Argh yet again... misfire over 5000rpm
09-29-2014, 08:50 PM
#121
Nordschleife Master
Thread Starter
Attached are the pics of the fuse panel connection. Pretty simple.
Put about 100 miles on the car today after I swapped in my spare caliper. (On a side note, I think I might really have a problem. Caliper leaking? No prob, I'll just dig out my spares..... My wife looked at me last night and said, "You have SPARE brake calipers?!?" Like I said, I think I have a problem...)
So anyways, 100 miles or so. No misfires. Actually ran great. 80 degrees outside. Stuffed my rear wheels in the hatch and ran it down to a buddy's shop for new rear tires... DE this weekend (woo-boo!)
But I noticed I have low vacuum at idle now. It used to be 17-18, now it's 13-14. I disabled the ICV and it struggled to hold 500 no matter where I set the idle screw. Makes boost fine, AFR's are right where they should be... just odd. Seems like some sort of vac leak (?) I'll have to do a pressure test later this week (and comb the RL archives). Kinda sick of working on it, happy it's running as good as it is, just going to enjoy it for a little while.
Thanks everybody for the long term efforts to help. Special call outs (not in any special order) to Shawn, Sid, Chris, Tom - this is what RL is all about!
Put about 100 miles on the car today after I swapped in my spare caliper. (On a side note, I think I might really have a problem. Caliper leaking? No prob, I'll just dig out my spares..... My wife looked at me last night and said, "You have SPARE brake calipers?!?" Like I said, I think I have a problem...)
So anyways, 100 miles or so. No misfires. Actually ran great. 80 degrees outside. Stuffed my rear wheels in the hatch and ran it down to a buddy's shop for new rear tires... DE this weekend (woo-boo!)
But I noticed I have low vacuum at idle now. It used to be 17-18, now it's 13-14. I disabled the ICV and it struggled to hold 500 no matter where I set the idle screw. Makes boost fine, AFR's are right where they should be... just odd. Seems like some sort of vac leak (?) I'll have to do a pressure test later this week (and comb the RL archives). Kinda sick of working on it, happy it's running as good as it is, just going to enjoy it for a little while.
Thanks everybody for the long term efforts to help. Special call outs (not in any special order) to Shawn, Sid, Chris, Tom - this is what RL is all about!
09-29-2014, 09:14 PM
#122
I don't know what's more impressive:
1- you solved the problem. ( nice work) I hate electrical problems.
2- you had a spare caliper or
3- your wife seems to have a good idea of what a caliper is
I vote for 3
1- you solved the problem. ( nice work) I hate electrical problems.
2- you had a spare caliper or
3- your wife seems to have a good idea of what a caliper is
I vote for 3
09-30-2014, 03:28 AM
#125
Three Wheelin'
Nice going, Jim.
Well, you could have fooled me, not that I saw your B+ wire routing in person but it seemed far away enough from everything per your description. It just goes to show how carefully everything is planned out at the factory, and that decades-later aftermarket modifications and wiring are not taken into account.
The founder of my shop also has an '86 951, and he had long cranking issues for ages until he got around to installing that updated speed/ref sensor bracket per the old school factory TSB. My 8/85 production car has never had such issues, and I don't know if it is installed or not.
In either case, try to enjoy a track event or two before you get snowed in!
Well, you could have fooled me, not that I saw your B+ wire routing in person but it seemed far away enough from everything per your description. It just goes to show how carefully everything is planned out at the factory, and that decades-later aftermarket modifications and wiring are not taken into account.
The founder of my shop also has an '86 951, and he had long cranking issues for ages until he got around to installing that updated speed/ref sensor bracket per the old school factory TSB. My 8/85 production car has never had such issues, and I don't know if it is installed or not.
In either case, try to enjoy a track event or two before you get snowed in!
09-30-2014, 10:12 AM
#126
Attached are the pics of the fuse panel connection. Pretty simple.
Put about 100 miles on the car today after I swapped in my spare caliper. (On a side note, I think I might really have a problem. Caliper leaking? No prob, I'll just dig out my spares..... My wife looked at me last night and said, "You have SPARE brake calipers?!?" Like I said, I think I have a problem...)
So anyways, 100 miles or so. No misfires. Actually ran great. 80 degrees outside. Stuffed my rear wheels in the hatch and ran it down to a buddy's shop for new rear tires... DE this weekend (woo-boo!)
But I noticed I have low vacuum at idle now. It used to be 17-18, now it's 13-14. I disabled the ICV and it struggled to hold 500 no matter where I set the idle screw. Makes boost fine, AFR's are right where they should be... just odd. Seems like some sort of vac leak (?) I'll have to do a pressure test later this week (and comb the RL archives). Kinda sick of working on it, happy it's running as good as it is, just going to enjoy it for a little while.
Thanks everybody for the long term efforts to help. Special call outs (not in any special order) to Shawn, Sid, Chris, Tom - this is what RL is all about!
Put about 100 miles on the car today after I swapped in my spare caliper. (On a side note, I think I might really have a problem. Caliper leaking? No prob, I'll just dig out my spares..... My wife looked at me last night and said, "You have SPARE brake calipers?!?" Like I said, I think I have a problem...)
So anyways, 100 miles or so. No misfires. Actually ran great. 80 degrees outside. Stuffed my rear wheels in the hatch and ran it down to a buddy's shop for new rear tires... DE this weekend (woo-boo!)
But I noticed I have low vacuum at idle now. It used to be 17-18, now it's 13-14. I disabled the ICV and it struggled to hold 500 no matter where I set the idle screw. Makes boost fine, AFR's are right where they should be... just odd. Seems like some sort of vac leak (?) I'll have to do a pressure test later this week (and comb the RL archives). Kinda sick of working on it, happy it's running as good as it is, just going to enjoy it for a little while.
Thanks everybody for the long term efforts to help. Special call outs (not in any special order) to Shawn, Sid, Chris, Tom - this is what RL is all about!
09-30-2014, 01:32 PM
#127
Nordschleife Master
Thread Starter
Nice going, Jim.
Well, you could have fooled me, not that I saw your B+ wire routing in person but it seemed far away enough from everything per your description. It just goes to show how carefully everything is planned out at the factory, and that decades-later aftermarket modifications and wiring are not taken into account.
The founder of my shop also has an '86 951, and he had long cranking issues for ages until he got around to installing that updated speed/ref sensor bracket per the old school factory TSB. My 8/85 production car has never had such issues, and I don't know if it is installed or not.
In either case, try to enjoy a track event or two before you get snowed in!
Well, you could have fooled me, not that I saw your B+ wire routing in person but it seemed far away enough from everything per your description. It just goes to show how carefully everything is planned out at the factory, and that decades-later aftermarket modifications and wiring are not taken into account.
The founder of my shop also has an '86 951, and he had long cranking issues for ages until he got around to installing that updated speed/ref sensor bracket per the old school factory TSB. My 8/85 production car has never had such issues, and I don't know if it is installed or not.
In either case, try to enjoy a track event or two before you get snowed in!
As for the updated bracket... I *did* have the occasional "kick back" yesterday, even WITH the updated ref sensor bracket. Just not nearly as pronounced.... and certainly much less frequent. For now it's just worth dealing - pulling that bracket SUCKED, and in the event I ever have to pull the bellhousing, I don't want to pull that damned bracket again. Leaving it slotted!
Snow isn't too far away, though I'll usually put the car away well before the first snowfall. My general rule is I'll drive the car until the first "salt", which is usually late October or early November. (They throw salt down on the roads when it gets wet and cold enough to freeze...) PCA's last track event of the year is this coming weekend, and (weather permitting) two other local tracks usually have an open event or two towards the end of October. I've barely driven the car at all this year, so hopefully I can get out there a bit.
I'm a little paranoid over this low vac/low idle thing... hopefully it's something simple. I'll do a pressure test tonight to see if I can find any leaks. Wondering if I've somehow got an intake gasket out of place or something, since I DID have good idle and idle vacuum before I pulled the intake manifold. For sure all the accessory stuff that runs off of vacuum (FPR, damper, MAP sensor, BOV) all *hold* vacuum just fine as tested with my MityVac so it's gotta be something else.
I don't recall off the top of my head. It's in the service manual - vol 4. electrical. Start around page 175 in the PDF.
09-30-2014, 06:58 PM
#129
Nordschleife Master
Thread Starter
There was a TSB out on it. (Attached) I found the TSB here on RL.
The difference between the two brackets is that the later bracket has a sheath that the reference sensor (one closest to the block) slides in to, that's pretty much the length of the entire sensor.
10-01-2014, 03:39 AM
#131
Rennlist Member
10-06-2014, 12:52 PM
#133
Nordschleife Master
Thread Starter
Well... car ran great all weekend! I think it's safe to call it "resolved". Wish it ran this well when I was at Laguna earlier this year!
Managed to knock .64s off my personal best from a few years ago at Blackhawk Farms (local track) and took BIG chunks off my consistent laps (probably 1-1.5s on average). Honestly I'm not sure how I squeaked out my old best lap based on how much better the car feels now....
Found myself up into the rev-limiter a few times exiting a few corners - car is happy to keep revving (and revving cleanly!)
The last session of the weekend, they relax the passing rules a bit in the Black group
and we get an hour-long session vs. the usual 30... good times were had. I'll have video eventually, going to take me a while to pick through it all. Had a couple good inside moves
Running on 180TW street tires held me back against all the other guys on Hoosiers.... had to use the HP to pull around folks LOL!
Managed to knock .64s off my personal best from a few years ago at Blackhawk Farms (local track) and took BIG chunks off my consistent laps (probably 1-1.5s on average). Honestly I'm not sure how I squeaked out my old best lap based on how much better the car feels now....
Found myself up into the rev-limiter a few times exiting a few corners - car is happy to keep revving (and revving cleanly!)
The last session of the weekend, they relax the passing rules a bit in the Black group
and we get an hour-long session vs. the usual 30... good times were had. I'll have video eventually, going to take me a while to pick through it all. Had a couple good inside moves Running on 180TW street tires held me back against all the other guys on Hoosiers.... had to use the HP to pull around folks LOL!
09-10-2022, 11:59 AM
#134
Advanced
Just wanted to resurrect this thread to let you know that your documentation of your issue allowed me to solve the same issue without pulling my hair out or burning the car to the ground. I don't know how I would have found this solution if not for this thread.
In my case, I pulled the engine to do a full reseal. Since it was out, I did the Nissan Quest alternator mod. When putting it back in, I completely forgot how the alternator wire was routed from factory, and the Nissan alt is physically shorter than the old Bosch one, which makes the stock wiring a little bit too short.
I was stuck in a loop of my mechanic saying it's the tune, my tuner saying it's the car before I found this thread. I ziptied the alt wire to the firewall and ziptied the sensor wires away and now it revs cleanly. Thank you!
In my case, I pulled the engine to do a full reseal. Since it was out, I did the Nissan Quest alternator mod. When putting it back in, I completely forgot how the alternator wire was routed from factory, and the Nissan alt is physically shorter than the old Bosch one, which makes the stock wiring a little bit too short.
I was stuck in a loop of my mechanic saying it's the tune, my tuner saying it's the car before I found this thread. I ziptied the alt wire to the firewall and ziptied the sensor wires away and now it revs cleanly. Thank you!