[V8] Rough Engine

Ed Kellock ekellock at gmail.com
Wed Aug 27 13:09:49 PDT 2008

Oxygen sensor is my first thought.  Then breather hoses leaking.

Then engine temp sounds normal.  Could it be that your memory of 1/4 mark on
the gauge was during the winter?

If you are indeed seeing higher engine temps now, I think that is compatible
with vacuum leaks as the engine may tend to run lean and therefore hotter.
Ditto the OXS if it's leaning the engine out too much.

Plugged catalytic converter(s)?


> -----Original Message-----
> From: v8-bounces at audifans.com 
> [mailto:v8-bounces at audifans.com] On Behalf Of Brad Hartman
> Sent: Wednesday, August 27, 2008 12:39 PM
> To: v8 at audifans.com
> Subject: [V8] Rough Engine
> My 1990 V8 runs fine when cold, but after warming up, the car 
> runs rough.
> By rough, what I mean is when I accelerate, the engine seems 
> to stutter. 
> The car still speeds up, but you can detect a rough accel profile.
> Also, when idling, it seems to lose RPMs just for a fraction 
> of a second, 
> them resume normal idle, and repeats this every few seconds.
> Once the car is cooled down, and I restart, all is well, both 
> during idle 
> and full speed.  But when it gets hot, it returns to rough operation.
> No Check Engine Light is on.
> My engine temp gauge seems to peak out at around 95 degrees C.
> Air filter is pretty new and not full of dust.
> I have noticed this for about the last 3-4 weeks.  I have changed gas 
> several times from diff sources, so i don't think it's gas.
> My first question:  Should the engine temp gauge almost reach 
> 100 degrees C 
> (red needle is almost at 12:00 O'clock)?
> It seems in the past, the hottest it would get is around 1/4 
> of the gauge 
> reading, or around 50 degrees C.
> Bad thermostat?
> Second question:  Any places I should check first for source of rough 
> engine?
> 198,000 miles on engine.
> Thanks,
> Brad
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