1pcarnut

That's great news, glad you got it fixed! I agree with the "parts hanger' analogy. I've seen so many instances of throwing parts at a problem. My rule of thumb is alway go to the basics. Start simplest first, work your way to the complex.

TMc993

While there may be "...waaay to many variables..." there aren't that many likely variables. It really comes down to three classes of variables: Fuel, air and spark.

The variables mentioned in the thread are:

Fuel= Fuel pump, fuel pump valving, injectors, throttle position sensor, and the gasoline itself.

Air= Air filter and mass air-flow sensor

Spark= Plugs, plug wires, dirtributor caps, and belt.

An added complication is the DME relay which could affect any or any combination of the three.

That's a total of 12 likely variables and some of them are more likely than others.

Actually, the OP didn't start with the easiest one...When he posted the first time, he had already checked the distributor functioning and replaced the DME relay (Logical choices, just not the easiest). If I remember correctly, he also tried a couple of other things before going to the MAFS...Which only points out the potential usefulness of a sequential task analysis (Do A...Yes?...No?...If "Yes" do B...If "No" do C, etc.)

Finally, it is because the factory manual doesn't contain stuff like "clean the MAFS" that our developing these types of sequences would be helpful. Factory manuals don't come close to the collective knowledge of the folks on this list with regard to the type of problems and failures seen in the cars over the past 12 years.

In the end, this really doesn't matter...It was just a suggestion.

Terry

flatsixforme

That's great!

When I first read this post I immediately thought of the time a fellow rennlister and I replaced our SAI valves (always keep track of that little pigtail hose in the back!) and when putting everything back together the MAF was put in backwards on his car. Upon startup the engine popped, spit, etc...it sounded cool and smelled great too (very rich mixture). The immediate thought was too much fuel which led us to flipping the MAF. I should have offered this as a possibility early on but I'm not too savvy on 993 mechanics so I figured it must be something else. I laughed when I read that this was the problem!

Have fun driving

TheOtherEric

Terry, yes I agree your suggestion is a good one. It just strikes me as hard to do, but I could be wrong. Maybe the best place to start would be to identify all of the things that can/do go wrong then identify the symptoms.

And indeed, this exercise would surely identify a LOT of things that the workshop manuals neglected. Six that come to mind are: MAF dirty, ISV dirty, collapsed lifters, clogged cats, improperly set timing, collapsed vacuum lines.

geolab

Hello Terry:

Your idea has been "suggested" by Porsche and this is the way they proceed to fixing cars.
Believe it or not, this is the way they instruct their mechanics to repair.
I do have those instructions.
But all those proceedures are in majority electronic dependent.
To be able to abide by their workaround, you have to have a PST2, not to mention special porsche tools, and especially, it's electronic tentacles. An example in the link:

http://www.pcarworkshop.com/images/d...4_-_p1126_.pdf

But this is where rennlist is an addiction.
Its a turn-around to these fly-by-wire proceedures, pointing out how we perceive the 993 as a mechanical achievement and not a perishable consumer product

TheOtherEric, I chose the link above because it has slightly better details for your 'Pressure testing intake system' thread earlier
best regards

geolab

So it was fuel after all.
Midnite said fuel hose was badly twisted @ pump

https://rennlist.com/forums/993-forum/424594-my-problem-is-back-again-not-the-maf-bad-new-fuel-pump.html