> -----Original Message----- > From: Joseph M. Mattiko [mailto:gates1@one.net] > Sent: Thursday, August 03, 2000 11:33 AM > To: 928 > Subject: [928] Help Me!!! GT running funny... > > > Hi All, > > Haven't run the car for about a week or so until last night. Get in the > car, starts ok, idle is a bit rought, runs a lot rough, has no power! > > Get up this morning, car starts ok, idle is just fine, car drives normal > for 200 yards, car looses power and runs bad again. > > Start the car at lunch, idle ok, didn't drive it. > > > From: Jim [jim@928intl.com] Sent: Thursday, August 03, 2000 5:59 PM To: 928 Subject: [928] RE: Help Me!!! GT running funny... All 89 and newer 928s have two temp sensors near the exhaust manifold on the heads -- If there is a perceived difference beyond a certain allowable amount it will shut down 1/2 of the fuel injection and the engine runs on 4 cylinders -- rough and little power about 150 hp less the drag of running the other 4 cylinders as air compressors --- these sensors feed into a relay on the LH Injection brain -The neat clear plastic one -(-now made larger and black a superceded part)part # 928 618 175 00 -" supervis. ignition circuit" As of the 1990 model the sensors were moved from the two rear most cylinders forward two the next one on each side , presumably to get more accurate readings ..It is also possible that there is a problem with one of the ignition systems and the engine is only getting spark to 4 cylinders in which case this relay is designed to shut off the injection to the effected cylinders to avoid filling the exhaust with unburned fuel and igniting the underside on the car . Driving on 4 cylinders is very stressful to the driveshaft and according to Porsche is on cause of broken driveshafts . SO once again relay problems may be at fault .. Jim Bailey 928 International jim@928intl.com 79 928 5spd 80 928 5spd 68 911 5spd From: Jim [jim@928intl.com] Sent: Friday, September 15, 2000 5:04 PM To: 928 Subject: [928] RE: Intermittent now regular power loss (long, sorry) the ignition monitoring relay formerly the clear plastic now superceded to black plastic # 928 618 175 00 tells the LH injection brain to shut down fuel to 4 cylinders -- not a bank of 4 but the 4 cylinders that receive spark from one distributor/ignition system . look at the wires coming out of one cap and note that two go to each side of the engine . your car has memory built into the LH injection brain the "Hammer " read out tool will tell overtime the car burped . If I were to guess and it is a guess it is possible that one of the ignition switch unit / final stage , located in front of the radiator , drivers side USA (on the panel that the hood latch ,latches to ) is overheating and failing . Each works with a coil to fire 4 cylinders , the two units are interchangeable , if you switch them and the engine now is shutting down the other 4 cylinders you have probably discovered the problem . It is not advisable to drive the car running on 4 cylinders unless you have a very good extended warranty -- the rough running firing 4 cylinders and using the other 4 as air compressors is a bad thing -- the driveshaft in particular finds this very offensive to be twisted and untwisted by the uneven firing . The cylinder head temp sensors are screwed into the cylinder head just below the exhaust port/manifold , for 89 models cylinder 4 an 8 for 1990 > number 3 and 7 . Jim Bailey 928 International jim@928intl.com 79 928 5spd 80 928 5spd 68 911 5spd > ----- From: Wally Plumley [wplumley@bellsouth.net] Sent: Friday, September 15, 2000 6:10 PM To: 928 Subject: [928] Re: Intermittent now regular power loss (long, sorry) At 03:52 PM 9/15/00 +0000, Rick Redpath wrote: >There is a red LED >lighting up on this relay (immediately before the engine is shutting down a >bank of cylinders?) and I'm pretty sure it is setting a trouble code, but >I'd like to try and find out what it is if I can. >Has anyone had this problem and had it solved? Does the red LED mean one >bank of cylinders shut down and a green LED the other? If so, which color >LED is right and which is left? Red LED is the right coil, cylinders 1, 7, 6, 4 Wally Plumley 928 Specialists From: Don Hanson [dhanson@gorge.net] Sent: Friday, September 15, 2000 7:00 PM To: 928 Subject: [928] Re: Intermittent now regular power loss (long, sorry) Rick, I had this problem on my 90 GT, only it was my Green relay that was lighting up, and only when the car was pretty hot. I had the car at Deveks for another problem but Jim also found the plug wires shorting, causing the relay to tell the computer that one side was miss firing, which causes that relay to shut down the faulty side. I replaced all the engine temp sensors, the plug wires, and the coils, which eliminated the problem. I have also heard you can remove the engine temp sensors and wire them out of the way, causing them both to return a similar signal, which will not alert that relay. I will say what I was told. " The relay is shutting down the motor for some reason." You should fix that reason. I think the 4 cylinders that shut down are not "one side" of the motor, rather scattered around on both sides. As a test, try running your car in the dark and look under the hood for electrical shorting. You could see mine indoors in daytime, zapping between plug wires. Good luck. I think this problem was the worst on 89-90 gt's and they might have fixed it a bit later on. It is fixable, keep after it. When right, these cars haul a**! Don Hanson