VW Fox No Idle?

[kokolaube]

My 1989 VW Fox 4 cyl 8 valve 1.8 liter will not idle.

Ive tested timing using a timing gun, tested cold start injector, all plugs seem to have spark, all injectors seem to spray good.
Any suggestions?

Any help is appreciated!

[Fat Rabbit]

Vacuum leak(s). Bad idle stabilizer valve (ISV) if the injection system is CIS-E. You might also check/replace the ECU temp sensor if it is CIS-E. It is a white sensor on the bottom of the upper radiator hose flange -- You need a multimeter to check it -- the resistance varies with engine coolant temp.

Check the air intake tube carefully for rips and tears. FR

Modified by Fat Rabbit at 8:19 AM 2-4-2009

[snowfox]

x2. No/low idle is 98% vac leaks, 1.99% CTS, 0.1% ISV on a Fox. Check the intake boot for cracks in the bellows section where it makes the 180º turn right at the throttle body.

[kokolaube]

Ok, ill check that out. What, though, is the cts?

[Canadian V-Dub]

Does yours tick? Sometimes mine will idle fine, sometimes it will idle low, and others it won't idle at all. It took me about a day or two to realize that I've got a bad lifter, so sometimes it won't run on all four cylinders. Also, check your throttle body for obstructions, and try raising your idle adjustment slightly. For some reason, it might not be getting enough air to begin with.

[kokolaube]

Holy canoli, your probably right. I replaced all the lifters not too long ago. Thats about when it started to suck. How do i identify a bad lifter?

[Canadian V-Dub]

http://forums.vwvortex.com/zerothread?id=1944667

Absolute awesome write-up. Remove them all and clean them, just to help prevent a good one from going bad. That should help a good bit, especially if they aren't fully filling with oil, then your valve(s) won't open, and you don't get enough gas/air. Plus, do an oil change at the same time so any gunk doesn't get back into them after you rebuild them.

[kokolaube]

Pulled all lifters, they all seem to have good spring, but im gonna re-oil em. see how she does after a reinstall of em. I guess ill re-time it while the belt is off.

[Canadian V-Dub]

Would the engine run at all at higher RPMS?

Did it shake or vibrate violently when it did run? I wonder if it was knocking.

Could've just been a plugged oil fill hole in a lifter or two.

[kokolaube]

where are these oil fill holes? yes it would run at high rpm, but it did shake violently at idle.

[Canadian V-Dub]

Not a clue as to their location, but they are somewhere on a lifter, and if they get blocked, then oil cannot enter/exit so the lifter will not fill up completely, and then you're valve will not open, or not open enough to get enough gas and air.

[snowfox]

Quote, originally posted by kokolaube »

Holy canoli, your probably right. I replaced all the lifters not too long ago. Thats about when it started to suck.

OK, but the question was "are they ticking?" If you have a flat lifter, it'll plain suck through the whole rev range - like it's on 3 cylinders. If that wasn't the case, then the likelihood of a bad idle being due to a lifter is very low. More likely, the cam or ignition timing was not set properly when you had it apart to change lifters or you have a damaged/leaking vacuum line or intake boot.

[Canadian V-Dub]

Well, yes, but mine has a slightly bad lifter, and it runs like **** at an idle, and it doesn't run worth a damn at higher RPM either, but it's a lot more noticeable at the lower RPMs. Mine runs at higher RPMs, but you definitely notice a loss of HP and torque. His lifter could only be partially filling, so it'll half-ass work.

I do agree with your comment regarding the timing. That's one reason I'm somewhat iffy as to doing my lifters; I'm somewhat paranoid about busting a valve stem or piston. Any tips on how to not screw up an 8V when re-timing it?

[snowfox]

Quote, originally posted by Canadian V-Dub »

Well, yes, but mine has a slightly bad lifter, and it runs like **** at an idle, and it doesn't run worth a damn at higher RPM either, but it's a lot more noticeable at the lower RPMs. Mine runs at higher RPMs, but you definitely notice a loss of HP and torque.

None of these symptoms specifically indicates that the lifter is the root cause. It is MUCH more common to have all of these symptoms be caused by a vacuum leak - particularly in the bellows section of the intake boot on a Fox or in the hoses at the ISV on the underside of the IM. Go ahead, ask me how I know...

Quote, originally posted by Canadian V-Dub »

Any tips on how to not screw up an 8V when re-timing it?

Got Bentley? Follow the directions and be methodical.

[Canadian V-Dub]

Ok, I'll bite. How do you know?

Also, what's an ISV? never heard of it.

And where in Canada can I find a Bentley manual? I've only been able to find Haynes, or Chiltons for diesel vehicles.

[kokolaube]

Ive noticed that at first startup, itll idle great for a moment, then dive. Still searching for a vacuum leak.

I got a bentley, and i wish they had included an intake vac diagram. so i could methodically check each line. O well...

BTW: If anyone is look for a head-gasket set for their fox,
http://cgi.ebay.com/ebaymotors...ories
Thats a smokin deal. I got me one.

Sorry for the long url, Tinyurl aint working...

Modified by kokolaube at 7:16 PM 3-3-2009

Modified by kokolaube at 7:17 PM 3-3-2009


Modified by kokolaube at 7:18 PM 3-3-2009

[snowfox]

Quote, originally posted by Canadian V-Dub »

Ok, I'll bite. How do you know? Also, what's an ISV? never heard of it.

I've spent long frustrating hours trying to track down elusive vac leaks. I was about to pull my friggin hair out in frustration one time when I leaned forward and rested my hand on the intake boot to have another peek back into the mess of vac lines. The simple act of resting my hand on the bellows flexed it enough to open up a crack (and major vac leak) that shut the motor down like RIGHT NOW. I started it again and gave me the same old crappy idle of vac leaking motor. Gave the bellows a little squeeze and it was like hitting a kill switch. Kaput. Swapped boots and it was good to go. The ISV is the valve on the underside of the (CIS-E) Fox manifold. I've had one of the hoses get funky and give me some very sporadic (and therefore difficult to isolate) vac leaks that drove me nuts for a while, too.

Basically, the "ask me how I know" was to indicate that I've had those two and they were not super straightforward to locate and caused a lot of frustration.

Thanks for biting.

[kokolaube]

Quote, originally posted by Canadian V-Dub »

Any tips on how to not screw up an 8V when re-timing it?

The fox has a non interference engine. No worries as to bending valves.

[Canadian V-Dub]

How do you distinguish an interference and non-interference engine?

[snowfox]

Quote, originally posted by Canadian V-Dub »

How do you distinguish an interference and non-interference engine?

Conventional wisdom says that 8V's with stock cams are not interference, but opinions and experiences vary on this topic. Shaving the head and/or running a larger cam profile can turn a non-interference motor into an interference one pretty easily. So...

The only 'sure-fire' way I know is to set any one of the pistons at the very top of its stroke (feeling with a suitable screwdriver or, better, a thinnish wooden dowel through a spark plug hole), then remove the timing belt and *carefully* rotate the cam. If you encounter a sudden increase in resistance while rotating the cam, it indicates that your valves are making contact with the piston.

[Canadian V-Dub]

So is there some form of indent in the head or in the piston that allows the valves to not contact the piston?

I've never heard of anything like this before, it's intriguing as to the advantages/disadvantages of it.

[SGLoki]

Pardon my ignorance, but didn't ALL the fox motors come with hydraulic lifters?... I see info here that I think is for both solid and hydraulic lifters....

Hydro lifters always make a ticking sound even when they are operating properly. In any event, if you discover you need a head for your motor, I have a hydro head long block out of my old 1988 fox for trade or sale.

EDIT:

Oh yeah... try disconnecting the cold start injector... that seems to help prevent issues for me. And try starting it with a bit of thrust start fluid, it might get it going, after it's run for about 2 minutes, you can plug the cold start valve's electrical connector back in.


Modified by SGLoki at 2:37 PM 3-7-2009

[Canadian V-Dub]

As far as I know all Foxes have hydraulic lifters.

Shouldn't the ticking in a hydro head be a lot less noticeable in a head with good lifters compared to a head with bad lifter(s)?

[kokolaube]

Quote, originally posted by Fat Rabbit »

Vacuum leak(s). Bad idle stabilizer valve (ISV) if the injection system is CIS-E. You might also check/replace the ECU temp sensor if it is CIS-E. It is a white sensor on the bottom of the upper radiator hose flange -- You need a multimeter to check it -- the resistance varies with engine coolant temp. Check the air intake tube carefully for rips and tears. FR Modified by Fat Rabbit at 8:19 AM 2-4-2009

Is the ISV the cylindrical thing on the firewall side of the intake mani? Just out of curiosity. I see no mention of it in bentley.

[kokolaube]

Any suggestions? Itll run for 10 seconds or so then the rpms will dive. Im thinking the CSV may be gone. For ten bucks at autohaus, might as well. Let me know of other suggestions.

[Fat Rabbit]

The ISV should be between the valve cover and the intake manifold. Two hoses at one end and an electrical connection at the other. It supplies additional air and fine tunes the idle air by bypassing the air around the throttle plates. FR

After re-reading your post there is also a possibility that you have an idle air valve (IAV) on your car instead of the Idle Stabilizer Valve. The IAV is tucked away under the intake manifold. It's function is to supply additional air on cold start. It is basically a disk with hoses that connect to both sides of the disk. There is a cigar shaped protrusion out one side with an electrical connection at the end of it. The IAV works like an old fashioned choke -- that is it uses a bimetal spring that opens or closes an internal plate to admit additional air or to block additional air. It works both electrically or through engine heat that's why it is located near the exhaust manifold. With a cold engine the plate in the valve is open and allows more measured air through increasing the idle. As the engine warms up, the plate closes either through engine heat or electrically. It is powered by 12V DC. I usually pull them and check them by shining a light through the valve. Overnight cold the valve should be 95% open -- after 5 minutes or so of 12V DC the plate should be 95% closed. FR


Modified by Fat Rabbit at 7:09 PM 4-1-2009

[Mcswagen.]

Try O2 sensor, best investment I ever made on my old 89 fox, feels like a 5O hp upgrade