88MB928

Hi guys,

So this might be something obvious (to you) but since most of us girls have no mechanical know-how I'm freaking out right now. My car is acting funny-I am going to describe it as best I can. I didn't use the search function because frankly I have no clue what keywords to use for this so please bear with me.

This is a 1988 auto with about 103k miles on it. As of yesterday the car started feeling funny as if it were losing power. It seems to be happening at all times but gets markedly worse when the car is stopped and the brake engaged. If the car is stopped but in Park then it is not bad (although still not normal) but if it is stopped and the brake pressed it starts sort of rattling and feels like its about to give out at any moment.

It is not overheating. The only thing I notice on the dash is the battery indicator gets really low. Since purchasing the car I had noticed the battery indicator seemed a bit low and it would get considerably lower when I first turned on the car and turned on the AC but would go back to its original position as soon as I hit the gas. This being my first 928 I didn't know if that was normal so I asked my mechanic about it and he tested the charging system and said everything seemed fine.

Before this problem started two other odd things started happening to the car which I'm not sure if related but will mention just in case. I noticed a knocking sound that occurs the first time I brake after turning the car on (?) And a few days before I tried turning the wipers off and they wouldn't turn off-they just kept wiping so I figured it was a bad relay and removed the relay until I ordered a new one. Other than this the car had been driving perfectly.

Anyone have any ideas?

Mrmerlin

the few things i would suggest first clean the ground strap connection in the hatch,
Look under the tool tray you will see a wingnut holding down a brass flat piece.
Also remove the spare tire and clean both of the battery terminals,
make sure to disconnect the ground side first then remove the Positive side ( positive terminal is closest to the front of the car)

Next under the hood look at both of the coil wires and see if they are rubbing on any metal parts, if they rub then they will chafe and eventually short out the ignition system .
After this visual inspection then remove each coil wire they are connected to each coil and then to the bottom of each distributor cap,
make sure the ends do not have any corrosion.

If you do find corroded connections you can use a tooth brush and somw elex spray cleaner to clean out the coil connection and the cap and the wire end.

Also look at the front corners of the engine next to the coils make sure that there is a thick black wire attached to the coil securing bolt and that it goes to the top corner of the engine ,and is secured to the engine, if you find a borken ground wire then you have t0o replace it.
Note both coils must be grounded to the engine so to tie the ignition systems together.

IF none of these things fix the problem the next time the car starts to run funny,
look under the center of the car and see if the cats are glowing,
if they are,
you should immediately shut the car off as it will possibly catch fire,
this would be an indication that fuel is being put into the engine and the plugs of one of the ignition systems are not firing , (Time for a tow truck, to the shop)

928mac

Well, to me the way you described it, it sounds like you have more then one problem. The first may be the brakes are sticking on and the second sounds like a common ground (wireing) problem.
You need one of the members in your area to stop over and give a second opinion.
Lets see if anyone answers from your area

michael j wright

I may be way off base here(probably am) but it sounds like a vacum leak to me. Check all the vacum hoses looking for cracks or loose conections, sometimes while the car is running you can hear them wistel- so listen carefully.-Mike

dcrasta

I will chime in.

When it 'seems like its dying and the volt meter reads low' is it cycling the idle (High , then low (almost stalling) then high again then low) 'Bouncing Idle' ?

If it is, that sounds strongly like a vacuum leak to me.

Sources of vacuum leaks.

-any vacuum hose under the intake
-MAS->Throttle body rubber boots
-Vacuum line to the trans modulator
-Bad Modulator

Being in florida im sure some of these brave and talented florida Rennlisters will come take a look for you..

Someone man up and go help out a fellow Pcar driver!

86'928S MeteorGrey

First the nice. All mentioned before are good to check. Also, there have been cases where the alternator actually makes a clunking sound on startup and goes away with warmup. Turning the headlights on will sometimes make the sound come back. If you are getting poor charge, and you battery is low, it could cause poor running issues. That said, check your power for +12 volts when running.

Now the damn scarry... You need to check your FLEXPLATE. Do a search for TBF here and follow the steps to check for flexplate tension first, then check endplay of your CRANK. I'll pray to the shark gods you have a simple vacuum or electrical problem.

blown 87

You really need to find some one who is familiar with 928's to look at it.

88MB928

dcrasta's description above is dead on-that's exactly what the
car is doing. If it is a vacuum leak is it safe to assume that I should not drive the car at all-not even to the mechanic's shop? He is about a 45 minute drive from me-think it's safe to drive it that far or should I have it towed?

Hopefully it is just a vacuum leak and not TBF. My flexplate has not been checked because as you can see from a previous post I had an issue with my mechanic not being familiar with the problem and even skeptical about the reality of TBF.

Mike Frye

Time for a new mechanic.

His beliefs do not affect the reality that a condition exists or whether or not your car is susceptible to it. That's like not going to a doctor because you're afraid of a bad prognosis.

Mrmerlin

you may get some assistance from a local southern florida ownwer.
What happened just before this running condition?
was the car washed ,
worked on,
battery run dead??

88MB928

Mike,

I hear ya. But I posted a thread asking for recommendations for another local mechanic back when I had the TBF issue with mine and got absolutely nothing at all...zero recs. Constantine (creator of the super clamp) was nice enough to call my mechanic and explain the TBF issue to him over the phone and he agreed to take a look next time I take my car in for service.

I can't believe my guy is the only wrench in south florida familiar with 928s though-there must be someone else out there but how to find them?! I learned of my current mechanic because he's the guy my car's PO uses.

88MB928

thanks Mrmerlin. none of those things happened just before the condition started. everything was fine except for the two strange things i mentioned (the knocking sound and wiper malfunction) which are probably unrelated.

dcrasta

This could be something simple. If its a vacuum leak, U can look under the hood.. Look for any vacuum hose or a nipple missing a hose. I would check your brake booster area. Brake booster is on the driver side firewall, the brake master cylinder bolts to it. It looks like a big flat whoooie cushion (but metal and rusty colored or black). It has a plastic check valve sticking out. That check valve connects to the big vacuum line from the intake to supply vacuum for the brakes. That hose can be cracked, and / or the check valve could be bad. Also a little hose connects to the nipple on the top of that check valve, and another check valve is on the small hose. That small hose supplies vacuum for the H-AC controls and some other accessories.

I mention this area because you mentioned associating this with hitting the brakes, which draws vacuum. Ruling these leaks out (these are minor-ish leaks so I dont think this is the entire problem) would help, but when I checked my car I had many vacuum leaks, and the problem got worst as the weather changes vacuum leaks etc get more obvious (especially in the winter with more density and cooler air).

Also Florida Porsche Club of America would probably be able to get you on track to find a good QUALITY 928 mechanic.

Or you can do what I do.

Get them hands dirty Its tougher than it looks, but not impossible with some guidance (Us), proper documention (Factory repair manual) and some careful attention to detail -

But if you have more $$ than time or talent check the Florida PCA group .

GOod luck -

86'928S MeteorGrey

Aren't there any 928 Rennlist folk in Florida? Hard to believe... 928 owners must all be Republicans... Performing the flexplate check only requires some jackstands a few minor hand tools, (ratchets sockets and allen wrenches, a dial indicator with a magnetic base, and a pry bar or large screwdriver...) plus about an our of your time. Once you do the check once, you can leave out two bolts from the housing cover which will allow future checks without having to drop the exhaust. You gotta find a new mechanic, or give him a chance since he spoke to Constantine. You could also supply your mechanic with the Rennlist website info. If he were to get online here, it would only make him a better mechanic. You might also explain that there aren't any good 928 mechanics in your area, and his presence here could lead to more bu$ine$$...

T M Gramentz

sent you a pm