911sc - Was running fine - now hesitation, small backfires, lumpy throttle.

[aib]

I have a problem and am in need of some advice and help.

I recently became the owner of a 1978 Porsche 911 SC. The car was originally sold in Germany and imported to the US in 1984.

Overall, the condition is good, but it is in need of some elbow greese and TLC. To that point, I have started working on cleaning up the exterior. Nothing too major, just some detailing steps to clean up the paint and exterior surfaces.

I drove the car a couple of weeks ago. It was running smoothly, with no problem starting, running, etc. As mentioned above, I recently started some exterior detailing work, and as part of the process, I sprayed some degreaser on the bottom of the engine to get rid of some of the years of road grime. I also shampoed the paint and rear wing with a strong automotive shampoo that was mixed to help remove the old wax. A good amount of soap and water entered the top of the engine compartment via the engine grate cover in the wing.

So, after I preformed the detail work, I took the car for a drive, and it was driving very differently. It started fine, but it felt like the engine was hesitating. It had a lumpy feeling in the power band, some small engine backfires, and an overall feeling of not running smoothly. It also felt underpowered and not "eager" like it usually does. Again, this was very different than how the car drove a short time ago.

After the drive, I checked the web for some thoughts on the problem. It looks like there are some postings that say chemicals that get onto the ignition coil can cause this type of problem. If possible, I was hoping to find out some thoughts on the subject. If you do think it is the coil, can you please advise of the steps I should take to address the problem? Thank you in advance for your help.

[slw911SC]

Always check, and maybe replace, the simple stuff first:

1. Plugs and distributor
2. Ignition wires and connections to plugs
3. Battery connections and grounding points
3. Fuel filter
4. Fuel pump

Then, go after the more complicated stuff:

1. Fuel distributor
2. Fuel accumulator
3. Warm up regulator
4. Vaccum leaks
5. Mass air flow sensor.

[Head416]

Sounds like a moisture problem. Same thing happens to my car after a wash if I'm not carefull. Drive it out. Take her for a nice long drive and see if it goes away.

[aib]

Thanks for the help guys. I appreciate the thoughts.......

[Head416]

Any change?

[aib]

Hi guys,

I drove the car last weekend.........after the water and car shampoo had a chance to dry out..........it was back to normal, so I think you were right....once the moisture problem was gone, the car drove fine.

Thanks again,

AIB

[Groesbeck Hurricane]

check your distributor cap for cracks. Check your wires for cracks. My '83 starts and runs well after a bath, no issues. Same for the very few times I have been caught in a rain storm.