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Section 1 of 5 - Prev - Next
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Archive-name: autos/vw/technical-faq
Rec-autos-vw-archive-name: technical-faq
Posting-Frequency: bi-monthly
Last-modified: 15 Jul 96
-------------------------------------------------------------------------------
==========================================
Frequently Asked Questions
for
Water Cooled VWs
-- Technical --
==========================================
rec.autos.vw
Version:
1 Jan 93 = Inception, more or less.
1 Feb 93 = Removing O2 Snsr; Offrd lights #; tools
1 Mar 93 = Brake rotor edits; VW part numbers; sagging doors; Compression
checks; adjusting valves.
1 Apr 93 = Stuff on interchangeability on parts; Rim offsets
1 May 93 = Eliminating rattles & squeaks, updated timing belt procedure,
water pump failure diagnosis, added keyword for easy
diagnosis, clutch sizes.
1 Jun 93 = CAM Baffles, Index.
1 Jul 93 = Edits.
1 Aug 93 = Chemical Info added.
1 Sep 93 = Edits, Tool info edits, dielectric grease, MTL caution
1 Oct 93 = Edits.
1 Nov 93 = Coolant/phosphates updated, rim ranges.
1 Dec 93 = Corrections on rim ranges, hesitation updates,
1 Jan 94 = Tom Coradeschi reformats.
15Jan 94 = Battery updates, Tire pressures, body care.
1 Feb 94 = Copyright BS added. Charge indicator diagnosis.
15Feb 94 = Split performance issues into its own faq!
1 Mar 94 = Edits, update recall info
1 Apr 94 = Edits. Updated brakes & transmissions a bit
1 May 94 = Remove bushings, edits
15May 94 = More rough idle & black smoke stuff added.
1 Jun 94 = Paint touch up procedure.
15Jun 94 = Updated with ND BBS stuff (coolant, bulbs)
1 Jul 94 = Edits
15Jul 94 = Tesing synchros. Overheating, windshields, seats, rim care
1 Aug 94 = Edits
15Aug 94 = Paintless dent removal.
1 Sep 94 = Inline fuel filter removal.
15Sep 94 = Edits.
1 Oct 94 = Edits
1 Nov 94 = Added some coolant service info, windshield Urethane, maintenance
schedule.
1 Dec 94 = Updated FI cleaners.
1 Jan 95 = Updated coolant.
15Jan 95 = Exhaust hangers, retrofittimg programmable wiper control
15Feb 95 = Leather care
15Mar 95 = Approval received for *.answers & archival @ MIT
1 Apr 95 = W6DP0 plug comparison
15Apr 95 = Tire build dates
1 May 95 = Vinyl/Rubber Conditioner update
16Jun 95 = Corrections
1 Jul 95 = Lots of additions by Jens Knickmeyer
15Jul 95 = Updated MAINTENANCE section a tad.
1 Sep 95 = VR6 Idle/stalling problems, start of cross post to
rec.autos.makers.vw.watercooled
1 Oct 95 = Undercoating info, bunch of EdW tips.
1 Nov 95 = Oil viscosity.
1 Jan 96 = VR6 Spark plug updates.
1 Feb 96 = Edits.
15Feb 96 = VR6 Sparkplug updates.
15Mar 96 = Edits.
15Apr 96 = Flushing VR6 engines.
15Jun 96 = How to drop the oil pan.
15Jul 96 = Bosch part # for prog interval wiper.
Moderator:
Jan Vandenbrande
jan@ug.eds.com
jan@lipari.usc.edu (school address, works)
See also the list of contributors at the end.
Please feel free to submit any additional info.
---------------------------------------------------------------------------
Copyright Notice (c) -- 1994 - 1996:
All Rights Reserved
The information contained here is collectively copyrighted by the
authors. The right to reproduce this is hereby given, provided it is
copied intact, with the copyright notice inclusive.
However, the authors explicitly prohibit selling this document, any
of its parts, or any document which contains parts of this document.
(Inspired from faq.audio ;->)
---------------------------------------------------------------------------
PURPOSE:
========
This FAQ is geared predominantly at the technical aspects of watercooled
VWs based on the Golf Chassis (A1-A3: Golf I/Rabbit, Golf II & III,
Sciroccos, Corrados, Jettas, Vento, Convertibles) using the original Audi
"1600 type" engine block (now available up 2 liters) and the new VR6
2.8/2.9l engine aimed at the US/Canadian market.
Not covered are the engines/fuel systems available outside North America
such as the 1300 cc engines, carburetors/mono-throttle FI systems.
These cars have many similarities with Dashers/Passats/Fox's. These are
mostly mechanical, but not for the styling, suspension & exhausts.
These technical aspects handles issues that will help you maintain the
car in near stock conditions. The perfomance FAQ discusses issues
to improve upon the stock design.
Quite often, to remain stock complient is as expensive as it is to
upgrade to better after market (performance) parts. Shocks and tires
are a good example of this.
Index:
======
General issues (tools, VW part no system)
Chemicals (Useful chemicals to have around)
Engine (Rough idle/stalling, oil filter, more power,
water pump, plugs, O2 sensor)
Electrical (Bosch # conventions, charging problems, lights, etc)
Transmission (CV Joints, shifting, gear oils)
Brakes (Types, fluids, rotors)
Tires/Rims/Suspension (shocks, tire widths & rim upgrades, performance)
Body/Interior (Eliminating rattles, waxing)
Miscellanea (Corrado spoilers squeaks)
--------------------------------------------------------------------
GENERAL
=======
Q: I have a problem with my car? What do I do? How should I go about
fixing it?
A: Diagnose the problem as well as you can: When does it happen? Is it speed
dependent? Is there a noise associated with it? Where is it coming from? Is
the problem temperature dependent? Happens at start up/after a while? Are
there any physical signs such as fluids/grease/wear marks? Does everything
look in good order/everything still attached?
While you are going over your car, check whether all the basic things are
in order.
VW engines run hot and the 4 cyl. vibrate a lot. As a result things rattle
loose and dry out quickly. This in turn causes a host of other problems.
Electrical connections & wires: Connectors tend to corrode, wires break
internally. Older VWs have a lot of problems which will make you think the
car is totally gone while all it may be is a loose wire, or a bad ground.
Also check out less obvious things: alternator brushes, fuse box, Hall
connections *inside* the distributor?
Vacuum hoses: They crack, they leak. Replace where needed.
Beware of all rubber components. They wear out with all the heat.
If your engine does not run, there are really two main sources: Mechanical
and periphery. Generally, VW engines hold up mechanically rather well, and
even with mechanical problems you can often get the engine to run.
Usually the problem is located with the periphery. You really only need two
basic things to make an engine run: Fuel and a spark at +/- the right
moment. Suspect a problem with either one first and trace it from there.
If for example the problems occurs each time it rains, suspect something
wrong with an electrical connection or water leaking onto the fuze box.
Yours truly once had problems with a carb and was able to start and run the
engine while spraying carb cleaner directly into the intake manifold (with
the carb REMOVED).
Cleaning the car and engine is often helpful in locating the problem,
especially leaks. It also make working on the car so much easier, for you
and the mechanic.
If you haven't found it yet, read through your manuals and try to identify
the offending piece?
Ask around. r.a.vw is an excellent source for help, but please be as
detailed as you can. If you are having trouble diagnosing the problem, just
imagine how hard it is for us not even having seen the car.
So *please* don't post: "My car makes a funny noise. What could it be?"
Start with make, model, year, and an accurate diagnosis.
After you narrow it down to a couple of potential sources, start with the
easiest and cheapest fix.
My experience is that a majority of seemingly serious problems can be
traced to very simple problems.
Mechanics do NOT have the time to check individual components.
Many work on commission (like department stores) and the more cars they
work on (not fix) the more they earn. Therefore, they usually take the
quickest route for them (replace stuff), and of course you end up paying
for that shiny new part through the nose even though it does not fix the
problem.
Besides, would you pay a mechanic $200 to fix a 50 cent connector because
it took him/her the whole day to find it?
Q: I want to work on my VW. What tools should I get?
A: I'd recommend Muir's (Complete Idiot) Stage I and Stage II tool list. Here
is roughly the "phylosophy" to follow:
Most people start with a couple of tools and then buy more as time
progresses and they learn how to work on their car.
It makes sense, except that it is usually cheaper to buy the most complete
"set" rather than buying a small set and then adding on (e.g., socket "set"
= 50 US cents a socket in the largest set, individual = 2-7 US$/piece).
My recommendation therefore is to buy the largest possible set of whatever
you can afford. Trust me, you will always be going back for more. In
addition, good tools will last you your lifetime!
Next, what brand name should you get. First look for tools with a life time
warrantee (though that may not be an indication of quality). In North
America, SnapOn, MAC, Stanley, Mechanix, Blackhawk, KD, and Sears Craftsman
tools (though their quality and warrantee policy is rumored to be
declining).
Avoid cheap tools, they are NOT worth the money, they can do more harm than
good (stripping), and may actually hurt you.
My order of preference is (and I'll be flamed for this, but this IS based
on 15 years of experience): Made in the USA or NW-Europe, & Japan. I
usually stay away from Taiwanese tools except for one shot "light" duty
items. They are getting better, but so far quality has varied too much to
be reliable.
A basic set should consist of:
Socket set:
Most versatile is a 3/8" ratchet drive set. It must contain 10, 13, 17,
19mm, and sparkplug socket, a couple extension bars and a 3/8-1/4"
adaptor.
12 pt sockets are the most common, but you may want to consider a 6 pt
set instead. They are MUCH less likely to strip and break if you need to
exert a good amount of torque.
Deep sockets are also useful in case you need to clear a bolt.
A torque wrench is also very useful. Unfortunately there is no one size
for all torques on the car. There are a variety of models: Cheapest are
those with a read out gauge. They work well but usually you end up in a
position that you cannot read the gauge.
I prefer the "click type" torque wrenches where you dial in the desired
torque and it will give you a loud click once you attain that.
Screw drivers:
Get a whole bunch of sizes, spade & Phillips
Allen Keys:
Get a whole bunch of sizes, though you may want to get Allen key Sockets
to use with your 3/8" drive (once you figure out the sizes you need).
Wrenches:
Get the largest set you can afford. Open and closed.
Same sizes as above. Get at least one large adjustable one.
Pliers:
Again, get the largest set you can afford, regular & miniature,
straight, needle nosed. Vise Grips are useful too.
Hammers:
Get a plastic & rubber one. The "normal" hammers are usually not used on
cars except in utter frustration.
Jack & Stands:
I'd recommend a floor jack over a bottle or scissor jack. A floor jack
will make raising your car *so* much easier. Stands are also a must. You
don't want you car crashing down on you. Use with wood and some foam
rubber to protect you car's undercoating.
Lights:
At the minimum get a knock-about light with a shatter proof heavy duty
lamp in it (don't even *think* of using a regular light bulb, dangerous,
and they only last 10 minutes under those conditions). A well lit garage
(i.e., 8" neon lamps is ideal).
Oil Filter wrench:
Different types exist and it depends on what works best for your car. My
favorite is the one that looks like an extension bar with a loop of seat
belt material.
Air Pump:
Pump up tires...
Tire gauges:
Dial types are usually the most accurate.
Odds an ends:
Tie wraps, electrical wires & connectors, elec. tape, vacuum hoses, hose
clamps.
"Oh-Oh" Type of Tools:
======================
Occasionally, things WILL go wrong, usually 5 minutes before all shops
close on a day before a long weekend, when your other car is gone or your
bike has a flat, all your neighbors with tools or out of town, and right
before you embark on a long trip, and a very unsympathetic spouse watching
on.
For many of these, you can wait for a sale, but do get them when you have a
chance.
Screw Extractor Set/Easy Out:
Get a set, just in case, to remove stripped screws/bolts/brake bleed
nipples.
Magnetic Pickup:
Basically a magnet on an antenna. Lose a nut down your intake manifold
throat or down a cylinder?...this should help. Don't even *think* on
starting the car.
Claw pick up:
Like the above except it has little claws on the end of a flexible tube
to pick things up. Similar use as above.
>>>> STILL NEEDS WORK <<<<<
Q: My A1 based VW sounds very buzzy and noisy, vibrations in the
engine compartment. What's wrong?
A: Check the front right engine mount. They wear out in ~50k miles.
From [KIRBY ERLANDSEN]: My tricks are to cut the old one out with a hacksaw
(this is easy because you can remove the hacksaw blade and cut from the
inside out ) and put the new mount in the freezer while you heat the
bracket in the oven. Then with gloves on, you can hammer the two together
fairly easily. [Note, oil the components FIRST] If that does not work,
bring it to a machine shop and have them press it in for you.
See also a1.mounts in the archives.
Q: My odometer/trip odometer stopped working. How do I fix it?
A: This is an old known problem. The odometer gear which drives the 1/10 mile
splits thus no longer engages the shaft to the 1/10 mile digit wheel. You
can glue it back with epoxy (after you spend some prime time behind your
dash removing the speedometer and opening it up).
Hints on removing: A2's are a lot easier than A1's. The hardest part is
unscrewing the speedo cable. Try taking the lower dash covers off and put
your hand up from the bottom. Also I just remove the steering wheel before
working on the cluster. It makes it a whole lot easier, but be sure your
steering wheel and shaft are marked so you can get them back on the same.
Otherwise your wheel will be crooked when you drive straight.
Reinstalling is harder because you have to be sure the square drive on the
speedo matches up with the cluster. Otherwise the cable will not seat fully
or the speedo nut is hard to start.
Also, be careful to align the wiring connector before trying to insert -
it's polarized.
Other hint: I also twisted some fine wire around the flanges of the gear
(near the shaft) and put glue over the wire and flanges. Make sure to get
the gear back in the proper position under the worm gear.
Other hint: I usually go down to the junk yard and look for damaged
dashboards and speedo's. Usually one has the gear I need -- I just pry it
off -- this is a no cost item if you have a friendly junk yard owner.
Other hint: Another approach I used on my '79 Rabbit was to go to a hobby
shop and find a small pinion gear for those electric race cars. It had the
right number of teeth, and same ID, but was slightly wider and had an Allen
set screw.
I filed off the outer edges to clear the other worm gears and mounted it on
the shaft with the set screw. Looked weird, but worked OK. The gear will
cost about $3 and you need the fine Allen key wrench.
You can also send it to have it fixed at:
VDO (the OEM) in VA, (703) 665-0100
Q: What is VWs part numbering scheme?
A: Each part number is composed of nine numbers in three groups, followed
optionally with a letter suffix (taken from WolfSport's catalog):
vvv ggg ppp [s]
vvv: Vehicle type ggg: PRIMARY INDEX
171 = R/G I 100-199 = Engine/Cooling/Clutch
161 = Jetta I 200-299 = Exhaust, Fuel Tank
165 = Jetta II 300-399 = Transmission/Transaxle
261 = 16V GTI 400-499 = Front Axle/Suspension
531 = Scirocco I 500-599 = Rear Axle
535 = Scirocco II 600-699 = Brake
155 = Convertible 700-799 = Cables, Bumpers and Foot control
191 = Golf 800-899 = Body/Interior
900-999 = Electrical, ignition, fuel injection
ppp: Individual Part Number s: Suffix, optional
The primary index and the part number are the most important numbers
because many of the cars share the same parts. So do not be surprised to
see a 171-Rabbit type part in a Jetta.
Note that some part numbers are exclusively related to certain parts
of the car. For example, vvv = 020 are related to the transmission,
vvv = 056 common oil filter.
Note: This is scheme has been in use since the Beetle days (111 - Standard
Beetle - LHD) but I leave that for the [A] FAQ. AUDI uses the same scheme
as well (?).
CHEMICALS
=========
NOTE:
This section lists some of the more useful chemicals to use on cars.
Be aware that many of these chemicals are harmful if used improperly and
could result in stripped paint, rubber becoming brittle, up to poisoning,
cancer and death.
Dispose of them environmentally!
See also the section of Waxing for body care chemicals.
Q: What are some of the useful chemicals to have around?
A: Cleaners:
---------
Brake Cleaner:
(Spray) Make sure it's not too harmful for rubber/plastic and keep it away
from paint. Also keep it away from any eye-ware that you may be waring.
Carb Cleaner:
Probably a bit dated by now, but the one that was most impressive
was Fire Dragon (Spray), however most others work fine as well.
If you have an oxy sensor and cat, make sure the stuff you get
is compaitible
I also used ChemClean to dunk the entire carb (see below)
Keep it away from any eye-ware that you may be waring.
FI/Valve Cleaner:
What ever you get make sure it does NOT harm catalytic conv or the
oxysensor.
The following are recommended and seem to work faily well. They are
added to a tank of gas, or fed directly into the FI system.
Lubro Molly: there are two products, an injector cleaner
and a valve cleaner. You can run the valve cleaner straight
through your injection system by hooking it to one of the
vaccum hoses and sucking it straight into the valves. Produces
lots of smoke but really helped my friends old 924. These are
expensive at $12-14 for both.
RedLine SL1: works very well and relatively cheap: $3.50 for the 12oz
bottle. My current favorite.
Chevron Techron: get the real thing, not the ProGuard stuff.
Not too expensive at $5.99/20oz bottle. (Imparts, others) Chevron
however, warns you not to use it too often between oil changes...
(I think no more than 5 treatments)
44K (BG Products): VW also recommends this more concentrated to be
used every 4k miles (= VW Part #208 (?)).
VW AutoBahn injector cleaner (rumored to be the same as Chevron Techron
for a lower price, for once).
Chevron ProGuard: only if none of the above is available. I used it
a few times, but couldn't tell a difference. I think it contains
Techron, but if you can get the real thing...
Note that ProGuard is a weaker version of Techron.
General:
--------
"Simple Green": General purpose cleaner (great and safe), engine cleaner
It's a non-oil soap (i.e., surfactant) based product that smells like
mint toothpaste. However, it does eat away wax.
"Chem Clean":
A can or bucket of chemicals that degreases bearings CVJs, or carbs REAL
fast (that stuff is amazing). It is however murder on skin and nails
and anything plastic and runner.
Hand Cleaner:
With pumice. Just buy a big vat. They are great, much better than
dishwash liquid or regular soap.
Lubricants:
-----------
Penetrant oil:
E.g., "Liquid Wrench". Eventually loosens stuck parts.
WD40 :
General purpose light "lubricant"/penetrant. WD-40 should NOT
be used for permanent lubrication.
Anti-Seize:
See below.
Case of engine Oil
Lithium Grease:
Spray can for hard to reach places
Molybdenum Grease:
For bearings (NOT CVJs!)
Talcum Powder:
For rubber components
Silicone Spray:
Good for lubricating metal & non-metal components.
Rumored to dry out rubber though.
Paint/Body:
-----------
Body Paint:
For touch ups/scratches.
Primer:
I prefer cold galvanizing primer
Naval Jelly:
Rust remover (Phosphoric acid, i.e., coka cola).
Others:
-------
Brake quiet:
Sticky stuff to put on the pad *backing* to eliminate squeals.
Glues:
Depending on what you need to glue, use Epoxy, rubber cement,
RTV/Silicone Rubber, etc.
ThreadLocker:
See below.
Distilled water:
Battery & for coolant mixing
There is more, but buy some only as you need them because they may dry out.
Q: What should I do with Loctite Threadlocker (tm) and Anti Seize (tm)?
A: Use Anti-seize on anything that you will disassemble again and is subject
to corrosion (water pump bolts, wheel bolts, exhaust bolts), but be
careful on sparkplugs and oxygen sensors (it contains lead which kills
the cat, make sure it's on the threads only).
Use Loctite Threadlocker (medium strength is ok) on anything you don't want
to rattle loose and you cannot use serrated o-rings: Brake bolts, etc.
I use anti-seize the most, and if you torque things right, I never had a
problem of anything rattling loose.
Note that Loctite also seals out air, and therefore prevents corrosion
which means that disassembly will also be facilitated, compared to
something rusted shut. A small tube of each goes A LONG way.
Q: What power steering fluid should I use?
A: Be very careful most newer VW cannot use generic power steering fluid.
From the ND BBS:
Just read up in the manual and all VW's use ATF II up till april 89.
After april 89 use the special Petrosin hydraulic fluid CHF
Q: What do those "20W50" numbers mean for my engine oil?
A: That's the viscosity range of the oil, i.e., how thick it is.
20W means that this oil behaves exactly like a 20 weight oil at 0F,
and behaves like a thicker 50 weight oil at 210F.
This type of oil is called a multi-viscosity oil because it is capable
of lubricating your engine under a wide range of temperature conditions.
More details are available at the various oil co web sites, and on
the oil FAQ available on many sites.
See also your owner's manual and further below on the recommended oil
weights to use for your car.
There are two opposing views on weight to choose. One says
to get as thin as possible (to pump better, especially at start up),
the other as thick as possible (better bearing protection).
Typically, manufacturers have specific recommendations depending
on the climate you live in. Contrary to other small engines, VWs
seem to like thicker oils better. Synthetics generally offer the
best protection. See the FAQ on that as well.
ENGINE
======
Q: I have a very rough idle/stalling/hesitation/bucking problem when the car
is cold (or warm in some cases). What can I do to fix it?
A: This is an old problem that may have numerous causes. Mostly A2
Golfs/GTIs/Jettas/GLIs (8v & 16V) are affected. First make sure everything
"obvious" is ok: vacuum (hoses, pipes, intake), electrical connections,
tuned up right, spark plugs, distributor, good tank of gas, etc.
These are by far the most likely causes of this annoying problem.
[jan, 19930902, overheard in the VW shop]
VW is going to embark in some form of campaign, not sure whether it is an
actual NHTSA mandated one, to replace all the ECU's with one using gold
plated connectors, replace and reroute several vacuum hoses, and replace
the throttle body (the shaft has a radial play causing a vacuum leak in
some cases). I believe that recent Passats, A2 Jettas and GTIs are included
in this.
Depending on the model, do the following:
- Change to a different brand/type of gas (4-5 tanks) VW had a bulletin out
on this. They recommend Shell, Chevron & AMOCO(?)
- Use a good Fuel Injector Cleaner every 4000 miles. See Chemicals
for recommendations.
- Use fuel dryer (using ISOPROPANOL NOT Methanol)
- Check (idle) throttle switch
- Clean sensor plate or airmass sensor & throttle body orifices
- Change the fuel filter
- Clean idle stabilizer VALVE with brake or carb cleaner (VW&P) (Note:
Earlier cars had a Digital Idle Stabilizer circuitry (DIS) which is
something different, and *rarely* fails).
For RD (8V) series idle stablilizer problems (& others probably):
Symptom: Idles extremely rough when cold, improves after warmup. Doesn't
compensate for A/C compressor load when on.
Diagnosis: Disconnect the connector from the valve, measure resistance
from the center pin to each side, both should be about 12.5 ohms.
If either one reads high or open, replace it. (will be about $200 at your
Bosch dealer, owww).
Reason: The internals of the valve form a bidirectional DC servomotor,
the windings of which are connected through a commutator, which has a
nasty habit of arcing until the connection is gone.
- Check *all* vacuum hoses (inc. those going to the brake booster & the
brake booster itself)
- Check *all* air pipe connections (esp. between the throttle body & air
cleaner housing). Look around hose clamps, crimped ends, where there may
be relative motion and cause a tear.
- Check for vacuum leaks anywhere else, e.g., around the intake manifold.
- Check *all* electrical connections (see also later on bad grounds)
Be aware of the old "leak in the windshield molding or firewall
gommets that drips and shorts out the fuse box" problem.
Many A1's suffer that problem, especially those with badly installed
replacement windshield (most places, BTW).
- Check inside the distributor (carbon build up will cause misfires/bad idle)
- Check warm-up regulator/thermo switches
- Check proper working of the Oxygen [Lambda] Sensor (see Bentley)
Hint: Disconnect the O2 sensor, if the car runs better suspect that it
may be bad.
Replace if suspect. Some O2 sensors will last longer than their
expected 30/60k miles lifetime, others fail *much* sooner.
Resetting the warning light for maintenance is NOT a good substitute.
- Clean contacts of the ECU, and all engine management related components
with an aerosol contact cleaner (note: Newer VWs use gold plated
contacts, so this definite a problem area in older cars!)
- Check ground of ECU. There is a bulletin out on this. Usually this
failure is acompanied with black smoke billowing from your exhaust.
- Check fuel pump relay, it may have an intermittent failure. HARD
to diagnose, until it cuts out entirely. If it does die,
jump the two large terminals on the relay block to operate the pump
so you won't be stranded. [frank.sikernitsky@mail.trincoll.edu]
- Check the working of the injectors (incl 5th one).
- Check the injector O-rings (older cars)
- Clean the tank screen at the bottom of the tank or on the transfer fuel
pump (& also clean the tank if you find junk)
From WENDTM@FIRNVX.FIRN.EDU (Mark): When I pulled the hose off the intake
side of the fuel pump it only dribbled slowly from the tank! No Gusher!
That was a real clue that the tank was faulty, and not the pump. :)
- Clean the screen *inside* the fuel pump.
- Check whether the filtering banjo bolt (has a screen) near the fuel
distributor has been removed at the first service (mostly A2 cars with FI
in the US, don't know about Europe). It's replaced with a bolt w/o a
screen (Part nos: Screw = N 0210715 Washers = N 0138128, for *most* A2
cars). If it is left, it may clog or restrict flow.
- Check the health of the fuel pump(s) (measure the amount of current it is
drawing). Note, many A2s have two pumps!
- Improperly grounded throttle position potentiometer
(90 Golf: scottz@pangea.Stanford.EDU), as well as VR6s
- VR6 models: Connector to the airmass sensor gone bad.
- VR6 models: Engine temperature sensor gone bad.
For a 1994 Corrado VR6 the temperature sensor in question was
FP NUMBER: 025-906-041-A.
- Check the CONTROL PRESSURE REGULATOR. Apparently the heating element
wears out, and it won't give correct pressure until it warms up
- Faulty oil pump relief valve. Pumps up the hydraulic lifters too much
limiting compression. Apparently mentioned in EuroCar.
- If nothing helped, you may need a new ECU! (The 91?,92? Jettas went
through 5 different ECUs, according to my mechanic).
- Catalytic converter clogged and breaking up. However, if that happens
it will rattle like a coffee can with coins in it.
- If the car bucks/loses power around 3000-4000 rpm when accelerating,
check the full throttle switch. seibed@lamar.ColoState.EDU (Edward Seibert)
- >>>> MORE????
- For Vanagons, see VANAGON_Stall in the archives.
Q: Car starts fine but hessitates at cold. Runs fine when warm.
[From: Bill N Gallas]
A: Rough running at cold can be caused by a bad coolant temp
sensor. On 8V engines the sensor is generally found on the
coolant flange bolted to the head and going to the radiator
upper hose. On 16 V Jettas it's next to the coolant outlet
at about the 7 o'clock position on the rear of the head (tranny
end) the sensor is a 2 wire unit and is about 17 MM socket size.
The sensor gets lazy and reading the resistance is a good check.
[Jan:] On Corrado G60s it is identified by a blue plug on the coolant
flange bolted to the head similar to the 8V cars.
Pulling the plug at idle usually will make the engine stall out.
Q: What oil filter should I use on my VW?
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