[V8] Starting Problems

[kyle leatherwood]

If I had to bet, I'd say start with the temp sensor and then the fuel 
pressure regulator.  Engine ECU gets it's inital fueling data from the 
engine speed sensor (crank sensor) and the coolant temperature sensor.  Once 
the coolant temperature gets to a certain point (where the ECU does not feel 
like the engine has to run in a choked state), it then passes fueling 
richness/leanness over to the Oxygen sensor.  From that point on the 
richness/ leanness of the fueling is determined from the data the ECU is 
reading from the O2 sensor.

Hope it helps a little.

Kyle L.

1991 V8Q 5speed
1990 V8Q autobox
1985 Jaguar XJS V12
1981 BMW 635 Alpina (greymarket)
1974 Porsche 911
1971 MG Midget
1969 MGB


>From: "Buchholz, Steven" <Steven.Buchholz at kla-tencor.com>
>To: <v8 at audifans.com>
>Subject: [V8] Starting Problems
>Date: Wed, 25 Jan 2006 15:35:27 -0800
>
>I spoke to a gentleman yesterday who owns a 1990 V8 that is languishing in 
>a service shop in San Francisco.  He had problems with the exhaust smoking, 
>which ended up being related to a scored cylinder (!).  The car has a 
>replacement engine installed and the smoking issue is resolved.  He is 
>still seeing excessive cranking times when starting cold.  The ECU is not 
>logging any trouble codes at this point.
>
>The shop is reporting that the fuel pressure is excessive (~90PSI), and the 
>tech is not able to get the pressure down.  The pump was tested, some level 
>of testing of the fuel pressure regulator was done (although I don't know 
>for sure that the FPR was replaced), and the return system was even checked 
>for blockage (!!!).  Has anyone ever checked the fuel pressure on their 
>car?  While that is a well known troubleshooting item for me on CIS cars, 
>I've never felt a need to check either of my V8s.  I do suspect that as the 
>FPR ages the pressure increases, as this would lead to the rich situation 
>that I associate with a FPR that needs to be replaced.
>
>At one point he mentioned that the spark plugs appeared to be wet with 
>fuel, and I shared with him that there were some on this list who had 
>troubles with the factory specified spark plugs.  I did not remember what 
>the general best recommendation was.  I did tell him that I personally have 
>not had a problem with the factory quad ground $15 each units.  I also 
>questioned whether or not he had replaced distributor caps and rotors ... 
>or ignition wires.  He was not aware of any changes there.
>
>I thought I'd post the situation here to see if there were any other 
>suggestions for fixes on excessive cold cranking situations.  Feel free to 
>respond to me or to post back to the list and I'll pass along the feedback 
>... perhaps we can marshal a new V8 owner to join our group!
>
>Thanks!
>Steve B
>San José, CA (USA)
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