MV8 Posted November 16, 2023 Share Posted November 16, 2023 I would determine if the two assemblies bind individually or if they are just not parallel on the manifold. Loosen the mounting bolts a turn so the assemblies can move around a bit and recheck for bind. If it still binds, take them off and check the movement individually for bind in returning to the idle stop. They may not completely close at idle. I don't know if idle air flow comes from having the throttle slightly open or if it is an adjustable mechanical leak or electronic valve (IAC) controlled by the ecu. Link to comment Share on other sites More sharing options...
KnifeySpoony Posted November 16, 2023 Share Posted November 16, 2023 (edited) You would have to be careful if you just loosen the throttle body assemblies; the little silicone noodle gaskets are not held in well and can easily fall out of position. I would just take them off completely. and make sure you understand the rotation of the barrel and getting it indexed properly when placing onto the head. Edited November 16, 2023 by KnifeySpoony Link to comment Share on other sites More sharing options...
ralph Posted November 16, 2023 Author Share Posted November 16, 2023 (edited) @MV8 they are definitely designed to be mated such that one assembly is supplying spring tension against the throttle cable, and the other is supplying spring tension against that one. @KnifeySpoony I dabbed some rtv in the silicone noodle grooves so they stay put. As to the 'wrong way around' theory, I'm definitely open to that, just not making sense of the physics with these parts as I see them. One thing I should have noted earlier is that, at rest without being conjoined, the barrels are a tad open, and I'm rolling the barrels 180 degrees to get them into a position where there is plenty of spring tension to get them to close all the way. There's no mention of this in the manual, and it develops enough tension that handling these things is a little scary (hence screwdriver handles, vs. fingers). If that doesn't track with what other RBTB installers recall, then I'm 100% doing that bit wrong...I just can't see another way it would work -- if their at-rest position is open, it's not (and cannot) open all the way, which is just another version of the same problem. I think this will remain confusing until I shoot some video of the assemblies separated and joined. Seems like if I do that, someone here is bound to catch my error... Edited November 16, 2023 by ralph Link to comment Share on other sites More sharing options...
ralph Posted November 17, 2023 Author Share Posted November 17, 2023 I pulled the barrels off and screwed them into a board (sprung and joined, as on the block), and I think I found the contention, but I'm not sure what to do about it. The idle screw stop (which is mounted on the 3/4 unit) is hitting the spring on the 1/2 unit. This explains why it only happens when they are joined, and also why the problem starts with the barrels sticking open (hitting the spring in the unwind/close direction), but then stopping full open as it hits the spring again going the other way. The "slightly progressive" feel of of the contention is explained by the fact that the idle stop is angled (the more you turn it, the more metal is in the way). Question is, why is it like this, and what can I do about it. Do I have the wrong parts (as @MV8 suggests, maybe the sprung assembly is simply not designed to be this close together?)?...do I grind down the idle stop? (probably not, since the idle screw is pretty close to the edge of it)...do I move the attach point of the spring on the 1/2 unit? (seems the least invasive, but I'm not sure the geometry works, and I have no idea what happens when I undo one of those screws). 1min video of me demonstrating the contention: https://www.dropbox.com/scl/fi/071ixhfa595pq94v7l10k/rbtb-contention.mp4?rlkey=6kge0zcaxkruqvvllr29hl4qw&dl=0 Asking CC and dealers, but suggestions are welcome... Link to comment Share on other sites More sharing options...
KnifeySpoony Posted November 17, 2023 Share Posted November 17, 2023 (edited) If you wanna bring it up here we can compare to mine and see if we can troubleshoot. Edited November 17, 2023 by KnifeySpoony Link to comment Share on other sites More sharing options...
MV8 Posted November 17, 2023 Share Posted November 17, 2023 (edited) The throttle plate was not machined correctly. Material needs to be removed adjacent to the spring area. You can do this with a carbide rotary file and a 3/8" drill. I'd expect to remove about 0.100" across the surface and probably square up the end toward the second assembly. If you bend it to make clearance (easy to do with a crescent wrench), that may bend the throttle cable guide on that side and possibly crack the plate, depending on what it is made of. Edited November 17, 2023 by MV8 Link to comment Share on other sites More sharing options...
KnifeySpoony Posted November 17, 2023 Share Posted November 17, 2023 I would not modify a brand new $5000 part... Link to comment Share on other sites More sharing options...
MV8 Posted November 17, 2023 Share Posted November 17, 2023 Understood from a warranty perspective. While furloughed from an airline, I worked for a period of time at Harley Davidson as a mech because I thought it would be fun and unusual. It was! Made me park my Honda Silverwing automatic scooter in the back when customer's wives were always asking about it but anyway, Harley's used to be mechanic bikes, then they got trendy and expensive but still very simple. People were afraid to to do anything to them; even an oil change. Link to comment Share on other sites More sharing options...
sltous Posted November 17, 2023 Share Posted November 17, 2023 (edited) Sent this offline as well but others may have helpful information. I believe this is a Titan Motorsports part sold under Caterham, Titan, and others. I do not think the Cosworth part is the same. I would check in with Titan (and ask for an exploded view of the system for part number references later) to see if they can provide feedback on if some of these machined parts are just wrong. Titan will sell individual components if you reach out via sales@titan.uk. https://www.burtonpower.com/titan-roller-barrel-throttle-body-ford-duratec-he-i4-tbi4.html Agree with KnifeySpooney, this looks to be made wrong and taking an angle grinder to this part is likely satisfying but a bad idea unless you can replace just the component. Would be happy to have a RBTB car meetup to look at the minor differences. I have a spare head if you want a more accurate test bed than screwing to a wood board. Edited November 17, 2023 by sltous 1 Link to comment Share on other sites More sharing options...
KnifeySpoony Posted November 17, 2023 Share Posted November 17, 2023 Although it is a Titan-made assembly, branded Caterham, I think it is the same as used by Cosworth on the 2.3 motors. I too used the Cosworth assembly instructions and the parts in the photos look identical to what I got from CC and the instructions were appropriate. 1 Link to comment Share on other sites More sharing options...
ralph Posted November 17, 2023 Author Share Posted November 17, 2023 Ok, some progress. My 1/2 barrel appears to have been assembled incorrectly at the factory, with the spring being mounted to the next screw clockwise from the idle screw bracket...shouldn't be there, should be on the next screw after that. Moved it, and can get from 6mm to WOT without issue....on to the tensioner... 1 Link to comment Share on other sites More sharing options...
ralph Posted November 18, 2023 Author Share Posted November 18, 2023 Milled the tensioner down (much easier than I expected), threw a shorter m8 in there, and things are nominally assembled now. To-do: - TPS installation and calibration (which looks 90degrees off, I'm hoping it's safe to rotate it) - bonnet cutting! (sans template...will measure 5 times, cut 3 times...or something...wish me luck...) 1 Link to comment Share on other sites More sharing options...
KnifeySpoony Posted November 18, 2023 Share Posted November 18, 2023 Out of curiosity - did your kit come with a grommet for the MAP sensor? I had to modify one to make my own. What do you mean about the TPS being 90deg off? As in the orientation of your sensor is different than in photos? Link to comment Share on other sites More sharing options...
ralph Posted November 19, 2023 Author Share Posted November 19, 2023 was feeling pretty good about progress here until my TPS snapped...will see if I can find one locally... Link to comment Share on other sites More sharing options...
KnifeySpoony Posted November 19, 2023 Share Posted November 19, 2023 Yeah you have to make sure the potentiometer is in the correct orientation before attaching to the intake. You can pick one up at any Ford dealer/parts dept. Link to comment Share on other sites More sharing options...
ralph Posted November 19, 2023 Author Share Posted November 19, 2023 For MAF, had to cut a grommet, and also threw an o ring under the screw to keep it even and leak free. Have ordered replacement tps, and will figure out its rotation range *before* installing it this time. Link to comment Share on other sites More sharing options...
fastg Posted November 19, 2023 Share Posted November 19, 2023 What size are the throttle bodies? Planning the winter upgrades and itb's are an option. Graham Link to comment Share on other sites More sharing options...
KnifeySpoony Posted November 19, 2023 Share Posted November 19, 2023 Surprised the TPS isn't on their shelf. If you're anxious to keep making progress, i have a spare one sitting here. Link to comment Share on other sites More sharing options...
ralph Posted November 19, 2023 Author Share Posted November 19, 2023 @fastg this setup (on an otherwise stock duratec in a 420R): https://caterhamparts.co.uk/other/3768-engine-upgrade-kit-r400-210bhp-to-220bhp.html @KnifeySpoony thanks for the offer, but I've got one showing up tomorrow; I do need to return your coil sub-loom...will figure something out in the next couple weeks... Link to comment Share on other sites More sharing options...
ralph Posted November 21, 2023 Author Share Posted November 21, 2023 Anyone happen to know if TPS voltage handling is different on the 9M4? According to Easimap, I have from .27v to 4.25v available ascending as the throttle opens. Everything I read about this setup suggests starting at 4.62v (which doesn't appear in the full range of motion of my TPS) and descending as the throttle opens. I would be ready to suspect the TPS (supposedly compatible knock-off: https://www.amazon.com/dp/B08SJ4L8T7?psc=1&ref=ppx_yo2ov_dt_b_product_details), except that doesn't make sense to me...irrespective of what voltages are available, I can't change the direction voltage goes as the barrels open -- clockwise is still clockwise, regardless of the position the TPS is in. Ideas? (have asked CC...will report)... Link to comment Share on other sites More sharing options...
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