VehiGAZ

You speak to soon.... BWA-HAH-HAH-HAH!!!

Now just how do you think you can say "most" when you don't know the final total?

Good luck with the tests. My suggestion is to focus on the wiring in the engine bay.

VehiGAZ

If they look old... they probably are and causing you problems.

Don't give up on us after just two tests! Bring the data back to us here and we'll have you jump through some more hoops!

Mrmerlin

please follow the sequence in post #7 and report back ,
jumping all around may bypass the actual problem so you wont know what you fixed or covered up.

The 14 pin connector is under the hot post cover sitting just above the hot post stud. (disconnect the battery first)

Make sure to reclean the battery connections even though you may have examined them,
do all of the connections not just the ground strap.

Once again be methodical , Alan will tell you the same thing!

Oli928

Thanks a lot for the last two replies. I agree, the problem is probably under the hood, I think I would have to have a very large hole near the fuse/relay board for humidity to cause this issue overnight...at least trying the "under hood" suggestions should be first plan of attack. I did clean every connector at the battery with dremel tool/brush attachment, hand wire brush and contact cleaner. I also roughed up ground point on body with fine grit paper. I applied contact stuff on applicable connectors to ward off corrosion. I'm very, very certain I got this area eliminated.

Now that I know where the 14 pin connector is, it could be in the top 3-4 items to check. The hot post protective cover was laying in a nest of wires when I bought it. I didn't "engineer" a plastic nut to hold it in place until about two weeks ago. Anyone have a part number for this?...I couldn't easily find on a couple of "parts" sites.


Thanks for everyone's patience with a new 928 owner and forum user. LOL on the "give up too soon" comment...I guess my frustration is showing. I guess I'm still smarting on the no-start issue that took me two weeks to diagnose/fix...and it turned out to be something simple like a green wire to the fuel pump.

Since everyone has been such a great help, any ideas on what the *%$#@** this is?


I spent 3 hours scouring sites to figure out this piece (I thought it may be my problem originally) I even found a thread labeled "what is this under my hood" and that person had no idea. I did clean the connectors, put contact stuff on it, siliconed it from moisture and wire tied back the pieces until I find out what it is/what to order (the same part on the right side of the engine is fine). I probably should have just started another thread on this, right?...but may be related...who know.

Mrmerlin

that is a connector block for the right front
brake pad warning sensor
and the ABS sensor.
the connectors will over time start to crumble its best to not disturb them as the replacement parts are expensive

Oli928

You are awesome! I'll try to find that other site where the guy explains all the parts under the hood, but didn't know this one. I had a similar looking item on my old 944 that crumbled just by breathing on it (I think it had something to do with the crankshaft position sensor) and performed the similar "engineering" of delicately cleaning it, encasing it in silicone and letting it cure over the weekend before starting it. Now I know why I couldn't find out what this was so easily, I never thought it could be a brake related item.

Thanks to all the great input, I'm motivated again to tackle the sputter issue. I'm glad I took the time to start this thread...more important, thanks to all who contributed...your time is greatly appreciated. It may take me up to a week to try everything, I'll let you know progress. I have a good plan of attack now!...I didn't even notice the 14 pin connector until mentioned (I will check this asap) . My fingers are crossed it is a simple as bad coil/plug wire/s or a small crack in the distributor cap. Isn't Porsche ownership fun? It is all worth it though when everything runs correctly and you step on the pedal or take that corner.

Leon Speed

982.612.073.00

There are btw a handful of very good 928-specific vendors on this forum, they help us to keep our babies in good shape. Call them and they can help you when looking for parts.

LOL (sorry)



Not to take you off topic, but after you fix your current problem, there a some maintenance jobs you must do to keep your baby healthy:
- replace all flexible fuel lines in the engine bay
- check the crank play if yours in an automatic
- check the tension and condition of the timing belt

Fix this problem first, then do these items.

Oli928

Thank you Aryan for your non-topic input. I have not inspected the fuel lines, if they don't look/feel new, I'll replace them as you suggest (I'm sure you mentioned this because it is an issue with 928's).

I do have a receipt (and also confirmed by calling shop) for the timing belt. It was just replaced in December, along with the water pump...thanks for reminder.

The crank play is a topic I'm on the fence about. Some very good sources say if it hasn't happened yet (car has 105K miles, which I didn't mention on post) it is probably safe to ignore the crank plate tension thing. Other posts make me want to check it tonight! I talked to 2 different people at 2 different Porsche repair places and they said (off the record...to avoid legal stuff) that if it was their car (meaning mine specifically) they wouldn't bother with it. One tech has about 120 928's that they service on a regular basis and he only saw this issue on about 2 cars in 10 years (he said both were driven like they were stolen). I'm still open to opinions. I know the price to check this is less than an engine, but I'm not convinced yet. I mention all this not to diminish your input, but rather to get more detail why there is much debate on this...am I missing something? Is one guy correct to say that if it has not happened after 105K miles, I am probably safe? They want to charge 6-8 hours labor for this. I can fix a lot of other small stuff for the amount it will cost me to check the plate tension.

I'm sure everyone still has to work for a living, so thanks again for ALL the input. I will do my best to return the favor by replying to any threads I have personal experience with...928 or from my old 944 experience.

Oli928

FYI I found the link to: Under the hood, what is it?

http://members.rennlist.com/v1uhoh/underthe.htm

I'll let him know what #10 is.

Mrmerlin

OK to set the record straight about crank end play on an 1985 and newer 928 's '
This is an important inspection, if its an automatic this is as important as checking the timing belt tension.

Any other info that you hear is false.

Anyone that tells you different should not be considered to work on your car.

In other words you must check it ASAP, as your crank could be taking out the thrust bearing.
To check it remove the lower bell housing and the rear exhaust. remove the rear heat shields. then look at the front flex plate and see if it looks flat or bowed towards the engine the driveshaft will usually push the flex pate towards the engine if the clamps are loose. relieve the tension of the front clamp then pry the flywheel aft measure then pry forward and measure normal spec is from .004 to .012 in. with .016 in max . once you have your measurement , then go to the rear clamp just in front and on the bottom of transaxle to TT joint and see how much it takes to loosen the bolt, I will bet its just snug( = no good) remove the bolt and inspect the shank for damage, if so replace the bolt, or just install a new set of clamp bolts,
I will reuse a bolt if its in good condition as it has not been torqued to 66ft/lbs.
look at the driveshaft and input shaft coupler for the trans axle see if the slots line up if not use the front clamp to move the drive shaft by clamping the front bolt on and prying the shaft forwrads or back.
Put some blue loctite on the rear pinch bolt threads andf install it torque to 66ft/lbs. then pry the flywheel back then install the front bolt the same way as the rear. Install the bell housing and the rear heat shields and the exhaust

Landseer

Ditto on what Stan says, above.
Crank thrust bearing failure seems to be occuring at an increasing rate.
Cars are aging.
Shame that it hasn't been recognized widely and prevented long before this.

Oli928

Thanks for the input guys. I'll start saving my pennies for this and continue to drive the 928 "gently" until this inspection. Although I have faith in my local Porsche repair shop, their experience is mostly regional. I put a lot more weight on your worldwide knowledge and experience from hundreds (maybe thousands) of 928 owners. The part about "...increasing rate" especially hit home / I'm convinced.

It was raining last night, so I didn't work on the car, but I did remove the hot post cover to locate the 14 pin connector. Yep, it is in a horrible spot for moisture if the cover is off. I'll check that this weekend in detail, along with the other items. Is this connector responsible for power to the fuel pump in some way? If so, it may explain why I don't get fuel smell or popping in the pipes when the engine sputters (and I have pedal floored). Or, maybe a sensor tells fuel to shut off during the sputter? It'll be interesting to find out what the culprit is.

I'll also be replacing my aux cooling fan that went stiff a couple of weeks ago (fan came in yesterday).

Leon Speed

Btw checking crank end play is not a 6-8 hour job. Most of "us" can do this in 1 hour or less (first time maybe a bit more to remove the cats). There are good write ups on this board and with some tools you can do it yourself.

Oli928

I Found it !!!!! I found the culprit in my engine sputter which occurred anytime after washing the car, rain or even high overnight humidity.

This is the driver's side coil (this coil faces forward in the engine compartment). The other coil was fine (doesn't face forward...my theory as to why it wasn't attacked by the green monster). Even though I cleaned the coil with contact cleaner and a small wire brush on a dremel tool, I'm going to obviously replace these (21 years/105K miles is pretty good and time to retire). The cover on the coils looked fine BTW.

Below is the coil wire after about 3/4 of the green powder already fell out by just from removing it:

I have already ordered (hard to find / everyone wants you to buy a complete set of spark plug wires) new coil wires, a couple of days ago.

During the weekend, I also:
1) Cleaned the 14-pin connector above the hot post (even though it looked good) and put a tiny dab (using a toothpick) of dielectric material on the contacts.
2) I cleaned the contacts (very, very gently) inside each distributor cap during inspection...and rotor. All looked okay, but probably should replace along with plug wires in next 9 months to a year.
3) Removed the MAS and cleaned with MAS spray
4) Replaced my dead radiator fan
5) Cleaned the ground straps connected to the coil brackets
6) Put plug boot grease stuff (forgot name) on coil boots to ward off corrosion from water/humidity.
7) I also figured out why there was water one time in the air filter housing after cleaning the engine; the last person to mess with the air filter, put it in upside down and it wasn't sealing 100%.
8) Cleaned the wires connected to the hot post
9) I even found the hot post cover retainer, it was underneath in a mess of wires. I can't believe it didn't fall down during driving. The strap had a break...

WOW !!! After all the above (magically) the engine starts quicker, idles more smooth and quieter. Car launches with a lot more guts...and I have not even replaced the coil or coil wires, just cleaned the heck out of them. Replacing the one dead radiator fan also helped my a/c run just a tad cooler in this Texas heat.

THANKS TO ALL WHO CONTRIBUTED ideas/suggestions in this post. I am so happy it wasn't a really expensive fix. After 3 months of living with this, it is fixed. Yes I washed the car and drove it all the way to work and back with no problems. I even let the car sit a little while and misted the engine area and drove again... NO MORE SPUTTERING!

Yippee...several more issues taken care of.

~Oli~

FYI When removing the fan shroud assembly, I did have to remove the upper radiator hose and swing the power steering reservoir and still barely was able to squeeze it past the other lines in the radiator. I share my experience because some people did very little to remove the unit, others had to even remove some other cooling lines.

Marine Blue

When you cleaned the coil wires, did you check the insulation for cracking? Seems these are prone to cracking/breaking down over time and this would cause an engine mis with the right ambient conditions.