QuestionI am adusting the screw that was sealed on top of the mass air flow sensor,I turn it about one turn in then out ,then out one more turn with no change, as far as the idle the air adjusting screw on the throttle plates responds fine, I can make the car race or stall,I hope to get the temp sensor today,Tony-------------------------
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Question -
First thanks for the reply,If I add air to the system by creating a vac leak it runs much better, The points & condenser are new, the auxilary air reg is closing,the timing is on the money, new plugs,egr is disconnected and plugged (as I also thought this was the problem), fuel filter and pump are new along with the hoses the return line is free to the tank,the compression is in good shape , the bus starts right up and runs fine for about a minute then it starts to load up, the air intake hose is in good shape,Just one other thing if I try to adjust the mass air flow sensor nothing changes as with the other two I have installed, I have ordered a cylinder head temp sensor I should have it on tuesday and I will try it ,again thanks for the response if you could think of anything else I would appreciate it as this has been going on for about a year, thanks Tony -------------------------
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Question -
Hello, I am at my wits end, I have a vw bus 78 vintage with electronic fuel injection It has a running rich problem , I have replaced the following items as per manual specs, fuel pump, fuel reg, mass air flow (3 times), cold start valve , I have inspected the thermal time switch, temp sensor,I have removed the cold start valve and watched for a spray with the engine warm and there is no problem,as it does not spray fuel after it starts , I have removed the fuel injectors and the pattern and sealing ability are in good shape ,I have cleaned and replaced ground wires, cables , still this vehicle runs with a poor acceleration, emitting black smoke and breaking up badly, can you help as I am leaning towards replacing the computer. thanks Tony
Answer -
Tony,
Have you made sure that you have no problems with:
1) Any stuck or bad hydraulic lifters?
2) Are the points shiny and new?
3) Condensor
4) Is the engine timed correctly?
5) Does it have new spark plugs?
6) Is the egr valve functioning properly (this is usually the cause).
7) Is the fuel filter clogged, or is there a restriction from the fuel pressure regulator back to the tank? (the return)
8) Check the compression at each cylinder.
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Sometimes, we overlook some of the more obvious and go right to the fuel injection. This is really a robust system and it takes a lot for the components to break.
Try 1-8 first.
Next, try the auxilary air regulator. With the engine cold, you should be able to blow air clear through it. With engine at operating temperature, it should be greatly restricted. If this device is stuck open (or broken) it will constantly let in more air, fooling the computer to create a 'rich running' situation.
Also, check the double relay to ensure that it is supplying the fuel pump with sufficient voltage.
If all else fails, take a careful look in two areas:
1) Electrical: Look at the wiring diagram for the fuel injection system in the Bentley guide. Make sure that everything is plugged in correctly - and all wires are tight and lead to the correct place.
2) Vacuum: Biggest problem area: make sure that ALL the hoses are 1) on correctly 2) are removed and inspected, and moved around and blown through to ENSURE there are no leaks. That large boot the Air Sensor is hooked to is notorius for having leaks/cracks in it, not visible to the naked eye. You literally have to take it off and look in between the baffles of it for cracks and bend it around a bit.
One other note on vacuum: I've noticed that many people have put the brake non-return valve on backwards, creating a 'fuel injection' problem. Make sure the plastic valve is on correctly: You should be able to suck air from the part that is heading towards the engine and not be able to blow any air through it. That is how it should correctly go.
Finally, instead of testing the temperature sensor, go get a new one. They are about 15.00, and make your engine run more efficient anyhow.
Try these basic tests, and let me know how you make out. Don't replace the computer as of yet!
Ron
Answer -
Hi Tony,
How are you adjusting the mass air flow sensor? (I'm presuming you are talking about the metal thing that looks like a waffle-iron underneath).
Also, on the throttle body --- are you able to adjust the idle OK?
Don't worry, we'll fix it!
Ron
AnswerTony,
That screw is for Carbon Dioxide/Emissions. It really should have no bearing on how it runs. Good the idle screw works.
What is throwing me, is that the FI system should not be emitting black smoke. I am not able to reproduce that condition on mine. Here are some more checks to do:
1) Turn ignition switch to "ON", have air cleaner removed. (engine should not be running). Take a screwdriver and push the flap of the air sensor open slightly. You should hear the fuel pump run at this point. If so, that circuit is good.
2) While engine is running, place the tip of a long screw driver on the electric fuel pump, and put your ear on the other end. The pump should be running just as fast as when you pushed the flap. (You will hear the 'hum' through the screw driver.
3) With engine running, carefully disconnect one plug wire (not center one). Start with #1, see if the engine slows down/misses/sputters/or changes idle. If so, replace plug and repeat process with all of the other plugs.
4) If you pull off #4 for instance, and there is no change in engine idle, that cylinder is not firing. Either the injector is not working, or not sealed properly and is leaking air. This is a common problem - the injectors must not have air running in them.
5) Ensure the firing order is 1-2-3-4 counter clockwise. #1 plug should be top most right of distributor cap if you are looking thru the bottom engine compartment.
6) Get that long screw driver again and through the top part of the engine access panel, place it on each injector and put your ear to the top of the screw driver. You should hear the 'clickety click' of each injector. If not, the wiring to one of the injectors could be faulty.
7) Check air sensor again:
Take ohmmeter to terminals 6 & 9 on air sensor: Resistance needs to be between 200 to 400 Ohms, otherwise, try another one.
Connect ohmmeter to terminals 7 & 8 on intake air sensor resistance needs to be 120-200 Ohms. Use the intake air sensor that has the best reading.
8) Are you using the correct parts:
(I am assuming this VW is a manual non-California)
Control Unit # 022 906 021N
Air Sensor # 022 906 301B
Double relay # 022 906 059
Thermo time switch # 043-906-163A
If you have a digital camera, and feel like taking some pictures of the engine (through the top looking down). and a picture of the fuel pump and set-up, I can take a birds-eye view and check out the hoses etc. (you probably have it all correct, sometimes a second set of eyes does help).
My e-mail is ronwolff@optonline.net
Let me know how these results turn out. I'll be standing by.
Ron
