rich07

Fellow 928ers I need your help! I have an 82 auto 928, I’ve had some excellent advice in the past and need your help again.
When starting the car from cold it runs very rich, as the exhaust is covered in black smoke and continues to pump black smoke until it has been driven for approx 20 minutes. Also if you try to give the car any stick over 2000 rpm the in the first 20 minutes the car will have total power lost as if someone has turned the ignition off, if you take your foot of the accelerator pedal then the car with resume to drive o.k under a certain rev range. Also the idle is up and down like a prostitutes knickers. These symptoms are all present in the first 20 minutes of use and the car seems to drive o.k after this time has elapsed but still has a slight lost of power.

Any ideas…..
I was thinking about maybe the cold start injector could be at fault, has anyone had any problems with this sticking? If so, where is it located…..

John Struthers

Rich07,
Pig indeed!
I'll assume you have a Euro...
1. When your ailing sHARk warms up and settles down check the timing see Wally's suggestion on the timing post on this page.
Before timing at 3000rpm as per Wally and Porsche. Hook up timing light if the mark is jumping -idle won't stabilize enough for a clear, solid adjustment-. Check vacuum line at dist. and for that matter any Vac. line in the ignition/fuel loop.
If you have a Euro you don't have the Cat., O2 sensor, smog/air pump problems which eliminate a bunch of checks.
If you are blowing that much fuel out the tailpipe in the form of black smoke your plugs are probably fouling a bit by now.
Check the plugs and do the after dark plug wire arc check. Check the cap and rotor as well.
At this point, other than a intermittent coil problem which usually shows up after warm up and at mid and high rpm range - when it's working harder - you have gone thru the easy part of the ignition checklist.
There might be something in the cold start portion of the list -Temp sensor that is dead for instance- check connections first, that may keep you in a open loop rich condition.
The cold start injector could be sticking, but I don't think that alone would be giving you those symptoms. After the ignition stuff, and vacuum checks I'd start with the Temp II sensor, Thermo-time switch, then fuel pressure regulator and Dampner.
You haven't mentioned a real problem on starting just the rich condition...
One last thing clean and snug ecu connectors and spray some cleaner and lube throttlebody linkages and cables - something might be sticking there.
Check the Nichols site, a great place to discover similar glitches and repairs.
If no cure keep asking until a Guru has time to respond, O.K.?
HTH,
John S. 82', Weissach, auto, 'Pattycakes'
Oops: <a href="http://nichols.nu/tips." target="_blank">http://nichols.nu/tips.</a>

WallyP

Check the Temp II sensor resistance readings.

Unplug the Cold Start Valve and see if that changes things.

tobinr

Check the Mass Airflow Sensor. I had to replace mine recently. The reostat that measures the flapper door position wears out in spots. My 928 ran very rich until it was replaced. Seems as though yours is similar in vintage to mine. Now I easily pass the tough emmissions test in Houston. The yearly emmissions check now requires that the car be put on a portable chassis dynomometer and run at speed. It is amazing that the 20 year old Porsche's emmissions are still in the bottom 5% of allowable emmissions.

It was kind of funny, when I took my car for the emmissions check I was the 5th car in line. The tester immediately moved my car up to the front of the line. As I sat inside, I heard my engine revving, tires screeching, several times, as he was supposed to be checking the brakes. I have just never heard that from any other cars that were being checked....

rich07

Thanks everyone for the help so far…..me and my mechanic friend have found a few problems that would definitely make a big difference when resolved.

1. Cold start valve (not sure of exact name) this should open and close depending on the temp of the engine, to increase or decrease air flow. This is working when 12 volts is applied. But there is no power at the connector, which suggests a break in the wire.

2. Air leak which is causing the idle to hunt (idle is going up and down)

These things are fairly easy to fix and I’ll sort them out this weekend but there must be another fault that we have not yet found which is causing the car to break down when ever any load is applied (after 3000rpm approx). This fault is still apparent even when the car has warmed up.
John did mention a possible faulty coil which we looked at, when testing the coil the readings we got did not match the ones from the manual and indicated that the resistors that run in line with the coil were either faulty or not giving the correct resistance, or the information in the manual is not for my model/year of car. Does anyone have an 82 euro 928 4.5 and could give me a sample of the resistance measured on the coil and from the two resistors that run in line with the coil? Or any other ideas? cheers

Mikey Mason

OK...you asked for advice here..No shark pro on troubleshooting but my advice is become a paying member and SUPPORT rennlist by becoming a paid member!You won't regret it and is much needed to keep this forum topnotch!

Michael

WallyP

You might get better responses without the derogatory "fat pig" comments. Most of us own 928s because we like them. I don't consider either of mine to be "fat pigs".

Mike LaBranche

On the other hand, I call my 928's 'pigs' all the time. I alternate that with 'beast' depending on the current maintenance to-do list or lack thereof. The 84 is leaking fluid at both ends and needs another week up on stands. It's a pig right now. The 78 is absolutely stunning at the moment. It's a beast. I also sometimes call my wife the 'rev-limiter' and her presence has saved a lot more than engines since we've been married. At any rate, I'm pretty sure we're all here because we love these cars. I know I am regardless of what anybody calls their 928.

User 4221

I think it might be the dry British humor (humour)

Sorry..... Couldn't resist.

Scott

rich07

Sorry, I luvvvv my 28.... it’s the sexiest motor end of story, it's called my 'fat pig' because 'fat' in the u.k is slang for cool or amazing, so if you see a Ferrari or a 928 you would might say that's 'fat', and pig because some people in the u.k refer to Porsches as porkers, or a pig. So don't take offence I love my porker just as much as you guys...anyway how about some help???

ViribusUnits

It could be any number of things.

I'm currently trying to trouble shoot a rich idle problem, but no where near as rich as yours!

Well, first, do you have the Euro w/ the K-jetronic, or the US with the L-jetronic? It makes a HUGE diffrence in trouble shooting the fuel system...

Since your in England, I'm willing to bet you've got the Euro w/ the K-jetronic. If so, all of the help the other folks have tryed to give you is pretty worthless. It's cool for a 82 US, but not the Euro.

I'm lusting to buy my neibor's wrecked 79 Euro, and did a look into trying to figure out what would need to be fixed to get her running again. As a result I have LIMITED experence with the K-jetronic. LIMITED is the key word.

First if I was you, I'd try to get a copy of the service mannauls. Failing that, I'd ask someone on the board for a copy of the relevent pages.

Second, I'd get a fuel pressure tester kit. If your useing a mechenic, they should have both of these.

A bit of termanology, just to get us on the same feet.

The valve that lets extra air by the throtal, raseing the idle when the engine is cold is called the "Throtal By-pass Valve" or on US cars, the "Aux. Air Valve"

The 9th fuel injector that adds fuel to the intake before it splits off to the runners is called the "cold start valve"

The "warm up regulater" is the boxy, kinda retangular thing that sits on the top frount of the engine. It always seems like it doesn't belong to me. It's got two vacume lines going to it, and two (steel?) fuel lines going to it. It controls if the cold start injector gets fuel or not.

I'd start by going after your warm up regulater. There are several things that I know can go wrong with a warm up regulater. It's basicly the K-jetronic's version of a Thermo-time sensor. It seems like it not cutting of in time, and nearly flooding the engine with fuel.

One your car, the first thing I would do, since you've already told me that your aux. air valve isn't getting current, I'd check to see if your warm up regulater is getting current.

If not, you MIGHT have found your problem. The aux. air valve, and the warm up regulater are suppost to be on the same electrical circut. I belive they are supplyed with power from the Fuel Pump Relay XVII, plug 87. That plug also provides power for the fuel pumps, so the relay and relay plugs are probably good.

The aux. air valve, and the warm up regulater, are supplyed by power from plug Q1 from the bottem of the fuse pannal. The connecters are hand lettered A B C D... starting from the left, going to the right. I belive the wire is red and white. It is possible that connecter Q1 isn't makeing a good contact. The next connecter to check is T14, plug 7. T14 is suppost to be located on the right of the engine bay. I belive it it a 14 plug connecter. Make sure it's getting power to plug 7, and that it also makeing good contact. Again, I belive it's a red and white wire.

Rember, my experence with the system is based on my reading of a 79 US wireing diagram, and my experence with a NOT RUNNING 79 Euro. Your milage may vary.

btw, check your privet messages. (through your profile.)

///Edited nm, I don't seem to be able to sent you a PM. How about droping me a line. chanzik@yahoo.com///