Have had my 914 for a couple of weeks now. It's a stock 1.7. It's in the garage getting a few little details taken care of but I need your collective wisdom. The car starts at the touch of the key. It idles at about 2 grand and once its' warm and I drive off it surges all the time. The car has sat for quite a while so I put fresh gas in and some gas dryer. The PO says it ran ok a couple of years ago. He had 18 cars and probably didn't pay much attention. I have been checking all the vacum hoses and they look ok but can't tell for sure if there are leaks.
Your Thoughts?

Mike

'72 adriatic blue 1.7 - my one and only

Welcome to the club, Michael.

Idleing cold at 2K indicates the Auxiliary Air Regulator is working properly. Is the surging at idle only, or while you are driving also. I need a little more info on the surging. Can you explain it in a little further detail? Does it do ok when accelerating? Under a steady speed?

PS, we love pics if ya got em.

You said that it sat for a few years, this prolly won't help your problem but you should replace the fuel lines in the engine compartment for safety sake. Also replace the vacuum hoses as well.

As vsg914 said give us some more detail on the problem.

And Welcome to the club!

Sean

I know it's hard to do any diagnosis this way but here is a little more detail.
The idle does not drop down when it warms up.
It does idle smooth.
It's like it's running really rough but it is not missing.
It is only doing it while accelerating.
At a higher rpm the surging seems to go away but it might just be because the engine is running faster.

I had a BMW that did the same thing but it went away as soon as it warmed up. The 914 doesn't.
Thanks again.
Mike

Change the damn fuel lines in the engine compartment and at the fuel pump ASAP before it catches fire. Old cracked lines spray gas on hot engine parts which burns the car to the ground.

Now, sounds like the AAR valve is stuck open so get sum PB Blaster and spray it into it alot. Let sit, do it again. This should free it up as it rust inside the rotary valve.
Surging driving around hmm, I would guess its old TPS that needs changing. This is evident off idle between 2500-3000 rpms as the car kinda bucks as you step on the gas. The TPS has metal traces that wear out so you get this poor idle to crusin effect.

Geoff

another piece of the puzzle emerges. Geoff is right on with the AAR, or another vacuum leak. It does sound like the tps. It may be possible to adjust it, or it may be need to be replaced. Misadjusted dwell and timing can give similar symptoms.

They are both right about the fuel lines.

could be a lot of things. after sitting for so long.

replace the fuel filter.

your high idle is a vacuum leak. replace all the hoses.

replace the fuel lines with the *proper* high pressure FI line and FI hose clamps !!! both of which you can buy at any VW store.

check the engine harness for brittle wires. clean ALL ground connections, like the ground terminal on the engine block, right next to the air filter.

check your relay board. are the relay contacts corroded? if so, clean them.
if you need to clean the sockets as well, disconnect the negative (-) from your battery first !!

check all connectores to the fuel-injectors.

check the cable to the CHT! check and see if the CHT itself is loose.

replace rotor/cap/sparkplus and wires. if you still have points, replace them too.
make sure you get the right spark plugs and don't cheap out on the wires.

MPS hooked up correctly?

did you clean the air-filter?

did you adjust the valves?

did you check the timing?

is there any sludge on the bottom of the fuel tank?


thats all i can think of right now, i'm sure there's more ...
Andy

Yeah what Andy said.

Mine had a similar problem after doing most of the stuff on Andy's list.

A new TPS solved the problem.

Would still be wise to go over and check your FI as much as possible

For a some reading on the subject check out - Brad Anders Djet info It can be overwhelming at first, just keep referring to it and it will help in understanding the system.

If you really suspect the TPS, do what I did, I took it apart and very carefully cleaned the contact points. I used a little denatured alcohol on a Q-tip. It took care of my hesitation problem.

New gas lines asap, adj valves, clean and lube trigger points, new ign points and condenser, set dwell then timing, Vaccume/Breather/PVC all hooked up tight, Vacuume check MPS mainfold pressuer sensor, the AAR valve can be capped off for testing hell I guess Im still testing mine everyday as its in the trunk. That's enough to keep someone going a while. None of the above may fix the problem but it sure wont hurt anything!!

Don´t know much about your problem, but nice to see an other adriatic blue car. This colour rocks.

You could also simply UNPLUG the TPS and see if the surging stops. The car won't accelerate quite as well without the TPS as it enrichens the mixture (adds pulses of fuel to the injectors), but it will run.

My thoughts are that you have some big air leaks (that you need to fix) and the car is having lean surging. If this is the case, when you fix the air leaks the surging will stop.