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GTI Loses Power



 
 
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  #1  
Old October 8th 04, 06:03 AM
Kent
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Posts: n/a
Default GTI Loses Power

Hi again folks. Now that I've finally completed my clutch job, replaced the
mysteriously absent drive flange springs/thrust washers, and fought the good
fight with Bentley Publishing over product support, the old GTI is on the
road again...but...

I have another problem that has been plaguing the car intermittently for a
bit. I'll be driving down the freeway and the engine will suddenly and
completely lose power. It happened again today on the way to work. It
doesn't surge or buck; it just completely loses power. It seems that I've
suddenly lost spark, and if I push the accelerator to the floor, absolutely
nothing happens. At this point I usually push in the clutch to coast, the
engine drops to idle, and then I can accelerate again.

Wires, plugs, cap, and rotor are fairly new. All other ignition components
are original. Anyone have any ideas what the problem is? TIA for your help.

--
Kent
1987 VW GTI 8V, original owner, 221,500+ miles


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  #2  
Old October 8th 04, 12:14 PM
Bernd Felsche
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Default

"Kent" > writes:

>Hi again folks. Now that I've finally completed my clutch job,
>replaced the mysteriously absent drive flange springs/thrust
>washers, and fought the good fight with Bentley Publishing over
>product support, the old GTI is on the road again...but...


>I have another problem that has been plaguing the car
>intermittently for a bit. I'll be driving down the freeway and the
>engine will suddenly and completely lose power. It happened again
>today on the way to work. It doesn't surge or buck; it just
>completely loses power. It seems that I've suddenly lost spark, and
>if I push the accelerator to the floor, absolutely nothing happens.
>At this point I usually push in the clutch to coast, the engine
>drops to idle, and then I can accelerate again.


>Wires, plugs, cap, and rotor are fairly new. All other ignition
>components are original. Anyone have any ideas what the problem is?
>TIA for your help.


Does the tacho needle drop suddenly when power is lost?

Check the wiring to the Hall sensor in the distributor.

The sensor itself doesn't last forever; nor would you, sitting in a
hot distributor with 30,000V or more arcing above your head.

If the tacho needle still reflect engine speed, then there's still a
signal coming from the Hall sensor. Maybe the fuel pump relay is
playing up... electrics differ quite a lot from one production run
to the next.

Also check that the rubber bellows between air flow meter/fuel
distributor and the throttle body is intact. A broken/weak engine
mount can cause the engine to tear open a crack when under load and
the engine will suck a lot of air that's not metered, resulting in a
very lean mixture.
--
/"\ Bernd Felsche - Innovative Reckoning, Perth, Western Australia
\ / ASCII ribbon campaign | I'm a .signature virus!
X against HTML mail | Copy me into your ~/.signature
/ \ and postings | to help me spread!
  #3  
Old October 8th 04, 01:14 PM
Darryl
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Default

>>Hi again folks. Now that I've finally completed my clutch job,
>>replaced the mysteriously absent drive flange springs/thrust
>>washers, and fought the good fight with Bentley Publishing over
>>product support, the old GTI is on the road again...but...

>
>>I have another problem that has been plaguing the car
>>intermittently for a bit. I'll be driving down the freeway and the
>>engine will suddenly and completely lose power. It happened again
>>today on the way to work. It doesn't surge or buck; it just
>>completely loses power. It seems that I've suddenly lost spark, and
>>if I push the accelerator to the floor, absolutely nothing happens.
>>At this point I usually push in the clutch to coast, the engine
>>drops to idle, and then I can accelerate again.

>
>>Wires, plugs, cap, and rotor are fairly new. All other ignition
>>components are original. Anyone have any ideas what the problem is?
>>TIA for your help.

>
>Does the tacho needle drop suddenly when power is lost?


If so, perhaps it's simply the ignition switch. Jiggle the key next
time power cuts out and see if it quickly returns.

Darryl.


>Check the wiring to the Hall sensor in the distributor.
>
>The sensor itself doesn't last forever; nor would you, sitting in a
>hot distributor with 30,000V or more arcing above your head.
>
>If the tacho needle still reflect engine speed, then there's still a
>signal coming from the Hall sensor. Maybe the fuel pump relay is
>playing up... electrics differ quite a lot from one production run
>to the next.
>
>Also check that the rubber bellows between air flow meter/fuel
>distributor and the throttle body is intact. A broken/weak engine
>mount can cause the engine to tear open a crack when under load and
>the engine will suck a lot of air that's not metered, resulting in a
>very lean mixture.

  #4  
Old October 8th 04, 04:10 PM
Matt B.
external usenet poster
 
Posts: n/a
Default

"Kent" > wrote in message
...
> Hi again folks. Now that I've finally completed my clutch job, replaced
> the
> mysteriously absent drive flange springs/thrust washers, and fought the
> good
> fight with Bentley Publishing over product support, the old GTI is on the
> road again...but...
>
> I have another problem that has been plaguing the car intermittently for a
> bit. I'll be driving down the freeway and the engine will suddenly and
> completely lose power. It happened again today on the way to work. It
> doesn't surge or buck; it just completely loses power. It seems that I've
> suddenly lost spark, and if I push the accelerator to the floor,
> absolutely
> nothing happens. At this point I usually push in the clutch to coast, the
> engine drops to idle, and then I can accelerate again.


Not sure what it is, but what is probably is *not* is ignition. If you lost
ignition it wouldn't even idle. Focus on fuel supply issues. The transfer
pump is the usual culprit in an A2.


  #5  
Old October 8th 04, 05:29 PM
Kent
external usenet poster
 
Posts: n/a
Default

I'm not sure I want to eliminate the ignition system as the culprit yet, as
the problem is very intermittent. At the time the sudden power loss occurs,
I'm sure the car wouldn't idle either. Problem is, by the time I start
moving over to the side of the road, power returns, and it may not happen
again for a few days.

I hear what you're saying about the transfer pump, as I've replaced a few of
them in the 18 or so years I've owned the car. However, my experience with a
failing transfer pump is that the engine tends to surge on acceleration
(instead of completely losing power) and there is usually an obvious buzz
from the main pump. An earlier post suggested a fuel pump relay problem;
that's something I'll be checking out.

Thanks for your input.

--
Kent
1987 VW GTI 8V, original owner, 221,500+ miles

"Matt B." > wrote in message
news:H4y9d.1125$cJ3.163@fed1read06...
> "Kent" > wrote in message
> ...
> > Hi again folks. Now that I've finally completed my clutch job, replaced
> > the
> > mysteriously absent drive flange springs/thrust washers, and fought the
> > good
> > fight with Bentley Publishing over product support, the old GTI is on

the
> > road again...but...
> >
> > I have another problem that has been plaguing the car intermittently for

a
> > bit. I'll be driving down the freeway and the engine will suddenly and
> > completely lose power. It happened again today on the way to work. It
> > doesn't surge or buck; it just completely loses power. It seems that

I've
> > suddenly lost spark, and if I push the accelerator to the floor,
> > absolutely
> > nothing happens. At this point I usually push in the clutch to coast,

the
> > engine drops to idle, and then I can accelerate again.

>
> Not sure what it is, but what is probably is *not* is ignition. If you

lost
> ignition it wouldn't even idle. Focus on fuel supply issues. The

transfer
> pump is the usual culprit in an A2.
>
>



  #6  
Old October 8th 04, 05:39 PM
Kent
external usenet poster
 
Posts: n/a
Default

You know, I can't tell you for sure if the tach needle drops or not; I'll be
keeping a close eye the next time it happens.

Is it your experience that the Hall sensor can experience intermittent,
rather than complete failure? The Bentley Manual led me to believe that
unless the car has completely lost spark, and will not start, the problem is
not likely to be the Hall sensor. I will take a close look at the sensor and
its wiring though.

I like your idea of a faulty fuel pump relay; I think I'll pony up the bucks
for a new one and see if that does the trick.

I have checked the intake system for obvious leaks and don't seem to find
any. I think I'll pull the bellows off the car and give it a good going
over.

I'll let you know what I find.

Thanks,
--
Kent
1987 VW GTI 8V, original owner, 221,500+ miles

"Bernd Felsche" > wrote in message
...
> "Kent" > writes:
>
> >Hi again folks. Now that I've finally completed my clutch job,
> >replaced the mysteriously absent drive flange springs/thrust
> >washers, and fought the good fight with Bentley Publishing over
> >product support, the old GTI is on the road again...but...

>
> >I have another problem that has been plaguing the car
> >intermittently for a bit. I'll be driving down the freeway and the
> >engine will suddenly and completely lose power. It happened again
> >today on the way to work. It doesn't surge or buck; it just
> >completely loses power. It seems that I've suddenly lost spark, and
> >if I push the accelerator to the floor, absolutely nothing happens.
> >At this point I usually push in the clutch to coast, the engine
> >drops to idle, and then I can accelerate again.

>
> >Wires, plugs, cap, and rotor are fairly new. All other ignition
> >components are original. Anyone have any ideas what the problem is?
> >TIA for your help.

>
> Does the tacho needle drop suddenly when power is lost?
>
> Check the wiring to the Hall sensor in the distributor.
>
> The sensor itself doesn't last forever; nor would you, sitting in a
> hot distributor with 30,000V or more arcing above your head.
>
> If the tacho needle still reflect engine speed, then there's still a
> signal coming from the Hall sensor. Maybe the fuel pump relay is
> playing up... electrics differ quite a lot from one production run
> to the next.
>
> Also check that the rubber bellows between air flow meter/fuel
> distributor and the throttle body is intact. A broken/weak engine
> mount can cause the engine to tear open a crack when under load and
> the engine will suck a lot of air that's not metered, resulting in a
> very lean mixture.
> --
> /"\ Bernd Felsche - Innovative Reckoning, Perth, Western Australia
> \ / ASCII ribbon campaign | I'm a .signature virus!
> X against HTML mail | Copy me into your ~/.signature
> / \ and postings | to help me spread!



  #7  
Old October 8th 04, 08:01 PM
external usenet poster
 
Posts: n/a
Default

go for the cheap first. a new fuel filter is always a good investment.
water in a cis will cause the exact same symptoms. rick.

  #8  
Old October 9th 04, 02:34 AM
Bernd Felsche
external usenet poster
 
Posts: n/a
Default

"Kent" > writes:

>You know, I can't tell you for sure if the tach needle drops or
>not; I'll be keeping a close eye the next time it happens.


>Is it your experience that the Hall sensor can experience intermittent,
>rather than complete failure? The Bentley Manual led me to believe that


Intermittent failure seems to be more characteristic than a total
failure from the few cars I've seen with that problem in the real
world.

The Bentley Manual is good; but it's not gospel. Much of it was
written well before the age-related issues came up.

>unless the car has completely lost spark, and will not start, the
>problem is not likely to be the Hall sensor. I will take a close
>look at the sensor and its wiring though.


The symptoms you described are fairly characteristic of an
intermittent Hall sensor dropout.

The tacho needle is the tell-tale. If the Hall sensor fails to send
pulses to the ignition module (or ECU), the coil won't be fired so
the tacho needle drops to zero.

>I like your idea of a faulty fuel pump relay; I think I'll pony up
>the bucks for a new one and see if that does the trick.


It's one of the typical "problem areas"; along with the ignition
switch that I didn't think of at the time of writing (dopey me!).

>I have checked the intake system for obvious leaks and don't seem
>to find any. I think I'll pull the bellows off the car and give it
>a good going over.


>I'll let you know what I find.

--
/"\ Bernd Felsche - Innovative Reckoning, Perth, Western Australia
\ / ASCII ribbon campaign | I'm a .signature virus!
X against HTML mail | Copy me into your ~/.signature
/ \ and postings | to help me spread!
  #9  
Old October 9th 04, 05:12 AM
Darryl
external usenet poster
 
Posts: n/a
Default

>>I like your idea of a faulty fuel pump relay; I think I'll pony up
>>the bucks for a new one and see if that does the trick.

>
>It's one of the typical "problem areas"; along with the ignition
>switch that I didn't think of at the time of writing (dopey me!).


I thought I'd subtly remind you. ;-) My money stays on the switch.
  #10  
Old October 9th 04, 06:32 AM
Kent
external usenet poster
 
Posts: n/a
Default

I think both you and Bernd were on the money with this one. The key seems to
be very loose in the ignition, and if I wiggle it while the engine is
running, it takes a remarkably small amount of up and down wiggle to shut
down the engine (without any obvious rotation of the key). I've reproduced
the problem in the garage several times, and it seems like normal vibration
during driving could do the same. I've never really paid attention to how
loose the ignition switch had become. I'm going to do some disassembly over
the weekend to take a closer look.

Follow-up question: do you think the problem is confined to the electrical
portion of the switch, or do you think the lock cylinder itself is worn and
also needs replacing?

Anyway, thanks for the tip!

--
Kent
1987 VW GTI 8V, original owner, 221,500+ miles

"Darryl" > wrote in message
...
> >>I like your idea of a faulty fuel pump relay; I think I'll pony up
> >>the bucks for a new one and see if that does the trick.

> >
> >It's one of the typical "problem areas"; along with the ignition
> >switch that I didn't think of at the time of writing (dopey me!).

>
> I thought I'd subtly remind you. ;-) My money stays on the switch.



 




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