Bogging Issues

EJZero1 · 11-04-2009, 05:37 PM

Greetings all, and TIA for listening.

Car: '89 N/A 944

Symptom(s): Car bogs on initial acceleration.

More when cold than any other time, and even then inconsistently. Upon initial acceleration (low rpm, heavy engine load) car will bog down irresponsive to accelerator position. If I push in the clutch and release the accelerator, the engine will just settle down to a normal idle. Occasionally, clutch work and "blipping" of the throttle will bring her back. Has never done it at cruise speed. Seems to only be a factor in 1st thru 3rd, perhaps because by then I'm no longer typically in "high load" acceleration?

First thoughts are vacuum leak or TPS, but that just after reading some previous posts of similar issues. (New and first time Porsche owner here.)

Inputs from those of you who have been there and done that are greatly appreciated.

Oh yeah... Just love this car! Why did I wait so long?!

Thanks much.
EJ

RichardE · RichardE's Garage

I am no mechanic EJ but given the lack of response I will give you my two pennies worth. It sounds to me like a fuel feed problem. Like when you are drawing max fuel under acceleration sufficient fuel flow is not getting through. Fuel filter?, strainer? Possibly?
Good luck anyway, hope you get it sorted.

Lapponia · 11-05-2009, 01:40 AM

++1 RichardE. I myself would add the AFM potentiometer may have a flat spot in that area of rpm.
It is quite easy to check and adjust reading ClarksGarage and FrWilks. Good Luck!
___________________________
Lapponia

rickharrison · 11-05-2009, 07:02 AM

Do the AFM clean project...search it out...the contacts wear down on the strip, and you get hesitation. kinda like your power window switches, really.

EJZero1 · 11-08-2009, 02:48 PM

Update, for what it's worth..

Fuel filter changed, and the issue persists.

In having a look around under the hood, I came across a very loose vacuum hose that actually disconnected as I touched it. Firmly reattached it and took it for a ride where I tried like crazy to duplicate the bogging to no avail. I know I should be thrilled, but I'm a pessimist. Sure I couldn't make it happen in the 45 minutes I was out with it, but I'd bet just about anything that within 5 minutes of leaving the garage for work in the morning it'll happen. Will post with great frustration when it does.