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- #21
Judder on acceleration at 2k rpm, where to start?
- Thread starter Jeff Elliott
- Start date
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- #22
Thanks again @Malleus for the snip on the IAC. I tried starting it up again today and plugged the vacuum going to the brake booster (which I suspect is going bad) to isolate that variable. She ran perfectly for 3 min and 24 sec and until achieving 124 degrees temp... then it was rough running as it was last time. Based on this, sounds like I need to dive into that throttle body as you suggested.
One question - the FSM says to sequentially ground s1 - s4 and then reverse the procedure... do they mean ground S1 then S1+S2 then S1+S2+S3 and so on OR do they mean ground S1 then S2 and so on?
One question - the FSM says to sequentially ground s1 - s4 and then reverse the procedure... do they mean ground S1 then S1+S2 then S1+S2+S3 and so on OR do they mean ground S1 then S2 and so on?
One pin at a time. In the correct sequence.
It's a stepper motor, which means powering each terminal one after the other will rotate it an equal step/amount each time.
The sequence needs to be correct, so the next terminal for motor windings is making contact
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- #24
Thanks! Do I really need to drain the coolant or can I just clamp off that No 2 water bypass hose? Been a while since I hat the throttle body off and I don't remember if I did it sans coolant or no.
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- #25
Well, I didn't drain the coolant and the turbo did indeed put up a fight but I got the throttle body out. Pulled the IAC and followed the procedure in the FSM - she's not moving at all. Guess I'll be buying one of those tonight. Thanks for the help all!
Jeff, sorry for not getting back to you earlier. Before you throw cash at it, at least try to unstick it. Open the case and clean the gunk out of the bore. You can't hurt it at this point, but be careful because I suspect it'll move again once it's clean.
There's a good write up with photos here.
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- #27
Thanks @Malleus. Read your post on the write up... didn't realize total movement was ~1mm. Gonna go back and retest before opening it up as I was expecting something more dramatic. Will report back.
Movement is kinda hard to see
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- #29
Ok, it didn't appear to be moving based on the caliper but the movement is so minimal I could have missed it. Took it apart, polished the stator as @Malleus suggested and put it back together. It does move but <1mm based on the caliper. However, I found this guy upon reassembly rattling around in the rotor housing that I didn't find when I disassembled it... any idea where this thing goes? I know it looks like one of those 45 rpm record spacers but it's too small for that 
Jeff, it goes under the piston
this is the third (last) photo in the link (post #2) I posted above. I think it functions as an anti-rattle device.
this is the third (last) photo in the link (post #2) I posted above. I think it functions as an anti-rattle device.
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- #31
Well, put it back together today and I don't think it's the IAC... I have high idle but its running rough and it's running lean - like 18-19 at high idle when it's supposed to (and consistently has been before all this started) at 14.7. I guess the next step is to look for vacuum leaks and pull the plugs to see if I've got a lean condition in a cylinder. As always, any suggestions are appreciated!
Try unplugging the EFI fuse for 37 seconds or so, then drive it. Park it, drive it.
The ECU will reset some parameters after a few drive cycles.
AND look for vacuum leaks.
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- #34
Haven't had time to work on her this week as I've been out of the country. Got to thinking... The o-ring was looking mighty flat and I didn't replace it - just reused it. I haven't been running nearly this lean before taking the throttle body off and now I am. @Malleus did you reuse or replace yours? Going to fire her up again and spray some carb cleaner in the direction of the IAC and see if she revs...
I can't remember; I'd have to look at my records. As cheap as it is, I'd bet I replaced it.
I do remember cleaning the throttle body, though. The IAC control passage was choked badly. I have a quart of Carbon-Off on the shelf now, for general schmutz removal. It's the best.
I bought mine from webrestaturantstore.com, which was the only place I could find it at the time, but apparently the secret's out.
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- #36
Got the plugs out... something definitely going on with the #6 plug - looks completely different than the others. Wires are relatively new so can't imagine that's the issue but they aren't OEM so I guess it's possible. My plan (unless you guys can advise me of a better one) is to put these back in and switch the #1 plug for the #6 plug. That should at least tell me wire or cylinder vs plug.
Just doesn't make sense as, upon start up and on high idle, it's a smooth running motor. After a couple of minutes, it's anything but. As always, any advice is appreciated!
Plugs 1-3
Plugs 4-6
#6 up close
Just doesn't make sense as, upon start up and on high idle, it's a smooth running motor. After a couple of minutes, it's anything but. As always, any advice is appreciated!
Plugs 1-3
Plugs 4-6
#6 up close
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- #37
Well, I can't believe it, but it was that pesky #6 plug which is <3K miles old. I moved it to the #1 cylinder and it still ran like crap so I kept trouble shooting with no success. Through several restarts, it threw a misfire code on #1 (P0301). Bought a new plug and she runs smoothly as she used to. I wonder what killed that plug or if it was defective from the start? I tested resistance and it tested the same as the other plugs.