Newbie electrical and wastegate questions

[PrimeMvr]

First, thank you to all of the experts who graciously share their experience here on this great board! I have learned a lot. I had my first "get to know your car" day with my first Porsche, a nicely sorted '87 930. Since I'm in Iowa, I've not had many warm weekends to work in our unheated garage.

When I was changing plugs 1-3, I found the connector below disconnected. I don't know if I pulled it apart when moving some things around, but from the dust pattern on it, I think it was already apart. Can someone tell me what it is? There are three pin connectors inside the plastic surround. One end of the wires heads toward the firewall under the fuel filter, the other disappears into a small hole in the engine bay in front of plug 3.


I also found a set of disconnected spade ends. By the corrosion they appear to have been off for a long time. Can't find anything they should be connected to. The loom they come out of heads over the top of the engine.


My last question is regarding a very small hole I found in the side of the wastegate. Do you think a dab of JB Weld would suffice or should I replace it? I am having a hard time finding the part online. It was tough to photograph clearly.


TIA!!

Everyone seems to like a story from us newbies, so here goes. I used to work on my cars out of necessity when I was younger (broke), but that went away once I could afford new cars with warranties. I don't think I've changed my own oil in 10 years. I've been itching for a fun car that I can wrench on, and came across my 930 through a friend of a friend.

The engine and transmission have about 6k miles since a rebuild. It has custom dual exhaust, big-red brakes, 18" Kinesis wheels with 235/315 rubber, and seems very well cared for. I have a dyno chart showing 355 RWHP. Stock boost, but setup very rich and the nearly wide-open exhaust helps the numbers. No smog testing here in Iowa.

My only seat time was driving it back from Florida in November, as it snowed early this year and we use a LOT of salt in these parts. I took a slight detour through the Tail of the Dragon, so I can't complain too much

I really love this car and enjoy the passion that the members of this board have. It's infectious and I can't wait to get back in the driver's seat. This will not be my last P-Car!

Steve

At the top of the Dragon on the way home:


Still in Florida before coming home. My favorite angle of the car:

[steely]

Beautiful car.
Just a guess - Is that the O2 sensor connector, can you follow the wire up from the sensor to the penetration?

[TibetanT]

Welcome and very nice Turbo you have there!!

I am with Steely Dan above...looks to me like that is your O2 sensor plugin.

Damn...that is a nice Turbo...just had to say that again I guess. Ha

[PrimeMvr]

Yep, the first one was the O2 sensor. I had a hard time following it top-down, but with your suggestions I started at the sensor and followed it easily. Now the question I have to wrestle is did I knock it loose or was it. I think it was already apart.

Why would someone disconnect it and what are the effects? The car runs super rich at idle, but it's a smooth idle once it's hot. It's sluggish below 2000 revs, but above that it pulls strongly up to about 6k. It runs great at steady highway speeds.

What engine behavior should I look for "connected" vs "disconnected"?

Thanks for your help and comments. All I can take credit for at this point is writing a check, but O look forward to making it my own over time. At this point I'm just getting familiar with everything since I can't drive it in the snow, and I've only owned Japanese cars my whole life. Very intriguing. Oh, I did put on a Momo steering wheel, but that hardly qualifies me as an expert now

Steve

[spuggy]

Originally Posted by PrimeMvr

Why would someone disconnect it and what are the effects? The car runs super rich at idle, but it's a smooth idle once it's hot. It's sluggish below 2000 revs, but above that it pulls strongly up to about 6k. It runs great at steady highway speeds.

Some people misunderstand what the Lambda circuit does (or is supposed to do), or it may be that some component is simply not working or badly maladjusted, and the car simply runs better without it for now.

A 930 lambda circuit should provide you with a nice lean cruise mixture, at least on the later cars (I'm a bit vague as to whether all the 930 lambda cars did this or just the very last ones) it also provides enrichment for part-throttle acceleration by lowering the control pressure, and has no effect on WOT/full boost application, where mixture is controlled entirely by boost enrichment in the WUR. It's possible the spades you have found disconnected should go to the TPS on the throttle body? (don't have one, so no idea what the connector is).

I'd suggest to check ignition timing and book some dyno time - ideally with someone who knows 930s - for a baseline and safety check for peace of mind. It's simply not practical or safe to check full boost AFR's without it. You also need to be sure that the ignition settings are exactly correct and the distributor works correctly - there's not much margin for error on a CIS car. Personally, I would do this before boosting too long or going to the track.

930's do tend to run better rich - but sounds like yours may be too rich in the low range. Bosch silver or OEM platinum ($$$pendy and not better) plugs are super-cold for safety, but they don't foul, even with in town driving with rich mixtures. Check the idle CO2 setting - this adjustment only tends to have any effect under light load up to about 3,000 RPM. Motor types without Lambda spec between 2-3% CO2 (early type 930/50 & 930/60 up to 4% CO2) at idle with air pump disconnected. "Surging" on a constant throttle setting below 3000 RPM and coughing & spluttering in the intake accelerating from low RPM (lean detonation) are both signs that the idle circuit needs more fuel. Mine seems to like idle mixture 3.0 - 3.25% CO2 (prefers fatter for colder weather).

355 RWHP @ factory boost is not a stock 930 by any means - Euro 930 makes 300 at the flywheel, cams and a free-flowing exhaust will make another 10% or so. At the flywheel. A long way short of what you're showing at the wheels - which is over 400 FWHP, allowing for 15% transmission loss. I make 370 RWHP, and that wasn't exactly by accident - a lot of stock parts have to be upgraded to get there.

So, yes, seems like a thoughtfully upgraded 930. Congrats! And kudos for driving it home. They like being driven.

I'd guess you have an upgraded turbo at a minimum, almost certainly cams and intercooler as well, late or RoW H/Es minimum, more likely aftermarket. If you're lucky, you'll have ARP or Raceware rod bolts already - if not, I would suggest that getting a set fitted is a lot cheaper than what happens when the stock rod bolts stretch and the rod bearing spins - because that typically takes out a crank journal and a rod.

It would be a good idea to figure out exactly what you have, as it will have a bearing on tuning or future plans. Look at your invoices, or post photos on the Turbo forum. Did you buy it from a member here? There could be threads with detailed history...

[onboost]

Originally Posted by PrimeMvr

Yep, the first one was the O2 sensor. I had a hard time following it top-down, but with your suggestions I started at the sensor and followed it easily. Now the question I have to wrestle is did I knock it loose or was it. I think it was already apart.

Why would someone disconnect it and what are the effects? The car runs super rich at idle, but it's a smooth idle once it's hot. It's sluggish below 2000 revs, but above that it pulls strongly up to about 6k. It runs great at steady highway speeds.

What engine behavior should I look for "connected" vs "disconnected"?

Thanks for your help and comments. All I can take credit for at this point is writing a check, but O look forward to making it my own over time. At this point I'm just getting familiar with everything since I can't drive it in the snow, and I've only owned Japanese cars my whole life. Very intriguing. Oh, I did put on a Momo steering wheel, but that hardly qualifies me as an expert now

Steve

Yes.. looks like 02 sensor connection. Judging from the pic of the wastegate, looks like you have headers so no Cat = no 02 unless you're equipped with an AFR gauge or EFI. Car does not appear to have EFI, however.. you might want to get yourself a good AFR gauge.

Based on the fact that your car is modded, I think your car is set a little rich to ensure that you have adequte fuel when onboost.. so it will be rich at idle and cleans-up as describe once you get on it... again, the addition of an AFR gauge will you understand whatually going on here.

The disconnected spades you refer to.. can't tell if it's one or two may be from the thermal time switch on the left timing chain cover.. check & see.

On the WG, are you talking about what looks like a pin hole between the fins? If so, and there is no carbon around it then it's probably not leaking... I'd say JB-Weld it as stated.

Good luck and enjoy your new toy!

Paul

[PrimeMvr]

Thanks for the great replies.

I left a lot out of my first post regarding the motor, which is not stock as spuggy pointed out. What I know from receipts is that the car spent most of it's life in Michigan. It was there that it had a lot of motor work done 6000 miles ago, both top and bottom. However, the part numbers appear to be shop numbers, so I'm not clear on what brand all of the parts are. Rods, cams, chains, valves, rockers, quite a list.

What I'm told, but cannot verify from receipts, is that it was stretched to 3.4 and has 964 cams.

Also from receipts I know that the person I bought it from had the exhaust redone, the turbo and wastegate insides rebuilt, and several hours of dyno tuning performed, along with the new brakes and corner balancing.

I'm not sure what turbo is in, I'll have to look at the markings when I get under it again. The insides of the wastegate were rebuilt recently at .8 bar, which was my comment about stock boost.

I talked to him today and he said he is sure the dyno work was done with the O2 sensor connected and that it must have come loose, which might explain the heavy rich situation at low revs. He also confirmed that it was purposely tuned rich at high revs.

Obviously I need to do some more research so I know what I have. I like the idea of an in-dash AFR for peace of mind. Based on my conversation with the PO, I'm confident that I'm ok at the moment, but it makes sense to keep an eye on it. I know enough to be terrified of a lean mix at full boost.