1. Home
  2. Volkswagen, everything else
  3. Air flow potentiometer and Fuel injector

Air flow potentiometer and Fuel injector

I've been trying figure out a nagging problem on my '86 GTI for a while now. (RD engine, ACH Trans) So far, I've replaced the Idle Stabilizer Valve (open coil), the rubber boot going to the throttle body (a couple big cracks), Idle/Full throttle switch (idle switch broken and not closing), new plugs, wires, cap, ect...

This has fixed some problems, but it's still not right. Today I started going through the Electrical Tests as outlined in the Bentley. The Differential Pressure Regulator current looked good on all the tests, the thing that was questionable was the Air Flow Pot readings. Bentley says you should get greater that 4000 ohms on terminals 1 and 2, I get about 6000, and less than 1000 on 2 and 3, I get about 990, close but still in spec. Raising the sensor plate shows a nice steady increase on 2 and 3 with no flat spots, but the max value is just over 6000 ohms. Bentley says it should about 4000 ohms at max. Is this max value being too high OK, or should the Pot be replaced. I still need to go through the Full Throttle Enrichmenct test and the Control Unit inputs test.

The current symptoms are, idle drops too low and almost stalls when downshfiting or stopping, (ISV is working), seems to have low power, acceleration is OK until the secondary throttle valve opens, then it feels like it's not getting enough fuel, rough idle and running when it's cold. Also, I can't get the timing set on the timing notch, if I set it on the notch, it will barely stay running.

Another thing I noticed today was the number one fuel injector was loose in it's insert. There is some play side to side. I suppose if the O-rings are bad, this would be causing problems and they need to be changed.

Any suggestions or comments woulod be appreciated.

Thanks Eddy

Reply to
MrEddy
Loading thread data ...

Replies within!!

Tell us everything......like all of the filters (gas, oil, air) were changed, ign. coil and Oxygen Sensor were checked. Tell us brands and part numbers. I prefer Bosch ign. parts (except the spark plug wires). What type of spark plugs are you using? Bosch W7TDCs? I have seen non-Bosch distributor rotors cause running problems. Also incorrect rotors installed too! I have seen new Bosch spark plug wires that were bad and failed the "wet" test. I have seen that metal screen above the fuel distributor flap installed upside down and that caused the flap not to fully open creating a lack of power.

Did you check the fuel pressure? Is the transfer pump working well, or do you easily hear buzzing from the main fuel pump?

Did you go back to the basics and check the timing of the camshaft to the crankshaft. I have seen too many that were off by a notch or two. Runs like crap until the camshaft timing is corrected. One or two have come from the dealer like this. SO CHECK IT FOR YOURSELF!

Spray some carb cleaner at the injectors with the engine running to see if the idle changes. If it does install new seals. The seals from the dealer or Bosch will be very soft.

later, dave Reminder........ Before you criticize someone, you should walk a mile in their shoes. That way, when you criticize them, you are a mile away from them, and you have their shoes. Frieda Norris

Reply to
dave

Answers within >> within

Eddy

All new Bosch ignition stuff (even Bosch wires. BAD? Why?). Have the Bosch platinums, but will not use them again. I don't see the difference. Need to check Ox Sen and coil yet. New Bosch oil filter 3400 miles ago. Fram (cringe) air filter 5500 miles ago. Need to change the fuel filter yet. This model does not have the screen in the air box. (I need more free time obviously)

Have not checked the fuel pressure. Pump seems to work, the buzz from it is obvious.

I did have the belt cover off last summer when I changed the water pump and the belt looked pretty new, so it's possible that it's off from whoever did it. I should have double-checked it then.

I'll try this this weekend.

Thanks

Reply to
MrEddy

snipped

The NEW Bosch spark plug wires that I had installed on a 92 Jetta failed the wet test. Wires arced and the engine died when spraying it with water. It could have just been that one set, but I will not assume that since the part is new it is good!!! I installed some OEM wires and engine was fine again. You could try the regular W7DC plugs but they won't last as long as some of the others.

That screen would be inside of the boot and not the air filter box. I am sure you have taken that boot off and your car may not even have one. :-)

You might have a bad transfer pump or even a clogged inlet for the main fuel pump box.

Yes please check the timing belt installation out. You could find more power possibly if the belt is off a notch or two. 8^)

later, dave Reminder........ Before you criticize someone, you should walk a mile in their shoes. That way, when you criticize them, you are a mile away from them, and you have their shoes. Frieda Norris

Reply to
dave

MotorsForum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.