After pretty much weekly "it'll be done Friday" expectations for 5 straight months at 2 different garages, 7 months after purchasing it, a year plus looking for it and a lifetime of wanting it, and around $8000 in parts and labor after buying it, I finally have my car...


To abbreviate:














Wow!!! Until last night, I basically never drove or even had a ride in one. I did spend a couple hundred hours sitting in it, pretending to drive, of course. I limped it around the block when it was delivered and once again to the first shop, but I really could only imagine the "feel" of a Porsche 928S4... (I under-imagined, all this time... - The car FAR EXCEEDS my "pretending to drive" fantasies, even after watching every 928 "youtube" video, SEVERAL TIMES...)

Really. WOW!!! I certainly have some bugs to work out ahead of me, but I'm ready for anything and expect to handle the work myself now. My overall evaluation of the car far exceeds my greatest expectations, and I harbored some rather high ones to begin with.

My car has an automatic transmission. I kind of understand now why it's designed to start in second gear. Now given; It was cold, and I have summer tires on it, but still, ANYTHING close to flooring it from a standstill results in massive tire spin. Even with the tires warmed up, it breaks loose really, really easily.

On the highway, the acceleration is pretty incredible. The roar when the car downshifts during 60-?+ runs is quite awesome - it surprised me actually. AWESOME gear ratios...

I've had a Roger X-Pipe installed with his high flow catalytic converters, but now that I've heard the car, I'm sure I can tolerate the additional noise from a rear muffler bypass. That might just make it all "perfect" by my tastes...


And now for the issues;

The automatic transmission felt a bit "clunky". The mechanic implied that it's normal, but I have no reference point to compare to. It certainly didn't shift as smoothly as a older Mercedes transmission. It wasn't violent or anything, but it did have a distinct "clunk" about it, particularly when gunning the throttle and bringing on a downshift... I hope this is normal, but am ready to deal with whatever, if it's not...

Later, once it cooled down, I noticed some surging at idle when it was first started again. (Engine wasn't cold - just cooled down a bit for an hour or so...) It had metronome-like constant, even revs - from about 1000RPM up to around 1800RPM... Within a minute, after I "blipped" the throttle, it seemed to stop. (The car has 6+ month old gasoline in it - super, of course, but nevertheless old...)

I have to bring the car back in soon, as he needed some sort of vacuum connector, and did try to glue the existing one - perhaps these issues are vacuum related and I still have a bit of a leak in the system?

I had the brake discs cut and installed new pads, sensors & spacers. I can't recall which pads I choose, but I recall they were one of the more expensive sets and perhaps are a bit more metallic than others I've mostly used with other cars.

At first, the braking seemed VERY poor, but the pads need to break in, I'm sure. It seemed to improve as I drove, but at the same time, that would have heated them up. I just don't know what "normal" should feel like...

Another thing that surprised me was how soft the brake pedal feels. It has a particularly soft feel through the first 20-30% of it's travel. The pedal cannot bottom out, and braking seems okay, but I've had a lot of cars, and most had a much more limited travel until significant pressure would be felt... (I had the system flushed with proper fluid, and had new stainless brake lines installed...)

It doesn't seem to have any electrical glitches, aside from not having dash lights when the headlights are on, until I fiddle with the rheostat under the dash. The car came that way. I'm not sure if I'll even worry about replacing/repairing it as I anticipate doing a full LED conversion soon enough, and with that, that rheostat would be useless, I feel. Perhaps I'll turn the space into a switch for something else...

I was comfortable with the "ride" of the car, even on Pennsylvania's smoothness-impaired roads. The ride wasn't very harsh by my standards, so I think I have some room to work with when I get to whatever the suspension will need, if anything, to make it perfect... I can't rule out 18" rims, or maybe even more, but 17"-18" seems most likely.

Unfortunately, I didn't get to do much in regards to seeing how it handles. The steering response is probably the BEST I've ever had in a car. I need to lose those summer tires IMMEDIATELY...



Anyway, it's really awesome to have it back. I'm happy with the work that was done by the last shop, and the charges were very reasonable. Typically, it snowed today, and I know after a close call last night with a patch of ice, that the car is immobilized for a little while. (I hit a bit of snow-dust/ice at an intersection and the car just slid, dangerously close into it. I did not feel ANY ABS modulation. I hope that's normal too...)

I am getting those snow tires ASAP, but need to decide on whether or not I'll get new wheels for them or use the current ones and get new ones for the summer tires. I see traction being an major issue, so perhaps going a bit wider would justify slapping some snows onto my current wheels, which I believe are of the "club sport II" variety.

Anyway, I can't express how happy I am to have the car back, just in time for the new year. This was intended as a 40th birthday type present of sorts for myself, and originally I hoped to have the car, and all the work that it would need out of the way by last April.

Although it's been one of the most frustrating experiences of my life, I've learned quite a lot and know already that I'm "hooked" on these cars. There really isn't anything else that can compare to a 928, and I'm sure I've got a lot more happy surprises coming to me regarding my expectations. I can't wait to see how it handles in the summer, on good roads, with decent summer tires...

Is it part of the sickness that I'm actually looking forward to working on it? How about that phenomenon of sensing that there just can't be such a thing as "enough" power, even if it had rockets strapped all over it??? Is it normal to already be looking for an ADDITIONAL 928? I see a 86.5 manual tranny project car as my next self-given "birthday present..."











Nick - Hazleton, Pennsylvania
1989 928 S4 - Automatic

 

Nick,

Congratulations!! It's been a long road, glad you are finally getting to drive the car!

I can't speak to the A/T question, but the surging idle could well be related to the vacuum-connector issue-- fix that first before digging deeper.

The soft brake pdeal sounds like there is still air in the lines- try bleeding again. The power-bleeder has been discussed a lot here- available from 928int'l (click here) and other vendors. We bought one and like it a lot, but use it in conjunction with stepping on the brake pedal- the 5 or 10psi air-pressure alone doesn't seem to push the air out but keeps the resevoir full and makes it much simpler.

One caveat: Bleeding with the pedal pushes the master/cyl piston beyond its normal range of travel, and if the m/c bore is corroded (e.g. years of neglect by the PO) then this can chew up the m/c piston and cause it to start leaking. That is a sign that the m/c needs rebuilding, but is also annoying.

Flaky dash-light reostats are common and easy to change, just pop the bottom cover on the dash console.

 

transmission shifting aggressiveness (both when, and how hard to do shifts) can be influenced by adjusting the trans cable where it arrives at the engine. From memory, it's cable number 3 of the 4 cables that arrive on the drivers side of the motor, counting from nearest-the-motor outward.

 

You are a NUT! Which puts you in good company of course ... Now, if you want to go right to the vein, start planning on SITM next June. I think you're gonna fit right in

Really fine to read your latest post - have a very Happy New Year!

 

Clunky harsh shifts is usually related to the modulating valve pressure being too high.

Talk the car to a Mercedes Benz Auto shop specalists and get them to set the modulating pressure to Porsche's specification and you should get very smooth changes.

Tails 1990 928S4 Auto

 

There are a few things you can do to fine tune the S4 auto. I think Bill Ball has a thread or two on here that are pretty instructive.

I really enjoyed your enthusiastic reporting of your first ride. Keep it up.

 

Nick,
You might consider having the transmission refreshed. I hope you have a good 928 knowledgeable mechanic. Have the tranny drained and replace the filter and fluids. Remember, check the tranny fluid regularly

 

For the A/T issue, the hard shift is probably vacuum related. There is a vacuum line from the back of the intake that runs to your gearbox. It usually follows the torqe tube most of the way. Somewhere above the bell housing this line has a coupling that tends to get brittle and come loose. This vacuum line goes to a shift modulator valve on the drivers side of your transmission. I had the very same problem until I found that line and replaced the coupling with another piece of hose. Now it shifts smooth as silk. There are several writeups about this on this forum as this is a common problem.

 

Soft pedal means air in lines or bulging brake lines (if you've got stainless, that shouldn't be you). A proper brake fluid bleed should have a power bleeder up front on your fluid reservoir, your Ignition to On (motor can be off, that's OK either way), and press the brake pedal enough times during each bleed to get the ABS pump to kick on.


Surging idle...do the cheap fixes first: disconnect your battery for a minute to reset your engine computers.

If that doesn't fix it then use CFC MAF cleaner to clean your MAF.

Clean/replace your air filter, insure no obstructions (I had ***leaves*** on top of my MAF screen under the air filter when I bought my 928, for instance).

Insure that your battery is fully charged and that your surging idle doesn't coincide with fluctuations on your voltmeter.

Still not fixed? Install a new O2 sensor.


For your tranny...drain your old transmission fluid and fill with 24 ounces of Lucas no slip tranny fluid or Trans-X, plus factory or Redline's ATF to bring to proper level (but insure on level ground that you aren't over-filled!). Lube the shift cable, too.

 

I had RMB first, then got X-pipe and it is even better sounding.

I had a 65 year old neighbor complement me on the sound the other night.

With 18 inch tires and wheels the wheelspin is not as easily accomplished as you describe. Mine came with those so I can't comment on stock tire sizes.

 

Auto transmission fluid level will have a huge effect on shifting - buy the filter kit and refill the transmission yourself with a new filter and dex III ATF.

When you said your mechanic needed a vacuum connector, I guessed it is the 7-way connector that sits beneath the airbox?? A common problem - it is also the one that feeds vacuum to the transmission, so could well be contributing to the shift issue.

For the idle, follow no-doubt's advice - cheap stuff first. The fact that it happens when cold and then settles suggests Temp II to me, so try measuring each pin of that sensor against ground - if either side is open, its buggered.

 

Congrats, Nick. Can't wait to see it. I know it's been a long wait.

 

Congratulations! Enjoy her, and drive her like you stole her!

Happy New Year!

 

I had a transmission kit/filter whatnot installed and the all fluids in the car replaced. I'm glad to hear that it may just be a vacuum issue with the transmission, but after that vacuum connector is replaced, and it still feels rough, I'll check the cables. If that doesn't work, I'll have a Mercedes dealer check/adjust the modulation valve pressure or maybe just change to another fluid. I don't know what type was used, but I requested synthetics where possible.

I don't mind the "clunky transmission" actually. For all I know, it's not far off from what is normal. By the way, my car has the normal differential.

It's another cold weather phenomenon with summer tires I suppose, but there were times, whence gunning it on the highway, that the car felt like it would perhaps lose traction a bit, and want to turn slightly, seemingly from one rear wheel grabbing a bit better than the other.

The cars option codes don't show the LSD option. I wonder if that conversion lies ahead for me?

I already have a pressurized bleeder. I bought one years ago from Griots Garage that hooks up to an air compressor, and using the venturi effect, sucks the brake fluid through the system. I even used it to pull oil up through the dipstick tube when I overfilled a Mercedes' engine oil by a half quart.

I'll get another can of brake fluid, and perform another flush myself, with the ignition on to benefit the ABS stuff. With an automatic tranny car, I'd just need to pull fluids through each of the brake calipers, right?

Looks like I might be snowed down for a few days, but I should have the snow tires in a week or so. I'm renovating my garage a bit and need to pop in an Alpine head unit that controls my iPhone. I already have an Alpine CD in the car, so hopefully that'll go smooth enough.

Speaking of stereos, although I intend to "go for the best" soon enough, the mods, whatever they are that the previous owners did do result in a half-decent sound system. It can stand to be louder, but that should be a fun little project.

I saw a really neat auto transmission shifter product video on eBay. I can't remember who did it, but it features a rod that you can pull out that effectively "locks" the shifter in place, and with an optional relay kit, does that 2nd gear start bypass thingie. Can't wait to do that too...

I'm also going to detail the car myself, and possibly add on some vinyl lettering over the newly painted valve covers and intake.

I may post another post on the off-topic section, but while I have your attention, is there anyone who knows anything about designing a garage door, with an opener, that can move two sections of a sliding, barn like door to one side, and a third section to the other, and still be able to lock it securely?

The garage I have is in a 120ish year old building, and originally had sliding doors. They're currently replaced with a poorly fitting normal door on tracks. I've always wanted to do that, but can't find ANYTHING out on internet about it. I could manufacture the system myself, if necessary, as well as the doors. The original tracks are sound and still in place. Anyway, any ideas or anything regarding that would be most appreciated...

I might be acquiring a Bitter SC soon. I'm pretty sure that I just have a "thing" for European GT's... I'm also pretty sure that the 928 will be the primary obsession, but I'd like to get the Citroen SM up to snuff too, and if the Bitter works out, that as well. (That car seems to primarily just need some cosmetic attention)

More to come. Thanks to all for the advice & kind words. It's really awesome to finally have it home. I see a lift parked outside by spring, and with that, my car hobby being allotted a lot of time for a while. I really like the work, and after all the frustrations and expense of paying others, I'm certain that I'll feel good about getting a lot deeper into classic cars than ever.










Nick - Hazleton, Pennsylvania
1989 928S4 Automatic: X-Pipe - High-Flow Cats - Various Euphoric Owner Savings Account Mods

 

If you're driving it in snow(BTW, BAD idea if they salt the roads in your area) then the LSD is going to make it harder to control in those conditions, not easier. The only places it will help you are in slow slippery situations where you might get stuck with one wheel spinning or if you're trying to get the power to the ground in a tight corner on the track. For regular driving in snowy conditions, an LSD will tend to make the whole rear end come around instead of just breaking one tire loose. Since you have an automatic, you can work around the slow/slippery one wheel spinning situation by just applying a little brake along with the gas.