951Dreams

Recently I've gotten the car pretty sorted out, and started turning my attention to bad running just after being started. It's the worst when it's cold, but does it when warm as well. Have a whole thread about it in the main forum. Part of the troubleshooting was to get the idle set correctly. During the process I found I didn't have a "throttle body adjustment screw", but instead a bolt in the adjustment hole on top of the TB. Ordered up a new adjustment screw and got it in the other day.

New screw started threading in, then got stuck. I mangled it all to heck trying to get it back out. The "nut/screw slot" on top broke. Man, these things are soft. I was able to get it out with some needle nose plyers and a lot of cussing. Took the bolt the PO had used, and the new adjustment screw, up to Lowes to use their "bolt size/thread pitch" testing... thing. The stock screw is a M8X1.0 thread pitch, the bolt the PO used was M8X1.25. Well, now I knew why the adjustment screw got stuck! PO had mangled the threads with an incorrect bolt. I bought a set of correctly threaded bolts at Lowes with the idea of at least trying to repair the threads.

With lots of patience, some oil off the dipstick, and a healthy share of luck, I got the threads repaired without totally stripping them out. The M8X1.0 bolts would screw in by finger after a lot of careful work. There seems to be a lip or stop on the bottom side of the hole in the TB for the screw that stops the bolt from going all the way through. I cut a new slot in the mangled adjustment screw with my Dremel and tried to reinstall it. It ends up binding about the same place it did the first time. And it's not as far down as I think it should be able to go. The bolt threads all the way down fine. And the adjustment screw does not get stuck anymore, and I can easily remove it now. It just stops before I feel it should.

The main reason I don't think it's screwing in as far as it should? Screwing it in until it stops, and screwing it back out till it almost comes back out of the hole, doesn't change the idle/running at all. Not a bit. And just looking at the distances involved, I think it should go farther into the hole. It did seem to start better though (more testing needed) and didn't break up like it normally does. It also didn't sound like I was setting off firecrackers all the way down the driveway. I get lots of denotation in my exhaust normally. But maybe it was having a good day. Just need to test it more.

Lart has 951 TB's for $99, and I'm thinking of just buying a new one. Does anyone know how far the adjustment screw normally will go down in the hole? Shouldn't the idle change when I screw it in and out? I suspect what I really need to do is take off the outlet hard line and make sure the butterfly is closing all the way at idle. That screw wouldn't do anything if it's not closing all the way I think. And I can see if the screw is protruding into the air bypass channel or not.

I'm mainly looking for input/ideas and experience from others that have had this part of the system apart and done troubleshooting on it before.

EDIT: Testing today (the next day) didn't show it started any better, idled any better, or didn't stop breaking up till "I got on it". Which is one of the things I'm trying to solve. It sometimes has a good day, yesterday was just one of those.

Frank@Work

When adjusting the idle you should disable the idle control valve.
http://www.clarks-garage.com/shop-manual/fuel-08.htm

Go for a used TB and buy a reseal kit. Sadly the reseal kits from Arnnworx are not available anymore.

951Dreams

Yep, jumper built and used when testing. Do you know who does sell a good kit since I've heard all the Arnnwotx stuff is NLA? Wish I'd picked up the belt tool when it was still being sold. ☹️

Frank@Work

Tools will be available soon. See the Arnnworx site.
I don't know any other suppliers for the seal kit, because I always used the Arnnworx kit and did several throttle bodies. I will check if I still have a kit (or a resealed throttle body) available.

951Dreams

Yeah, they were saying on or around Feb 15th, but that's come and gone. Wonder if they will reissue the reseal kits? Guess we'll see when the new owner brings it back online. Anyone know what happened to Bruce? Hope he just retired.

I ordered up the TB from Lart just after my last reply. I'm not sure it's my problem, but I know it's been jacked up by the PO, and I want to take it out of the picture as a possible source of issues. I guess I'll just hope either Arnnworx comes back soon, and has the kits again, or someone has one sitting around they want to sell. Jason is showing out-of-stock, but he was reselling the AW kit.

951Dreams

I'm hoping I get a good TB from @lart951, I can't trust the one I've got is OK after what I found the PO did. If the new screw had threaded correctly, or would even go as far down in the hole as I've seen some pictures indicate it should be able to, I'd have been ok with my re-threading attempt. Or if it had even changed the idle at all running the screw in and out. I'd have called it good and moved on. I know I could remove my current TB, test its closing all the way, and visually see if the screw is able to fill the bypass/mix channel, but I'll always know those threads were borked up and wonder when troubleshooting if my fix of the PO's bad fix is the problem. A new (to me) TB vetted by someone as knowledgeable as Lart will make me feel better that at least that piece of the puzzle is behind me. And I can check the TB and idle settings off my list for good.

And I don't know what else the PO might have done before resorting to an incorrect bolt through the idle screw hole. Or why they chose that as a solution. I'm going to trust Lart would notice if one of his had been borked up by someone being inventive, as I'm sure he's seen countless more of these than just about anyone else on the planet! This will be my first 951 TB to ever see the inside of, I'd have no idea if there was more redneck engineering attempted on this thing as I don't know what a correct one should look like.

I know you should never just throw parts at a problem. But in this case, I KNOW my part was damaged. So, I'll just start from scratch with a new part.