7MGE temp sensors

[Slim]

How many temperature sensors (engine related) are there in a 7M?

I'm thinking that a reason for the poor starting of my Cressida and subsequent black smoke when it actually does fire up is because the computer is getting a signal telling it that the engine is dead cold.

I reckon it's getting excessive fuel as a result and practically flooding it. Never has it ever not started and when the engine is actually dead cold it fires into life before the engine has done a single revolution.

I'm going to make it a mission to solve this annoying problem and i'm going to start with the temp sensors. Where are they and which ones do what? (i've been told that there's a few).

Thanks.

[Robbos_Toyotas]

How many temperature sensors (engine related) are there in a 7M?

I'm thinking that a reason for the poor starting of my Cressida and subsequent black smoke when it actually does fire up is because the computer is getting a signal telling it that the engine is dead cold.

I reckon it's getting excessive fuel as a result and practically flooding it. Never has it ever not started and when the engine is actually dead cold it fires into life before the engine has done a single revolution.

I'm going to make it a mission to solve this annoying problem and i'm going to start with the temp sensors. Where are they and which ones do what? (i've been told that there's a few).

Thanks.

theres 2, both in the alloy part that bolts to the head and houses the thermostat. the spade bit connector type one with a single wire is for the gauge, and if you got me a pic to refresh my memory i think the other one mught have two wires.

[amichie]

How many temperature sensors (engine related) are there in a 7M?

I'm thinking that a reason for the poor starting of my Cressida and subsequent black smoke when it actually does fire up is because the computer is getting a signal telling it that the engine is dead cold.

I reckon it's getting excessive fuel as a result and practically flooding it. Never has it ever not started and when the engine is actually dead cold it fires into life before the engine has done a single revolution.

I'm going to make it a mission to solve this annoying problem and i'm going to start with the temp sensors. Where are they and which ones do what? (i've been told that there's a few).

Thanks.

Get your fuel pressure checked.

I had this problem and it was caused by too much pressure.
I first fixed it by fitting an adjustable fuel pressure regulator.
I have since found a better solution. I've gone back to the factory pressure regulator and fitted smaller injectors from a 1UZ.

The 7mge came with 315cc/min injectors and most 1UZ FE engines have 251CC/min.
They are a straight plug and play change over but it takes an hour or two to do the job since you have to remove the ISCV and the throttle body to get to the fuel rail.

BTW do you also have sluggish performance after a cold start???

[madmont]

I have three in my thermostat housing. The bottom one with 1 wire goes to the temp gauge. The middle one with 2 wires tells the ecu the water temp and the top one with 2 wires is for cold start injector.

[Slim]

...and if you got me a pic to refresh my memory...

Get your fuel pressure checked.

I had this problem and it was caused by too much pressure.
I first fixed it by fitting an adjustable fuel pressure regulator.
I have since found a better solution. I've gone back to the factory pressure regulator and fitted smaller injectors from a 1UZ.

The 7mge came with 315cc/min injectors and most 1UZ FE engines have 251CC/min.
They are a straight plug and play change over but it takes an hour or two to do the job since you have to remove the ISCV and the throttle body to get to the fuel rail.

BTW do you also have sluggish performance after a cold start???

So why is the adjustable pressure regulator a bad idea? Sounds to me like if it's really a fuel pressure problem then that would solve it.

I'm also wondering if maybe you create a new problem when fitting smaller injectors... ie: will it starve for fuel when it needs a lot of it at WOT?

Where is the fuel pressure regulator located?

I spent a lot of money trying to fix this problem in the past which included purchasing new injectors (so i'd rather not replace them again) checking fuel rail pressures (but i think that was to test for leaky injectors when switched off) testing cold start injector, replacing O2 sensor... etc. I disconnected the cold start injector althogether at one stage in the belief that it may be firing when it's not needed. No noticable change.

Sluggish performance after a cold start?? Nope, and i don't push it at all when cold so i wouldn't really know.



One thing to note though... whilst this startup problem has been with the car since i bought it as well as after the engine was stripped down and rebuilt i have a new problem that now occurs occasionally (only the last couple of months). Sometimes when i go to take off from the lights the engine misses for a split second like i've done a single bunnyhop and on one occassion actually stalled. It's as if there's a cut in the spark because it's a very abrupt jolt... All power for a second, then bang, NO power for a split second, then back to normal.

It only happens about once a fortnight and thus i can't predict when it will happen or pinpoint similarities in the circumstances.

[amichie]

So why is the adjustable pressure regulator a bad idea? Sounds to me like if it's really a fuel pressure problem then that would solve it.

I'm also wondering if maybe you create a new problem when fitting smaller injectors... ie: will it starve for fuel when it needs a lot of it at WOT?

Where is the fuel pressure regulator located?
.

I didnt like the cheap adjustable fuel pressure reg that I bought and I'm too tight to buy a quality one like a SARD so I went back to the factory reg. Fitting the adjustable unit involved bodging up some rubber hoses etc. I wanted to go back to the factory metal fuel lines also.

I've also got a oxygen sensor monitor on the dash that tells me its still running rich at WOT even with the smaller injectors.
The regulator is on the end of the fuel rail.

[Slim]

... and I'm too tight to buy a quality one like a SARD...

but how much do 1uz injectors cost?

[amichie]

but how much do 1uz injectors cost?

I got a set off ebay for $50

[Slim]

Hmmm... interesting. So how does you car start now? Is it instantaneous or still kinda crap but better than before? It still seems like a bit of a patch up solution... there must be something broken that's causing this high pressure, i just need to find what it is.

[amichie]

Hmmm... interesting. So how does you car start now? Is it instantaneous or still kinda crap but better than before? It still seems like a bit of a patch up solution... there must be something broken that's causing this high pressure, i just need to find what it is.

Car starts easy now when hot.

Car is now a bit cranky to start when cold but my cold start injector is disconnected at the moment. I'm hoping that when I reconnect it then cold starts will be easier also.

Did a Sydney to Newcastle run today (towing a trailer) on the new injectors. No real signs of running over lean. The oxygen sensor monitor was busy the whole trip.

[supra_cam]

One thing to note though... whilst this startup problem has been with the car since i bought it as well as after the engine was stripped down and rebuilt i have a new problem that now occurs occasionally (only the last couple of months). Sometimes when i go to take off from the lights the engine misses for a split second like i've done a single bunnyhop and on one occassion actually stalled. It's as if there's a cut in the spark because it's a very abrupt jolt... All power for a second, then bang, NO power for a split second, then back to normal.

It only happens about once a fortnight and thus i can't predict when it will happen or pinpoint similarities in the circumstances.

Thats the same problem my 7mge has! It will be fine for a week or two then it will miss heaps for a couple of days and then it will be fine for another week or so. How did you go fixing it? Did just replacing the oxygen sensor fix it or was it the new injectors that did the trick?

[Slim]

I am still in the process of fixing it... i'm fitting a 1JZ.

Nah, seriously... that wasn't the reason for going for the 1J. The 7M blew a 3rd head gasket and i got fed up with it.

I have all the sensors and bits off the 7M. I wonder how easy it is to test them out. I'd preferrably like to sell the bits of the 7M but would like to know that they all work so i'm not passing on problems.


EDIT!!! I was thinking you were talking about the startup problem... i fixed the other problem by getting new leads and plugs. Basically a good service did the trick.

I still have the leads which are only 5-10 thousand km old. They cost about $110. You could have them for $75 if interested.

[supra_cam]

my leads and plugs are only 4-5 thousand k's old but thanks anyway. maybe I should take a look at the distributor and coil.

[CrUZida]

I'd start by replacing all the capacitors in the ECU.

It will cost about $3 and a few hours work.

Any startup issues I'd point your finger straight at the ecu as being the culprit.