KnifeySpoony

Plenum or roller barrels? If rollers, I'd guess TPS Idle voltage is low. I've had mine creep down for some reason.

Not spring loaded. Just a freely turning pot.

Checked voltage this AM after car cooled. Voltage still at proper setting after adjusting yesterday afternoon hot. Went for shortish drive, came back and voltage stable with car hot. I don't get it. Line voltage at the plug was 4.92V - which was on 2 out of the 3 pins (not sure I understand that). Not sure if that being under 5V is significant or not.

I drive mostly track, but still drive to/from the track. My first set of tires were ZZS. I started with 2.25 deg camber up front and the standard 1.5deg de dion ears in rear. Running zero toe up front and 7 deg of caster (to answer your question, ride height does not affect caster angle). Rear is 0.25 deg toe in. I found that the fronts seemed to wear well edge to edge, but the rears had severe outer wear - not just shoulder wear but a broad angled wear across the tires. Currently running ZZR (A64 compound)- now have 3.0 deg up front and swapped to the 2.0 deg de dion ears. Overall tire wear looking very good now, even on the rears - I was worried that the ZZR would require even more camber, but it seems not. Some minimal shoulder wear front and rear but no obvious signs of too much/too little camber. In terms of ride height I am running quite low, but I have the track rate springs (250F/215R). I set the front ride height to have the lower wishbone parallel with the ground. This puts the ride height at 119mm (giving me about 68mm clearance to ground at the bellhousing). Rear ride height is at 138mm. In order to accomplish this, I had to remove the rear locking collars and the main perch is ran all the way down. Rear ARB is set one hole from stiffest. Overall the balance is excellent, easily adjustable at any phase of cornering with driver inputs.

Afaik, there is no set number of washers. You need as many on each side to center the dedion, while filling the gap.

Ok now OP"s turn. ;)

Tires? Which springs/dampers do you have?

BTW I reset voltage when I got home with the car hot. Will check in AM with car cool to see if it changes again.

I've been dealing with a part throttle/low load hesitation/misfire on my 420R (w/roller barrels) - /forum/420r-hesitation-part-throttle-when-hot I thought I had it figured out after realizing that my TPS voltage had drifted up. It's supposed to be 4.62V at idle. I found that it was 4.71V and this seemed to be the cause of my hesitation issue. Resetting it to 4.62 quickly allowed the engine rev normally. However I saw that the voltage was hunting a bit just sitting there connected to easimap, so I decided to replace it. The first sensor I put in I set to 4.62, then did a short drive. After the car got warm (about 5-10min) I noticed the idle speed had crept up to 1800rpm (normally ~1100rpm). Sure enough when I got back, the voltage was 4.55 (too low a voltage causes the ECU to think more throttle is applied as the voltage from the TPS goes down as the throttle is opened). So I thought maybe that sensor was bad. I got a new OEM Ford TPS sensor and swapped it in yesterday, set to 4.62 of course. Took the car out again and noticed that it was still doing the part throttle hesitation, although just a tiny bit and barely noticeable. Totally driveable, not the severe misfire it had before, and only over a tiny range of the throttle sweep (ie dead spot between 10-12% throttle, where before it was severely sputtering between 1 and 40%). However the idle speed had gradually crept up to 2000rpm. I got home (with the car still hot) and checked the voltage, which was now 4.51V. Needless to say I am confused. The sensor is fastened tightly - I don't think it's moving. Could this be a temperature issue? The TPS does get quite hot being mounted directly to the roller barrel assembly. I don't think Ford intended this part to get this hot. Could the lower voltage be caused by increased resistance in the wiring with heat? I have jiggled the wiring while connected to easimap and didn't see the voltage change at all. Any thoughts are appreciated.

Funny looking injectors to have on carbs too...

So it seems that the idle voltage being off by just a few hundredths is enough to cause such behavior. I guess 4.62V really means 4.62V. Live and learn...

Fwiw here in the states, center caps are generally advised to be removed before trackdays. They tend to not last long. I just leave them out on my cars. More rccr than way...

I am going on the wiring diagram in the back of the 2015 build guide which AFAIK is the most current published? My 420R is a 2021 build btw.

Ah ok i figured it was something like that given the consistent, but higher residence. What is the mfu?

I unplugged the coil loom plug at the Coil itself, then tested from the ground pin on the loom plug to the main chassis ground by the battery. For the other pin on the coil loom plug, I unplugged the ECU and tested at the appropriate ECU pin.

FYI resistance was check with ECU plugged in, kill switch on, but car's ignition/power off.

So I'm still trying to diagnose my part throttle misfire on my 420R. I went and checked continuity on various things - coils, injectors, sensors, etc. Using the continuity check on my multimeter everything was ok with a BEEP. However I realized that it will beep with anything less than 120ohms. So looking at the actual resistance, I noticed that all of the coil (and I think injector) grounds are consistent at 44ohms. Is this normal?

What are the characteristics of the misfire? I'm curious, as I'm diagnosing one as well.

On the modern dry sumped cars, with the oil tank up front, apparently an inline thermostat only gets you a few degrees warmer. Blocking the cooler will likely be more effective.

I do have the easimap setup. I will try to decipher the lambda readings. Also i need to confirm 100% that it's a misfire on #4. I will run it then pull the plugs hot to see if #4 is wet. If it is a misfire only on one cylinder, that would seem to eliminate a sensor issue i would think. And tonight i have just checked my wiring continuity on the #4 coil and injector, as well as lambda and MAP sensors. So if #4 is really misfiring then perhaps the ECU coil driver could indeed be the culprit. All this is new to me. Fun times.

In my mind, it would be odd if it was a connector or some other wiring fault to the coil, as I had exactly that issue last year, which created the exact opposite symptom from what I am having now- ie the car was fine at part throttle and low RPM/load, but then misfired only at WOT at high RPM. My first order of business is to check wire continuity from the coil to the ECU. Will also check for the 02 sensor, as the behavior seems to fit with a toggle between open loop/closed loop operation to me. Another thing that I am considering is the MAP sensor - I have seen threads saying failure there could cause similar issues, but I'm not sure. In the RBTB setup, it's just acting as a temp/barometric pressure sensor.

Did a trackday at Laguna yesterday - Once again the car was fine on track (new PR actually), however the part throttle issues have deteriorated significantly. It's extremely unpleasant/challenging to drive on the street at this point. It does it even when cold, and doesn't like to rev at all on light throttle in neutral; sputters and coughs bad. I checked the plugs again - they all look fine and all look the same- don't see anything obviously wet - does this mean it's NOT a misfire then? The most rearward cylinder exhaust primary is a little cooler than the other 3 but not cold. While idling (which is smooth, btw), I unplugged each coil plug one by one: the front three cylinders this produces an immediately rougher idle. Unplugging the rear cylinder created no change in idle, however revving is even worse. I swapped coil harness and no change. Swapped coils between 2 cylinders - same behavior. The picture is confusing me more and more... One thing that I noticed is that immediately coming off track with the car very hot, it runs fine around the paddock - However in stop and go traffic on the way home with equivalent water and oil temps, the car was almost undriveable. Any thoughts?

I would never drive with an unpadded [full] cage, especially sans helmet. I see it around though. Pad it and run it that way all the time imo.

What's a wear bar lol? Run em till the cords are showing. That's how we do it in California. No pesky rain to deal with though...

I just use 4 little squares (maybe 2cm at each corner) and it's plenty strong.