Question about ECT

Vinalero · 02-12-2009, 06:53 PM

I know its a long post, but I tried to put everything I was thinking of in it

So, I'm down to the point I wonder if its not my ECT that is screwing my idle. (Idling at 1500 rpm steady when car is hot)

So far for trying to fix this problem Ive :

-changed my IAC
-cleaned the IAC air passage in the TB
-Dissassembled the TB in -5 F weather, all the sensors, cleaned everything good, the butterfly close perfectly.
-probed the TPS at the TB to see if I had correct voltage, was ok
-probed the TPS at the PCM to see if the TPS was sending a correct voltage, was ok
-probed the IAC to see if voltage was ok, seems fine.
-looked everywhere for a vacuum leak, in 2 different occasion. One time we sprayed brake cleaner everywhere, no change in idle. Second time we used propane near every vacuum tubes and intake manifold itself hoping to see a rise in idle, no results either. (Thanks to GuiGuiLandry)

My ABS and parking brake lights are on, fluid is full, braking works fine. I suspect the sensor in the brake fluid tank. (I dont see this having anything to do with my idle problem anyways)

checked the codes with a cheap scanner, only code showing is a VSS code (Vehicule speed sensor) BUT my speedometer works fine, no fluctuation, nothing suspicious, and anyways it wouldn't matter when talking about idle.

So now I'm wondering if its my ECT that is playing with me. However, the gauge in the car works in a correct way. Fans kicks on when they should and car doesnt overheat. Needle stays approximatly at middle mark.

I feel the car drives fine, except that for example, when I accelerate to 3500 rpm and push the clutch so the car is in neutral, RPM takes a lot of time to go down to idle, even a lot longer than before I had the supercharger installed. Of course after the supercharger was installed, because of more load on the engine from the SC, I felt the RPM got down really faster between shifts than before the SC. Now its taking forever btw shifts to get down. Other than that, the car has no hesitation and drives fine.

Thinking about it, it kinda feels like the car is always running like if the engine was cold. It feels like something is telling my IAC to stay open more when i release the gas pedal.

I have one question: Could the ECT be bad, but still give me proper temperature on my gauge cluster????

Is there a second sensor ONLY for the gauge in the dash??

Ive looked in my Haynes, but apperently, its only one sensor.

[ion] C2 · 02-12-2009, 07:05 PM

Yes, if the ECT sensor is faulty and defaults to -40 degrees, the idle speed will be targeted at something high like that (mine is 1200, auto, with a manual it will be much higher).

I don't know how the gauge can be accurate and the sensor be faulty, however.

Considering what you've tested and changed, the IAC and TPS are fine.

Vinalero · 02-12-2009, 07:10 PM

Yeah, thats what i think, it idles at the same speed than my engine used to rev at every first 30 seconds of a really cold start up.

But I'm clueless as to why my gauge is reading right.

[ion] C2 · 02-12-2009, 07:12 PM

A new sensor is $12, try it out and see what happens?

http://www.autozone.com/R,3837429/ve...ductDetail.htm

Vinalero · 02-12-2009, 07:16 PM

Ya, I have one used shipped to me right now, along with 2 IAC and 2 TPS. I was just asking if someone could think of something I didnt think about already :P

[ion] C2 · 02-12-2009, 07:23 PM

No vacuum leaks, TPS and IAC are fine... IAT doesn't affect idle RPM... O2 sensor issue wouldn't cause steady high idle speed... I don't see anything else that would cause it.

Fans should only come on if 223 degrees is passed. (I think that equates to like, a bit past the middle mark (middle is 200))

I'll take a TPS if you don't need it lol. Who knows how long til my current one fails (I had a major problem with the one that came on my used 62mm TB, so I put on my 180k mile TPS and it runs fine, but I don't know if/when it'll die too)

Vinalero · 03-08-2009, 04:43 PM

Update:

- Changed IAC for a second time
- Changed TPS for second time
- Changed ECT for first time
- Unwrapped all the wires and soldered the two wires from the TPS that I previously cut when installing my Supercharged instead of only twisting them together (Thanks a guigui

)
- Rechecked all the vaccum hoses, all fine
- Tried to tight back all the bolts from the intake manifold, all ok.

Problem persist... GuiGui and me are completely lost.

what else?

Knock sensor?
Camshaft sensor?
Crankshaft sensor?
Is there a power steering regulator switch on the LD9? (we could not find one on the wiring diagram.)

Actually, theres only the PCV baffle that is left to check, but I wonder how this could be the problem, since its a solid piece of "cement-like material" that is bolted with 8-9 bolts. The hose of the Baffle are both OK.

Plz help me kill those Gremlins!!!

[ion] C2 · 03-08-2009, 06:53 PM

Something that fits the description: Your throttle plate doesn't close all the way or as far as it used to.

Vinalero · 03-08-2009, 11:17 PM

Quote:

Originally Posted by [ion] C2

Something that fits the description: Your throttle plate doesn't close all the way or as far as it used to.

Actually, we checked that like 4 times, and it does close completely.

guiguilandry · 03-08-2009, 11:21 PM

hey Vince I got your HO TB , call me when you can, on my cellphone

[ion] C2 · 03-08-2009, 11:27 PM

Ugh...
- vacuum leak
- bypass valve not working properly. would cause weird things. if it's not open all the way at idle it could allow more pressure to build than needed. if it doesn't close all the way at WOT it would lessen your boost.

Vinalero · 03-09-2009, 03:24 AM

Do you know of any way to test the bypass valve? I really dont feel like getting the SC out of the car...

For Vaccum leaks, well I dunno I'm clueless on that part, theres absolutly no reaction from the engine when spraying every place around intake's ports, and all the vaccum hoses.

Ion, you sure you didnt ship me your Gremlins by mistake?

GuiGui: Ok I'll give you a call dude.

[ion] C2 · 03-09-2009, 10:34 PM

Did you ever have any pressurized air hooked up to your throttle body to pressurize it and your intake manifold to see if you hear any hissing and spray soapy water to see if it makes bubbles?

That is a far superior test. I found many leaks around my throttle body and vacuum hose connections that were otherwise undetectable.

I must have shipped you my gremlins, as I haven't had any weird issues lately besides a stupid coolant hose that kept leaking and dumping coolant on my header but that's an easy one.

Vinalero · 03-16-2009, 10:48 PM

Update :

I got myself a Quad4 TB and tried to put it on. We made a new paper gasket for it and we also used high temp silicone to be sure theres no air leak btw the TB and the supercharge. Also I thought maybe the rubber on the brake booster line was maybe letting some air thru, so I got two collar and tighted them like a madman.

Now the car is revving at 2000 rpm....... GODDAMN!!

Is it possible that the programmation of the PCM got wrong at some point? I've seen some post on other forums about PCM needed to be reflashed for LD9 engines because it was idling high...

Here comes another question : I can't just go to a dealer and say "plz flash my car" Because I have the supercharger programmation in my PCM. Also, I guess if I ask them if they can get me the SC flash, they will have no effing clue, like the first time, and they are gonna charge me 1 hour for hooking the goddamn diagnostic machine to the car, then another hour to flash the car, After taking another effing hour to figure out how to do it... and 250 bucks later I wont even be sure its fixed. I'm on a tight budget, real tight.

I'm in a kind of a bad mood...