No check engine light with speedo disconnected?

vrg3 · Post by **vrg3** » Sat Jun 27, 2009 4:14 pm

It's less likely to happen in a non-turbo because the non-turbo pump doesn't draw as much current. A Walbro may actually draw even more current than a stock turbo pump and so exacerbate the problem. In my car it became a problem only after I had swapped in a MkIV Supra turbo pump.

Are you sure those are all burn marks underneath? If I remember right there's some kind of tarry substance right there for sound deadening or something.

Post by **Legacy777** » Mon Jun 29, 2009 12:22 am

Yeah the tar substance can kind of be misleading.

ericem · Post by **ericem** » Tue Jul 07, 2009 4:21 am

Update on this thread. Today went to the dealership for a nice coolant flush and alignment. Things went good. Got to plug in a select monitor showed all the sensors. under rad fan's said YES while the temperature was at the highest right when we came to a stop at 96C which is 204F and rested at 93 after less then a minute which is like 189F I think. Fans still stayed on. We cleared any previous codes and restarted a few times and there were no codes current. All sensors seem to be operating just fine. So I didn't want to pay $100 for the mechanic to look further into this issue, although I was very happy to see the ECU is no getting a overheating temp input.

Nice to know my coolant is now nice and clean. Yet what should I do to fix this issue. Why does the ECU want to continue running the fans even after the ecu sees the coolant is under 190F :S any idea's guys? I am thinking bad ECU at this point. What's really weird is there are still previous codes like there was 10 codes in the history yet I THOUGHT i reset the ECU. I unplugged it many times for like 1 hour. Yet all sorts of codes were in the history. (pressure snesor, o2 sensor, MAF sensor, ECU malfunction or something, knock sensor, um starter switch, a bunch more) regardless never saw a check engine light after replacing my knock sensor.

vrg3 · Post by **vrg3** » Tue Jul 07, 2009 4:51 am

Just removing power from the ECU doesn't clear the codes. You have to either do the clear memory procedure with the connectors or use a Select Monitor or equivalent.

Hm. 93 degrees Celsius is not under 190 degrees Fahrenheit -- it's just under 200 degrees Fahrenheit. I don't believe that's cool enough for the ECU to shut the fans off. Like Josh says, it needs to get down to around 87 degrees Celsius before the fans will turn off.

So that sounds like the ECU's fan control is working correctly. The actual problem is that your coolant temperature is staying too high.

I'm puzzled, though. The first thing I'd suspect is a coolant temperature sensor that reads too high, but you've tried several. And bad temperature sensor wiring would tend to make it read low, not high. The other thing I'd suspect is a bad thermostat, but you've tried replacing that too, and I can't imagine you'd have allowed the dealership to do a coolant flush without replacing it as well.

When you swapped in different temperature sensors, you were replacing the ECU's temperature sensor, right? Not the sender used for the temperature gauge? They're next to each other. The sensor has a two-pin connector; the sender has a single quick-disconnect-type connection.

ericem · Post by **ericem** » Tue Jul 07, 2009 4:58 am

Yup I did replace the thermostat the 2nd brand new OEM thermostat in a few months lol.

Yup I am replacing the sensor with the two pin red connector.

Actually your probably right. Does the coolant tank have some sort of valve so it doesn't not overload the cooling system in it? I remember when I was cleanign it I would shake it and I heard something make a slight ticking sort of noise I rinsed it and shaked it like crazy yet nothing came out. No flow issues out of the pipes. Hmm.

vrg3 · Post by **vrg3** » Tue Jul 07, 2009 5:19 am

You mean the tank attached to the intake manifold? It has a check valve built into the small fitting on the back; that's probably what you heard. It's there so air can burp from the radiator up to the tank but water doesn't flow backwards into the radiator from above.

ericem · Post by **ericem** » Tue Jul 07, 2009 5:47 am

ya thats it. I dont know what else to do

vrg3 · Post by **vrg3** » Tue Jul 07, 2009 7:09 am

I'm at a loss too. I suppose it's not really a problem.

Not yet, anyway.

ericem · Post by **ericem** » Tue Jul 07, 2009 3:25 pm

i tried rads ,thermostats, rad caps, sensors , flushing. Maybe there was air bubbles from yesterday right after the flush. Ill check today!

ericem · Post by **ericem** » Tue Jul 07, 2009 7:05 pm

ok well now i am thinking water pump. Could the timing belt be slipping the mechanic seemed to think it might be the issue. I took off the driver side cover dont see any glazing other then between the teeth. Not sure if thats normal anything i should try wiping on the belt to degrease it?

ericem · Post by **ericem** » Tue Jul 07, 2009 7:07 pm

ok actually i waited like 5 mins and came out the fans were still running. I tapped the pedal a few times to get the rpms up to like 1 2 k and the fans shut off after a few seconds....

vrg3 · Post by **vrg3** » Tue Jul 07, 2009 8:49 pm

Hm. That may indeed be the water pump then. Revving the engine speeds the pump up.

Did you inspect the smooth back side of the belt? That's the side that drives the water pump.

Is the timing belt greasy? You have to be careful degreasing belts because some solvents are damaging to the rubber. I would actually use dishwashing soap and water if you have to clean it.

ericem · Post by **ericem** » Wed Jul 08, 2009 5:11 pm

well what i was thinking of doing was from the driver side cover wipe the belt with a soapy wet cloth carefully with the motor running. My dad seems to think its impossible for it to be slipping.

vrg3 · Post by **vrg3** » Wed Jul 08, 2009 6:25 pm

To me the belt slipping seems less likely than just the pump being worn out. Speeding the engine up made it cool off, for one thing, and also I feel like you're pretty observant and would have noticed the sound of it slipping.

How old is the water pump?

ericem · Post by **ericem** » Wed Jul 08, 2009 6:50 pm

Brand new less then a few months. I did not get it from a dealer, but the pump looked exactly the same as a OEM pump and was made in japan.

vrg3 · Post by **vrg3** » Wed Jul 08, 2009 7:25 pm

Oh.

Well, now I don't know again.

Let's just recap: What we think is happening is that for some reason the engine is not able to fully cool itself at idle. And the fan behavior is just a side effect of that. Right?

I'm reaching here, but have you tried doing a leakdown test? I suppose a very slightly leaking head gasket could make something like this happen.

I dunno.

93forestpearl · Post by **93forestpearl** » Thu Jul 09, 2009 12:35 am

Yikes, I'd pull the fuel pump out just to take a look at it.

Maybe if it is really as loud as you think it is, you could possibly have a defective pump?

My connector at that point looked mint after two years of running that pump.

ericem · Post by **ericem** » Thu Jul 09, 2009 3:31 am

Just a update. Tried wiping the outside of the belt with a soapy cloth till the belt seemed cleaner to the point where rubbing my finger over it had my friction. For a bit i thought the fans started cycling but i also restarted the car many times but again stopped working after driving for a bit. Now the headgasket is bothering me. Going to bleed the air out of the system again. If something like a turbo line or the iac to tb lines are clogged would it create a issue when fully pressurized ? Grr i cant sleep with problems like this.

vrg3 · Post by **vrg3** » Thu Jul 09, 2009 3:14 pm

If one coolant line is clogged it shouldn't really cause this to happen... There are other collateral paths for coolant to flow.

If the IAC or TB coolant passages were completely blocked, your car wouldn't idle correctly, since the IAC valve's position depends on coolant temperature.

I didn't mean to alarm you by mentioning head gaskets. I'm just reaching. If it'll ease your mind, try a compression test and a coolant sniff test. Or, if you have the equipment, a leakdown test.

ericem · Post by **ericem** » Thu Jul 09, 2009 6:46 pm

There are no real signs of headgasket. I am just hoping its not detuning the car. I need to fix a bunch of possible vacuum leaks. I think ill leave it like this but i dont think the fans are cycling off when i am moving. Are they suppost to ? With the windows down it doesnt seem like they shut off at any point because at like 30kmh if i make a complete stop i dont hear them just turn on. Going to get a leak down and the sniffer test. Going to track the car august 2nd.

vrg3 · Post by **vrg3** » Thu Jul 09, 2009 7:06 pm

They are supposed to turn off when you're moving above a certain speed, but I don't know what that speed is. 30 kilometers per hour might not be fast enough.

If the engine's even mildly overheating I believe the fans will stay on regardless of speed though.

Do you have an old laptop you can run my scantool on?

ericem · Post by **ericem** » Thu Jul 09, 2009 11:22 pm

i think im going to buy a old laptop just so i can make the cable. Just needs a serial port right ?

vrg3 · Post by **vrg3** » Fri Jul 10, 2009 2:54 am

Either a serial port or a parallel port. The parallel port interface is easier to build (just three wires) and I've tested it more.

ericem · Post by **ericem** » Fri Jul 10, 2009 5:45 am

your talking about that printer cable right? Why cant i use any laptop with a parallel port ?

vrg3 · Post by **vrg3** » Fri Jul 10, 2009 5:47 am

The parallel port is also called the printer port, yes.

You should be able to use most any laptop with a parallel port.

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No check engine light with speedo disconnected?