Throw a vacumm gauge on it and check the vacuum at idle. If the idle is eighteen inches of vacuum then the mechanical side of things are good. If t's sixteen then it's borderline and you can expect problems starting occassionaly, decreased performance and economy.
Check all the small hoses.
Check the temp sensor, the throttle position sensor, the air flow sensor, the map sensor as per the manual.
Help with reading plugs..
Moderators: Helpinators, Moderators
Ok, since we haven't been able to log data yet, lets try checking the timing isn't being retarded by knock. If it's a manual you can just go out and load up the motor in a high gear and see how it pulls, then, disconnect the knock sensor and drive it the same way as a minute ago and listen for knock. If you have knock on the second run then the sensor was doing it's job on the first run. So... if the sensor was doing it's job it could have been retarding timing. To see if that is your problem try coaxing the revs and throttle up without causing knock. Keep an eye out for the black smoke and take note how it goes. If you can coax it up to full throttle and high revs without the smoke or knocking then the timing getting retarded could well be your trouble right from the start.
The other think I can think of that you can test fairly easily is a blocked muffler. I know you reckon the cat's ok, and they are usually where blockages happen but the rear mufflers can shed baffles and block things up as well.
The next test is for a blocked muffler. Put the vacumm gauge on and warm up the motor. Watch the vacumm as you start to open the throttle at a stand-still, if you open the throttle fastish the vacumm will drop for a second until the air gets flowing then it should rise to about twenty-two/twenty-four inches of mercury at about 1500-2000 revs, keep opening the throttle and take it up to about 4500 revs and the vacumm should stay steady, if it falls off significantly, and especially if it falls off quickly once it has started to fall and as you keep increasing revs/throttle then you have got a blocked muffler. To confirm that you really need to disconnect the catylitic converter(just because that isolates the whole system), and swing it to one side then, either try again with the gauge or, even better, go for a quick midnight blat and see if the car goes better.
The other think I can think of that you can test fairly easily is a blocked muffler. I know you reckon the cat's ok, and they are usually where blockages happen but the rear mufflers can shed baffles and block things up as well.
The next test is for a blocked muffler. Put the vacumm gauge on and warm up the motor. Watch the vacumm as you start to open the throttle at a stand-still, if you open the throttle fastish the vacumm will drop for a second until the air gets flowing then it should rise to about twenty-two/twenty-four inches of mercury at about 1500-2000 revs, keep opening the throttle and take it up to about 4500 revs and the vacumm should stay steady, if it falls off significantly, and especially if it falls off quickly once it has started to fall and as you keep increasing revs/throttle then you have got a blocked muffler. To confirm that you really need to disconnect the catylitic converter(just because that isolates the whole system), and swing it to one side then, either try again with the gauge or, even better, go for a quick midnight blat and see if the car goes better.
it's impossible on the N/A to remove the cat since it's integrated into the Manifold Y pipe 
. I held revs last night on the vacuum gauge at about 3K rpms, and it was steady. Muffler is aftermarket (thrush turbo muffler) as the OEM was rotted most away. Secondary Cat was removed.
I drove around with the KS unplugged the other day, and didn't hear any knock. I laid into it a couple times (close to WOT), and it still smoked.
I've since then put a new OEM cam sensor in it, and the KS wire was fixed (a day before I did the test). I need to do a hard reset of the ECM to reset it, and re-check. From visually looking out the window, it seems to have gotten a lot better. Where it did it the worst was driving 70mph, then laying into it to pass someone. Like I said it's a bear to test anythign like this on second shift, because at 12am I can't see smoke from the back of my car :..
. I held revs last night on the vacuum gauge at about 3K rpms, and it was steady. Muffler is aftermarket (thrush turbo muffler) as the OEM was rotted most away. Secondary Cat was removed. I drove around with the KS unplugged the other day, and didn't hear any knock. I laid into it a couple times (close to WOT), and it still smoked.
I've since then put a new OEM cam sensor in it, and the KS wire was fixed (a day before I did the test). I need to do a hard reset of the ECM to reset it, and re-check. From visually looking out the window, it seems to have gotten a lot better. Where it did it the worst was driving 70mph, then laying into it to pass someone. Like I said it's a bear to test anythign like this on second shift, because at 12am I can't see smoke from the back of my car :..
1992 Legacy LS Special Wagon..
Well the only other simple thing I can think of is to get the fuel pressure regulator tested.
If that's ok, you could have something like one leaky injector running rich, causing one cylinder to be down on power, and at the same time making all the other injectors work overtime trying to keep the power up.
if it was a leaky injectro though the O2 would probably set a code. But then for that matter I would have expected anything causing black smoke to set an O2 code so who knows.
Have a read up and try getting that cable to go. On that other site they recommend using an Opamp, but in my experiance those little buggers are hellishly sensitive to any sore of interference... even breathing on them can cause them to switch. I don't really know if opamps are a viable option for the average home-handyman.
Good luck and I'd be interested to hear how you get on.
If that's ok, you could have something like one leaky injector running rich, causing one cylinder to be down on power, and at the same time making all the other injectors work overtime trying to keep the power up.
if it was a leaky injectro though the O2 would probably set a code. But then for that matter I would have expected anything causing black smoke to set an O2 code so who knows.
Have a read up and try getting that cable to go. On that other site they recommend using an Opamp, but in my experiance those little buggers are hellishly sensitive to any sore of interference... even breathing on them can cause them to switch. I don't really know if opamps are a viable option for the average home-handyman.
Good luck and I'd be interested to hear how you get on.
I've got a spare ECM coming this week to swap out to see if I can get better communication. I've tested the FPR with vacuum on and off, and it's functioning as it should. I'd have to pull the injectors but the fuel system seemed to hold pressure for quite some time after shutdown.
1992 Legacy LS Special Wagon..
I played this game on my Roadmaster for 1.5yrs trying to figure out a cold start issue it had. Everything (because it was my summer only car) had been replaced by OEM sensors. I was constantly checking this and that, logging this and that. I swore up and down it couldn't be the optispark I put on a year before.
Well that was the last thing I finally looked at (have take water pump and balancer off to change) and low and behold, moisture somehow got in it, and rusted the opti sensor disc!
Well that was the last thing I finally looked at (have take water pump and balancer off to change) and low and behold, moisture somehow got in it, and rusted the opti sensor disc!
1992 Legacy LS Special Wagon..
NEW ECU is in today. Old one was covered in dirt. Mainboard has all sorts of dirt all over it, so I will clean it. new ECU ends in 932, whereas the stock was 930 (both superceeded by 933). Will not know if no start issue is resolved until it either happens again or it doesn't. Still getting no ID from Dump, and when logging (picks up as 92 N/A) still is dropping data.
I'm going to shorten wires and get a USB extension cable to bring the converter closer to the plug.
I'm going to shorten wires and get a USB extension cable to bring the converter closer to the plug.
1992 Legacy LS Special Wagon..