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Guest
sr20 bogs down
good evening everyone.
i would like to know if anyone can shed a light on an issue a friend has on his car.
he has an 180sx shell with full s14a mechanics and electronics. it also has hdev 3a chipped ecu, 2871r with external wastegate, z32 afm and 555 injectors. the intank fuel pump is also uprated with its own remote fuse and relay.
the issue is as follows.
after the swap/conversion was done, the car ran great for months.
unfortunately the car was stored for 3/4 months without running and when it was started after this period it started to show bogging symptoms.
the car starts fine, but as soon as you touch the accelerator the car starts to bog a little. after you let it run for 2/3 minutes, it gets better, but if you accelerate more than 40% (it gets worse if you push full throttle) the bogs really bad to the point that it wants to shut down. its not always the same behavior, because one time, when i let it go to operating temperature, i can even do some boost (stationary).
i cant really tell if its electrical, fuelling or ignition.
we swapped the maf for a new one
swapped the spark plugs from my s14a (they work good on my car), the plugs i removed were very dark, maybe the reason is excess fuel or no ignition????
swapped the coil packs for my old ones that worked good (i installed r8 coils on my car)
swapped the coil pack loom (again from my car)
cleaned aac valve
swapped the lambda sensor.
we also cleaned the electrical plugs on the cas, on the tps, on the maf and on a component which i dont know what it is but is located near the tps, carved in the cylinder head (looks like a 21mm hex block)
i would be thankful for some insight as we are getting a bit lost on where to go next.
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Guest
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Guest
Checked the earths?
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Guest
Thanks for the reply, buddy. We're not 100% sure yet, because he still didn't get to drive the car.
But at least stationary, the car behaves normally after replacing the ecu coolant temperature sensor.
Fingers crossed!
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Guest
no joy.
when hot everything is fine (although a bit rich) and when cold it bogs if accelerated.
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Guest
As no-one else has asked, have you checked for boost leaks?
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Guest
Thanks for the reply, pea.
No, I have not.
But the problem is definitely temperature related. O
When he starts the car, he can't even touch the throttle pedal, as the engine will bog (in my opinion, because it is too rich, as the spark plugs get all black). After 30 seconds he can throttle it, but it must be gently. If it's sudden, it will once again bog (too rich). When it's hot (80+ degrees water temp) you can throttle it at will as it won't bog again (but still too rich in my opinion as it backfires a little bit when you let go of the throttle).
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I <3 BBS LM
There are 2 water temperature sensors, 1 for the dash and 1 for the ECU. Did you change both?
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Guest
Thanks for the input, Ben.
He has swapped the ecu coolant temp sensor but not the other one.
Does it have any impact on the actual mixture of the engine?
I thought that its only function was to send info to the cluster.
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Banned
Am thinking Maf but......
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Guest
He has swapped the maf for a "Chinese copy" and the car didn't change the behavior. Today I will help him measure the wiring from the ecu to the maf and also from the ecu to the temp sensor.
Thanks for the various inputs. Keep them coming.
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Guest
Could it actually be running too lean? If it's been running fine in the summer months, it's possibly cause it didn't need the extra fueling associated with a cold start in cold weather. And as such, didn't have an issue to start/run when it were 'warm'. But now that it's gotten pretty cold, it may be just a tad too lean with the current cold start settings.
A cold engine still won't burn all of the mixture, even if lean, hence the reason why you may think it's running lean based off the fumes/smell
Last edited by speedingmofa; 16-11-2020 at 15:32.
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Guest
Thanks for the reply.
When I meant hot/cold, it wasn't dependent on the day overall temperature. It happens at 15c as it happens at 25c.
What I meant is coolant/engine temperature.
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Guest
Ecu replaced. Injector orings were in very bad shape. New ones installed. Coil packs replaced, spark plugs replaced. Coil loom replaced.
Behavior exactly the same. Lol.
After 80 degrees water temp, the car behaves 99%. I believe that 85 degrees will 100% behavior... Any other inputs? Should he send the injectors for a good flow clean?
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