Low speed surging - updated

[stewardc]

I have a completely rebuilt AAZ with a Giles pump. Often, at slow speeds 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. I have contacted Giles, so I will keep you all updated on any suggestions.
Does anyone have any ideas or cures for this problem?

[burn_your_money]

Have you talked to Giles about it?

[stewardc]

Not yet. I haven't been able to get him.

[jtanguay]

i think it has to do with the governor and how its modded.  after getting the pump changed on my 1.6TD i noticed the same "surging" (more like the car was more jerky?) which wasn't there before with the old (leaky) pump.  and the re-sealed pump had the governor mod... but it did have more power, and the power kept going right till the redline, which was cool but scary at times 

i can't remember if adding the small lift pump helped though...  

[Jettage1]

I am VERY interested to hear any answers to this question.  My car has done exactly the same thing since I installed my Giles pump this year.  Never did it at all with the stock pump.  I don't particularly like it, but it's #3 on my list of driveability issues to resolve, so haven't pestered Giles about it yet.  (#1 is cold start issues, #2 is smoke-tuning, in case you were wondering  )

If anyone has any solutions to the surging, I'm all ears!! (and it's not related to loose IP mounting bolts, either)

[stewardc]

I've gotten hold of Giles and he's thinking it over. I'll share his findings later.

[stewardc]

Changed all filters---still the same and getting worse.

[stewardc]

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.

[Jettage1]

that is indeed interesting.  My surging has remained at about the same level since installing the pump - no better, no worse. 

It will be informative to see if your surging stays gone, or returns after you've burned through the tank of fuel with the additives in it.

[catlin_cava]

I think it may just be a sign with those pumps...Hold it to the floor

[burn_your_money]

Sounds like you could have injector problems. Have you had them tested lately? (both opening pressures)

[stewardc]

PROBLEM SOLVED !!!!!;D


It is 100% fuel-related. The next tank I put in a different brand of fuel than I normally use, and added 3 oz of Stanadyne, at Gyles suggestion. No more problem. The surge is gone.

[Jettage1]

Good for you!   Not so good for me    My problem has persisted through multiple tanks as well as on both diesel and SVO.  (and I installed rebuilt TD injectors from Giles when I did the pump). 

[stewardc]

Put additive in the fuel to boost the cetane rating. Multiple tanks of crappy fuel will never cure anything. Only Stanadyne for me from now on !

[Jettage1]

Is Stanadyne an auto parts store item?    Course it still begs the question of why the car ran fine with a stock pump but surges & possibly requires this additive with the performance pump...