engine won't rev over 2000 RPM (thanks)

Wed Feb 6 10:06:43 EST 2002

Hi Bob,

We have already been there. The car has a new idle switch. I also forgot
  the possibility of the

- cat itself could be plugged.

Bob wrote:

> Try disconnecting your idle switch, if its shorted, this is what you would see.
> Bob
>
> Zsolt wrote:
>
>
>>*This message was transferred with a trial version of CommuniGate(tm) Pro*
>>Hi Martin,
>>
>>It is no coincidence. It makes it up to 2000 load or no load, but
>>sometimes even before it gets there it starts bucking. I can set the
>>cruise at 2000 though and sail quite smoothly with only occasional
>>jerking. If I step on the gas however, it looses all power, it does not
>>stall, but it kills all power. Weird!
>>
>>So far I was told it could be
>>
>>- oxygen sensor
>>- mass air flow sensor (MAF)
>>- fuel filter/plugged fuel line
>>- fuel pump
>>- wiring connections
>>- speed sending unit/missing teeth on flywheel
>>
>>Zsolt
>>
>>Martin Pajak wrote:
>>
>>
>>>Don't know, coincidence?
>>>If the speed sensor was faulty most likely the engine would not even start.
>>>If it fails at high rpm possibly wiring or mounting.  However does it
>>>consistently fail at 2000 rpm?
>>>Does not make much sense, than again it's an Audi ;o)
>>>
>>>Hope this helps.
>>>
>>>Cheers
>>>Martin
>>>
>>>
>>>
>>>>-----Original Message-----
>>>>From: Zsolt [mailto:zed123 at telusplanet.net]
>>>>Sent: February 5, 2002 10:47 PM
>>>>To: Martin Pajak
>>>>Subject: Re: engine won't rev over 2000 RPM (thanks)
>>>>
>>>>
>>>>Thanks Martin. That's an interesting one. But why would it cause to give
>>>> me a speed sensor error?
>>>>
>>>>Zsolt
>>>>
>>>>Martin Pajak wrote:
>>>>
>>>>
>>>>
>>>>>Try your catalytic.
>>>>>If it's pluged it would prevent the engine from reving up.
>>>>>I used to work at a place that had a Ford Ranger in.
>>>>>The thing would not rev past 2500rpm.
>>>>>Any attempt would see it rev-limited.
>>>>>After half an hour of floorin' someone smeled burning.
>>>>>It was the exhaust before the cat, cherry red hot.
>>>>>Very impressive.
>>>>>
>>>>>Onece a cat goes, it cloggs pretty quickly.
>>>>>
>>>>>Cheers
>>>>>Martin Pajak
>>>>>
>>>>>http://www.quattro.ca
>>>>>
>>>>>1983 Audi Ur-quattro (265,000 km) Winter car
>>>>>1985 Audi Ur-quattro (141,000 km) Euro spec. import ;o)
>>>>>1986 Audi 4000 S Quattro (442,000 km) with 5 bolt pattern RIP
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>>-----Original Message-----
>>>>>>From: quattro-admin at audifans.com [mailto:quattro-admin at audifans.com]On
>>>>>>Behalf Of Zsolt
>>>>>>Sent: February 5, 2002 9:47 PM
>>>>>>To: quattro at audifans.com
>>>>>>Cc: V8
>>>>>>Subject: engine won't rev over 2000 RPM (thanks)
>>>>>>
>>>>>>
>>>>>>Thanks for all your responses.
>>>>>>
>>>>>>We haven't done anything yet, I wanted to see the responses first in
>>>>>>case somebody had to deal with a similar problem. I hope we can sort it
>>>>>>out soon.
>>>>>>
>>>>>>Zsolt
>>>>>>
>>>>>>
>>>>>>
>>>>>>dsaad at icehouse.net wrote:
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>>This is a problem no matter what kind of car you have. I
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>scrounge up connectors
>>>>>>
>>>>>>
>>>>>>
>>>>>>>of all sizes at the junk yard. For the 2 and 3 wire varieties
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>you have some
>>>>>>
>>>>>>
>>>>>>
>>>>>>>choices. For the bigger stuff like the MAF I would suggest
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>making individual
>>>>>>
>>>>>>
>>>>>>
>>>>>>>jumper wires using the contacts from old connectors. You end up
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>with a sort of
>>>>>>
>>>>>>
>>>>>>
>>>>>>>universal breakout box. Fortunately most of the Audi/VW
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>contacts are the same.
>>>>>>
>>>>>>
>>>>>>
>>>>>>>Only the number and housing shape change.
>>>>>>>If you can access the back of the connector (on the MAF this is
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>possible) you
>>>>>>
>>>>>>
>>>>>>
>>>>>>>can just pull back the boot and probe the backside of the
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>contacts directly.
>>>>>>
>>>>>>
>>>>>>
>>>>>>>You really have to be careful whenever playing with connectors
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>to not damage
>>>>>>
>>>>>>
>>>>>>
>>>>>>>the contacts with your meter probe or whatever. This is a well
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>known and common
>>>>>>
>>>>>>
>>>>>>
>>>>>>>cause of future problems.
>>>>>>>For hard to reach connectors I often can just use a length of
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>wire stuffed into
>>>>>>
>>>>>>
>>>>>>
>>>>>>>the interesting contact cavity and taped onto the wire harness.
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>It aint pretty
>>>>>>
>>>>>>
>>>>>>
>>>>>>>or fast  but it is effective and cheap.
>>>>>>>btw, the manual gives a fair amount of detail for checking the MAF. I
>>>>>>>discovered that it is also electrically quite similar to other
>>>>>>>
>>>>>>>
>>>>Bosch MAF
>>>>
>>>>
>>>>>>>sensors so any testing methods for them would probably apply.
>>>>>>>There are pinout differences though.
>>>>>>>When I wanted to check mine out, I made a test harness from a
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>junk connector,
>>>>>>
>>>>>>
>>>>>>
>>>>>>>and had another Bosch MAF (actually from a Mazda!) and just
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>compared readings
>>>>>>
>>>>>>
>>>>>>
>>>>>>>while blasting them with my shop-vac. They both responded the
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>same way so I
>>>>>>
>>>>>>
>>>>>>
>>>>>>>concluded mine was OK.
>>>>>>>
>>>>>>>The timing senders are just inductors (coil of wire) so off the
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>car a good test
>>>>>>
>>>>>>
>>>>>>
>>>>>>>would be to measure resistance while heating it up with a hot
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>air gun. If it
>>>>>>
>>>>>>
>>>>>>
>>>>>>>opens up it is bad. On the car try an AC measurement across the
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>terminals. The
>>>>>>
>>>>>>
>>>>>>
>>>>>>>voltage should vary with speed. If you have an o-scope you
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>should see a sort of
>>>>>>
>>>>>>
>>>>>>
>>>>>>>sine wave that changes frequency and amplitude with speed.
>>>>>>>btw, the anti-lock senders work the same way.
>>>>>>>
>>>>>>>Dave
>>>>>>>
>>>>>>>
>>>>>>>Quoting "Buchholz, Steven" <Steven.Buchholz at kla-tencor.com>:
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>>... seems to me this is easier said than done!  It so happens I was
>>>>>>>>looking
>>>>>>>>at the same signals on my urq yesterday ... I want to build a
>>>>>>>>"stimulator"
>>>>>>>>so I can test the MAC-xx boxes off line.  What I ended up doing was to
>>>>>>>>open
>>>>>>>>up the ECU and probe the signals inside it to see what they
>>>>>>>>
>>>>>>>>
>>>>looked like.
>>>>
>>>>
>>>>>>>>This is not the sort of thing I'd recommend that the normal
>>>>>>>>
>>>>>>>>
>>>>"shade tree"
>>>>
>>>>
>>>>>>>>V8
>>>>>>>>mechanic try ...
>>>>>>>>
>>>>>>>>BTW, I do plan to test the sensors I pulled from my V8 *somehow* ...
>>>>>>>>actually I'm contemplating comparing the sensor iteslf to the part on
>>>>>>>>the
>>>>>>>>ury, and may well simply install one of the sensors from my
>>>>>>>>
>>>>>>>>
>>>>V8 onto the
>>>>
>>>>
>>>>>>>>urq
>>>>>>>>and scope the signal out to see what characteristic failed.
>>>>>>>>
>>>>>>>>
>>>>Given these
>>>>
>>>>
>>>>>>>>things are not cheap I may see if there is some way that I
>>>>>>>>
>>>>>>>>
>>>>might be able
>>>>
>>>>
>>>>>>>>to
>>>>>>>>make something that would allow an otherwise "bad" sensor to
>>>>>>>>
>>>>>>>>
>>>>be made to
>>>>
>>>>
>>>>>>>>work
>>>>>>>>again ...
>>>>>>>>
>>>>>>>>Steve Buchholz
>>>>>>>>San Jose, CA (USA)
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>>Look at the timing and reference sender signals with an
>>>>>>>>>oscilloscope. If there is a problem you should see it this way.
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
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>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>_______________________________________________
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>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>
>>>
>
>