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> Is this bad?, engine runs better without temp sensor
jrcui
post Jan 30 2006, 03:32 PM
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Was cleaning out the air box when I noticed the temp sensor was unplugged from the throttle body (I hope I sound somewhat knowledgable). I plugged the temp sensor back in but the engine ran like crap... unplugged and it ran smooth. Is this a bad thing?

Thanks in advance,
Vince (IMG:http://www.914world.com/bbs2/html/emoticons/wacko.gif)
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bd1308
post Jan 30 2006, 03:36 PM
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unplugging that temp sensor enrichens the mixture of fuel and air by some 10% or so, according to the BOSCH fuel Injection book I have somewhere.

That means you probably have a leak somewhere, or you gotten used to the "good running" slightly rich mix of having that unplugged.

It's an old VW tech trick I read up on that above mentioned book.

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jrcui
post Jan 30 2006, 03:38 PM
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Thanks!! Car was running rough so I took it to Motor Sports International in Beaverton/Portland a couple of months back. The tech was an old time 914 owner so I think he's behind it....
Vince
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bd1308
post Jan 30 2006, 03:42 PM
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yeah, I would just start replacing those hoses...the german braided ones get brittle and crack on the inside, even though they appear okay on the outside....

you might find your problem somewhere there.

I would assume that running rough = lean, due to the tech tip.

b
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SirAndy
post Jan 30 2006, 03:43 PM
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QUOTE (jrcui @ Jan 30 2006, 01:38 PM)
The tech was an old time 914 owner so I think he's behind it....

sounds like he sold you a "Band-Aid" ... (IMG:http://www.914world.com/bbs2/html/emoticons/dry.gif)
i hope you didn't pay too much for that.

something in your setup is obviously not right. try to find it, then fix it the right way ...
(IMG:http://www.914world.com/bbs2/html/emoticons/wink.gif) Andy
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Joe Ricard
post Jan 30 2006, 03:49 PM
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What the hell happened when I wasn't looking?
our Son Britt is becoming a good Wrench...
WOW!!!!!!!! (IMG:http://www.914world.com/bbs2/html/emoticons/beer.gif)
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bd1308
post Jan 30 2006, 03:53 PM
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QUOTE (Joe Ricard @ Jan 30 2006, 03:49 PM)
What the hell happened when I wasn't looking?
our Son Britt is becoming a good Wrench...
WOW!!!!!!!! (IMG:http://www.914world.com/bbs2/html/emoticons/beer.gif)

thank ya Joe.

b
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jrcui
post Jan 30 2006, 06:10 PM
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When I got the car, I replaced all the hoses but I think there was an issue with a leak coming from the distributor (if that makes sense). The fuel pressure sensor was also changed out but she was still running rough.

The disconnected temp sensor has the car running ok. When you plug it in, the car idles bad and dies.

I'm the kinda guy who keeps mechanics in business......

V
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Mueller
post Jan 30 2006, 06:33 PM
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QUOTE (jrcui @ Jan 30 2006, 05:10 PM)
When I got the car, I replaced all the hoses but I think there was an issue with a leak coming from the distributor (if that makes sense). The fuel pressure sensor was also changed out but she was still running rough.

The disconnected temp sensor has the car running ok. When you plug it in, the car idles bad and dies.

I'm the kinda guy who keeps mechanics in business......

V

what engine/FI do you have?

if a d-jet, I thought the air temp sensor is mounted on the plenum, not connected to the throttle body (IMG:http://www.914world.com/bbs2/html/emoticons/wacko.gif)

fuel pressure sensor??? (IMG:http://www.914world.com/bbs2/html/emoticons/WTF.gif) .......what is that?

do you mean fuel pressure regulator? which I doubt was bad, did your mechanic even check the fuel pressure with a gauge??
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bd1308
post Jan 30 2006, 06:51 PM
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how many pins is the connector?

4/5 is the Throttle Position Sensor

2 is the Air Intake Temp Sensor.

If the 4/5 pin connector is unplugged and plugging it in causes the idle to be REAL rough, the sensor needs to be adjusted per the Pelican Parts TPS Calibration article, and then the adjustment pot needs to be tuned a bit to find the best idle quality. The adjustment pot is located ON TOP of the ECU, near the battery. Black knob looking thing.

Make friends with the technical article though on Pelicanparts.com


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jrcui
post Jan 30 2006, 07:59 PM
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It's the two pin....... the one just below the five pin which I assume is the larger plug on the throttle body..
V
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bd1308
post Jan 30 2006, 08:01 PM
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okay, so yeah i had it right.

That thing the sensor is inserted into is actually called the "plenum"

check vac leaks.

b
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jrcui
post Jan 30 2006, 08:01 PM
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I'll take a pic when I can for better illustration.....
V
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jrcui
post Jan 30 2006, 08:19 PM
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Pardon if I don't get the names right but everyday is learning day for me when I attempt to look at my engine... ('75 2.0).

I hope the picture is clear enough.

V


Attached image(s)
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bd1308
post Jan 30 2006, 08:22 PM
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yep.

that be da one.

(IMG:http://www.914world.com/bbs2/html/emoticons/biggrin.gif)

unplugging that richens the mix by around 10-15%

if ya got a rough *IDLE* only, try adjusting that knob on top of your engine "computer" by the battery tray. The idle mixture (if your throttle position sensor is calibrated to spec) is derived from that adjustment knob, and not from the MPS. So make adjustments there. Also, check for vacuum leaks as well.

b
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jrcui
post Jan 30 2006, 08:28 PM
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Thanks B!!!
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bd1308
post Jan 30 2006, 08:31 PM
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QUOTE (jrcui @ Jan 30 2006, 08:28 PM)
Thanks B!!!
(IMG:http://www.914world.com/bbs2/html/emoticons/smiley_notworthy.gif)

with over 4000 posts, i knew one day i'd help somebody out.

(IMG:http://www.914world.com/bbs2/html/emoticons/smile.gif)

no problem man....

go hunt those leaks (IMG:http://www.914world.com/bbs2/html/emoticons/wink.gif)

b
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