Motosport

Hello everyone,

This is my first real post here, even though I have spent many hours reading the forum and learned lots about the 951. So I better introduce myself properly.. My name is Alex and I'm located in Denmark near Copenhagen. I have always liked german cars in general and porsches in particular. And since I took my first driving lessons in a 944 NA back in '88, I have always lusted after a 944, and mostly a Turbo.

So about a year ago I started looking around for a good clean 944 Turbo. This was pretty quickly done, since the 944 community is very small here in DK, and even smaller for the 951. I think there's only a handful of them in Denmark so I started looking south to Germany. But then suddenly during a visit to my favorite BMW dealership, they had a really nice '89 951 Turbo S sitting in the workshop. Black with white interior and all original and stock. Turns out it was a trade in from one of their long time customers, and came with a full service history and really nice clean condition. It was originally a Swiss one owners car, which in 2006 was imported to Denmark by one of the top Porsche shops here. It was by order from a Porsche enthusiast who wanted a 951 S for his daughters birthday. The car was pampered and only used as a weekend toy for the next five years until traded in for a new BMW.

Well, to cut a long story short, we made a deal on the car and I even managed to get it a pretty good price and including all new belts, waterpump, battery, oil and fluid change, and getting the aircon converted to R134 and recharged. I am very happy with the car and it brings a big smile to my face every time I drive it. There is only a few small issues I could use some advice on..

First is fuel consumption.. I know its suppose to do around 25 mpg when just cruising and during gently highway driving, but mine will only do half that at 12-13 mpg even when I just drive gently and mostly staying off boost.. Any good advice on whats the problem here, since its getting a bit pricey with our high fuel costs..

Second is a boost issue. When I go WOT it will boost to 1,7 - 1,8 bar and stay there until it gets to around 5000 rpm - it can vary a bit - and then boost suddenly falls to 1,3 - 1,4 bar for the remaining rpm range until I shift gear. It does this most times, but occasionally it will hold boost at 1,7 bar all the way to redline, but during next gear it will loose boost again. What causes this.??

Besides the above issues, the car runs really well, starts first time every time, idles perfect, doesnt use oil or water, doesnt smoke and hold all its liquids well..

Thanks in advance..

Alex.

minho78

Hi Alex Welcome to Rennlist.

For the fuel consumption it may be the Coolant temp sensor. A tune up may also help, do you have black soot in the bumper? Other thing that may affect it is the TPS no being adjusted correctly.
For the boost, it could be your wastegate, bypass valve, or the gauge no giving the correct value(I doubt it). Since it's a S version it should hold the boost of .8 fine(Absolute pressure so the 1 actually means 0) in that gauge.

Let us know.

spammajamma

Vacuum lines?, I have an 89 and I just replaced my lines and noticed my tank is hitting around 360-380 miles per fill up, used to get about 320 before my dash light came on

Motosport

I looked at the bumper and there is no soot or other deposits on it, and there is no excessive smell of fuel from the exhaust.. If the coolant temp sensor is the culprit, wouldn't it show in the temp gauge.? And where is the coolant temp sensor located and how can I test if its working properly.?

Same question with the TPS, how can I check if its not adjusted correctly, and how do I adjust it if thats needed.? Lots of newbie questions, so please bear with me..

I was also reading elsewhere that a faulty FPR could cause excessive fuel consumption, has anyone else experienced this.? Is it possible to check if the FPR is functioning properly or should I just replace it.?

I plan on ordering a silicone vacuum hose set and simply replace all the vacuum hoses, to eliminate future - and possibly present - vacuum problems.

Regarding the boost issue, I'm pretty sure its not the boost gauge being inaccurate, because when the boost drops off accelerations drops off accordingly, and when it occasionally holds boost all the way to redline the acceleration also continues relentlessly.

Alex.

Motosport

Well, one problem solved, only one to go.. While I was spending a lovely indian summer afternoon cleaning out the intercooler, I decided to check all the hoses, pipes and boots on the intake side as well. And not only was the hose on the compressor housing so loose I could twist it with my hand, but the small vacuum hose that's connected to the banjo bolt on the hard pipe was a size to big and just clamped down. So after fixing these small issues my black beauty now holds max boost all the way to redline in all gears and just runs like a champ.. Except...

It still drinks fuel like we were living in Saudi Arabia.. Spammajamma mentioned that replacing vacuum hoses increased his mileage, what specific hoses would that be.? I have ordered a new FPR, mainly because of the Roque A-tune I have lying on my desk which requires a 3 bar FPR, so that's one possible cause eliminated when I get that installed. I have also figured out how to check the TPS, and it seems to be fine and clicks as soon as the throttle is opened.

I guess the coolant temp sensor would be a good bet, but wouldn't a faulty one show up on the temp gauge.? And where is the temp sensor located.? Anything else that could cause this bad habit of excessive drinking..? Please throw you best suggestions, guesses and experiences at me.. 12-13 mpg is getting pretty expensive when premium is currently at just over $8 a gallon here in DK.

Ohh, and its for sure running very rich, because the back wall in my carport where the car is backed up against is all black and sooty, and running the finger inside the tailpipe is showing same result. Hardly a surprise, but a least the extra fuel is going through the engine and not leaking somewhere.

Alex.

racerxrick

I'll let the experts who build brains for a hobby answer your tech questions...just wanted to say hello and REQUEST PHOTOS!

Black51

That would be ALL his vacuum lines; the small ones. Wouldn't hurt to replace everything rubber in there though. There are some hose kits out there that are silicon, but it's pretty $$$'ey, but worth it in the long run.

Are you 100% sure your chips are stock? It could be a badly tuned chip if they're aftermarket.

What do your spark plugs look like after a drive? How old is the ignition system (coil, cap, rotor, plug wires, plugs...)?

If the temp sensor is faulty and reads that the engine is always on "cold start mode", then that could be a possibility I would think. But better to start with the fundamentals first and eliminate them before assuming other stuff.

Crackership

First off: Welcome, Alex! Also, I second the request for photos.

I'm not completely sure whether or not your temp sensor is the culprit, but it is a good possibility. And, I don't think it would necessarily show on the gauge. The car actually has two temp sensors. There's one for the dash gauge, and there's another for the DME. So, if the one for the DME is bad, it'll never show on the gauge.



Another possible culprit is O2 sensor, but I don't know if your car even has one. I don't know if Swiss-spec cars were equipped with them from the factory. Either way, you're running very rich to achieve that level of fuel consumption. Have you considered adding a wide band O2 so that you can monitor?

Motosport

I have seen those vacuum hose kits, but unfortunately always on the other side of the atlantic - your side that is. So I think my best bet is to make a run to my local parts store and by a couple of meters of silicone hose and make my own vacuum kit..

Yep, chips are bone stock as the rest of the car, I checked them the other day thinking the same. Cant wait to get my A-tune chip installed though... Haven't checked the spark plugs, will do that asap. Ignition system is original parts, but they seem to be in pretty good condition though, at least from a visual inspection. And the car always start right up, even in cold winter weather and always runs very well.

I get the idea with the temp sensor and it definitely sounds like a plausible explanation if thats the cause. But can the temp sensor be faulty if the temp gauge is showing normal temp levels.?

Pics, pics.. hmm, well - yes, I'm trying.. Just got this new macbook and still havent figured out how to resize pics in order to upload them.. I know its required for new members to post pics and I'll figure it out before the shame kills me..

Alex.

Alex.

Motosport

Hey Crackership, you already answered my question while I was posting.. Pretty impressive stuff here on Rennlist..

I think I'll just replace that DME temp sensor, unless there is a way of testing if it works properly.. And yes, my car has an O2 sensor, or lambda sensor as they are called here, and I have already taken a good look at it from the outside. It looks fine as in no broken parts or wires or anything. Is it possible to check if the O2 sensor works properly or not, or should I just replace that as well.?

I have considered a wideband O2, but more for future engine upgrades actually. But even if I install one now wouldn't it just tell me something I already know - that the car is running very rich, and not so much the cause of this condition.?

Alex.

schip43

Welcome aboard sounds like your enjoying your new ride. $8 bucks a gallon holy crap!

About the 02 sensor you answered your on question but... yes it will tell you the car is running rich, it will also tell you how rich. At idle and part throttle you should be seeing 14.7 plus or minus (it dithers back and forth). If your lower than that your using excess fuel.

You'll still have to find and fix the issue but you'll have a valuable tool to help you out.

PS, if it's dumping fuel, you might be running crazy rich under boost, less than 11 to 1. Wide band will show that also.


,

Crackership

As for testing the O2, there's a procedure on Clark's Garage in the Garage Shop Manual. There's a wealth of other knowledge there as well. I didn't see anything there about testing the DME temp sensor, I'm sure it's possible, but all I can think is to measure voltage as the car warms up... but then again, I don't know what the appropriate voltages are.. someone else might have a clever answer to that one. I will say, however, that one thing to check for is the condition of the wires, and check for corrosion on the connections. It's quite possible for corrosion to throw the readings off and give the same symptoms as a bad sensor.

As for the WBO2, sure, it'll tell you that you're running rich, but it'll tell you when and where. If you go with something like a Zeitronix that data logs and supports multiple inputs, it'll give you a better idea of where to look for your problem and under what conditions it presents. I never really considered a WBO2/data logger a worthy investment for anything less than a highly modded car until I bought a car with one already installed... now, I can't live without it.

Best of luck!

Motosport

Yes, I am really enjoying my ride, in fact I totally love this car especially after sorting the boost issue.. The combination of speed, comfort, race car handling and drivers feedback is just phenomenal. And for some strange reason I especially enjoy driving this car at night.. The intimacy of the interior, body held tight by excellent seats, 250 hp at the disposal of my right foot and those pop up headlights just makes me feel special...

Yep, everything is more expensive over here and to make things even worse here in Denmark, we also have extremely high taxes on motorized vehicles. 180% vehicle tax and 25% sales tax on top of that, so basically you buy one car but pays for three.. I just checked the new price for a 951 and it was exactly $200.000 back in the eighties. And that's just for a standard version, since no 951S was ever sold new in DK. I don't even want to know how much a 951S was. No wonder theres only a very few 951's in DK.. And for my '89 951S with all the options I had to hand over $28.500 notes which is actually a pretty good deal and considered some $5000 below value. The good thing though is that there's only 2 or 3 951S cars in Denmark to my knowledge - all imported - so its pretty rare, and classic rare Porsche cars hold their value very well despite the current economic climate. So all in all its a bit expensive being a petrol head over here..

Oh well, got a bit sidetracked there, back to topic... I will look into checking the temp sensor connections and O2 sensor as per Clarks Garages most excellent guidelines as soon as time permits. I need to do some outside painting while the weather is warm and sunny and also have a funeral to attend this weekend.. Bummer.. And then I'll strongly consider installing one of those wideband O2 displays sooner rather then later.. Does it have to have data logging features.? Reason for asking is my local turbo shop has one at a decent price which shows air/fuel ratios continuously but no data logging. Do they piggyback the factory O2 sensor or do they use their own O2 sensor in a separate exhaust bung.?

Alex.

Motosport

I think I've got this pic resize thing worked out.. Here's a few from when I just got the car. Not that is has changed much since, besides more leaves on the trees.. '89 944 Turbo S black with linen interior, M030 option, LSD, forged wheels, big radial brakes, aircon converted to R134. 91.000 miles, bone stock and never messed with. Seems like it has received much love and spent all its live in a garage when not driven. Enjoy and be gentle on her..

racerxrick

wow...very nice..THANKS! Love the wheels too..perfect!