87 5SPD- Starts out rough and sputters-update
11-22-2010, 12:02 PM
#16
Burning Brakes
Thread Starter
The WD 40 fix ( if it works) is usu temporary. I agree it's not something you do daily or long term. Disconnect #12 and spray a dose in the hose running toward firewall under the plenum. Of course immediately it should run better b/c you just introduced a flammable spray. The question is what does it do on the next start up? If it runs better, it's b/c you freed up the ISV. In a couple weeks it will stick again, but at least you have found the problem w/o removing the intake. The part used to be $165, so it's not something you want to replace w/o being sure that is the cause. There are different techniques: Spray it, let it sit an hour or over night so the lube can do it's thing. It may take a couple applications. YMMV.
11-22-2010, 12:04 PM
#17
Burning Brakes
Thread Starter
Thanks. I'm sure you will see me rolling up soon.
11-22-2010, 12:30 PM
#19
Burning Brakes
Thread Starter
11-22-2010, 10:32 PM
#20
Burning Brakes
Thread Starter
Cleaned the engine ground. Jim checked the WOT (Bad) and the throttle was stuck a little but not as bad as its been the last time it was checked a week ago.
Fired it up again and drove it back. idle was better and went between normal and 1100. Did notice when an intermittent quirk. When I floor it in most gears RPM gauge kind of held a 4500 then released and jumped to . Almost like it was stuck.
Question does the 87 have an adaptive brain? I have seen posts that say only the later models have them.
Thanks Jim for your help and support on this.
11-23-2010, 06:04 AM
#21
Rennlist Member
All 87 and later cars have LH ECUs that adapt both idle and O2 loops. A battery ground disconnect of only a second or tow will clear any adaptation paramters from the volatile memory of the LH.
Usually a car will quickly adapt it's idle speed. O2 adaptaion take some miles of driving and can have an interactive effect of idle, as the y both modify the fuel mapping to achieve their setting points.
Is the high a new problem ? You can upgrade your LH and EZK ECUs with diagnostic chips from a MY88 car, then use a tester with the required 12way lead.
Usually a car will quickly adapt it's idle speed. O2 adaptaion take some miles of driving and can have an interactive effect of idle, as the y both modify the fuel mapping to achieve their setting points.
Is the high a new problem ? You can upgrade your LH and EZK ECUs with diagnostic chips from a MY88 car, then use a tester with the required 12way lead.
11-23-2010, 10:03 AM
#22
Burning Brakes
Thread Starter
All 87 and later cars have LH ECUs that adapt both idle and O2 loops. A battery ground disconnect of only a second or tow will clear any adaptation paramters from the volatile memory of the LH.
Usually a car will quickly adapt it's idle speed. O2 adaptaion take some miles of driving and can have an interactive effect of idle, as the y both modify the fuel mapping to achieve their setting points.
Is the high a new problem ? You can upgrade your LH and EZK ECUs with diagnostic chips from a MY88 car, then use a tester with the required 12way lead.
Usually a car will quickly adapt it's idle speed. O2 adaptaion take some miles of driving and can have an interactive effect of idle, as the y both modify the fuel mapping to achieve their setting points.
Is the high a new problem ? You can upgrade your LH and EZK ECUs with diagnostic chips from a MY88 car, then use a tester with the required 12way lead.
11-23-2010, 02:15 PM
#23
Rennlist Member
Sounds to me that the idle throttle switch is mostly not working, to trigger the idle loop. You mentioned the throttle was sticking, this may be the cause of the idle problem. You should hear a click from the switch when you operate the throttle quadrant on the side of the plenum, just as you come off the closed position, and then another click as the quadrant returns to the closed postiton.
11-23-2010, 02:40 PM
#24
Burning Brakes
Thread Starter
Sounds to me that the idle throttle switch is mostly not working, to trigger the idle loop. You mentioned the throttle was sticking, this may be the cause of the idle problem. You should hear a click from the switch when you operate the throttle quadrant on the side of the plenum, just as you come off the closed position, and then another click as the quadrant returns to the closed postiton.
11-23-2010, 04:13 PM
#28
Three Wheelin'
I would in addition to Malcolm's suggestion locate the throttle horn and see if hoses #26, 27 in the picture are catching and not allowing the throttle to close.
11-23-2010, 04:33 PM
#29
Burning Brakes
Thread Starter
11-23-2010, 04:33 PM
#30
Rennlist Member