Engine issue
 

'99 boxster; 125k miles
Driving home on the interstate yesterday, I felt a rythmic deceleration...almost like I was tapping the brake, only it felt like the engine was pulling me back (similar to engine braking to control decent on a long hill). The rythm was about every 1-1.5 seconds. Rythm did not change as RPM channged, up or down. When I pulled off the road and let the car idle, the rpms would vary between 200 and 800...again, with a 1 second "rythm" to the variation. I was less than a mile from the house and made it home. No CEL. No fluid leaks. No noise (beyond the air intake matching the idle rythm). I didnt lose power and didnt feel like the car was struggling to drive. It never stalled. Thoughts on a potential cause? Am I safe to drive to the shop (10 miles; 4 Interstate)?

Thanks

original fuel pump ?

That or the filter would be my first guess too.

Yes, its the original fuel pump. Would I be risking any major damage by driving to the shop? Would like to avoid a tow if possible.

You can drive it.

Thanks for the info. Drove it to the shop. Ran fine/normal for the first 4-5 miles and then the issue began again. Shop agreed (wihtout initiation) that a fuel pump/relay could be the issue...cutting in/out causing the symptom I was describing. Will hear back in a day or so.

Thanks again

Luke

VDO fuel pump $216.95 Relay $18.69 relay location front fuse box. third row/third relay /Location 13

Shop Response
 

Well...I feel like an idiot. After taking the car to my local indp. shop, the diagnosis was a faulty A/C Compressor. The compressor was kicking on/off rapidly once the pressure built to a certain point and would cause the "surging" effect while driving. It started to cause the engine to stall while at idle while the mechanic was testing it. Shop quoted $1100 to replace the compressor...im thinking about DIY and will be waiting until the weather warms a bit. Anyone tried this particular job?

Driving the car (without the compressor and with the refrigerant removed) and it runs great once more...

Thanks for the helpful tips

Luke thanks for following up and lettting us know the cause (some posts leave us all hanging without an outcome!).

I have to say that the A/C was not one of my top five potential problems - learn something new here everyday.