Loss of power 91 jetta 8valve

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
 >> Stay informed about: Loss of power 91 jetta 8valve 

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<!-- ~MESSAGE_AFTER~ -->
 >> Stay informed about: Loss of power 91 jetta 8valve 

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


PS I found a page on Digifant computers http://www.members.tripod.com/~fuelie/whatis.htm
 >> Stay informed about: Loss of power 91 jetta 8valve 

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" <UseLinkToEmail.DeleteThis@AutoForumz.com> 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 <a style='text-decoration: underline;' href="http://www.autoforumz.com" target="_blank">http://www.autoforumz.com</a> interface, at author's request
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 >> Stay informed about: Loss of power 91 jetta 8valve 

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" <UseLinkToEmail.TakeThisOut@AutoForumz.com> 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-Loss-power-91-jetta-8valve-ftopict120690.html (http://www.autoforumz.com/Volkswagen-Loss-power-91-jetta-8valve-ftopic...0690.ht) > Visit Topic URL to contact author (reg. req'd). Report abuse: > http://www.autoforumz.com/eform.php?p=587716</font>

 >> Stay informed about: Loss of power 91 jetta 8valve 

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" <DoNotEmail.RemoveThis@AutoForumz.com> wrote in message
news:1_588056_610d449ab147b0eddadf802893e59007@autoforumz.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.<!-- ~MESSAGE_AFTER~ -->
 >> Stay informed about: Loss of power 91 jetta 8valve 

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 suspission 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
 >> Stay informed about: Loss of power 91 jetta 8valve 

"dubljay" <UseLinkToEmail.RemoveThis@AutoForumz.com> wrote in message
news:1_591716_8f122c4dd3c83215a5cea085f04ed432@autoforumz.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 suspission 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 <a style='text-decoration: underline;' href="http://www.autoforumz.com" target="_blank">http://www.autoforumz.com</a> interface, at author's request
 > Articles individually checked for conformance to usenet standards
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Could it be a blocked catalytic converter?
.... and wouldn't a 91 have Digifant II or is it a California car or
something?<!-- ~MESSAGE_AFTER~ -->
 >> Stay informed about: Loss of power 91 jetta 8valve 

how did you set the ignition timing?
did you check the ign advance which should check the knock sensor operation
too?
did you check the fuel pressure regulator since it may be allowing fuel into
the intake manifold?
Did you check the air flow box?
Are you sure you have the firing order correct on the distributor?
You also need to check the TDC mark on the flywheel with the position of the
#1 piston!

Time to check the wiring and sensors going to the ECM at the ECM's plug!

good luck,
dave
(One out of many daves)
 >> Stay informed about: Loss of power 91 jetta 8valve 

"dave AKA vwdoc1" <vwdoc1.DeleteThis@ameritech.net> writes:
 >"dubljay" <UseLinkToEmail.DeleteThis@AutoForumz.com> wrote:
  >>I have a 1991 Jetta gl, 1.8L 8valve, with about 184k miles.

  >> 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.

Maybe the previous owner also had some work done on the camshaft or
head.

Make sure that the cam sprocket is the right way around. If timing
appears to correctly set up according to Bentley, yet has poor power
until you get to almost 5000 rpm, then the sprocket is probably
reversed so the wrong marks line up resulting in cam timing being
retarded by some 30 degrees.

Check the sprocket orientation to make sure it's not on back to
front -- or inside-out -- whichever way you think of it.

Another "quick" check is to check the cam lobe positions. At TDC on
cylinder 1, a straight-edge placed diagonally across the lobes
should be parallel to the top of the head.

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

Digifant has a habit of doing that!

 >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?
--
/"\ 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!<!-- ~MESSAGE_AFTER~ -->
 >> Stay informed about: Loss of power 91 jetta 8valve 

OK I am pretty sure that it is not an ignition problem. I know that the fuel pumps (both) are good, as is the relay, and the pressure regulator. I've tested a few sensors using an ohm meter and the Bently, and come up negative. I think the ECU is dead. I have doubts that it is even the original ECU. So I think the problem lies within the ECU. There is an '87 jetta GL with Digifant 1 in it, will that ECU work or do I have to get one out of a '91? Also I can't seem to find an EGR valve anywhere, and the part of the EGR that is supposed to be plugged into the cad. converter is no there... the hole is just plugged, no sensor or wires coming from it. Could this be part of the problem?
 >> Stay informed about: Loss of power 91 jetta 8valve 

You will need to make sure the ECM/ECU numbers are exactly alike. Just post
the numbers you find on yours here too.

I doubt if it is the ECM but it might be. I think I have replaced one
Digifant II ECM where the vehicle did not start at all. I am not sure why
this one went bad, but all has been well for years.
Did you test all sensors/switches at the ECM harness plug? Very important
to check those grounding wires!!!!

Are you sure you have an exhaust that is not clogged? Check the vacuum with
a gauge during different engine loads (idling, part throttle, full throttle
and deceleration). Post results!

Are you sure you checked the ignition very carefully while checking the
spark advance? That will tell you if the knock sensor is working correctly.
If it is not working correctly then you will have a loss of power while
accelerating.

Not sure if your CA equipped Jetta has an EGR valve. Maybe that is a test
pipe you are looking at. If it has a rubber cover over it's tip you can
remove it to see if the exhaust comes out of it slowly or almost like a
tailpipe. (Another test for restrictive exhaust)

Time to think about taking this Jetta over to a good VW shop so you don't
spend unnecessary $$$.

JMHO
dave
(One out of many daves)

"dubljay" <DoNotEmail.DeleteThis@AutoForumz.com> wrote in message
snip
 > OK I am pretty sure that it is not an ignition problem. I know that
 > the fuel pumps (both) are good, as is the relay, and the pressure
 > regulator. I've tested a few sensors using an ohm meter and the
 > Bently, and come up negative. I think the ECU is dead. I have doubts
 > that it is even the original ECU. So I think the problem lies within
 > the ECU. There is an '87 jetta GL with Digifant 1 in it, will that
 > ECU work or do I have to get one out of a '91? Also I can't seem to
 > find an EGR valve anywhere, and the part of the EGR that is supposed
 > to be plugged into the cad. converter is no there... the hole is just
 > plugged, no sensor or wires coming from it. Could this be part of the
 > problem?<!-- ~MESSAGE_AFTER~ -->
 >> Stay informed about: Loss of power 91 jetta 8valve 

Acutally I have given up. I was right they have replaced the engine, and in doing so they have cliped wires and connectors off leaving me no way to tell what is what. Anyone want a 91 jetta parts car? I would take it to a shop however there isn't a mechanic within 100 miles that i would trust to work on a VW.
 >> Stay informed about: Loss of power 91 jetta 8valve