high load from actually powering your car, but at idle, the power the engine is producing is only just enough to sustain the idle and any change in mechanical loads will affect the idle, unless the ecu is able to compensate for it, either by opening the TB more if it is an ETB or opening the idle valve more, but this requires an input to the ecu.

How does the FICD helps with my situation, from what i know so far, it supposed to bypass the throttle or operates the throttle butterfly directly. My issue right now is not engine stalled at idle with all accessories turned on, its actually the RPM cluster kill itself when voltage drops near 12v. As per experimented, driving without accessories on shown the RPM cluster works perfectly.

Thanks,
Ken
The ficd helps by allowing more air to go past the tb, it's like opening the throttle slightly in a way, to compensate for the increased mechanical loads placed by the alternator when the fan kicks in. Just like how it compensates when you turn on your aircond because the compressor places additik al mechanical loads on the engine. Same goes to the alternator when there is an increase of electrical loads

Ah! reminds me of my ex colleagues Citreon ZX, twin fans, twin speed. Hot time really wheeeeee sound when both fans at high speed.....
My car now with 2 SPAL fans sounds like a jet taking off whenever the aircond turns on or the fan turns on due to temp :laugh:
 

Mitevo7

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yeah..agree on this






maybe u can ask your wireman to swap fan wiring... low speed for ac control, then high speed for water temp control...
The speed control of fan, can i bypass the ECU and use an after market fan controller instead? I just noticed the car's fan only got 1 speed, HIGH at all range. LOL.

Thanks,
Ken
 

Mitevo7

1,000 RPM
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Jan 14, 2008
1,456
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Yes, when the radiator fan kicks in, it draws Alot of current, which the alternator tries to compensate by increasing the actual mechanical load placed on he engine. Your alternator have a regulator which also affects the alternator 'load' on the engine. And it seems like there are 2 things that are happening now.

1. When your fan kicks in, it draws damn alot of current, creates a voltage drop which the alternator tries to compensate by increasing the mechanical loads placed on the engine
2. When the mechanical load from the alternator increase, your engine itself is not ready for it, the ecu does not expects a sudden increase in load and thus your idle drops as it cannot sustain the excess load from the alternator. The drop in rpm, causes the voltage to drop EVEN lower, below the threshold of what your meter requires to operate at probably.

When you are driving this is a non issue as the engine is already at a higher rpm and relatively high load from actually powering your car, but at idle, the power the engine is producing is only just enough to sustain the idle and any change in mechanical loads will affect the idle, unless the ecu is able to compensate for it, either by opening the TB more if it is an ETB or opening the idle valve more, but this requires an input to the ecu.



The ficd helps by allowing more air to go past the tb, it's like opening the throttle slightly in a way, to compensate for the increased mechanical loads placed by the alternator when the fan kicks in. Just like how it compensates when you turn on your aircond because the compressor places additik al mechanical loads on the engine. Same goes to the alternator when there is an increase of electrical loads



My car now with 2 SPAL fans sounds like a jet taking off whenever the aircond turns on or the fan turns on due to temp :laugh:
I will explore on FICD part. May be that will stabilize my rev even more when in traffic. I will do the pulley or diode mod first to the alternator.

My mechanic that did the swap said i should not use SPAL fans, very problematic for this kinda swap. I would like to hear the fan sound though. :banana:

Thanks,
Ken
 

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