86.5 rough running above idle. low fuel pressure?
06-28-2018, 10:41 AM
#32
Burning Brakes
Thread Starter
Off the subject here a bit, I was reading another thread on here this morning and saw someone mention "DEVEK" swaybars or something. It clicked to me that the name written on my airfilter is also DEVEK. Poking around it looks like they may have made parts or done service for 928s at some point in the past. Wondered if that might lead to some history on this car.
If you zoom in you can see "DEVEK - 11/29/04" on the filter.
If you zoom in you can see "DEVEK - 11/29/04" on the filter.
06-28-2018, 12:02 PM
#33
Rennlist Member
^This.
All the MAF equipped cars have a very simple 'limp' mode where the engine will run (badly) without input from the MAF to properly adjust mixture. A MAF failure can easily be diagnosed by simply unplugging it. If it runs the same, the MAF is bad (you are already in 'limp' mode).
The 'failed ignition fuel shutoff' temp detector system is intended to detect ignition failure, where the lack of spark allows raw fuel to go down the exhaust, burn in the catalytic converter and start the bottom of the car on fire.
It shuts off half of the ignition, so the car only runs on 4 cylinders. However, the unusual combustion impulse pattern can set up a weird harmonic that can snap the torque tube shaft.
All the MAF equipped cars have a very simple 'limp' mode where the engine will run (badly) without input from the MAF to properly adjust mixture. A MAF failure can easily be diagnosed by simply unplugging it. If it runs the same, the MAF is bad (you are already in 'limp' mode).
The 'failed ignition fuel shutoff' temp detector system is intended to detect ignition failure, where the lack of spark allows raw fuel to go down the exhaust, burn in the catalytic converter and start the bottom of the car on fire.
It shuts off half of the ignition, so the car only runs on 4 cylinders. However, the unusual combustion impulse pattern can set up a weird harmonic that can snap the torque tube shaft.
Dave
06-28-2018, 02:12 PM
#34
Nordschleife Master
06-30-2018, 12:04 PM
#35
Rennlist Member
Prioritize
OCD: I understand the deferred maint. is not your history. I see a nice new 14 pin connector cover. We have now established that you have old wires and I bet equally old fuel lines. Giving you the benefit of the doubt on the 14 pin cover, maybe someone else just stuck that on there because they had one handy (yes judgement here), but with all due respect this process is about prioritizing and of course $$. It seems you should replace the fuel lines before anything else.
06-30-2018, 01:42 PM
#36
Burning Brakes
Thread Starter
OCD: I understand the deferred maint. is not your history. I see a nice new 14 pin connector cover. We have now established that you have old wires and I bet equally old fuel lines. Giving you the benefit of the doubt on the 14 pin cover, maybe someone else just stuck that on there because they had one handy (yes judgement here), but with all due respect this process is about prioritizing and of course $$. It seems you should replace the fuel lines before anything else.
06-30-2018, 03:31 PM
#37
Burning Brakes
Thread Starter
About to fire it up after the timing belt job. I was looking at the map before putting the airbox on and saw that it looks like the wiring near it has been repaired at some point. Looks like the wires going to the maf, it, and drivers side injectors.
06-30-2018, 08:36 PM
#38
Burning Brakes
Thread Starter
Still kind of lumpy, but does seem to get a little better each time it gets run. I'm letting it cool off to top off the coolant (got chased in by storms too), but later tonight or tomorrow I'm going to put some seafoam or lucas in the tank and run it a while to try and clean out the injectors.
07-04-2018, 06:08 PM
#39
Burning Brakes
Thread Starter
Drove the car around just a bit to see how it was shifting after changing the trans fluid today. I really hope it's not just my imagination, but it kind of seemed like it was running a bit smoother. Maybe it is actually clearing up some.
07-04-2018, 08:21 PM
#40
The sooner people get rid of the myth that there is a “limp home” mode on our cars the better. There isn’t one. Your ***** broke so it needs to be fixed.
07-09-2018, 04:38 PM
#41
Burning Brakes
Thread Starter
So after running a good bit of the 5 gallons of fresh gas and a can of seafoam the car seems to be running a good bit better. When it was all warmed up the stumbling was pretty much gone. It seemed much mores responsive too. Took it around the street a couple times, and then pulling back in the driveway it seemed a little rough again. Has me kind of confused again, but it being intermittent definitely makes me think something electrical. I did find a broken vacuum line in the passenger's side fender well after driving it. I think it's just an evap line, but I'm going to fix it and see if that makes any difference.