savagete2860

Josh from RMC recommended Mobil 1 5w-50 (the normal stuff, not the expensive "supercar" stuff made for the c8) for the oil and a Wix 51348 for the filter from O'Reillys. Also kind of cross posting from my issue thread to here - anyone know what replacement to use for O2 sensor stateside that has the correct connector as well as spark plugs and coils?

Hey nice car! I saw you up at log44 I was there in the orange 420r at the autocross. I only signed up for the autox though so I missed the rest of the event unfortunately. I changed my oil at 1k miles and plan to change it again soon at a little over 2k miles before settling in to a normal longer interval. I think early changes are a good idea for a new motor, it’s probably going through more wear now than it will the rest of its life. Cheap insurance IMO. I also had bolts disappear on the engine cover. I ended up just removing the cover. There are a lot of reports of that cover rubbing on coils and wires causing damage. My plan is to just put that cover on if I might end up in rain or I am washing the car only. Its worth checking to see of the coils and wires show signs of rubbing. I would go through all the bolts mention in this video and also save it a do this every so often. The torque values are all in the owners manual for any he is missing.

I don[t think its related to TPS voltage. For some reason at idle the car cant hit the desired lambda target. I ordered a new O2 sensor Bosch Universal Oxygen Sensor | BOS 15727 from here: https://www.oreillyauto.com/detail/c/universal/bosch-universal-oxygen-sensor/b02u/15727?q=BOS+15727 and an supposed to get it sometime today. I am hoping the current O2 sensor just doesn't read properly and that is causing the issue. If nothing else the O2 sensor will at least be ruled out. My kit was purchased from Caterham in 2024, the same year they switched over to the 9M4 from the 9A4. Rocky Mountain Caterham is going to be sending me out a new 9M4 ECU with the RBTB tune eventually to test with to check that off the list too.

Hi @pethier it was good to see you at LOG44. I was the guy in the orange 420R. Wanted to drop a photo and a video I had of your car at the autocross. Hope you had as much fun as I did!

I was driving around today and noticed the car seems to not have the same hesitation while in open loop. Took a video of my thoughts. Maybe it would help give clues? I am really suspecting the 02 sensor right now. Is there a "better" version of the OE one available int he states? I think I want to try a replacement. To drive around the stumble, I have been doing a blip (on then completely off the pedal) of throttle followed quickly by how much throttle I actually want. If i didn't do this, the car would stall with load, especially on hills. Seeing how the car revs with and without the -20% STFT and it makes sense why I had to drive it like that. I still drive the car like that. I mentioned in the video I thought the rbtb gasket was the main issue, but I'm really not so sure. I think the TPS migrating might have been more the issue. The car does seem to do better at a slightly lower voltage like 4.61 vs 4.62 and the car starts to get worst at 4.63 (this voltage actually cause the car to die on its on on a hot start) - all of those are at throttle site 0.0 and my understanding is anything under 0.4 is considered "idle" by the ecu.

That's good to know you also can cause a small stumble from idle with fast throttle changes. If that is normal I can live with it - since my last adjustment it has been way easier to drive than before where it would actually pop from the intake try to stall the car. The car feels totally normal everywhere aside from off idle - and now it feels pretty close to normal. If you remember the next time you have Easimap hooked up to you car would you be able to see if you also have similar STFT at idle when hot and is your lambda reading and targets are different? Those might also be "normal" but I haven't been able to find anyone else discussing it.

There should be sound on the previous videos, they're muted by default you to have to un-mute them on the bottom right. I pulled off the roller barrels again in hopes I would find a vacuum leak from the intake seals. Sure enough one of the gaskets was stretched and no longer fit in the groove. I didn't have a replacement so i just cut some length off and put RTV on and assembled the throttle bodies again. I took the car to an autocross yesterday for LOG44 (I am a local) and the car was misfiring really bad trying to free rev the car to launch it. I thought that means the seal wasn't the issue but I checked with Easimap today and the TPS migrated to 4.65v! I set it back to 4.62v (it shifted to 4.61v though) and I drove it around today and it seems fine now. STFT still seem out of whack and cold start and idle isnt great, but the bulk of the bogging seems to be fixed. I wont call it 100% until I drive around some more but its headed in the right direction. I made a video that hopefully gives some insight to the issue or non-issue. STFT is the % value above RPM in the videos. Note the lam value on the bottom left (actual value) and the one to the right of it (lam target). These never match at idle even in closed loop - is that normal? Also looking for protips on how to make the tps not migrate from where its set.

Moving the injector didn't do anything. I continuity tested the sub loom wires for the coils and the injectors and they all are good. Here is a video I took yesterday when I decided #1 was an issue (its in open loop during this video) https://imgur.com/a/iAGt4mH This is a video of the car when it just got into close looped from a few days ago. The TPS at this point was still lower to help with the misfire issue. Hopefully you can hear the miss but more notable is the temperature on cylinder #1 being much lower than the others. https://imgur.com/a/RKxOROV And here is a video of the idle tip in not cooperating - each throttle application is about the same. THe one that revs high must have been a little slower but it seems inconsistent. https://imgur.com/a/CBKiJ3A Based on those videos do I have a legitimate issue? I am starting to wonder if I am just going crazy. Is it possible this is just normal and my fuel trims are out of whack. Is it normal with RBTBs that opening quickly from a low RPM just adds more air than the system can compensate for? If I am not crazy and this doesn't seem right, what are the potential issues? - Wiring from the sub loom to the ecu? - ECU itself? - Vacuum leak somewhere? - Could long term fuel trims just be way off from the TPS voltage being wrong for so long? Does the car use LTFT in open loop? Only wondering this since STFT according to Easimap were pulling 20% fuel meaning LTFTs were way off what the car wants.

I will test swapping the fuel injector and with continuity check the plug wires - those seems like solid first steps and if those are both okay I would guess I'd be looking at the ECU itself. I am a little bit of a smooth brain though so I need some help with the continuity testing. I understand I will need one probe at the plug that connects to the coil, but where would I put the other? EDIT: I checked just the sub-loom and it was fine on #1. Not sure if there is a way to test it further back or not.

Last time I had an issue with my car with sticking RBTBs this forum helped me tremendously. I have a new issue I am hoping I can get some help and advice on. Pretty much the same day I got the roller barrels to stop sticking, I noticed on cold starts or for a little on hot starts (in open loop) the car would idle pretty low - bouncing from 5xx-700 RPM. Once in closed loop, things would behave as far as idle RPM is concerned. The bigger issue however was trying to press the gas off idle would bog the car down before the RPMs start climbing. Drivability was pretty poor and would lead to stalling especially on hills. I ended up setting the TPS voltage a little lower than normal which bumped the idle enough you can fairly easily drive around the issue. It would still miss though, and you can hear it pop from the intake occasionally. I ended up ordering an Easimap cable to properly set the TPS voltage. It seemed like even at 4.62v at the middle pin it wasn't running right so I figured the ECU might see a different value so to be sure I wanted to check it with Easimap. Turns out that was correct - there was 0.03-0.04v difference between what the ECU would see and what my multimeter on the middle TPS pin would see (Easimap values were lower). I adjusted it to exactly 4.62v seen by Easimap and wanted to test if it would still have a low idle and misfire. Same deal unfortunately. With the TPS set correctly now, I fired up the car and while idling, I disconnected the cylinder #1 coil. It didn't change the idle at all. I moved the COP and the plug from cylinder #1 to #2, but the problem was still at #1. All the other cylinders seems to cause an RPM drop when disconnected aside from #1. Of note, I pulled all of the plugs and they were pretty black. Short term fuel trim was pulling 20% fuel as well (not sure if that's because the TPS was misadjusted for a while and long term fuel is wrong now or what) I read the "coil driver" on the ECU can go bad or the loom wiring to the COP. I guess I am wondering if there are any good ways I can test that. Also is there a way I can rule out any other issues, like the fuel injector on #1? Since I crossed over the 500 mile break in period and I have not be shy with the WOT. It doesn't seem to misfire with load. Not sure if that is another clue - or maybe I have been driving around a 3 cylinder Caterham and I just assume it feels normal. Any thoughts?

Ended up buying both TPS's I linked above. The autozone one is a bue-ish color and seems very cheap. It was so cheap and blue I drove to an advanceauto to pick up the other which seems better made and is black like the OE. Popped it on the car, adjusted voltage to 4.62v and everything is well in the world again. Thanks @KnifeySpoony and @sltous for all of your hand holding. Not only do I now have a working car but I learned what I am pretty sure is everything I would ever need to know about roller barrel throttle bodies on these cars.

Just FYI for anyone looking and because Caterham was kind enough to scratch off all the logos and part numbers, the Ford part for a TPS replacement is ys4z9b989bb. Unfortunately it is considered "obsolete" by Ford and as of typing this, there only select parts departments that have them in stock. None are really close to me so I think I am rolling the dice on a Duralast version from AutoZone to see if if fixes the car and I will plan to get a genuine Ford part down the road. https://www.autozone.com/engine-management/throttle-position-sensor-tps/p/duralast-throttle-position-sensor-tps-tps274/364464_0_0 https://shop.advanceautoparts.com/p/carquest-premium-throttle-position-sensor-ecc1036/12424329-P I will post an update when its back on the car.

Easimap setup is on the list of things to buy. So is a de-pinning tool, air flow meter, and a 6mm rod. I de-pinned the TPS connector as @sltous showed- voltage was 4.58v at idle, which while not 4.62v, I can't imagine thats enough to really throw off the fueling on very light low rpm revs. I have been wrong before in this thread though so who knows. I did however open the throttle a little with my thumb on the throttle cable attachment behind the filter backing plate and the voltage on the middle pin never changed. Is that confirmed bad TPS? Is the TPS something I can pick up from a local autoparts store/ford/mazda dealer or does it need to come from Caterham?

I just went to take if for drive. Before I pulled out of the garage I tested modulating the throttle with the car running. Results: I must have messed something up. I only tested very light throttle to slowly raise the RPMs and it shuts power down quickly. Guessing this is related to TPS. I do not have easimap - how/where can I check the voltage for the TPS with a multimeter? If the voltage is high/low, how is it adjusted - rotating the TPS? I am guessing easimap and a cable is something I should buy. Here is a video of the hesitation. https://imgur.com/a/twUGzIC

Dang.. I ended up getting it off before seeing your response @KnifeySpoony and kept the TPS on thinking it couldn't possibly need to come off. I don't know if that did indeed damage the TPS or not but I will probably try to get a spare just in case. I just got done putting it all back together. Its dumping rain but hopefully tomorrow i can fire it up again and test it out. If the TPS is damaged, what would some tell-tale signs be? Would that throw a light or just cause drivablity issues? Regarding the initial sticking issue, I am pretty confident its now fixed. I took the RBs off and loosened the bolt that holds the return spring to the housing which immediately stopped the sticking. Tightening it again and the sticking came back. With the bolt loose I then tried to position the throttle openings to around where idle is and tightened the spring screw. With that adjustment it seems totally normal again. I put it back on the car, attached and adjusted the throttle cable. With the car not running, I couldn't get it to stick and felt, looked, and sounded normal (metal snap). Before I put the backing plate, trumpets, and filter back on it did start the car - it fired up and idled fine (no revs since the filter wasn't on - and also i accidentally left the TPS unplugged). I am hoping the sticking throttle is now a thing of the past and fingers crossed my TPS is okay too.

Taking off the RBs and I am a little stuck. There are 5 studs from the block that secure the rollers via 10mm nuts. I have all 3 bottom nuts removed and the top two undone as much as they can be. At this point I would expect the intakes to come off, but they do not budge. Is there a trick to this? Also the install instructions from the csr260 manual says Do I need to remove the TPS? It seems like its just mounted to the side. Is the manual referring to the actual "barrel" that rotates inside of the housing which I am not touching?

Thanks - any I totally understand on not wanting to take the backing plate off, it is indeed annoying as you stated lol. Really I am just curious if the return springs favor the one side or the other on a car that has working RBs though and if they have any side to side movement with throttle application.

Still scratching my head on this. Waiting to hear back from Caterham to see what they say as this is a part assembled and installed form the factory. I saw a few photos from other owners where the right spring looks as though it is supposed to be more towards the rear of the car, so maybe how the spring is moving is correct but the stop just need filed down or something. Its peculiar that this whole setup worked from for a good bit and then started to bind. Im wondering if the coating on the spring slowly wearing away from contact increased the friction between the spring and the stop. I really have no idea. If anyone with RBTBs can post a few photos of the return springs or a video if their operation that would be hugely helpful to have a reference and just validate mine looks correct or incorrectly installed. I will be sure to post any updates as they come.

I figured out whats causing the issue - for sure this time. It is indeed the right roller barrel return spring. For some reason, the spring shifts when operating the throttle and binds between the roller barrel and the WOT stop. I validated this using a screw driver. How is this spring is meant to stay in place? RBTB-binding.mp4

The WOT stop was adjusted correctly but the screw was making contact with the spring so I backed it off for testing. Seemed to help a little at least from larger opening to quickly letting off the throttle, but re-assembling quickly showed it did not fix the problem. Car started and was idling, then i gave a very small blip of throttle and RPMs raised and never came back down. Considering the front right screw was a stop for full throttle, I am guessing the rear facing adjuster screw on the left is for idle. Other threads indicate this is to be used to adjust the opening to 6mm via a dowel/drill bit/blank. That sound right? This adjustment would set the lowest the throttle should close - which seems to be set correctly again - but I can't see if if its interfering with the return spring, like the WOT stop. Fact check me here. I have been ignoring the throttle cable itself because when I took the backing plate off, I manually moved the barrels to WOT position with my fingers and released to simulate closing the throttle, and the barrels got stuck and there was slack in the cable. The cable should only be under tension when opening the throttle, right? Its pulling the throttle open but the return springs on the barrels are what should be working against the cable tension to close. So in theory the throttle cable, unless getting in the way of operation, should not be relevant to my issue.

Thanks @KnifeySpoony. I don't mind working on the car but I stopped short of removing the barrels themselves. Are there any tune implications to removing the barrel completely? My only concern is I don't have a way to check/set tps voltage and Id be worried I might change something there. I don't believe it is the throttle cable itself - adding and picking up slack didnt change the behavior and its routed in a way that wouldnt interfere or be interfered with by anything else that I can tell. I took another look and I don't really know how I missed it, but there is evidence of the return spring on the right barrel making contact with the adjustment bolt on that side. Is that bolt the full throttle stop adjustment? I think that is my smoking gun for the binding. Edit: adjusted this and that seems to solve the issue when manually testing. However now WOT isn’t actually fully opened, it overshoots just slightly. Not a big deal while I’m breaking the car in though. Edit on the edit: Still an issue with the WOT screw backed out a good bit to not touch the spring IMG_3060.mov

Hi everyone, long time lurker new 7 owner here. I will make an intro post soon, but I figured this was as good as time as any to dip my toes into the usa7s community pool. I ordered a 420R kit with roller barrel throttle bodies through Rocky Mountain Caterham and had them assemble the car. I took delivery of it earlier this month and it has been great up until a few days ago. For some reason, the throttle started "sticking". For example, if I am in gear with the throttle opened ~10% to maintain cruising speed, let off the gas, it will be like I am still pressing the accelerator and I will not slow down. If I put the car in neutral or press in the clutch, the RPMs will rise to 3-6k rpm rather than settle into idle. Giving it a quick jab or two of throttle seems to correct things (or make them worse until jabbed again) but it will just happen again to the point where its probably not that safe to drive. It's also seems like the barrels don’t want to go back to their idle position. Also - maybe related, maybe not, the car does not always start which is also a new behavior. I have had about 5 cold starts just crank with no signs of life until hitting the battery cut off switch off and back on at which point it just starts. I looked at the throttle pedal and it and the cable appear normal to me. The pedal seems to always return to it's starting position and when the throttle sticks there is no play in the pedal to move it. This leads me to believe the issue is at the RBTB end of the throttle cable. I pulled the filter and back plate off and notice i can use my hand to close the barrels further than they normally would be. If the throttle is actuated again, the barrels never return to what I imagine should be their resting idle position. Below is a video of what I am talking about. So my assumption, which very well could be incorrect, is that because there s a kind of dead space between the lowest opening and where the cable start to get tight to open the throttle and it seems like the barrels can get randomly stuck at any position in that dead space. Any ideas of what to look at or do next? rbtbs-issue-720.mov