Author Topic: need help fast, VERY rough idleing (Read 8270 times)

psyte · « **on:** December 11, 2006, 05:41:17 pm »

in the last few days my 86 jetta 1.6l N/A diesel has developed a very rough idle that sounds like its going to stall any second. but the wierd thing is, it keeps going away for a few minutes and then comeing back. this problem is only at idle and i dont have any problems accelerateing or cruiseing. today it was especialy bad and i had to pull over untill traffic died down. theres a noticeable flat spot when its doing this, the rpm's dont increase untill a few seconds after i stomp it wich is causeing me to nearly stall it every time i stop. this car is my daily driver and i need to fix this problem asap. any help would be greatly appreciated.

jtanguay · « **Reply #1 on:** December 11, 2006, 06:05:59 pm »

hmmm sounds like air in the lines or something... check the clear line going to the pump and check for bubbles. if you see lots of bubbles, then there is your problem.

psyte · « **Reply #2 on:** December 11, 2006, 06:18:27 pm »

i looked at it and i didnt see any bubbles, however i do rerember seeing little bubbles in the line a few months ago when i first bought this car. how would air be getting in the lines if that was the problem?

ok i just went out again and checked it with a bright light and theres a steady stream of tiny little bubbles going from the filter to the pump, theres about one tiny bubble floating down every 3/4 inch. however, when i give it *** i get some big air bubbles floating down the line. how should i go about checking the lines for leaks? would it help if i losened up the vent screw on the top of the fuel filter?

burn_your_money · « **Reply #3 on:** December 11, 2006, 08:04:03 pm »

air bubbles are a pain to track down. I'd start by disconnting one thing at a time and running the car out of a bucket of fuel, starting close to the pump and then working forward. When you start getting bubbles the piece of line between where you are and what you just tested needs to be replaced.

When you give your car full throttle does it take a few seconds for the line to fill with bubbles? If so I'd guess that your water seperator by the passnager tire is leaking. Try running a chunk of hose to bypass it and see what happens

psyte · « **Reply #4 on:** December 12, 2006, 05:21:53 pm »

well, i bypassed the water seperator with a small see-through gasoline fuel filter and the bubbles were gone for a while and it was running like a champ. however, it started idleing rough again half way home from work and the fuel filter collapsed. the wierd thing is, tons more bubbles were now going down the line and it wasnt idleing half as bad as it was the other day when less bubbles were going down the line. is there suppost to be absolutly zero bubbles going through that line from idle to wot?

jtanguay · « **Reply #5 on:** December 13, 2006, 07:43:40 am »

you can have some bubbles at wot. the only way you would get rid of bubbles is with a lift pump, and even then it would be doubtful to get rid of 100% of the bubbles.

if you bypass the water separator, get a good fuel conditioner like power systems. you will need something get the water out of your fuel. did you try draining the water separator?

Doug · « **Reply #6 on:** December 13, 2006, 09:57:38 am »

Change your fuel filter, the one under the hood. It's probably blocked by water soaking into the filter media. After you do that if you are still having the problem try opening the unions of the fuel lines to the injectors on the head to isolate a possible defective injector. Do one at a time, closing it before moving on to the next one.Each loosening of a good injector will be immediately noticeable by the engine operation. When you find the bad one there wil be no change.

psyte · « **Reply #7 on:** December 13, 2006, 06:12:14 pm »

it was deffinately the fuel filter/water seperator. i drove it to work and back with no filter today(just bridged the lines) and it ran perfectly and no more air bubbles. i called up a volkswagon dealership today and they want $178 canadian for a new one, what a rip off.

burn_your_money · « **Reply #8 on:** December 13, 2006, 06:42:14 pm »

http://parts.autopartsonlinecanada.com/parts/apocanada/parts.jsp?year=1984&make=VW&model=RAB-D-001

I order from them on a regular basis. Stand up service, quality and pricing

Doug · « **Reply #9 on:** December 13, 2006, 07:29:23 pm »

You don't need the separator under the car. It's good when it works but on the older cars it usually leaks. When it leaks badly you will lose the siphon from the fuel tank. Keep it bypassed if it is leaking but replace the filter under the hood and chase the system with an additive. Be prepared to change the filter under the hood a couple of times until you get the fuel system dried out. Maybe you have been buying fuel at a less than reputable dealer. I got caught that way years ago buying fuel at a no name station because it was CHEAP!!!

jtanguay · « **Reply #10 on:** December 14, 2006, 04:40:44 am »

wow sweet... auto parts online canada now sells rebuilt turbo injectors for about 60 bucks a piece... pretty cool! but funny.. they do not show up when i put in 1992 vw jetta...

Doug · « **Reply #11 on:** December 14, 2006, 04:57:08 am »

Where did you find the T injectors? I see the n/a injectors on each model page but no turbo ones.

jtanguay · « **Reply #12 on:** December 14, 2006, 12:51:37 pm »

http://parts.autopartsonlinecanada.com/parts/apocanada/wizard.jsp?year=1984&make=VW&model=RAB-D-001&category=D&part=Diesel+Injector

don't know if that works... first on the list

Doug · « **Reply #13 on:** December 14, 2006, 04:46:56 pm »

Thanks JT. I believe that the nozzles are the same with all injectors (n/a or turbo). The difference is in the shimming of the spring assembly which gives a higher breaking pressure for the turbo models because of the higher combustion chamber pressure due to the turbo boost. BTW, I had a local diesel rebuilder quote me a price almost the same to take my injectors and rebuild them with new nozzles and calibrate for turbo operation. Thanks again for the update from autopartsonline. These guys look like they may be worthy of some business from me soon.

jtanguay · « **Reply #14 on:** December 15, 2006, 05:59:13 am »

Quote from: Doug

Thanks JT. I believe that the nozzles are the same with all injectors (n/a or turbo). The difference is in the shimming of the spring assembly which gives a higher breaking pressure for the turbo models because of the higher combustion chamber pressure due to the turbo boost. BTW, I had a local diesel rebuilder quote me a price almost the same to take my injectors and rebuild them with new nozzles and calibrate for turbo operation. Thanks again for the update from autopartsonline. These guys look like they may be worthy of some business from me soon.

yeah i've been looking for a good place to get rebuilt injectors... finally!!! n/a's would run on our motors, but smoke like hell. :lol:

i would have to say that they are REALLY fast to ship! free shipping on orders over $75. might as well take a list of whatever you need, and order it all at the same time. i've ordered belts, an a/c fan resistor, an an oil cooler from them.