# digifant car stalls when coolant temp sensor is plugged in..and mad rich



## autobahnjs (Sep 14, 2002)

its my friends car and driving us crazy...
i did new o2 worked fine and fixed the ground for it.. and also tried a new cts and the car goes mad rich when its pluged in and ready to stall? any extra help would be great


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## secondgen (Jan 9, 2004)

*Re: digifant car stalls when coolant temp sensor is plugged in..and mad rich (autobahnjs)*

bad ecu?


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## autobahnjs (Sep 14, 2002)

*Re: digifant car stalls when coolant temp sensor is plugged in..and mad rich (secondgen)*

nope i tried a spare one and spare maf too


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## autobahnjs (Sep 14, 2002)

*Re: digifant car stalls when coolant temp sensor is plugged in..and mad rich (autobahnjs)*

ttt


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## rychas1 (Mar 2, 2004)

*Re: digifant car stalls when coolant temp sensor is plugged in..and mad rich (autobahnjs)*

try going back to the 02 change...sounds like the source http://****************.com/smile/emthup.gif


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## autobahnjs (Sep 14, 2002)

*Re: digifant car stalls when coolant temp sensor is plugged in..and mad rich (rychas1)*

ya true prob is its being happening b4 and after new 02
plus i check the wires look good and i fixed the o2 ground


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## rychas1 (Mar 2, 2004)

*Re: digifant car stalls when coolant temp sensor is plugged in..and mad rich (autobahnjs)*

u clear the ecu yet?


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## autobahnjs (Sep 14, 2002)

*Re: digifant car stalls when coolant temp sensor is plugged in..and mad rich (rychas1)*

by reving it over 3000? or by batt disconnect?
also noticed something weird... if i disconnec the o2 then it will be ok to plug in the coolant sensor? any ideas i changed the cts 3 times so i dont think its it and the o2 is new


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## rychas1 (Mar 2, 2004)

*Re: digifant car stalls when coolant temp sensor is plugged in..and mad rich (autobahnjs)*

no..by disconnecting CTS, starting car, revving over 4k (just to be sure, lol) a few times, until it can hold idle on its own and not cut off, 5 or 6 revs works for me. adjust idle screw according to digi specs if u need to. cut car off. reconnect CTS. start car. be happy (hopefully). simple.


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## autobahnjs (Sep 14, 2002)

*Re: digifant car stalls when coolant temp sensor is plugged in..and mad rich (rychas1)*

i never knew you were to shut the car off?


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## rychas1 (Mar 2, 2004)

*Re: (Supermoves)*

did u reset the ecu yet?


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## autobahnjs (Sep 14, 2002)

*Re: (rychas1)*

well i did it the book way.. unplug ecu rev 3-4 times over 3000
set idle plug back in


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## rychas1 (Mar 2, 2004)

*Re: (autobahnjs)*

unplug ecu? nonono....unplug CTS!!!! argh...


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## autobahnjs (Sep 14, 2002)

*Re: (rychas1)*

sorry ment to say cts http://****************.com/smile/emthup.gif


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## autobahnjs (Sep 14, 2002)

*Re: (autobahnjs)*

so far i ahve tested all wiring and all well but the new o2 is gove in a reading of .1-.4 so longs like this should be it..will post what happens


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## autobahnjs (Sep 14, 2002)

*Re: (autobahnjs)*

i tested all wiring and put in a another used o2 and the reading on the meter is .01 to .045 ish wtf is going on..the o2 worked in the other car fine... so right now the car runs with either cts on or o2...not both at the same time.. or else bogggggggg


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## mxman (Jul 31, 2003)

*Re: (autobahnjs)*

Autobahn dude, there is no known fix for this man, i had this exact problem with my car. 
EVERY single thing was checked over, ECU reset, CTS ecu reset, I even plugged in the narroband on my LC-1 into the stock wiring.
My car would run fine until it warmed up and then would start...run, die, start run die... Theres something seriously wrong with the Digifant 2 ecu, it's flawed. I tried other computers too!

BTW, i reset my idle mixture screw with the o2 unplugged, maybe you need to pop that little cap off of your friends VAM, take a 6mm? allen and turn it until it will idle and run .... ? 
When i was using a mustang narrowband o2 sensor it would start and bog and if i revved the **** out of it, the problem would allieviate itself.
GOOD LUCK!


_Modified by mxman at 6:09 PM 6-1-2006_


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## OTIS311 (May 25, 2004)

*Re: (mxman)*


_Quote, originally posted by *mxman* »_take a 6mm? allen

5mm


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## autobahnjs (Sep 14, 2002)

*Re: (mxman)*

well i have tried different 02,maf .ecu, hall, distributor,rellays, i am really stuck here ..


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## MK2SnowPilot (Sep 8, 2005)

*Re: (autobahnjs)*

Before you keep blaming the electronics consider this:
Is the o2 sensor in seating properly? If there is air getting into the exhause BEFORE or AT the o2 then you will have problems. 
The ECU will attempt to compensate for a false reading and dump more fuel in - choking the engine. With either sensor unplugged the ECU ignores the readings and uses a preset fuel map.
You might want to wrap the base of the o2 where it connects to the exhaust with a good bead of RTV silicone just to see if it fixes the problem temporarily. If this doesn't work then you may have a cracked exhaust manifold or a failed manifold gasket.... not common problems but known to happen.


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## MK2SnowPilot (Sep 8, 2005)

*Re: (LewsCabbyTherin)*

Oh and please buy my cabby for $1000 =D
I need to buy parts.... http://forums.vwvortex.com/zerothread?id=2283813


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## autobahnjs (Sep 14, 2002)

*Re: (LewsCabbyTherin)*

well the o2 is in good..there is a leak at the d/p to cat but thats nothing to do with anything due to the o2 being in the mani..
so anyone explain the multimeter say .0x to .087.. it should be going from .1-.9


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## MK2SnowPilot (Sep 8, 2005)

*Re: (autobahnjs)*

The lower the reading the leaner the mixture.
It still sounds tgo me like you have air getting in before the o2 sensor.....
And VW specialty mechanics have told me that cracked manifolds do happen.
Here is a link to explain your readings a little better...http://www.asashop.org/autoinc/june/Tech2tech.htm


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## MK2SnowPilot (Sep 8, 2005)

*Re: (LewsCabbyTherin)*

And just in case you're feeling lazy here is the paragraph I refer too:

_Quote, originally posted by *LewsCabbyTherin* »_False air at the O2 sensor. This air can come from a misfiring cylinder, giving the O2 sensor a false indication. False O2 can also come from a malfunctioning AIR injection system dumping air onto the sensor. The false O2 can also come from exhaust leaks. Leaking exhaust manifold gaskets, cracked exhaust manifolds, and even an improperly tightened O2 sensor can cause this problem. Remember, the exhaust manifold is not always under pressure, the pulsing nature of the exhaust causes negative pressure waves to draw air into the manifold. Sometimes, this problem is so severe that you may think the O2 sensor is dead.http://www.asashop.org/autoinc/june/Tech2tech.htm


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## autobahnjs (Sep 14, 2002)

*Re: (LewsCabbyTherin)*

ya maybe will look into it some more..prob is car is not really drive .but will see thou


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## Supermoves (Dec 9, 2005)

Hey guys this is my car, thanks for trying to help us out.
Well today something new happened. Actually, it's happened before and we think it's related to the cts and o2 sensor. Usually when I drive my car, the temp gauge reads just over quarter of the way. It's pretty cold for an mk2 but I figured that it's better for a car to run cooler anyways.
SO, today I take the car out for a 20 min run..get off the highway and all of a sudden I see the coolant temp gauge start reading halfway, and starting to get past halfway. I turn onto a sidestreet and I can hear the fuel pump start buzzing loudly...the idle drops and the car starts bogging and rich. I stop the car and it just dies on me. I try to start it up and it won't..so I let it cool off for about 10 minutes, start it up and I made it home without it happening again.
My thoughts: I havn't driven the car that much (only 500 km) but so far this problem has happened 2 or 3 times, and it was during the day when its hot outside. Now, that might be a coindicence, but like I said every other time I've driven it has generally been in the evening or night when its not too warm out and the the gauge is usually at around qaurter, below half. 
The O2 and the Coolant sensor can NOT be plugged in at the same time. The car will bog and go really rich..so thats why I've been driving the car with the o2 unplugged. I have a brand new o2 and coolant sensor and ALL the wiring was checked to make sure it was correct and giving signal. 
I noticed a guy with the same problem in this thread: http://forums.vwvortex.com/zerothread?id=1191702
-CDN20valve had the exact same symptoms as me...and he said that he moved the ground and it fixed it. However, my grounds are all in the proper places and they are clean. 
Any thoughts? suggestions? I really need help guys I've got the car insured now but I can't drive it being worried about it bogging and stalling like this!
Thanks in advance


_Modified by Supermoves at 4:03 PM 6-22-2006_


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## MK2SnowPilot (Sep 8, 2005)

*Re: (Supermoves)*

I really don't think they are related....
I think your Thermostat needs to be replaced. Yours seems to try and work and then get stuck closed...
When I bought my 91 Jetta last November the temp gage would stay low as well - just over the quart mark. (solid section of gage)
As part of my "new used car" maintenance I drained and flushed the coolant and replace the Thermostat with a good used one I happened to have in my toolbox from my 94 Jetta. (thought it was causing issues - it turned out it was the brand new temp gage sensor I had just put in)
Since then my temp has hung pretty steady around the first line while driving around. It peaks at the second line before the fan comes on.
And it's NOT good to run your car too cool. You need the heat to help keep your engine clean. Otherwise what's the point of the thermostat? why not run an open loop and just take it out entirely? Run it too cool and crap builds up in the cylinders and your emmisions aren't as clean as they could be. 

Now as for your other problem with the fuel - Go to Autobahnjs's place, grab a good used downpipe and Exhaust manifold and put them in your car. I really do believe false air at the O2 is your problem. replacing these parts won't hurt anything but it just might fix your problem...
Edit: almost forgot - since autobahnjs is in Newmarket... if you need any help with the car you can go see my mechanic in Queensville (5 minutes north of Newmarket) Name is Johannes and he's great! He's an amazing VW mechanic and he can get you cheap OEM parts too. The name of his shop is Almark Auto service but he's not in the yellow pages because he's just a small (only himself) shop.
IM me if you want his info as I don't want him getting crank calls from the masses on the net










_Modified by LewsCabbyTherin at 7:35 AM 6-23-2006_


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## umeng2002 (Jul 9, 2003)

*Re: digifant car stalls when coolant temp sensor is plugged in..and mad rich (autobahnjs)*

maybe your wiring harness is bad. make sure your ignition timing and/or hall sender are good.


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## autobahnjs (Sep 14, 2002)

*Re: digifant car stalls when coolant temp sensor is plugged in..and mad rich (umeng2002)*

i re did timing and timing light set to 6 stock.. wiring i fixed and checked all with the meter for high (ohms) all checked out
going to change the thermostat this week to fix that problem


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## autobahnjs (Sep 14, 2002)

*Re: digifant car stalls when coolant temp sensor is plugged in..and mad rich (autobahnjs)*

manifold will be next the rest of exhaust is new including the d/p http://****************.com/smile/emthup.gif


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## GoKart_16v (Dec 17, 2004)

*Re: digifant car stalls when coolant temp sensor is plugged in..and mad rich (umeng2002)*


_Quote, originally posted by *umeng2002* »_ hall sender are good.

I've replaced so many on my car...with similar problem. Hall sender and idle/wot switch are some of the few i have yet to replace...never got a chance to do it cuz my timing belt slipped. But def check the hall at least.


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## autobahnjs (Sep 14, 2002)

*Re: digifant car stalls when coolant temp sensor is plugged in..and mad rich (GoKart_16v)*

the hall came from a working car so when we popped it in the prob is still there


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## betajetta (May 29, 2006)

*Re: digifant car stalls when coolant temp sensor is plugged in..and mad rich (autobahnjs)*

ok. one thing i have learned when i owned my old car, (1990 Jetta 8V) is that Digifant 2...or should i say Digifu#% 2, is indeed digifuc#$erd. 
for one, your thermostat needs changed. your temp gauge should be in the middle and sometimes a little over the middle. when your engine runs too cool like yours with a broken thermostat it confuses the CTS and it wont get as good of fuel emissions because the engine wont ever get hot enough to completey burn the fuel. It will also have less power because of this.
Digifu%^ also needs alot of good grounds. if yours are clean...thats great. now...go buy the biggest wire you can find...most people i know use 4gauge, and run it from the body to the motor, then to the tranny, then back to the battery. now your digifu%^ is properly grounded.
make double double sure the CTS is brand new.
next, check the wires for the CTS, make sure none of them are bad or shorted out
now, there is a WOT switch on your throttle body that clicks open when the throttle is opened to a certain point. this WOT sensor turns off the O2 sensor alltogether and runs the system in an open loop. if these wires are bad then its digifu#$erd. make sure none of them are cut shorted or showing copper.
have your friend listen as you rev up the car and listen for any hisses from the front of the car....that means you have an exhaust leak. it doesnt matter as long as its not in the manifold. but i doubt thats the problem because unplugging the O2 sensor reverts digifu%^ to a pre-programmed fuel map that is perfectly safe and requires no O2 sensor. and you said that you did that and it was still digifu#$erd.
check your O2 sensor wired from the O2 to the plug in the engine bay. i have seen these wires exposing copper and shorting out for no apparant reason other than its digifu#$erd.
most likely one of these will un-fu$% your digifu$% ECU. if not then send me an IM.
get your thermostat changed asap, as cold coolant will confuse the CTS and make digifu%^ think its not getting warm and it will keep an enrichened mixture.
hope that helps. if not IM me.


_Modified by betajetta at 2:45 AM 6-30-2006_


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## autobahnjs (Sep 14, 2002)

*Re: digifant car stalls when coolant temp sensor is plugged in..and mad rich (betajetta)*

nice post we both thank you....... i own 2 digi cars my jetta and corrado now i thought i have had ever problem happen to me but with his car i guess i am wrong.....
i did check all main sensors wiring from the plug to the ecu..no shorts or high ohms....stock ground have been fixed and clean
we will soon add new ground i know on my cars i did the 4gauge and wow my vdo gauge came up... sweet i did thew power wires too
cts is new new 2 times 
thermostate is being done as we speak...
after that is done i have a listening tool i will use for the mani to listen for leaks will post if anything new comes up


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## betajetta (May 29, 2006)

*Re: digifant car stalls when coolant temp sensor is plugged in..and mad rich (autobahnjs)*

get er fixed yet?


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## autobahnjs (Sep 14, 2002)

*Re: digifant car stalls when coolant temp sensor is plugged in..and mad rich (betajetta)*

thermostat is in temp gauge is better..will see soon


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