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I have a 1986 1/2 928S and am having running and now starting issues. The symptoms are:
It was running rough, 2 X it went into lean mode (people call it Limp Mode).
When first starting, It would start and shut immediately off or,
when it did start and continue running, It would die when I put it in gear until warmed up.
I did replace the Mass Air Sensor (280-214-001) after this issue started. Now it only turns over and makes no attempt to start.
Any help brothers is greatly appreciated. I did search the thread and that appeared to be the consensus.
I did replace the Mass Air Sensor (280-214-001) after this issue started. Now it only turns over and makes no attempt to start.
These MAFs get finicky with age. Was the one you put in used from a car that was known to run, or rebuilt from one of the rebuilders that are well-known around here? If not, if you put in the old MAF, does it at least start again?
These MAFs get finicky with age. Was the one you put in used from a car that was known to run, or rebuilt from one of the rebuilders that are well-known around here? If not, if you put in the old MAF, does it at least start again?
Going to put the old one back in, it at least tried to start. The rebuilt replacement was from 928 International.
Going to put the old one back in, it at least tried to start. The rebuilt replacement was from 928 International.
Damn.
A rebuilt from Int'l should be good as gold. But still check with the old one, now I'm betting the crispy harness wiring cracked or didn't seat correctly.
A rebuilt from Int'l should be good as gold. But still check with the old one, now I'm betting the crispy harness wiring cracked or didn't seat correctly.
I removed and installed several times. There may be wires that are not fully seated, but will do my best to diagnose why old one tried to start and new one did not. Arrgh Thanks man, appreciate you.
You may have more than one thing wrong with your car.
Your injectors could have been gummed up and are just now getting enough fuel through them to allow the engine to "run" (although apparently not well)
Your temp II sensor may be bad. You can test each side of the sensor with a multimeter (each terminal individually with one lead and the other to a known god ground)
Your Crank Position Sensor (CPS) could be intermittent or just plain bad. You will not have spark if the CPS doesn't work correctly.
As Greg Brown posted, test your Fuel Pressure Regulator and fuel Dampeners. Do they hold vacuum? Does the vacuum line smell like fuel?
Your LH computer could be bad as well. If you know someone close that has an 85-86 928 that runs, ask the owner if they can put your computer into their car to see if it still runs correctly. If it doesn't, there could be something wrong with your LH computer and you can have it rebuilt.
Good Luck!
You may have more than one thing wrong with your car.
Your injectors could have been gummed up and are just now getting enough fuel through them to allow the engine to "run" (although apparently not well)
Your temp II sensor may be bad. You can test each side of the sensor with a multimeter (each terminal individually with one lead and the other to a known god ground)
Your Crank Position Sensor (CPS) could be intermittent or just plain bad. You will not have spark if the CPS doesn't work correctly.
As Greg Brown posted, test your Fuel Pressure Regulator and fuel Dampeners. Do they hold vacuum? Does the vacuum line smell like fuel?
Your LH computer could be bad as well. If you know someone close that has an 85-86 928 that runs, ask the owner if they can put your computer into their car to see if it still runs correctly. If it doesn't, there could be something wrong with your LH computer and you can have it rebuilt.
Good Luck!
The bummer thoughts that I have is the LH has crapped out. But will look at the simple and go to the complex. Replaced the Temp II 1 year ago. I will check fuel pressures. I also replaced the Fuel pump and filter 3 years ago and done 6000 miles since.
you have good suggestions to investigate. The other item (also related to fuel) is there is some kind of sensor that enriches the fuel when the care is cold (like a choke). IN PA during winter, I use to stall in the cold when I stepped on the fuel when it was cold.
Do you have the CD with all of the scans of the factory service manuals? We're lucky that there's one in there that's specifically for us, the '85 Test Plan for EZF Ignition and LH-Jetronic (same kit for '86es). If you work your way through that, you should be able to rule out everything else before thinking about replacement brains.
The bummer thoughts that I have is the LH has crapped out. But will look at the simple and go to the complex. Replaced the Temp II 1 year ago. I will check fuel pressures. I also replaced the Fuel pump and filter 3 years ago and done 6000 miles since.
you have good suggestions to investigate. The other item (also related to fuel) is there is some kind of sensor that enriches the fuel when the care is cold (like a choke). IN PA during winter, I use to stall in the cold when I stepped on the fuel when it was cold.
Thanks man
The LH in the 86.5 is pretty robust. I would look elsewhere first. It's possible, but I would test other systems first, and before replacing anything else.
I do have the CD and will peruse through it before any computer replacement. Doing the simple first Fuel, Air Spark.
Where is the Port located for the 86 1/2 928S? The Manual shows the 928 S 4 connector. I don't recall if there is an OBD II port for the 86 1/2, is there?
I do have the CD and will peruse through it before any computer replacement. Doing the simple first Fuel, Air Spark.
Where is the Port located for the 86 1/2 928S? The Manual shows the 928 S 4 connector. I don't recall if there is an OBD II port for the 86 1/2, is there?
I recently had the shop do a belt service (first time I let someone do it). Also had them replace a vacuum for the vents which are under the Air Box. Not their fault.
The 3 pin connector was brittle and crumbled in my fingers. I plugged in just the connectors and the car fired up. I am going to by a 3 pin connector and replace the plug. Does anyone know what the 3 pin Porsche connector part number is? If not, I will just get once from my local parts store and splice it in.
Alternatively, just give Roger or Mercedes of 928srus.com a call, they sell the connectors, as well as a lot of other stuff you're likely going to need including genuine Porsche parts and appropriate aftermarket replacements.
Umm NO, you don’t replace the connectors on the CPS
you replace the sensor.
Replace with a Bosch part.
NOTE based on this picture you might also need the TPS short harness and fuel lines
Roger sells them get the MAF rebuilt as well.
Note all of this usually means it’s time for an intake refresh
Umm NO, you don’t replace the connectors on the CPS
you replace the sensor.
Replace with a Bosch part.
NOTE based on this picture you might also need the TPS short harness and fuel lines
Roger sells them get the MAF rebuilt as well.
Note all of this usually means it’s time for an intake refresh
I was thinking that refresh in the summer. Whole top half.
01-09-2023, 02:54 PM
No Start for 928S
