# Quest to fix my idle problem. (digifant II)



## javdj2fan (Jun 12, 2005)

I have been trying to fix my idle problem since I got my timing belt changed or about six months now. Idles irratic when cold. Some times high some times low. When it started doing this it would idle really low at start up and some times even stall. I checked all the timing marks and they are all where they need to be so the mechanic did not screw that up. Since checking the marks I have gone on to clean the isv then replaced it with a used one which I also cleaned. No change there so I replaced the throttle body with a used one that I cleaned the heck out of and new throttle switches. When I did that the irratic part went away but the idle was to low. I thought I had it fixed then. I did a search on how to adjust the idle speed and did that. Ok, I'm not going to make a big long book but that didn't fix my problem. I have gone on to replace the coolant temp sensor (blue one), cleaned the MAF with CRC MAF sensor cleaner, replaced all of the vacuum hoses, replaced the o-ring between the idle screw and the TB and reset the ecu. I have run out of ideas. These are the symptoms that I have now. Car starts up with high idle some times. When I say high I mean between 1100-1300rpms. Some times it starts at 1100 and just stays there for a few seconds then starts going from 800-1200 up and down, up and down, with out me even touching the pedal. When the car is warm it will idle right around 950 with an occasional jump to 1000 and some times 1100 but for the most part it is steady and I can deal with that although would love for it to be perfect. I have checked the intake boot and that is fine. I've done a search on this but it seems to me that some how everyone elses problem is slightly different although some of the symptoms are the same. They have been able to fix their problem with one or more of the things that I have already done. What else can I do?








Oh, I forgot to add, there has been a popping sound coming out of my exhuast when I decelerate. This has been happening for as long as I've had the idle problem.

_Modified by javdj2fan at 10:58 AM 3-30-2008_


_Modified by javdj2fan at 11:04 AM 3-30-2008_


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## jason08 (Dec 1, 2007)

I've been having simular issues with my car, mine usually idles at about mid 900's like yours, sometimes i can be driving along on the highway, stop at a light and it it will be idling over 1000, sometimes i can give it some gas and it will go back down to normal.. but not always, i also get the popping noise sometimes.. Sorry I'm no help, Im curious to what could cause this too. I dunno if this other problem Im having is linked, but Sometimes I can be driving along on the highway and the engine will all of a sudden start to sputter and lug, but as soon as i restart the engine its fine, i've been trying to find an answer forever... :S


_Modified by jason08 at 9:10 AM 3-30-2008_


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## custom66 (Feb 7, 2005)

sorry for adding to your post, my car does the same thing but also when i give it gas and release the idle jumps up and down almost stalling out before it steadies again.  Someone has got to have an answer for our problems


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## jettajunker (Jan 20, 2008)

*Re: (custom66)*

I third this problem!!! any info woud be great!!! Stupid fuel management. Seems everytime i think i fix it it starts doing it again


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## javdj2fan (Jun 12, 2005)

*Re: (custom66)*

yeah mine does that too.


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## kkelter (Aug 6, 2007)

yeah mine does this sometimes when I go into neutral, the revs don't go back down to 900, they stay at about 1100 or 1000.


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## JETnycTa (Jan 12, 2008)

same here wtf!!! help!


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## McBoner (Mar 29, 2008)

*Re: (JETnycTa)*

Whenever I've seen engine rpms hunting it's _always_ been caused by a vacuum leak. Every time. So go & super-triple check all your hoses & connections etc - one of my friends had it happen to him, & when we were checking the hoses we found the throttle body was only held on with two (loose!) bolts. Once this was rectified the car ran fine again.
Also it's worth having a look at the microswitch underneath the throttle body: http://forums.vwvortex.com/zerothread?id=731083
Good luck!


_Modified by McBoner at 12:34 PM 4-3-2008_


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## B4S (Apr 16, 2003)

*Re: (McBoner)*

The throttle microswitches would be the first place I started to look. The second place would be electrical grounds, all of them. Digi is SUPER sensitive to voltage fluctuations, make sure it's getting a steady reading, as high as you can get it (no higher than 14.4v obviously). Re-ground the battery, run a ground cable from the alt case to the block, and then from the block to the battery. I had a digi-1 setup that idled like ass, until I realised it was only getting 10v at idle...after that got tidied up, it idled great.
When the ecu sees the voltage drop, it adds fuel to the injectors, which makes the idle go up. Then the ISV sees this, and closes it down. Vicious circle.


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## javdj2fan (Jun 12, 2005)

*Re: (B4S)*

O.k. I did replace the throttle switches. I also replaced the battery ground. This is the first time I hear anything about the ground having something to do with the idle. I will try the ground on the alt. I also noticed that the idle gets crazier when the A/C is on. I will check this out. Thanks for your thoughts. I will let you guys know.


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## blazk0 (Apr 5, 2008)

same problem Golf 3 gti 8v...changed trottle position sensor, temp sensor, vaf sensor...and the problem remains


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## B4S (Apr 16, 2003)

*Re: (javdj2fan)*


_Quote, originally posted by *javdj2fan* »_O.k. I did replace the throttle switches. I also replaced the battery ground. This is the first time I hear anything about the ground having something to do with the idle. I will try the ground on the alt. I also noticed that the idle gets crazier when the A/C is on. I will check this out. Thanks for your thoughts. I will let you guys know.

It's not so much the ground, as the fluctuating voltage put out by the old alternator, through a weakened electrical system (due to age). Older ECUs on all cars suffer from the same symptoms when voltage is low. Get a voltmeter and see for yourself what happens when you're idling, and when each accessory is turned on. If the computer doesn't get good voltage, then it's not going to be able to work properly. It's probably fine under load (cruising), but at idle it's a different story.


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## subwire (Apr 24, 2006)

lol,i have the same prb with my idle,glad im not the only one....


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## javdj2fan (Jun 12, 2005)

*Re: (B4S)*

I don't have a day off until monday so I won't be doing anything until then but let me get this straight. If I replace the ground at the alt., this might fix my problem? You are defenetly right. When the car is cruising it is fine but when it is just sitting it idles really crazy some times.


_Modified by javdj2fan at 12:06 AM 4-6-2008_


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## B4S (Apr 16, 2003)

*Re: (javdj2fan)*

It's more than that, really. That will definitely help, but the best thing to do is to re-do all the grounds in the bay. A quick test is to get the car running, and then hook jumper cables to a newer, non-VW car (to eliminate the crappy VW wiring variables







). At that point, the newer car's charging system will boost the VW's voltage up and your idle should stabilize. I had a GTI here that idled like hell on it's own, but once we slapped the cables on to it (connected to my DD Saturn), it became a new car.


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## javdj2fan (Jun 12, 2005)

*Re: (B4S)*

Sounds like a plan. I am going to try this (jumper cables) tomorrow. When you say all the grounds in the bay, what other grounds are you refering to?


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## B4S (Apr 16, 2003)

*Re: (javdj2fan)*

Any brown wire you can see. There is one at the back of the valve cover, one from the battery to the chassis, the chassis to the tranny, and adding one from the block to the alternator casing really helps with the voltage. Pretty much anywhere you see a brown wire that bolts to the body/engine, at least clean up the mounting point and connector and rebolt it. You'd be surprised how much that helps.
Oh yeah, there should be a ground strap from near the ECU to the hood, that one should be cleaned up too.


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