dbf73

Last week my car started having the odd hiccup (picture a momentary ignition switchoff) while driving down the road. Happens once or twice per 100 miles and at both constant speed and under acceleration. Of course my first thought was DME relay but replacing that made no difference. No CEL. Plan to replace (overdue) the fuel filter this weekend but are there any other obvious culprits to check? Car has 98K and other than the fuel filter, all maintenance is up to date. Otherwise, car runs strong.

OverBoosted28

Being that it's momentary, and no cel, I would start at all battery/ground connections. From there, it's a hunt to eliminate possible causes. Good luck.

Quadcammer

I agree, make sure the battery cables are well connected.

LexVan

Well, the "new" DME relay could also be bad. What is the part number? Porsche relay or aftermarket?

MAF sensor good?
You say all maintenance is up to date, and this includes plugs and plug wires? How old are both?
Could be the start of a failed/failing fuel pump. Is the fuel pump more noisy than you remember from the past?

Using a new gas station?

Are you sure your CEL works? Do you have a code reader? Maybe there are codes there.

Made me think of this old post:

https://rennlist.com/forums/993-foru...incinatti.html

911PERVY

Tray yet another DME, exact same thing happened to me last month, the relay was about a year old. See how hot it gets after an hour or so and you can understand why they fail!

Battery cables need to be really tight too

rinlv1

Mine had the same problem which turned out to be MAF sensor.

good luck.

carguy19

Plugs, wires, distributor cap and rotor.... all maintenance items to be sure. Then you know everything is in tip top shape and it's really not wasting money.

ACEparts_com

Change the flywheel sensor. When on the way out my car had all sorts of random stalling, non starting issues, much like DME relay failure.

WhiteCab

Had similar problem. It was the temp sensor on head

Vince964T

Had similar issue but only at max boost, was a wire to one of the plugs

ACEparts_com

OK, do what I did in the end; just change everything back there! If you buy Bosch parts from sources other than Porsche the total cost isn't that great.

dbf73

I even have the most expensive of said bits (the MAF sensor) on the shelf having found a bargain on one several years ago. It has been a bit better lately so I have not been compelled to dive in just yet. All advice appreciated. Will report back when I do dig in and resolve

carguy19

You may want to get the car looked at and data logged or dyno'd. If the car is detonating, you can blow a head gasket or blow the motor up. Its hard to hear these cars ping over the fan and exhaust.

PiB993

On these early OBDII cars I forget what all information is provided but couldn't you just plug in a simple reader and see if any information is missing? This might help you see if any sensor is malfunctioning. The only issue is the modern cars have way more sensors then our cars provided back then and the reader would have a blank for those.

Not sure if that would help so I am just enquiring if that would be a reasonable way to start. I use something called 'U-Scan' and it's probably not the best but it has helped me with readiness codes.