the flyin' scotsman

ok........nothing change despite the flex plate moving......the vibes are still there.

sitting in park or neutral the engine revs freely........in any gear the car vibrates from the intial move off, smooths out then gets real bad at 3k rpm then smooths out again.

Now Im thinking TT......is there a defined diagnosis process for the TT?

the flyin' scotsman

The new injectors are rebuilt 4 hole Ford items.......is there any possibility one or more could cause a bad enough misfire to cause the vibration?

As described above 'washing machine on spin cycle" is close to description but if its the TT I dont understand why it got so bad from sitting while the engine was worked.

JoeTaylor

It the rubber... always the rubber/plastic parts wearing or aging out.

The bearings have a rubber surround that holds it in place in the torque tube. When this wears or ages out the bearings don't fit tightly causing vibration and the bearings can even move up or down the torque tube. Same thing applies the the damper.

Since I bought the 928, a 23 year old car, most problems have been related to rubber/plastic parts wearing or aging out... Seals, hoses, belts, etc. It's seems to be the place to start looking.

the flyin' scotsman

appreciate that Joe.....what I dont get is it didnt seem that bad when I drove it before the intake r&r although it did have 'issues' with stalling, getting hot, etc etc

Jerry Feather

One thing about this that concerns me, Joe, is that since it didn't do it before and is now is doing it, I would tend to discount the likelyhood of the TT bearings or balancer. However, one thing you seemed to have mentioned is about how the transmission was hanging down for a period or such while you were doing your last project on the car.

Can you describe in more detail what you actually did with the trans or how you had it suspended? If so, I'll be able to tell you more about what I think might be the problem.

Jerry Feather

Imo000

Changing the injectors on an S4 is fairly easy, Put the old set back in and see if the problem goes away.

the flyin' scotsman

The car was on jack stands at the proper points for 2 months.....other than inspection of the driveline nothing was done to it.

the flyin' scotsman

I know so I think I shall. I have a few sets lying around here

Jerry Feather

Thanks, Malcom. I had read more into your previous question about that situation causing "stress to the flexplate" than I think there is. I was concerned that you had somehow suspended the transmission unsupported and that if so it might have bent the TT at the foreward end. There are a couple of threads about how that will cause some vibration and result in cracking and breaking the flex plate.

I guess I cannot be of help. I hope the injector idea pans out. Good Luck.

Jerry Feather

928mac

I think he will find that it is a engine miss as 2 months on stands should not have hurt anything.

Good luck Malcom, waiting for your diag.

Black Sea RD

Sitting on jack stands that were placed in the appropriate places will not have any effect on the driveline. The transmission is supported by the rear cradle that is mounted to the body and the engine is supported by the front cross member, also bolted to the body. Same support for both as it sits on the wheels. We have had our own cars sitting for months on jack stands without any ill effect.

Usually the TT vibe problems get worse as RPMs climb under load.

Go through everything you just did and make sure it's all okay. Sounds more of an engine related problem IMHO. You might want to disconnect the battery to zero out the computer again since it might have grabbed some bad information from the engine upon initial start up after your work.

We did have similiar a problem once when the overhead lamp blew out while the 928 was running. I immediately shut off the car since it caused some concern and after I made sure it was only the lamp that blew, I restarted our 928. The computer had grabbed some bad code when the light blew and kept it, which caused rough running and dying under load after every start up afterwards. Disconnected the battery which zeroed the computer and all was good.

Good luck,

the flyin' scotsman

thx Constantine

Resetting the computers was the easiest so batt. grd. strap was unbolted for ~15mins. Reconnect, starts and idles perfect, slow drive down the driveway all fine, onto the highway and ease her up to 3k and she starts to vibe so no change. Once warmed I had the car pull like a freight train up to 6k with no issue but always around 3k its bad.

On the way back into the garage you have to give her a little gas and there was a slight vibe/misfire.....Im swapping the injectors once she cools.

928mac

I wonder if 1 on the wires are bad.
Did you replace them Malcolm? this could also be another easy check by swapping the wires back to original, if they were replaced.

the flyin' scotsman

which wires Brad? The injector harness is OEM and the ignition wires are as they were when car was dropped off and I assume they're OEM.

I dont have a spare set of ign wires but theres always the 'other' 928.....the black one.

Black Sea RD

Hi Malcolm,

Well it was worth a try.

Probably swap out the fuel injectors and see what happens since it does sound like its engine related.

Best regards,