Just enough to be dangerous

Thanks Josh. Your web page is the guide he followed when doing the swap, and it is a very thorough and informative write-up, I must say. I notice you went with '92 engine management which is the same between AT & MT. For whatever reason it is not the same on the 90-91. What the differences are, and why Subaru would bother.....I would speculate as follows, (and remember I know just enough about this stuff to...make me dangerous...): 1) with AT the engine has somewhat of a load at idle 2) with MT the engine must be able to respond to much more rapid throttle changes especially backing off the throttle during gear changes as well as deal with emissions curing such conditions Whether that's right or wrong, the question before us is whether this engine, with the increased displacement and compression would run any better with the MT-specific system And I guess a question to ask first is are there other causes of poor idling, stumbe, and hesitation that we can check first

I have inherited the task of sorting out some issues with a family member's 91 Legacy, following 2 big modifications a) converted from AT to 5 speed earlier this year recently has also had short block replaced with 2.5 L, retaining existing 2.2 heads, injection, sensors, ECU etc. After driving this a couple hundred miles, it seems to run great at speed, but the idle is rather rough, with what I would call a "spitty" sound at the exhaust pipe--like rrrrrm-ppptt-rrrrrrrrrrmmm-pt-pt-rrrrrrrrrm. Also, there is a bit of stumble or hesitation when letting the clutch out in 1st gear which sometimes accentuates into a fore & aft lurching sensation The other thing I notice is that with the car warmed up when you shut it off for a while and restart, the idle speed goes up to maybe 1100, down to the lowest pt on the tach, back up again (but not as far), back down, through a couple of cycles before settling down to normal idle speed which is maybe 650 rpm. I took it to a local independent Subaru specialist who confirmed that it was performing poorly at idle, and noted that the ECU, air flow sensor, injectors, harness, and idle speed control were different between AT and MT cars in 90 and 91. These components were not changed when the transmission swap was done. The shop said we need to get the MT-specific parts in order for the engine to run right He also said the cat might be plugged Interestingly, 92 and later use the same management systems for both AT and MT I don't know if the 2.2 engine manifested these idle problems after the tranismission swap. I only drove it once, and that was on the highway, and would not have noticed any idling issues Does anybody know enough about the differences between the AT and MT engine management systems to give an opinion on whether the mechanic is on the right track? Or, given the difference in displacement and higher compression ration, is the bad idle something we just have to deal with? Thanks in advance. Mark

Well, the next morning I started it up again, drove it half way around the block and the engine died. I said "Enough of this BS" and pushed it to the closest shop with the help of my neighbor. I was a little leery of taking it there because in my past experience they have been kind of creative when writing up the bill. They always delete the questionable stuff when I call them on it, but I kind of pity their customers that don't know enough to ask questions. The shop found loose ground wires, tightened them up, and didn't try to stick me with anything. I sort of wonder if it really took an hour to track down, but what are you going to do?

Thanks Folks. I think Josh pretty well nailed it as far as being severely flooded. After a lot of cranking it finally began to fire briefly, then took several more cranks before running continuously. The behavior of the panel lights has gone back to normal too.

Early 90's Legacy, manual trans. Previously running until I did the following: Pulled the spark plugs. Disconnected the 3 pin connector to the coil unit. Did this without disconnecting the battery Ran compression test. Note that I did not disconnect the fuel injectors as the Subaru manual calls for. I was following a generic procedure, had not seen the official procedure at that point After reinstalling the plugs and reconnecting the coil unit, the engine will crank but not start. After cranking, all the trouble lights on the dash stay on even with the ignition off and key removed. These lights stay on until you disconnect the battery. The lights stay off until you crank the engine again. Any ideas or suggestions how to proceed with trouble shooting this? New to this forum, would really appreciate your help