Former VWDieselParts.com Forum

I have a completely rebuilt AAZ with a rebuilt/modified pump. Often, at slow speeds and light loads I get surging or Jerking which I can only fix be stepping down hard on the throttle. My old 1.6 TD, and an old AAZ in a Jetta, never had this issue, and it has me baffled. I've even replaced all the motor mounts in hopes of eliminating it, but to no avail. A friend also has a modded AAZ in a Rocco with the same issues. He says it is a result of all the modifications, and is a small price to pay for all the power. I agree, but it sure is annoying.
Does anyone have any ideas or cures for this problem?

I had a bad injector a while back in my 1.6NA where the engine flat out wouldn't run a specific RPM. The slightest push or pull back on the throttle when you were right at that edge point had a large change in engine RPM. If you tried to hold the throttle in this band there would be a surge, then a drop in RPM's, then surge, etc. It was extremely noticable in 1st gear (it's the highest gear ratio). If you held the throttle at the point where it would surge in 1st gear, it would get progressively worse, unless you moved the throttle to open or close it more to move the engine out of the particular RPM band. It was less noticable in other gears, but there in all gears at that specific engine RPM.

I thought I got a bad rebuilt IP, but after rebuilding my injectors, the problem went away.

Can you see if you can do some more testing to see if there's a certain RPM band (in any gear) that your engine flat out wouldn't run and see if it's a situation like I describe? If I remember correctly, with my problem, in 4th gear (4 speed trans) I could not run the car at 46, 47, or 48 MPH. If I was at 45MPH and gave just a slight amount of gas, it would go up to 49MPH. Same thing when slowing down, it would go from 49 down to 45 and nothing inbetween. Ever gear at the same engine RPM had a range of vehicle speed that the car flat out wouldn't run in.

Check all your injection pump mounting bolts.
Even the 2 behind the pump, holding the bracket to the block.

I had a surging in my Golf TD until I did the governor mod.
A 1/16" thick washer in place of the small spring.
Sooo maybe that small spring controls surging and has gotten weak or something.
Just as thought.

Fatmobile, please tell me more about the governor mod. I have some of the same problems. Thanks, Kanzan

The other night I was idling along slowly towards a traffic light and the car started surging... but the lights also got bright and dim at the same time. I think it's probably the alternator. Later on, at speed, the lights were fluctuating again, but I was at a high enough rpm that the engine speed wasn't really affected. Seems like a long shot in your case, but might be worth looking into.

It's hard to explain the governor mod without a picture or a governor spring in front of you. There is a small spring on the end, the spring seats only allow this spring to be compressed about 1/16" before the seats hit.
I remove the small spring and put a 1/16" thick washer between the spring seats.
Green79, I wonder if your stop solenoid is getting wacky.

Thanks, but nada so far. Injectors are new, and all is as it should be. Jerking continues.

dubdoc wrote:Injectors are new, and all is as it should be.

I replaced my nozzles and replaced the IP with a rebuilt unit. Long story, but by the time I got it running, the IP was way past the warranty period, so returning anything was out of the order. My assumption for my problem was the IP, but it ended up not the IP, but the injectors. So, the problem I described above was a result of new nozzles (ie: new injectors). Just becuase they are new does not mean that one of them isn't bad.

Fatmobile, Is this the spring you are talking about, for the Gov. Mod.? Thanks, Kanzan

here's a thread on governor mod from vwvortex forum

http://forums.vwvortex.com/zerothread?id=3107325

Kanzan, No that's not the spring.
The link bscutt posted has a great picture.
I'm talking about the intermediate spring,.. the one in the link has 3 washers where I used one.

Interesting happenings - I am getting desperate...it's getting worse. Last tank I added 6 oz. of Power Service (white bottle) instead of the recommended 3 oz. I also added 2 cups of ATF. Immediately, the surging is almost completely gone.
More to follow.

Problem completely solved. It is fuel related. This time, at Giles' suggestion, I added 3 oz of Stanadyne to my tank of fuel and the problem is gone. Looks like summer fuel equates to "Crap fuel".

Didn't think of it until your last post. A couple years ago I started running some fuel additive in the tank of fuel. The car ran like crap, so bad that I ran with the cold start lever pulled out. I got to thinking that it could be cleaning out water that may be in the fuel system, so I replaced the fuel filter and the problem went away.