I noticed today that I have a slight hesitation at 4500 RPM when my car kicked down into second gear on acceleration on the freeway. I'm not sure if that could be related to the fact that I haven't done spark plugs in about 7,000 miles. I'm currently running Bosch Platinum 4's in there.

I know the flappy also opens up at 4,000. It's strange though. I can feel full response at WOT, but only a slight hesitation on kickdown at 4500 only. Thoughts are more than welcome on this issue so I can see if I can get her fixed this coming up weekend. Thanks.

 

oh and it's an '87 S4 car btw!

 

Your flappy closes again around there IIRC. So ... is the plate sticking, or is there a flappy issue?

 

I think the flappy close point is around 5300 or so?...

Later,
Tom
89GT

 

I have never had trouble with it sticking before. On a side note, the car does have a fairly rough idle up until it reaches operating temperature. It feels like it's missing sometimes. I'm going to do the plugs and see if that changes anything.

Tony has a good write up on checking the flappy valve. I will try that this weekend and get back to you guys on whether or not the flappy is the case. If it does close at 5300 RPM, I must not be having problems with it. I think???

 

HELP!

Big Time Surge this time at 4500 RPM. Violent enough to feel like the car stopped dead at 4500 RPM. Flappy is opening alright. Still intermittent. The second and third WOT downshifts accelerated fine. Is this ignition related or could this be an auto transmission issue...the car shifts fine BTW.

If Ignition/Fuel, I have replaced:

-Fuel Pressure Reglator
-Spark Plugs
-Ignition Wires
-Fuel Pump Check Valve
-TPS
-Intake Manifold Vacuum Lines
-Flappy Solenoid
-BRAND NEW INJECTORS
-Idle Stabilizer Valve
-MAF
-Oxygen Sensor 10,000 miles ago
-Fuel Filter


I don't know what else it could be. Again my crank sensor is old, it has a hard time starting every now and then, and I don't remember when the coils were ever changed as the look original.