bad mileage in my rabbit

I think your 83 would have continuous injection (CIS). So the injection would be central and there would not be an injector for each cylinder.

Check your exhaust. If it smells of gasoline or it has black smoke or deposits, that could indicate things.

Does the car run rough? Suppose you had a bad plug or wire.

One troubleshooting method you could do is to start the car with one plug wire unplugged in turn. Note the RPM on the tach and roughness. If you find one that does not impact things as much as the others, look to something associated with that cylinder.

HUH? Every CIS I've ever seen has an injector for each cylinder.

You are right of course. I was mis-remembering.

First off it should have a "tune-up" to make sure that the spark plugs & wires along with all of the other ign components are in good shape. Next replace all filters (air, oil, fuel) along with the oil. Clean the fuel distributor bore also since they usually get cruddy. Then you might want to have the fuel pressure tested to see if the fuel pressure control regulator is operating correctly and the fuel pressure is correct. Check that ignition timing and also the timing belt timing. It might be off

And then check: Oxygen Sensor = might be faulty. Frequency Valve. You can also see if the frequency valve is operating which helps to improve driveability and fuel economy. This can be done with a dwell meter. I have seen some wiring broken and it stopped the frequency valve from operating. The frequency valve is the little electrical device on your fuel distributor that buzzes after the engine warms up. Or it should buzz like a bee! lol

I will assume that the car rolls freely and the exhaust system is not clogged. You can check the vacuum too which usually can tell you what is right or wrong with the engine.

Of course that automatic transmission may have issues too! 8^o

JMHO

On Apr 26, 7:27 pm, "dave AKA vwdoc1" wrote:

WOW, you all have given me a great list of things to check out that I had not considered. Thank you so much. This is why I love this group.

I will let you know a little more about the car to help any further diagnosis.

It runs fine, although it does not seem to have any zip to it. I have never had another rabbit to compare it to so I am not sure if I am being a little hard on it or not.Could this possibly be a transmission symptom ?? Does anyone have a vague idea as to how long the automatic transmissions typically last? There is no noticeable exhaust or smoke other than the white on cold mornings. I have not smelled any gas in the exhaust either but will take a closer look at it as I can not say I make a habit of smelling the stuff on a regular basis. I very recently, (this winter), had a new timing belt installed and it was timed. When I purchased the car the timing was off and it was extremely noticeable when driving so I feel comfortable saying that the timing is good on it now. I also replaced the air filter and checked it about a month ago and it was still like new. The car had brand new spark plug wires and cap when I purchased it 2 yrs ago, but now that I think about it I am unsure of the plugs so I will look at those for sure. When I purchased the car it had been sitting for a few years so when it came into my care I have changed the oil several times to work any gunk out of the engine, I would say about every 1,000 miles. My last oil change was about 2 weeks ago or so and the old oil was very black still. I use a full synthetic oil and this time I also used a synthetic oil stabilizer to thicken the oil. Previous to that the oil buzzer would come on almost constantly after the car was at normal temperature, very annoying. I had the oil pressure checked and it was low but the mechanic said normal for a car with 170,000 miles. After I used the stabilizer it has not gone off once. I am hoping the engine will last me for awhile yet, (fingers crossed). I do plan on eventually having it rebuilt but I also have a 63 Nova that is first in line.

Again thanks for all your advice I will definitely have something to talk to the mechanic about now. I will also poke around a bit based on your suggestions and see if I come up with anything. I will keep you updated.

Thanks!!!

-chris

Happens... I always pass it off as old age, makes the kids feel good.

If the oil was black then that could be caused by the engine running too rich. Your engine usually runs much better when it does not run so rich. YES let us know what happens during the Rabbit's examination! ;-)

Listen for that frequency valve buzzing! If it does not buzz then try adjusting the CO. Turn the adjuster counterclockwise slowly to lean it out and use the dwell meter to check the frequency valve reading.

Do not believe that the timing belt is correct. Make sure it is correct.

Exhaust blocks. I have melted down a few catalytic converters. The honey comb matrix turns in to a blob. Chunks can fall off the back end and clog the muffler. Visual inspection of both ends of the converter is required. While the converter is removed you can take the car for a noisy test drive to see if performance improves. A chunk of converter in the muffler makes for poor performance and some interesting noises as exhaust tries to escape everywhere.

Injectors should be removed and inspected for flow and pattern. Any good VW shop knows how to do this. All screens should be cleaned. That would be the screens in the Control Pressure Regulator and in the fuel injector banjo bolts of the fuel distributor.

The car should get 30 mpg if you drive 15 mile one way trips and do not drive like a maniac. This mileage is for manual transmission with a person who knows when to shift.

Tire pressure at 30 psi checked a few times a month.

Fast is not what the car is. Zippy enough though for general driving. It should feel faster than a 1970 Nova with a 250 and a Powerglide.

I guess this has already been covered by others. Never mind.

No carb. I have worked on factory carb VWs. Not as zippy as injected. The cost to convert probably as expensive as replacing clogged injectors. The unreliablilty of the injector system is overblown. I had my Rabbits for 15 years with little injector maintenance. Probably

The CIS injectors are more prone to bad flow patterns when dirty. When clean, they will actually perform better than modern electronic injectors.

Whoever told you that is an anti-fuel injection luddite. K-Jetronic is

Well, it depends on your driving what you should be getting, but 13 mpg is very very bad no matter what you are doing. The most obvious problems would be a bad O2 sensor/frequency valve, warm up regulator, and timing (both cam and ignition). You can also check for dragging brakes. The easiest way to do that in my opinion would be to get on the highway and have a friend drive along side you with a infrared thermometer aimed at your wheels.

Its also possible was monkeying with the mixture adjustment screw on the fuel distributor. Don't touch that if you don't know what you are doing, its easy to screw up.

You should take the car to a shop that knows CIS cars (which might be hard to find since VW was one of the last users and they abandonded it on most of their cars by 88). If you are getting that bad gas mileage the cause should be pretty obvious, and I suspect they can find it in 2 hours.

The real question is, is it worth it. It's an automatic 83 rabbit with a low-end motor. If its going to cost 3 hours labor and $150 in parts... Oh and btw, there's a good chance your cat is shot... Is that really worth it to fix a car thats worth maybe $1000 if running perfect?

Its going to depend on the weather. A manual car should probably be getting at least low 30s on the highway and mid 20s in town. Automatics would be worse, but I doubt it would be 20.

Absolutely, gas mileage would go down.

Hello to everyone, Thanks again for all the advise. I will have the VW mechanic check over and clean the injectors as well as any needed adjustments to the fuel distributer. I do not feel comfortable messing around with them. The car is over 20 years old after all, and from what I could tell had been neglected for some time. I am sure that it is need of some basic TLC. I will go ahead and replace the oxygen sensor for I have no idea when the last time it has been changed is. I am sure it is probably over due. I read that they should be changed every 50,000 miles or so. Maybe it has never been changed in my car.

Also thanks for the information pertaining to the injection system vs. carb. I will definitely stick with the injectors. As for my driving, I always try to keep all the tires on the ground (lol). Actually I baby it. It is not a race car and I do not treat it as such. It is my daily driver and is used for mostly short trips around town. To and from work and the occasional errand. I do try to take it on the highway occasionally if for nothing else than the health of the car.

Oh- I do not need to ask myself if it is worth it, to me it is. I love the car, I am a total sucker for a hatchback. They are getting harder and harder to find in decent shape. I am in Wisconsin so most cars that old are held together by rust. Maybe it is not worth fixing it monetarily, but i don't plan on selling it. I bought the car to drive, not to make a profit. I have never been accused of being very practical. I am hoping to completely redo the front suspension this weekend, while I am under there I will also take a look at the front brakes and rotors. I should be able to tell if something is amiss with the brakes causing my bad mileage. Perhaps if I am feeling even more ambitious I will pull the muffler off and look at the exhaust as well. If I do not find anything then to the mechanic it goes!

Thanks again to everyone who has helped, I really do appreciate it. Chris

If you do a longish drive, then feel the brakes and they are not really hot, then it would not be the brakes causing that mileage drop. Maybe you should use a wet Q-tip and listen for the sizzle rather than using your finger.

Wet your finger, tap the rotor... Just like checking the iron when doing your shirts, right?

Actually draging brakes will usually heat up the rim and hub enough so it is noticable in a few miles.

A wealth of knowledge you are daveaka!

Me too. I miss my '87 Chrysler HB. I may have to get an SUC (crossover) next, to replace my sedan.

Because of the production of SUCs and SUVs.

If yours is, I wouldn't drive in it, I'd scrap it ASAP. A good strong car body is your defense in a collision.

Road trip to Atlanta to get a solid body can be a good thing. You can have 30-40 year old solid cars here. No salt, just lots of sun to dry up paint, rubber and plastic.

No, it has very little rust for an 83 here, which is why I bought it even though much else was bad and needed Floor pans are in decent shape and the body is good. Of course I'll be replacing all the brake lines etc. in the future for safety purposes as the car is older. I am still working on the bad mileage problem. I am going to try a new O2 sensor and see if that does anything for it. I'll keep everyone posted once I have found the problem (or problems). I just have not has much time as of late to get in there. chris