Just got car out of storage, ran rough & now won't run at all

[sodakporsche944]

I was a member 6 or 7 years ago and forgot my username and password so I'm back as a Newbie.

I have an 84 Porsche 944. Had it in storage over the winter and when I started it yesterday it was only running on cylinders 2 & 4, I checked the spark plugs and they were pretty fouled so I put 4 new ones in and the car would still only run on cylinders 2 & 4. Next I did a compression test and the lowest cylinder was 130 lbs and the highest was 160lbs, after I did the compression test the car wouldn't even run at all. So next I drained what little bit of nasty fuel was in the tank and put on a new fuel filter with injector cleaner and 5 gallons of fresh gas, the car still wouldn't run. Then I noticed the fuel pump is not running, if I pull the relay out and use a jumper wire I can get it to run but there is no power at the fuel pump fuse & even with the fuel pump hot wired the car still won't run, it runs for a couple seconds then dies. Does the fuse supply power to the relay or does the relay supply power to the fuse? If I spray either into the intake the car hits on all 4 cylinders and sounds decent so I assume the number #1 & #3 injectors are plugged.

So first things first, to get the fuel pump to run what should I do first replace the relay or is it possible that it's a faulty ignition switch. Once I can get it running again I wanna dump a bunch of injector cleaner in it to see if it will start hitting on all 4 & if not I'm gonna put new injectors in.

Any help?
Thanks, A.J.

[mytrplseven]

It's possible the injectors could use a rebuild. Witch Hunter in Bellingham, WA does a bang-up job for about $100 and all data back-up is included. A lot of us use him and he's great. Also might consider the fuel tank strainer being plugged. Fuel pump has to come off to get to it. Do you know if the fuel pump is creating enough fuel pressure? Autozone will LOAN you fuel pressure test gauge kit to test the system. Clark's Garage has the procedure. A replacement FPR might be in the offing. The test should tell.

[sodakporsche944]

Upon further inspection the fuel pump is pumping when it should, fuel pressure is good & checked the regulator as to clarks garage's directions and that checked out good too so I just ordered 4 new injectors and a new fuel filter so I'm hoping that should fix it. It's got air, spark, good fuel pressure to the injectors & runs on ether so I'm 99% sure the injectors are at fault.

[TibetanT]

Soda:

Just a thought. And, maybe you already checked this.

What is the tachometer doing? Is it bouncing, or does it register an RPM number when you are cranking the engine over?

Check the connections for the Speed and Reference sensors making sure they are tight. These sensors are responsible for sending signals to the DME/ECU brain, which in turn runs the fuel pump, as well as sending signals to each fuel injector. Easy to check this with a "noid light" from AutoZone or NAPA type auto stores.

Fuse number 2 in the auxiliary fuse area is responsible for the fuel pump's electricity.

Could be the injectors got foiled with varnish since the car sat for a while.

Hope this helps and good luck!

[sodakporsche944]

Hooked the test light up to the fuel pump and it lights up when I start cranking the engine and I can hear the fuel pump too, hooked the test light up to the injectors and there's power there when there's supposed to be, good fuel pressure. With the car running on ether the tach functions like it should. I think the injectors are just really....really gummed up. I could have swore I put stabil in the tank before I stored the car but maybe I forgot. 4 new injectors and a fuel filter was only $110 so it's not to bad.

I dumped 5 gallons of clean gas into the tank, gonna blow some air into the tank through the hose connected to the fuel pump to loosen up an setiment that might be in the tank & then drain it, put some more fresh gas in the tank, put the new filter on and run the fuel pump for a couple seconds til I get fresh fuel out of the fuel rail supply line, then put the new injectors in & hopefully that cures it.

I don't drive the car that much so I'm just getting it ready to sell, hope to have it listed on ebay by the weekend.

[DannoXYZ]

Typical fuel-issues causes identical symptoms on all injectors. A pair of injectors not firing would indicate one of the two injector-driver lines from DME isn't working. Check the wires going to each injector. The old crispy wiring can fail easily.

Simple test would be:

1. carefully disconnect each injector connector. Use a small screwdriver and push off the spring-clip first, then pull on the body of the connector to disconnect.

2. with key ON, one pin of each connector should be at + battery-voltage.

3. the other pin gets grounded by DME to fire injectors.

You can also hook up an LED test-light to each connector and see if each one flickers when you crank the engine.

[sodakporsche944]

OK, put new injectors in today, flushed out fuel tank and fuel system, put in fresh gas. Car still starts and dies almost immediately but hits on all 4 cylinders now when it does run so I gained some ground there. Looked on the clarks garage website and thought maybe it's the fuel pressure regulator so I checked it the way they said, pulled one injector wire off but the car still dies almost immediately, so I doubt it's the regulator & the tach moves like it should so I doubt it's the fuel pump/dme relay. Am I missing something or what else is there to check?

[TibetanT]

Soda:

This is just a guess on my part, but it could be the reference and speed sensors are on there way out; in other words one of them, or both, are failing. Or your battery voltage has dropped below 12.4-12.5volts which would cause the fuel injectors not to fire.

Another thought is fuel pressure. Do you smell fuel after cranking the engine over? If so, then the cylinders are being flooded with gas. If you have a test gauge you could test the fuel pressure at the fuel rail; should be about 32 psi.

Another reason the car is running on ether, but not on the gasoline coming via the rail could point to a bad DME/ECU brain. The "brain", under the passenger floor, gets its signals from the reference and speed sensors which in turn provides electrical current to the fuel injectors. If there is someone near by with the same year/type/model 944, you could swap out the box to see if the car runs. I can tell you what I have done in the past, I take the box out of the non-running car and place it into the known-running car to test. If the "known-running" car doesn't start-up, then you know the box is bad.

Now, sometimes these suspect "bad DME/ECU" brain boxes just need to have their respective solder joints re-soldered to fix them. There are several folks available to do that, if need be.

Lastly, when was the last time the distributor cap and rotor were changed out for new? Although, by what you are saying here that the car runs with ether and is firing on all four cylinders, then I would say you are getting spark.

Hope this helps and keep us posted on your progress so we can get you going again.

[sodakporsche944]

When I got the car out of storage and it was only hitting on two cylinders the first thing I checked was the distributor cap and rotor and they looked good, but the spark plugs looked pretty bad so I replaced all 4, at this point in time it was still only hitting on 2 cylinders. I then pulled the coil wire off and did a compression check which checked out good, next I hooked the coil wire back up to start the car and this is when it would not even run anymore. Next I drained and cleaned the entire fuel system, put in fresh gas with a new fuel filter and 4 new injectors, car still would not run but would run on all 4 cylinders the little bit that it would run. Checked fuel pressure at the rail and have 36 psi & car will still run on ether but not on it's own. The tachometer works when the car runs so I doubt it's the reference sensors.

[porschetub]

Originally Posted by sodakporsche944

When I got the car out of storage and it was only hitting on two cylinders the first thing I checked was the distributor cap and rotor and they looked good, but the spark plugs looked pretty bad so I replaced all 4, at this point in time it was still only hitting on 2 cylinders. I then pulled the coil wire off and did a compression check which checked out good, next I hooked the coil wire back up to start the car and this is when it would not even run anymore. Next I drained and cleaned the entire fuel system, put in fresh gas with a new fuel filter and 4 new injectors, car still would not run but would run on all 4 cylinders the little bit that it would run. Checked fuel pressure at the rail and have 36 psi & car will still run on ether but not on it's own. The tachometer works when the car runs so I doubt it's the reference sensors.

Looks like we have covered all the typical 944 no start/poor running issues and you have certainly checked enough things,where the 2 plugs that were dead wet with fuel when the car was running on the other 2 cylinders?,could you have had to bad ignition leads?
Have you pulled the ecu plug to see if the pins are clean?,if yours is a latter car the ecu can get water in to it (why do Porsche put ecu's @ floor level?).
Get a multimeter and go right thru the ecu plug pinout as it sounds like you may have a bad earth/earths,this test will find any broken wires and also check the body earth male pins make good connection with all those brown wires.
I also would check your your main fuse and relay board for moisture damage,loose/overheated wires @ the area were the f/pump relay plugs in.
Keep us posted and good luck.

[sodakporsche944]

I unplugged the #1 injector and with the key on using a test light both terminals are hot, with the motor running on ether both terminals are still hot, the test light didn't pulse. So for some reason the computer is telling the injectors not to fire. Bad relay or computer? Nobody in my area has a similar car to borrow the computer from so what's the next best thing to do?

[DannoXYZ]

Incandescent test-light isn't good for testing the duty-cycle signal. An LED one would be better as it doens't have the persistence.

You have to disconnect ALL the injectors due to them being all wired in parallel on the same circuit. With the 3 out of 4 connected, the voltage flowing across the others will end up giving you same voltage on both pins of the disconnected one.

With ALL of them disconnected, you should get:

1. hot terminal of injector-connector at 13.5v of battery with key ON.

2. other grounding-terminal should be zero volts and fully-open relative to ground (infinite ohms). If you have ANY voltage on the grounding-pin, then you've got a short in your injector-harness somewhere. This causes some of the current that should be going through the injectors to bypass them, thus not driving the injectors or doing it intermittently.

3. when cranking, the grounding-terminal should flip between open and grounded (no voltage in either state). You'll have to connect an LED test-light to detect the grounding pulses.

Find the DME/KLR test-plan and follow each step in order. You'll need an oscilloscope to measure the speed/ref-sensor signals. Ignore any of the KLR tests.



Also, try swapping the DME relay. There's also a diode-fix for repairing the common issue with DME relays.

[wrench1]

Early cars (82 thru 85) are known for weak ignition switches. My sons 83 was literally in the weeds when I bought it and drug it home. Found the normal crack in the plastic housing of the switch. Had power and would hit and fire then die once I released the key. Change the switch, its cheap in the earlies. Get the good switch, not the cheap ones you find on line. There is a difference as I found out.

[TibetanT]

Soda:

My best guess, at this time, would point to the reference sensor being bad since you are able to get a response on the tachometer when the car does run showing RPM. The reference sensor's job is to tell the "brain" when you are at TDC, so the injectors will fire at the proper time. Just a thought.

Yes, it is possible the computer brain, DME/ECU, has been damaged. Usually due to water damage or bad solder joints on the board. I would send you one to try, but I don't have one for your MY, sorry.

Have you cleaned all of the ground points on the car, or at least inspected it for corrosion?

[sodakporsche944]

Got home this afternoon and pulled the relay and tried the 3 wire jumper trick and got the same results, the car fires and tries to run but dies almost immediately so I'm gonna rule out the relay. I'm gonna check all ground connections tomorrow evening & test the reference sensor. The car tries to run after I quit cranking and put the key into the run position so I don't think it's the ignition switch. If the reference sensor checks out good what's the next plan of attack, try a new computer???

[sodakporsche944]

Got a noid light kit today, the light appears to blink when cranking but for the few seconds the car wants to run on it's own and while it's running on ether the light stays lit and does not pulse.

[sodakporsche944]

I'm down to trying a new computer/ecu to see if that's the problem. I can buy one out of a running car for $80, same part numbers and everything but it came out of an automatic car and mine is a manual, does that make a difference??

[TibetanT]

There is no difference between the DME/ECU brains in an automatic or manual transmission. If the part numbers are the same as yours, came out of same MY 944that will work.
Good luck!

[sodakporsche944]

Originally Posted by TibetanT

There is no difference between the DME/ECU brains in an automatic or manual transmission. If the part numbers are the same as yours, came out of same MY 944that will work.
Good luck!

Thanks!!! Ordered one with the same exact numbers as mine out of a working/driving car for $93 dollars shipped, hope this works 'cause it's about my last resort.

[TibetanT]

As a caution, when you get ready to plug in the "new" brain, I would remove the ground strap from the battery negative post. Then, hook-up the brain and then put the negative battery strap back onto the negative post.

This ensures no electrical currents, or static electricity, zaps the "new" brain.

If it turns out to be the brain, and I am betting it is, send the bad brain to Florida for a check-up and repair. It shouldn't cost too much and will be a good back-up for you later in the cars life.

Hoping for good news soon!