Troubleshooting

[Grant Lenahan]

very good point. O2 sensor is out of the loop when cold.

Grant

On Jan 8, 2011, at 5:19 PM, Ben Swann wrote:

> The reason I asked about the warmup is I have had several that basically started up -
> VROOM and ran fine a few minutes into warmup.  Then shortly into the drive or idling,
> the car would start running like crap and stalling out.  Took me awhile to figure it out
> then, but now is one thing I'd check right away, especicially if I did not just replace
> it.  If the car starts OK but runs like crap when it goes into closed loop operation,
> then disconnect the oxygen sensor and see if it runs better.  
> 
> I've had bad O2 sensors make the car sound like it was going to throw a rod or like the
> the lifters were all collapsed.  Makes the engine run so bad like there is a totally
> different problem and you end up chasing tail checking compression, replacing lifters -
> all of course after replacing vacuum lines, messing with timing, etc.
> 
> Let us know what you find.
> 
> Ben
> 
>  _____  
> 
> From: Ben Swann [mailto:benswann at verizon.net] 
> Sent: Saturday, January 08, 2011 5:02 PM
> To: 'Vincent Gelinas'; 'quattro at audifans.com'
> Subject: RE: Troubleshooting
> 
> 
> Bad fuel?  Lifters?
> 
> Does it start and run OK when cold and begins to run crappy after warmup?
> 
> Ben
> 
>  _____  
> 
> From: Vincent Gelinas [mailto:vrgelinas at gmail.com] 
> Sent: Saturday, January 08, 2011 4:49 PM
> To: Ben Swann; quattro at audifans.com
> Subject: Re: Troubleshooting
> 
> 
> 
> Okay to recap I have replaced - battery, coil, cap, rotor, plugs, wires, fuel filter,
> and fuel pump. I drove it around for a while just waiting for it to cool down so I could
> restart when it stalled (under any sort of moderate load, even while revving hard in
> neutral). My water temp gauge never worked but my oil temp will go up to the first hash
> mark above the bottom number (60c?). Now when I go to start, it will crank and then
> sound like a cold diesel. Tick. Tick. Tick. Firing but slowly and not on all cylinders.
> Are our cars particularly sensitive to low/bad fuel? I can take vids and post them on
> youtube or something. Would that help?
> 
> On Jan 8, 2011 4:36 PM, "Ben Swann" <benswann at verizon.net> wrote:
>> 
>> Vincent,
>> 
>> You might want to recap what you have done and what overall symptoms you are having. 
>> 
>> Some things to try/confirm..sometimes a little starting fluid directed into the intake
>> manifold can reveal if there is or not spark. You might need to remove a vaccume cap
> to
>> spray in there, and I think there is a vaccuum port on the side of the throttle body -
>> use the one inside the throttle - closer to the cylinders.
>> 
>> Remember the fuel pump is ignition primary triggered. You can try to jumper fuel pump
>> hot and prime the injectors by lifting the air fuel plate up - either with 3mm allen
>> wrench inserted in the adjustment hole, or remove filterbox and lift plate up by hand.
>> When pump is running, you should hear a sqeal as fuel goes through injectors. Don't
>> overdo it as you will flood the engine. If there is resistance on lifting the plate,
>> then you may have clogged differential pressure regulator.
>> 
>> You should be able to verify spark - crank with primary coil lead connected to plug
> and
>> ground metal casing - I use a large alligator clip, but somehow connect the spark plug
>> to ground. You should see good healthy spark. If so then see if spark is making it
>> through wires to the plugs - could just be a bad cap or rotor.
>> 
>> Compression would need to be very bad or almost non-existant if there is no running at
>> all. That would be a broken timing belt or slipped crank pully - not usual.
>> 
>> You can revise what you said to be - air, fuel, spark, compression -all in the correct
>> amount at the proper time. Then the engine will run correctly.
>> 
>> This engine is picky about having intake fully sealed in order to draw in air and lift
>> the plate while cranking.
> <snip> > Some troubleshooting tips here: http://www.gtquattro.com/FAQ.html
>> 
>> 
>> [Date: Sat, 8 Jan 2011 13:07:28 -0500
>> From: Vincent Gelinas <vrgelinas at gmail.com>
>> Subject: Troubleshooting
>> To: "quattro at audifans.com" <quattro at audifans.com>
>> Message-ID:
>> <AANLkTimk8Y3iKs7jvVVgc4ULD4EtAkNnyRqQbnZ53DgM at mail.gmail.com>
>> Content-Type: text/plain; charset=ISO-8859-1
>> 
>> Okay so I know the four things that an engine needs are fuel, air, spark,
>> and compression. Engine is NG in 1989 90q. I know I am getting fuel and
>> air.
> <snip> 
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Grant Lenahan
glenahan at vfemail.net