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Loss of power 91 jetta 8valve



 
 
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  #1  
Old May 18th 05, 07:35 PM
dubljay
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Default Loss of power 91 jetta 8valve

I have a 1991 Jetta gl, 1.8L 8valve, with about 184k miles.

I am at a loss of what to do, there is lack of power and rough idle.
There is no hint of knocking, timing is good. I have replaced the
spark plugs and wires. The distributor cap and rotar both seem fine.
Checked the coil, it was operating at the right ohms. fuel pumps and
filter are good, as is the fuel pump relay (replaced). Replaced the
fuel pressure regulator no help. All plugs are getting spark, and it
is not missing.

I thought perhaps that it was a air flow problem, as the previous
owner had installed an aftermarket Neuspeed P-Flo air intake.
Replaced it with a stock air intake from a salvage yard, no help.
Checked Digfiant computer (according to shop manual) no indication of
computer problem.

I am out of ideas as to what the problem could be. The Oxygen sensor
seems fine, as does the CO sensor. Perhaps it is the air flow sensor
on the intake? I know the car has been run out of gas at least
once... could that have fouled an injector? Tried running premium
gas, thinking that may have been the problem, even added ’injector
cleaner’ No help.

The crazy part is that the car passed California smog standards
despite all these problems.

I greatly appreciate any thoughts and suggestions. (Frustrated enough
to see how bullet proof the block is :x )

Sorry if this has been asked and answered already... lots of posts to
sift though.

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  #2  
Old May 19th 05, 04:17 AM
dave AKA vwdoc1
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Default

and how is your cat. conv.?
Maybe it is partially clogged?

How did you check the ECM? Ohm meter at it's plug to check the sensors out?

good luck,
dave
(One out of many daves)

"dubljay" > wrote in message
news:1_586678_579371bf1fe991b22560e3ead0317fcf@aut oforumz.com...
>I have a 1991 Jetta gl, 1.8L 8valve, with about 184k miles.
>
> I am at a loss of what to do, there is lack of power and rough idle.
> There is no hint of knocking, timing is good. I have replaced the
> spark plugs and wires. The distributor cap and rotar both seem fine.
> Checked the coil, it was operating at the right ohms. fuel pumps and
> filter are good, as is the fuel pump relay (replaced). Replaced the
> fuel pressure regulator no help. All plugs are getting spark, and it
> is not missing.
>
> I thought perhaps that it was a air flow problem, as the previous
> owner had installed an aftermarket Neuspeed P-Flo air intake.
> Replaced it with a stock air intake from a salvage yard, no help.
> Checked Digfiant computer (according to shop manual) no indication of
> computer problem.
>
> I am out of ideas as to what the problem could be. The Oxygen sensor
> seems fine, as does the CO sensor. Perhaps it is the air flow sensor
> on the intake? I know the car has been run out of gas at least
> once... could that have fouled an injector? Tried running premium
> gas, thinking that may have been the problem, even added 'injector
> cleaner' No help.
>
> The crazy part is that the car passed California smog standards
> despite all these problems.
>
> I greatly appreciate any thoughts and suggestions. (Frustrated enough
> to see how bullet proof the block is :x )
>
> Sorry if this has been asked and answered already... lots of posts to
> sift though.
>


  #3  
Old May 19th 05, 05:35 AM
dubljay
external usenet poster
 
Posts: n/a
Default

"dave AKA vwdoc11" wrote:
> and how is your cat. conv.?
> Maybe it is partially clogged?
>
> How did you check the ECM? Ohm meter at it's plug to check
> the sensors out?
>
> good luck,
> dave
> (One out of many daves)
>
> "dubljay" > wrote in message
> news:1_586678_579371bf1fe991b22560e3ead0317fcf@aut oforumz.com...
> >I have a 1991 Jetta gl, 1.8L 8valve, with about 184k miles.
> >
> > I am at a loss of what to do, there is lack of power and

> rough idle.
> > There is no hint of knocking, timing is good. I have

> replaced the
> > spark plugs and wires. The distributor cap and rotar both

> seem fine.
> > Checked the coil, it was operating at the right ohms. fuel

> pumps and
> > filter are good, as is the fuel pump relay (replaced).

> Replaced the
> > fuel pressure regulator no help. All plugs are getting

> spark, and it
> > is not missing.
> >
> > I thought perhaps that it was a air flow problem, as the

> previous
> > owner had installed an aftermarket Neuspeed P-Flo air

> intake.
> > Replaced it with a stock air intake from a salvage yard, no

> help.
> > Checked Digfiant computer (according to shop manual) no

> indication of
> > computer problem.
> >
> > I am out of ideas as to what the problem could be. The

> Oxygen sensor
> > seems fine, as does the CO sensor. Perhaps it is the air

> flow sensor
> > on the intake? I know the car has been run out of gas at

> least
> > once... could that have fouled an injector? Tried running

> premium
> > gas, thinking that may have been the problem, even added

> 'injector
> > cleaner' No help.
> >
> > The crazy part is that the car passed California smog

> standards
> > despite all these problems.
> >
> > I greatly appreciate any thoughts and suggestions.

> (Frustrated enough
> > to see how bullet proof the block is :x )
> >
> > Sorry if this has been asked and answered already... lots of

> posts to
> > sift though.
> >


I am not sure how the ECM was checked, my father did that after I left
for school (break ended). As for the cad. converter, there is plenty
of pressure coming out of the exhaust. Also wouldn’t a partial cloged
converter show up on an emisions test? (which was run just after I
bought the car)

Thanks for the input.

-Josh

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  #4  
Old May 19th 05, 01:35 PM
One out of many daves
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Default

Well if you just bought the car and it passed the emissions AND it was
running this way...........How do you know you have a loss of power?


Well back to the basics....
Check compression.....maybe even a leak down test
Examine spark plugs well and make sure that they are gapped properly.
Check timing and advance since that will tell you the condition of the knock
sensor. The knock sensor will give you a big loss of power if it is bad or
not torqued down correctly.
Check vacuum since a leak could cause your problems too.
Oh and get a Bentley for your vehicle. I think someone has a website
dedicated to the Digifant II system if that is what you have on your CA
equipped Jetta.

Hope this gives you a few leads. ;-)
--
later,
dave
One out of many daves.


>
> I am not sure how the ECM was checked, my father did that after I left
> for school (break ended). As for the cad. converter, there is plenty
> of pressure coming out of the exhaust. Also wouldn't a partial cloged
> converter show up on an emisions test? (which was run just after I
> bought the car)
>
> Thanks for the input.
>
> -Josh



  #5  
Old May 19th 05, 07:37 PM
dubljay
external usenet poster
 
Posts: n/a
Default

"One out of many daves" wrote:
> Well if you just bought the car and it passed the emissions
> AND it was
> running this way...........How do you know you have a loss of
> power?
>
>
> Well back to the basics....
> Check compression.....maybe even a leak down test
> Examine spark plugs well and make sure that they are gapped
> properly.
> Check timing and advance since that will tell you the
> condition of the knock
> sensor. The knock sensor will give you a big loss of power if
> it is bad or
> not torqued down correctly.
> Check vacuum since a leak could cause your problems too.
> Oh and get a Bentley for your vehicle. I think someone has a
> website
> dedicated to the Digifant II system if that is what you have
> on your CA
> equipped Jetta.
>
> Hope this gives you a few leads. ;-)
> --
> later,
> dave
> One out of many daves.
>
>
> >
> > I am not sure how the ECM was checked, my father did that

> after I left
> > for school (break ended). As for the cad. converter, there

> is plenty
> > of pressure coming out of the exhaust. Also wouldn't a

> partial cloged
> > converter show up on an emisions test? (which was run just

> after I
> > bought the car)
> >
> > Thanks for the input.
> >
> > -Josh


Well I am no expert on jettas, or any car, however I had an 87
Cabriolet with a 1.8L 8valve that would tackle hills at 70mph+ This
jetta barely makes 60 in thrid gear (5 spped manual) on the same
hill. There is not much of a weight difference between the two cars (
I checked), so I know it’s not because the Jetta is significantly
heavier. The other thing is that there is a slight hesitation when
you put your foot down.. there is a very noticible response time. The
reason I believe there is a loss of power is beacuse if an engine with
the same displacement yet older style fuel injection (as in no
computer) can perform one way, it stands to reason that this engine
should be at least as good. Checking stock specs the 1.8 in my 87 had
was rated at 90 hp (i forget the rpm) and the 1.8 in the Jetta is
rated at 100hp.

Again thanks for the input.

-Josh

--
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  #6  
Old May 20th 05, 02:34 AM
dave AKA vwdoc1
external usenet poster
 
Posts: n/a
Default

So if it is generally slow make sure that the timing belt is correctly
installed. I have seen quite a few off by one notch. The engines still run
but are sluggish like what you describe. Usually the 91 1.8 engines are
quite peppy when it is working correctly.
Also make sure that the timing belt tensioner is turned clockwise to tighten
belt.

let us know what you find, but check that T-Belt first. Really easy to
check too! ;-)
later,
dave
(One out of many daves)


"dubljay" > wrote in message
snip
>
> Well I am no expert on jettas, or any car, however I had an 87
> Cabriolet with a 1.8L 8valve that would tackle hills at 70mph+ This
> jetta barely makes 60 in thrid gear (5 spped manual) on the same
> hill. There is not much of a weight difference between the two cars (
> I checked), so I know it's not because the Jetta is significantly
> heavier. The other thing is that there is a slight hesitation when
> you put your foot down.. there is a very noticible response time. The
> reason I believe there is a loss of power is beacuse if an engine with
> the same displacement yet older style fuel injection (as in no
> computer) can perform one way, it stands to reason that this engine
> should be at least as good. Checking stock specs the 1.8 in my 87 had
> was rated at 90 hp (i forget the rpm) and the 1.8 in the Jetta is
> rated at 100hp.
>
> Again thanks for the input.
>
> -Josh
>
> --
> Posted using the http://www.autoforumz.com interface, at author's request
> Articles individually checked for conformance to usenet standards
> Topic URL:
> http://www.autoforumz.com/Volkswagen...ict120690.html
> Visit Topic URL to contact author (reg. req'd). Report abuse:
> http://www.autoforumz.com/eform.php?p=587716



  #7  
Old May 20th 05, 05:35 AM
dubljay
external usenet poster
 
Posts: n/a
Default

I think you may be on to something with this. When I purchased the
car I found a service manual (cover looks similar to that of a Bently)
in the trunk. In the manual were print outs of another manual
concerning the installation of a timing belt. These prints were in
the same section in the maunal. I have a feeling that the timing belt
was replaced. I didn’t even think to check to see if it was installed
correctly, I figured if I hadn’t been the car wouldn’t have run at
all.


Thank you!

-Josh







"dave AKA vwdoc1" wrote:
>So if it is generally slow make sure that the timing belt is

correctly
>
>installed. I have seen quite a few off by one notch. The engines
>still run
>
>but are sluggish like what you describe. Usually the 91 1.8 engines
>are
>quite peppy when it is working correctly.
>Also make sure that the timing belt tensioner is turned clockwise to
>tighten
>belt.
>
>let us know what you find, but check that T-Belt first. Really easy
>to
>check too! ;-)
>later,
>dave
>(One out of many daves)
>
>
>"dubljay" > wrote in message
>snip
>>
>> Well I am no expert on jettas, or any car, however I had an 87
>> Cabriolet with a 1.8L 8valve that would tackle hills at 70mph+

>This
>> jetta barely makes 60 in thrid gear (5 spped manual) on the same
>> hill. There is not much of a weight difference between the two

>cars (
>> I checked), so I know it’s not because the Jetta is

>significantly
>> heavier. The other thing is that there is a slight hesitation

>when
>> you put your foot down.. there is a very noticible response time.

> The
>> reason I believe there is a loss of power is beacuse if an engine

>with
>> the same displacement yet older style fuel injection (as in no
>> computer) can perform one way, it stands to reason that this

>engine
>> should be at least as good. Checking stock specs the 1.8 in my

>87 had
>> was rated at 90 hp (i forget the rpm) and the 1.8 in the Jetta is
>> rated at 100hp.
>>
>> Again thanks for the input.
>>
>> -Josh
>>
>> --
>> Posted using the http://www.autoforumz.com interface, at

>author’s request
>> Articles individually checked for conformance to usenet standards
>> Topic URL:
>>

>http://www.autoforumz.com/Volkswagen...ict120690.html
>> Visit Topic URL to contact author (reg. req’d). Report

>abuse:
>> http://www.autoforumz.com/eform.php?p=587716</font>


  #8  
Old May 22nd 05, 05:22 AM
dave AKA vwdoc1
external usenet poster
 
Posts: n/a
Default

WELL go out and check right now!!! lol
Just kidding. ;-)

let us know what you find and take your time checking the timing belt.
later,
dave
(One out of many daves)

"dubljay" > wrote in message
news:1_588056_610d449ab147b0eddadf802893e59007@aut oforumz.com...
>I think you may be on to something with this. When I purchased the
> car I found a service manual (cover looks similar to that of a Bently)
> in the trunk. In the manual were print outs of another manual
> concerning the installation of a timing belt. These prints were in
> the same section in the maunal. I have a feeling that the timing belt
> was replaced. I didn't even think to check to see if it was installed
> correctly, I figured if I hadn't been the car wouldn't have run at
> all.



  #9  
Old May 27th 05, 04:35 AM
dubljay
external usenet poster
 
Posts: n/a
Default

"dave AKA vwdoc11" wrote:
> WELL go out and check right now!!! lol
> Just kidding. ;-)
>
> let us know what you find and take your time checking the
> timing belt.
> later,
> dave
> (One out of many daves)
>
> "dubljay" > wrote in message
> news:1_588056_610d449ab147b0eddadf802893e59007@aut oforumz.com...
> >I think you may be on to something with this. When I

> purchased the
> > car I found a service manual (cover looks similar to that of

> a Bently)
> > in the trunk. In the manual were print outs of another

> manual
> > concerning the installation of a timing belt. These prints

> were in
> > the same section in the maunal. I have a feeling that the

> timing belt
> > was replaced. I didn't even think to check to see if it was

> installed
> > correctly, I figured if I hadn't been the car wouldn't have

> run at
> > all.


OK, I really don’t know what to think now. I checked the timing
belt.. and it couldn’t be more perfectly alligned. So now that is
ruled out. I double checked the fault codes for the Digifant I
computer, (bridged the two connectors under the shift cover and check
engine light blinked for the codes). got 4 4 4 4, no fualts. When
poking around the distributor I broke the Hall sending unit... I
replaced the whole distributor with a used one, Hall sending unit and
all. Set the timing as per Bently. End result even less power. Now
the damn thing drives like the hand break is on. With the accelerator
to the floor in first gear I hit about 5500 rpm and about 25 mph.
When I let off the accelerator or down shift it sounds like it is
backfiring in the intake. There is no problem with starting, there
is an intermitent surging at idle, of about +/-300 RPM (which was also
a problem before replacing the distributor and hall sending unit).
What in the hell do I do now? The plugs, wires, rotor, cap all seem to
be fine... should I replace them anyway? Could the computer itself be
toast and still give no fault readings? Could there be bad wiring
between sensors and the computer allowing for a no fault reading? I
checked the torque on the knock sensor mounting bolt, and reset it to
13 ft-lbs. I have the sinking sus****ion that this is not the
original engine for the vehicle, I double checked to make sure that it
was indeed an RV engine, which it is. If it is not the original
engine would that cause a problem for the Digifant I computer? Is
there anyway to tell if the engine is indeed the original one or if it
is a replacement?

Thanks for the help

-Josh

--
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  #10  
Old May 27th 05, 03:09 PM
John
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Posts: n/a
Default

"dubljay" > wrote in message
news:1_591716_8f122c4dd3c83215a5cea085f04ed432@aut oforumz.com...
>
> OK, I really don't know what to think now. I checked the timing
> belt.. and it couldn't be more perfectly alligned. So now that is
> ruled out. I double checked the fault codes for the Digifant I
> computer, (bridged the two connectors under the shift cover and check
> engine light blinked for the codes). got 4 4 4 4, no fualts. When
> poking around the distributor I broke the Hall sending unit... I
> replaced the whole distributor with a used one, Hall sending unit and
> all. Set the timing as per Bently. End result even less power. Now
> the damn thing drives like the hand break is on. With the accelerator
> to the floor in first gear I hit about 5500 rpm and about 25 mph.
> When I let off the accelerator or down shift it sounds like it is
> backfiring in the intake. There is no problem with starting, there
> is an intermitent surging at idle, of about +/-300 RPM (which was also
> a problem before replacing the distributor and hall sending unit).
> What in the hell do I do now? The plugs, wires, rotor, cap all seem to
> be fine... should I replace them anyway? Could the computer itself be
> toast and still give no fault readings? Could there be bad wiring
> between sensors and the computer allowing for a no fault reading? I
> checked the torque on the knock sensor mounting bolt, and reset it to
> 13 ft-lbs. I have the sinking sus****ion that this is not the
> original engine for the vehicle, I double checked to make sure that it
> was indeed an RV engine, which it is. If it is not the original
> engine would that cause a problem for the Digifant I computer? Is
> there anyway to tell if the engine is indeed the original one or if it
> is a replacement?
>
> Thanks for the help
>
> -Josh
>
> --
> Posted using the http://www.autoforumz.com interface, at author's request
> Articles individually checked for conformance to usenet standards
> Topic URL:

http://www.autoforumz.com/Fiat-Tempr...ict119177.html
> Visit Topic URL to contact author (reg. req'd). Report abuse:

http://www.autoforumz.com/eform.php?p=591716

Could it be a blocked catalytic converter?
.... and wouldn't a 91 have Digifant II or is it a California car or
something?


 




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