moorsd123 Posted September 12, 2023 Share Posted September 12, 2023 Hoping someone might be able to point me in the right direction with finding a fault?...Driving back from a track day yesterday I noticed that the car was idling at around 2000rpm but occasionally dropped to 1500rpm and was generally uneven, this was accompanied by the temperature gauge dropping to zero and again intermittently reading normal engine temp! The temperature guage basically looked like it wasn't working and then occasionally jumped back to life for a bit, then back to zero?Any ideas on best place to start and where to look, TPS?, Lambda?, wiring/poor earth?Car is a 2008 R400D Link to comment Share on other sites More sharing options...
KnifeySpoony Posted September 13, 2023 Share Posted September 13, 2023 Plenum or roller barrels? If rollers, I'd guess TPS Idle voltage is low. I've had mine creep down for some reason. Link to comment Share on other sites More sharing options...
moorsd123 Posted September 13, 2023 Author Share Posted September 13, 2023 Aluminium Plenum fitted.May be a coincidence that the high idle occurred at the same time as the temp gauge was playing up? Link to comment Share on other sites More sharing options...
aerobod - near CYYC Posted September 13, 2023 Share Posted September 13, 2023 I would look for a loose earth strap under the dash. follow the black wire from the temp gauge, at some point it will be crimped to other black wires of which one should be attached to a ring terminal to the chassis or firewall, check for the integrity of that ring terminal from a tightness and corrosion perspective. Link to comment Share on other sites More sharing options...
moorsd123 Posted September 13, 2023 Author Share Posted September 13, 2023 Help!!....Decided to take a closer look tonight and decided to spray some contact cleaner in the TPS, and around the various terminals in the engine bay (didn't disconnected any of the terminals other than the TPS).Went to start the engine and didn't want to fire at all! !! Went back to basics and checked there was a spark and fuel using No 4 Cylinder and there was...more attempts to start later and the engine fired but was really rough and possibly missing, and just stalls once off the accelerator pedal?...it also smells really rich?Bit stuck to be honest as not sure how the contact cleaner would have had such a dire effect given the engine was running OK (other than high idle previously)...or could it be the TPS is totally screwed now and the engine can't idle as a result?? Link to comment Share on other sites More sharing options...
John Vine Posted September 13, 2023 Share Posted September 13, 2023 R400Ds of that vintage are very prone to wiring fractures. Check the three wires at the TPS connector for damaged or broken strands.JV Link to comment Share on other sites More sharing options...
moorsd123 Posted September 13, 2023 Author Share Posted September 13, 2023 Thanks John, I'd seen your previous posts about this (but not all the links work now), so looked at the TPS plug wiring but couldn't see anything obvious?Good news is that the panic is slightly over in that I have got the car started OK now and it's idling OK!...very strange?The temperature gauge is also working so need to take it out for a longer drive to get properly hot, as I wonder if that might be a factor in causing the symptoms I experienced on Monday? Link to comment Share on other sites More sharing options...
John Vine Posted September 13, 2023 Share Posted September 13, 2023 If all is working ok now, it looks as though there's definitely an earthing problem somewhere.I guess the broken links you mentioned are to the photos (no longer accessible via Photobucket). I should still have the originals somewhere so I'll add them to that TPS thread.JV Link to comment Share on other sites More sharing options...
moorsd123 Posted September 16, 2023 Author Share Posted September 16, 2023 Had a closer look today in the daylight (after ordering a new TPS)...turns out you were right John, two wires going into the TPS connector were fractured.Quick go on the econoseal crimping tool (something that is proving to be of value since owning the R400D!!), and now all fixed.The temperature gauge also appears to be behaving, but think that is down to a dodgy earth somewhere, so will look into that further another day! Link to comment Share on other sites More sharing options...
John Vine Posted September 16, 2023 Share Posted September 16, 2023 #7 ...I'd seen your previous posts about this (but not all the links work now)...If this was the thread, I've posted some of the photos (no thanks to Photobucket).JV Link to comment Share on other sites More sharing options...
moorsd123 Posted September 16, 2023 Author Share Posted September 16, 2023 Yeah thanks John, I saw the post come up and didn't realise it was from the original post you made...so replied with my experience (I've edited my response now so my comment makes more sense and to be helpful for anyone searching with the same issue in future).Looks like this is definitely a common failure point on R400D's...shame Caterham didn't use beefier wiring originally!!Thanks for your help again! Link to comment Share on other sites More sharing options...
John Vine Posted September 16, 2023 Share Posted September 16, 2023 #11 Pleased to help. Did you simply repair the fractured wires, or do you plan to fit the upgraded TPS sub-loom?JV Link to comment Share on other sites More sharing options...
moorsd123 Posted September 16, 2023 Author Share Posted September 16, 2023 I just shortened the wires and put new pins on, and strengthened them a bit using electrical tape.This will get me by for the time being, but I intend to make up a better connector like you have done (rather than buying the Caterham Upgrade).The standard wires are obviously a weak point and now they are slightly shorter will be under a bit more stress, so making a new loom will be a "winter" job! Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now