rap2chin;1672080 said:
Because you fabricated GM hydraboost?
rap2chin;1672098 said:
Pay close attention to where the power for the cold start injector comes from.
http://www.cygnusx1.net/Supra/Library/TEWD/MK3/manual.aspx?S=Main&P=038
89 supra runs good when cold but like crap when hot.
- Thread starter rap2chin
- Start date
Because you fabricated GM hydraboost?
Pay close attention to where the power for the cold start injector comes from.
http://www.cygnusx1.net/Supra/Library/TEWD/MK3/manual.aspx?S=Main&P=038
bro honestly i cant read that diagram. im so bad at it its not even funny.. i just would like to know why my anti-lock light comes on. and when its on why my steering gets a bit tighter
---------- Post added at 10:47 AM ---------- Previous post was at 10:46 AM ----------
and whats GM hydroboost u f**king with me?
---------- Post added at 10:47 AM ---------- Previous post was at 10:46 AM ----------
and whats GM hydroboost u f**king with me?
jetjock;1672110 said:
It was always my understanding that coolant temp input was required to drive the TCCS into closed loop. I wasn't aware that a supplemented ect was enough to allow it to enter closed loop, which is why I thought it failed safe to cold.
I assume theres a timer countdown before it starts to read o2 feedback even with the ect circuit open?
The diag code detects when the sensor is open or shorted and subs the default hot value. Thereafter the EFI code (the routines that determine injection, timing, and idle) use it. The code doesn't "know" whether it's operating off the actual variable or the default, it just goes by what happens to be in that particular register at the time. The default value is simply static.
Remember, most of the reasoning behind EFI is emissions based. A proper emissions strategy would never permit the approach you're suggesting. Nor would it wait until the engine is hot to enter closed loop. The opposite is desired. In fact if you monitor cross counting you'll see it occurs rather soon after engine start, long before coolant reaches anywhere near operating temperature and with or without the sensor connected.
Assuming everything else is working an open or shorted sensor will typically cause opposite of what the OP reported: the engine will falter when cold but run OK when hot. It's because the hot default deprives it of warm up enrichment. It's no different than having a faulty carburetor choke.
Course, it's going to depend on just how cold the coolant is. At 50 degrees it may only run rough for a minute or two but as it gets colder the lack of warm up enrichment will show for a longer period until things warm up. Try it on your car and see...
Remember, most of the reasoning behind EFI is emissions based. A proper emissions strategy would never permit the approach you're suggesting. Nor would it wait until the engine is hot to enter closed loop. The opposite is desired. In fact if you monitor cross counting you'll see it occurs rather soon after engine start, long before coolant reaches anywhere near operating temperature and with or without the sensor connected.
Assuming everything else is working an open or shorted sensor will typically cause opposite of what the OP reported: the engine will falter when cold but run OK when hot. It's because the hot default deprives it of warm up enrichment. It's no different than having a faulty carburetor choke.
Course, it's going to depend on just how cold the coolant is. At 50 degrees it may only run rough for a minute or two but as it gets colder the lack of warm up enrichment will show for a longer period until things warm up. Try it on your car and see...
maybe im not fully understanding here...so your saying that once the car enters closed loop regardless of temp that you can unplug the temp sensor with no effect? i must be miss understanding cause my car simply will not run right without it hooked up no matter what....it runs like an injector is bad when unhooked and i get a CEL right away....or does this lead to another issue?
rap2chin;1672138 said:
Power is only applied to the cold start injector while the key is in the crank position. And ground is lost when the coolant is heated. What you stated is impossible without rewiring.
Yeah. Pretty much. GM used the power steering pump to drive the brakes on some models. That is copied from some Diesel applications where there is no engine vacuum. Steering and brakes are not related, aside from tires. So if the tires are not flat, the problem is a loose nut behind the wheel.
jrot;1672544 said:
The ECT sensor defaults to hot, on every car I know sold in America. On older OBD cars, you can leave closed loop with moderate to heavy accelaration. Temperature is a correction, not the main input. So it doesn't matter as much when running. It matters, but you probably wouldn't notice.
then why in my car do i notice it when its come unplugged at anytime(due to crappy plug)? cold hot luke warm or whatever? is it leading to another problem? like maybe im stuck in open loop or something? or is that even possible?
man fix the plug its easy ur problem will be solved.... and when i unplug my coolant temperature sensor my car will run but it will run rough as soon as i plug it back in it runs like a champ. i struggled with this problem for 3 months everyone i talked to gave me advice but nothing helped Until i got a diagram from a guy a few pages back i wired it in and dah da da daaahhh it worked.
ive got a new home made plug thats doing well now but it will occasionally slip...i need to just get a new one and wire it...just been kinda lazy about it....mine was the same though...drivable but not pleasurable...
If the engine runs noticeably different with the coolant sensor unplugged at operating temperature or even warm there's something wrong with it. Period. And regardless of how it seems to run otherwise the *only* way to know for sure it's working 100% is by properly instrumenting it.