Can a CPS output be dependent on temperature?

[bigaaron]

Technically speaking from years of in depth research and analysis......

the 7m-gte will run like shit with a busted knock sensor. :biglaugh:

 

[drjonez]

Technically speaking from years of in depth research and analysis......

the 7m-gte will run like shit with a busted knock sensor. :biglaugh:

i beg to differ. i've had several cars that have run just fine whilst throwing code 52.

the real way to find out would be to call up reg and ask him.

 

[bfr1992t]

two knock sensors are needed regardless of it being "active" or not due to the length of the block.

This sounds like a misadjusted or failing TPS to me.

 

[JustAnotherVictim]

Any time I had a cps problem it was due to the wiring being burnt or old. Never a bad thing to check.

 

[jetjock]

Good point, although I wonder why the N/A has the same block and only uses one. Must be that turbo thing

 

[bigaaron]

i beg to differ. i've had several cars that have run just fine whilst throwing code 52.

the real way to find out would be to call up reg and ask him.

You must not have had a turbo on it then, or you were not running any boost. :icon_razz
If it is a loose wire it could throw an intermittent code and still work but if the sensor or wire is broken completely it will run like crap, unless of course, it always ran like crap and you just didn't notice. :icon_razz

 

[bfr1992t]

Good point, although I wonder why the N/A has the same block and only uses one. Must be that turbo thing

Yeah, knock sensing is a little more important on the turbo motor when you have warranties to worry about.

 

[drjonez]

You must not have had a turbo on it then, or you were not running any boost. :icon_razz
If it is a loose wire it could throw an intermittent code and still work but if the sensor or wire is broken completely it will run like crap, unless of course, it always ran like crap and you just didn't notice. :icon_razz

YMMV. you have your exp, i have mine....

 

[Joel W.]

I also have a 1990 version of Toyota's TCCS Service Training Information manual and I can confirm that Jetjock's information is also in my book.

If the sensor's (referring to the knock sensors) connector is disconnected, while the engine is running under heavy load or maintaining a high speed for a short time (one or two minuts), the CHECK ENGINE lamp lights up, At the same time, the ignition timing is retarted no more than 10 degrees from normal.

 

[Nick M]

For example in all my Toyota TCCS manuals (which are very comprehensive) nowhere does it mention two trip detection logic for code setting while the aftermarket manuals do. Yet I know from introducing faults on my car that Toyota uses it. (It's also commonly used by other car companies).

This is true. It isn't a common thing, but Toyota is sometimes silent on its systems. And this will sometimes show in the repair manual also.

 

[toml]

I'm glad I managed to spark an interesting converstaion on ESA / Knock Sensors.

jetjock: As I believe the "So stop thinking of the knock system as passive." comments were directed at me, I'll respond by saying that I completely understand where everyone in this thread is coming from regarding knock sensors and understand that a code 52 should be resolved right away.

Please don't think that I've just gone "Oh, a code 52... meh!" and ignored it, I'm working on trying to get it fixed. I've replaced all the wiring but that didn't help, so I'm now trying to source a new knock sensor to test (I don't really want to have to buy a brand new one from Toyota for $200+).

Now, back to the subject - the ESA system could not cause misfiring or troubles starting, as far as I'm aware. So, the suggestions I've seen so far for these are:

• Fuel pressure (I have a new fuel pump, fuel filter and AFPR on the way)
• CPS
• TPS

CPS: I've checked the resistance of the CPS, which was fine. I'm going to go check the air gaps of the pickups and see if they're in spec. I also tried measuring the CPS signals at the ECU connector with my scope but couldn't get a decent reading, so I'm going to go try that again today too.

TPS: I haven't dealt with the TPS before, so I'm not sure what sort of problems it can have (I'm not even sure how it works ). But, I'll go test it as per the TSRM and see what I can find out.


Thanks,
Tom

 

[Nick M]

I understand that if the engine was cranking slowly that the CPS may be causing issues starting, but my problem goes away when the engine is warm, so it doesn't seem to be a cranking speed related problem.

Yeah, back to the topic.

In my experience, drivability problems that go away are one of two things. One is a worn engine, and that is not usually the case. The other is ECT circuit. If your sensor sends a phony signal, the ECU may not run rich enough for the cold temps. A lean condition will cause a miss just as easily as ignition.

 

[toml]

Thanks jetjock. No problems on the hijack!

I haven't checked the CSI yet, so I will go do that.

I've tried jumping the FP connector in diag box before starting, but that didn't help - does that rule out a fuel pressure issue? I don't have a Fuel Pressure Up VSV on the car (it broke and was $220 for a new one), but I can't see why that would make a difference for cold starts. I have no problems starting when the engine is warm.

My coolant temp sensor is OK.

I haven't tested for vacuum leaks yet, as I don't have a decent vacuum gauge (might go see if I can get one today)... however I was mucking around with the vacuum lines around my engine bay the other day - are any of them 'important' enough that the engine will react to me taking the tubes off or plugging the ports? I was just messing around to see 'what happens when I do this?', but nothing seemed to change.

 

[toml]

In my experience, drivability problems that go away are one of two things. One is a worn engine, and that is not usually the case. The other is ECT circuit. If your sensor sends a phony signal, the ECU may not run rich enough for the cold temps. A lean condition will cause a miss just as easily as ignition.

You triggered my memory - There's a strong smell of fuel in my garage after a cold/hard start. I'm assuming this is because of the extra cranking time, more fuel getting pumped around and not being used? Does this sound normal or could it be a symptom of the problems i'm having?

 

[toml]

Fuel Pressure Up is for hot starts. The CSI is for cold. The car will cold start with no CSI in warm temps but the CSI makes it quicker and really helps when chilly. My car starts with a touch of the key, hot or cold, for example. Toyo didn't stick it in there just to make the car heavier you know. A good battery helps too.

Yep, I understand it's there for a reason.
[also just bought a brand new battery]


Here's my newbieness showing again, can you expand the TTS acronym for me? I searched but the three letter acronyms don't turn up too easily.

If you smell fuel at least that means you're getting spark (if you didn't have spark the ECU would kill injection soon after cranking) so it's likely a cold enrichment problem. The fuel smell is a symptom of your problem. Reminds me, when you do get it started (when it starts hard) are you holding the pedal to the floor to put the ECU in flooded start mode? Might want to try that until you get the problem fixed.

"Cold enrichment problem" = "something is wrong with my air/fuel mixture when the engine is cold"?
So is my logic correct: I'm looking for whatever changes to the fuel injection and air intake systems when the car is hot versus when it is cold? Since nothing changes to the air intake, the CSI is the primary suspect?

I have tried changing the throttle position whilst starting (didn't help), but I wasn't aware of a 'flooded start mode'. Can you expand on this? I searched the forum and found another of your posts explaining the TPS pot which mentioned flooded start mode but didn't actually say what the ECU does in this mode.

There isn't much in those vacuum lines that'd keep the engine from starting. Do you hear the ISCV step back on engine shutdown? Is this an N/A or turbo car?

Yes, I can here the ISCV click back to its start position on engine shutdown. This is a turbo car (it's pretty much stock 7M-GTE + air filter + new pistons, rings, bearings)

 

[Nick M]

How do you know the ECT sensor is good? The best way to check is not on your ohm scale, but voltage.

When the engine is stone cold, check the voltage, and watch it change as the car runs. The air temp signal will do the same, but stop half way. Air temp is THW on your computer pins. It might not be your problem, but when the symptom stops after warming, then you should check its rise.

The ECT sensor is designed backwards from a normal circuit. As it warms, resistance goes down, so your return voltage goes up. If you are even getting a voltage.

If you did already check that, then disregard.

 

[toml]

I checked it as per the TSRM, resistance scale. I will check the voltage of it too..

 

[toml]

Wow, I think you've covered everything too (and more)!

Yes i've checked all the basics, and now I think I have a lot more to go check and hopefully find out what's going on!

(ps. I wouldn't know where to get a real TSRM from in Australia, but I do have most of one printed out )

 

[toml]

Oh, and, yes - the FPU vacuum line is connected to the manifold

 

[toml]

Found a few things so far:
The CSI was clogged to hell - couldn't even see the fuel nozzles. I've cleaned that up and it seems to spray fuel when I give it 12 volts. It was also within the 2-4 ohm resistance spec.

I put a voltmeter on THA and THW (air and water temp sensors). Now, I'm not sure how they're meant to work, but they seemed to lower in voltage as temperature rised, is that correct? Water temp started at around 0.9V and linearly dropped to stay steady at 0.3V as it reached operating temperature. The air temp started at about 1.9V and was about 1.3 to 1.5V when I turned off the engine.

I'll have to wait until morning to try a 'cold start' and see if cleaning the CSI makes a difference. I didn't have a chance to test my CPS or TPS, but I will do that tomorrow.

Would any of this cause bad fuel economy? (three quarters of a tank of fuel gets me about 125 km - 75 miles ... but that could be unrelated )