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The Saab we are working with is an 87' 900 turbo (LH2.2 fuel system) which has had a continuing ‘hunting’ idle problem. I have adjusted and replaced just about every thing I could think of that might cause this problem (O2 sensor, NTC sensor, tested and adjusted 2 different AMMs, clean and swapped 2 dif AIC valves) I even tried soldering a resistor inline with the temp sensor like some one on this board had suggested, but the problem is still persistent. When I start the car with a cold engine it idles steady for a minute then begins to rev up spastically and will stall if we try to drive it immediately. After the engine warms up the idle problem stops, but you can tell that something is not right in the way she drives (kind of hesitant, maybe burning lean due to incorrect sensor readings. I’m not sure how to describe it.)
Anyway, so today we decided to check out the wire harness to the ECU and test to make sure all the correct values are reaching the emissions computer. Using the Robert Bentley Saab 900 16valve service manual ‘85-‘93 and a digital multimeter I started testing and noticed that I could not get proper readings (or any readings) on any of the tests. So looking further into the problem I opened up the harness connector and noticed, by color code, that all the wiring is backwards from what it says it should be in the Bentley manual. See page 240-19 and 240-20 of the fuel injection section and note that on page 240-20 it says that for testing control unit grounds you test from pins 18 and 5, 18 and 11, 18 and 25 and you should get 12Volts DC for each test. But when I inspected the inside of the connector I found the reason I was not getting a 12V reading was because the ground wire for pin 25 was in the place of pin 14 and visa versa (see Fig 26 of page 240-19) I then realized that the whole wire harness was wired backwards from what it says in the Bentley book.
Now. Is this a Bentley misprint? Or is our car seriously messed up? I tested the sensors by reversing the Bentley instructions and all the sensors test okay. What is causing this cold start problem? We have been trying to fix it for months now and I am beginning to think it is a curse. Can anyone comment on this strange situation? HELP ME LH2.2 GODS!!!
posted by 12.224....
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