Fly Navy

I had a "looker" test drive my 928 this morning and he came back telling me he thought it was not running on all 8 cylinders?

The car idles fine (about 750 revs)...accellerates fine (it's an automatic with kickdown - 87 S4).

I would have thought if it were true that one of the plugs was not firing the car would be a mess, on idle and under accelleration.

So I asked him to drive it with me...we accellerated to 60, "see, shouldn't it be faster there." I didn't want to argue...and off he and his wife went to look at a Boxster.

But what would an 8-cylinder without all 8 cylinders firing run like? I can't imagine it would be as smooth as mine is running.

Mike

Panzer9

Sounds like a typical Boxster dweebe to me- Shouldn't your wife's *** be slimmer there?

Mako 928

When he calls back to see if the car sold tell him "Thanks for the advise I found a loose spark plug wire and the last guy that just looked at it offered more than I was asking"

Shark Attack

Who knows. I doubt the guy had enough experiance to know, But lets say he did. I know my 82 with 2 sparkplug wires on the wrong cylinders idled what i thought was perfect. even when I drove it it seemed ok. But later tinkering I found the two wrong wires. When I put them on correctly I could tell.

Here is what I did to make sure all were firing.
I noted the rpm at idle. Then shut it down and pulled a wire. crancked it back up and it lost about 100-200 rpm. If you go through every cylinder and get no loss... I would say everyone above me is right

JHowell37

I like Boxters. But Boxsters aren't 928s. There is a world of difference between a '87 S4 and any year of the Boxster. I don't think the guy had any intention of buying it at any price unless you were giving it to him.

Fly Navy

Shark Attack - interesting stuff.

It won't hurt to double check the wires I suppose. I may pull some of the plugs too - when I changed out the plugs a while back, #8 was wet.

Mike

michaelathome

Mike, just be careful when doing this as when you are ideling the unspent fuel is going somewhere. That somewhere is into the exhausts. Another local lister experienced a bank not firing and let it idle to see if it would "fix" itself. Instead he filled a cat w/fuel and it caught his car on fire!!

Not me but just keep it in mind when you are trying to diagnose your problem.

That said, I agree with Shark Attack the guy probubly just didn't like the "feel" of the 928. It dows drive like a heavy car and maybe he was looking for a more nimble feeling car.

Michael

Mrmerlin

since you may have a bad wire try spraying the wires lightly with water mist at night see if you find any tell tales, also check the fire order, might have had an unscrupulous buyer swap a set of plug wires

NoVector

Just to see if #8 is sparking, you could clamp a timing light to the #8 plug wire. / Bruce

Fly Navy

The wires are new from 928 Int'l about a year ago...

With regards the kickdown feature - If I agressively launch the car from stop, it kicks in. If however, I slowly depress the accelerator to the floor and depress the kickdown switch, mine doesn't seem to want to drop to a lower gear - I think that's what he had issue with.

Still haven't pulled the 8-plug yet, but am curious if it is wet.

Mike

Mrmerlin

try checking the bowden cable tension its critical , it sounds like it may be loose by a turn or two

Jim bailey - 928 International

There are several different possible reasons for an S-4 to be down on power. Like the throttle cable is stretched and the throttle body never gets wide open. The flappy valve is not flapping. The knock sensors hall signal generator are not working and the ignition timing is retarded. But I would not be too concerned yours may well have been the ONLY 928 that the guy ever has driven. As a test find an open safe road and from a standing start hold the gas pedal on the floor for 14 seconds at which time you should be going about 100 mph.

Mrmerlin

Jim that sounds like a fun test , If i did that in the Learjet I`d be going about 200 knots

David L. Lutz

Mike,
As far as the kick down, after you check the bowden cable if that doesn't help here are some other items to look at;

1. Kick down fuse/relay
2. kick down switch under the acc. pedal. Make sure it is clicking when you push your pedal to the metal!
3. Tranny fluid level
4. Last on the list is the kick down solenoid. Rear of tranny on passenger side. It has a single wire pluged in from the rear. When your kick down switch is closed, it sends 12v to this solenoid.

Hope this helps,
David

Andre Hedrick

Pull one of your fuel injector connections and drive it.