Why is my GTI doing this to me?

I've replaced the transfer pump at least five times in the almost 20 years I've owned the car. Definitely a weak point in the design. I think there was also a recall associated with excessive pressure drop through the screen filter that would cause the same symptoms of transfer pump failure due to fuel vaporization on warm days. Similar to a vapor lock effect. This effect would also overheat the pump and accelerate failure, as a steady flow of fuel through the pump is required to keep it cool. Some say the VDO pump offers better longevity than the Piedmont (sp?), but I'm not certain if this is true. I actually carry a spare one with me for swap out, cause it's not a matter of "if" it fails, it's a matter of "when". I recognize the symptoms of transfer pump failure well by now: surging and bucking upon acceleration, more prominent buzzing from the main pump, etc. My current power loss problem is definitely a different animal, but as I've postulated (see my later post in this thread), it is likely still a fuel supply issue.

What brand was your replacement? Years ago I remember reading on this group that the bad OEM one was by VDO and that the Pierburg replacement was the better one. Did you replace with VDO or Pierburg?

I've owned my A2 since new and it's 14 years old and only replaced the xfer pump about 2 years ago at most with a Pierburg unit.

Pierburg, and I've heard it's the other way around. I know I saw 'VDO' on my original one that went bad.

Pierburg, that's right. I don't know why I remembered it as Piedmont. I'm not sure what type's currently in the car is, but the spare I've been carrying around is a VDO. It's been quite a while since my transfer pump has failed, so I don't remember where I bought it. Recently I've been buying all my parts from Adirondack, and I know they only sell the Pierburg unit with a new filter screen. My experience has been that the folks at Adirondack know their stuff, so I'm guessing the Pierburg unit is the best bet, not VDO. Thanks for straightening me out on this Matt.

Now that I think of it, maybe I've only replaced the transfer pump three or four times, although the first one or two didn't last as long as the others, perhaps because of a bad filter screen. I know I did a great deal of hot weather driving at that time. I recall that my transfer pump failed for the first time when the car was not very old. I remember replacing it myself with a unit purchased from a dealer, and it didn't include the filter, so I just installed the new pump with the original filter. I was moving alot back then, so I never received notification of the recall associated with the screen filter. I think the replacement pump failed not too long after, and I think I did the same thing again: replaced the pump, but used the original filter again. Dumb ass. I think I finally bought a new screen filter for the third replacement, and it seems that the pumps have lasted much longer since then. In the last ten years, I think I've replaced the transfer pump only once, but I'm not completely certain.

Speaking of recalls, I also wasn't aware of the recall on the heater core until it failed, stranding me and my girlfriend without coolant. Again, dumb ass.

I got mine from Adirondack so yeah it's Pierburg they carry.

The engine (AKA air pump) needs fuel and ignition. So there is some problem or problems with either: Fuel Ignition Compression (which could mean exhaust also)

Well was it the idle switch? Yes it could be a fuel pressure problem. Check the fuses and also the ground wires that might go to the cold start valve bolt. Hooking up a VOM to the Fuel Pressure Regulator to measure the current might help determine if you have problems with wiring to it. BTW I have replaced a couple of CIS-E fuel distributors that were causing problems like yours even though I tried to clean out the plunger in the center first.

I was also thinking that it could be some blockage in the exhaust. I had a problem with my rear muffler restricting the flow of exhaust on my 91 Passat. I could hear the problem though and feel the power loss. If I slowed down the blockage may open back up but it would soon return. Of course another rear muffler solved that problem. You could use a vacuum gauge to help determine if this is your problem.

Oh I remember another Jetta that had too much oil pressure causing the hydraulic lifters to pump up and actually cause the valves to stay open and cause a compression loss. Freaky problem that I have never seen before.

- later, dave (One out of many daves)

Drove it another 50 or so miles yesterday with the throttle switches unhooked, still no problems. The sluggish performance I referred to in my original post turned out to be a big leak in the intake system where the intake pipe connects to the rubber boot on the mixture control unit. My fault, I took the intake pipe off when I changed my injectors last Sunday and didn't tighten down the clamp when I replaced it. No question the leak was enlarging at speed and seriously leaning out the mixture. Feels really strong now. I'm going to drive around with the throttle switches unhooked for another week or so before I invest in a new switch. I think I've licked this one.

You don't know what you're talking about.

There is no such thing as a "security mode" on a 1987 KE-Jetronic motor.

His car has only ONE coil, you idiot.

This kind of idiotic misinformation reminds me of why I left this group

Good answer, and only 8 days after someone else pointed it out! Glad to have you back.

Kent wrote: : This problem with my GTI is driving me CRAZY!!! I'll be driving along on the : highway, and the engine will suddenly and completely lose power. There is : absolutely no response from the accelerator. When I coast to a stop at the : side of the highway, the car returns to idle as if nothing happened. This : may happen again in a few minutes, hours, or days. It's completely : intermittent and can't be duplicated in my garage. I also note that the car : feels a bit sluggish, and tends to stall now and then when the clutch is : released at stop signs, etc.

Hi, I haven't had this problem with my 86 GTI (knock on wood), but had a similar problem with my 944 (by coincidence, the 944 low temp thermostat has the same part number as my GTI...)

Anyway, just as my 944 got up to temperature, it would stall.. not every time, just occasionally... turned out the be the DME (computer) relay...

Best $29 bucks I ever spent cause it was driving me nuts...