Request for advice, car won't idle

[Jonathan Kay]

Fascinating story. Exemplary support. Neat notes for the next victim.

I can only follow a bit of it, but thanks for sharing.

Jonathan

[StevehS3]

Glad you’re sorted and a lot of good info captured for other owners too.

[CtrMint]

I'll be posting details on my blog in due course.  Again thanks to everyone that helped 

[CtrMint]

Started the car this evening, perfect start-up and idle when cold.   Went for a run, 3/4 of tank later still perfect, no idle issues what so ever!  So happy with this, been a bit of faff, but plenty of experience gained.

Got my first blog on the topic written too.

https://www.caterham7diaries.com/post/setting-up-easymap-mbe985

[CtrMint]

For those not bored by this thread, I've now published the throttle stop adjustment blog post.  Hope you enjoy.

https://www.caterham7diaries.com/post/correcting-the-idle-via-the-throttle-stop

[aerobod - near CYYC]

Thanks Mark, your blog is an excellent resource for future use.

[John Vine]

For those not bored by this thread...

Bored?  By your blog?  Never!  What a great write-up, Mark.  Well done.

The only addition I would suggest is to include a link to SBD's website.

JV

[CtrMint]

Thanks guys, I appreciate it.  I'll add the SBD link tomorrow.  Just got in from the garage having sorted the max pedal throw and tps values.  I've now got maximum at 15.1   I had to get the pedal stop out and remove a nut, more will follow in my blog.

cheers

[anthonym]

Glad it’s sorted :-)

[CtrMint]

And the final blog post relating to throttle adjustment...

https://www.caterham7diaries.com/post/throttle-pedal-stop-and-cable-equals-max-power

Enjoy.

[Geoff Brown]

Aaaah...now I know why you had all the problems - standard plenum.

When reading I was envisaging future potential problems with my RBTB set up but it is now obvious that will not be the case!!

[John Vine]

Well, Geoff, I think you've just started Mark on the upgrade path!

JV

[Geoff Brown]

Should have gone for RBTB fit when ordering the kit. Caterham will do it but under extreme pressure.

The RBTB fit does seem to rule out a lot of problems encountered with the plenum set up. Not to say that RBTB do not have their own potential array of problems in service.

Fingers crossed now into year six & nothing as yet..........

[CtrMint]

I've never experienced a 7 fitted with RBTB, so can't comment from an informed position, but I do think the kit is expensive for the power increase.

I think long term if the 7 is still with me I'll have probably sold the Exige, just because both seem to overlap too much.  In such a case I might upgrade to a 620 or have a sequential fitted to the 420R.  For the time being there's no intention to change the 7 other than getting the aeroscreen fitted and even that's only temporary.

Oh I do sometimes wonder whether I should have had the noseband and 7 logo painted.   At the time of order, I was convinced the 7 logo painted looked a little retro for my tastes, now I think I'm swinging the other way.  I was thinking of wrapping the 7 logo to test.

 

[Geoff Brown]

The RBTB upgrade may appear to be expensive just for a 10bhp upgrade but it is worth it! It sems to clear many of the maladies that plenum engines appear to have from time to time.

• Instant engine response to the throttle
• Good idle control 
• Furious acceleration -  Especially 3rd gear which is just an explosion of noise & warp sensations when throttle planted 
• Wonderful induction noise
• Smooth, low speed, lower gear control - no hunting
• Problem free feathered throttle control
• Terrible mpg!

Couple all this with a de-cat pipe = the entertainment of extra exhaust noise & blue flames at night on the over run.  

[Alan Reeves]

RTBs for sale on e bay !!

[Rich Goddard]

Hi

Hijacking the post slightly, but it’s a related query. Just acquired a 2015 Supersport R (with 210bhp conversion). It won’t idle from cold without some throttle…just stalls. Have fitted new uprated TPS and coil sub loom as a precaution. 

So, reading advice here and other threads I’m aiming to reset the throttle position at idle, because I assumed it was just set wrong. I’ve made sure throttle cable has slack, wound the stop screw right down and plugged into Easimap. And was going to adjust back up from there. But I'm getting some results I don’t understand.  At rest the throttle normally sits at Site 1.0 (~0.86v), but when I press on the throttle mechanism (cable retaining part) against the stop screw I can get it to read Site 0.0. Another time I plugged in I was getting 1.05v at Site 1.0 sitting on the stop screw. Very inconsistent results. I’m now thinking I must be doing something fundamentally wrong but don’t know what. 

Also sometimes when i open the throttle and let it return back to rest on the stop it’s resting at ~Site 2, up to ~Site 3 even.  I thought it might be a sticky valve blade so I flushed a light-ish coating of accumulated black gunk out of that. Very clean now. Made no difference. The valve does still appear to get very slightly stuck when it’s completely closed. It operates very smoothly otherwise, from being just  cracked open to fully open. 

I read above CtrMint (#71) that you’d set Throttle Angle at 1.21v, and this corresponded to Site 0.0 for you.  If I adjust to read around 1.25v it’s showing Site 8.7. Is that wrong?

I’m a bit lost with this and would appreciate any advice. I’ve clearly got a problem somewhere but don’t know where to start. 

Thanks, Rich

[Mark w]

Rich

You need to sort out the mechanical bit first . Release of your throttle needs to ALWAYS return to a consistent position . Sounds like you have a worn spindle / gunk in the way or an iffy spring .

Sort that out first ....

 

if it's not the throttle body then your TPS is worn out .

[aerobod - near CYYC]

An overtight air filter jubilee clip can also distort the throat of the throttle body, causing the blade to stick.

With the plenum system it should give throttle site 0.0 to 0.4 at idle against the stop (1.2-1.3V or so) with a smooth transition to at least throttle site 14.5 with the blade fully open (4.6V or so).

[Rich Goddard]

Thanks for the advice chaps. It's a brand new TPS, so I'm going to try find a nearly-new throttle body to fit to see if that's the issue.

Good point James about possibility of an over-tightened clamp on the air intake. Think that could be the case. It was still sticky when fully closed with the air intake removed, so might be permanently distorted.  

I'll put a post in "Wanted" but if anyone reading this has a spare throttle body in very good nick (maybe after fitting TBs upgrade) then I might be interested in it. 

Cheers 

[John Vine]

#95

MTW might well have one going spare, after his RBTB upgrade.

JV

[AlastairA]

Hi Mark,

I've just finished my 420 build (yet to go through PBC / IVA) but have the same hunting and stalling issue after a cold start that you described. I've read this thread and your blog with great interest but I'm trying to get to grips with the root cause of the problem. I did have to replace the TPS during the build so that could have something to do with it. I've informed Caterham that I have this issue and they said it will be investigated during PBC - but in the meantime I'm wondering whether it would be sensible to get the Easimap cable and software - clearly a very sensitive area for set up.

Seems like the two variables that are critical are the Throttle Site at idle and the Throttle Angle Increasing. I understand that the Throttle Site at idle is creating a relationship between the actual TPS voltage when no throttle is used and the Throttle Site number used by the ECU - but what does "Throttle Angle Increasing" represent?

Thanks,

Alastair

 

[John Vine]

#97:  ...but what does "Throttle Angle Increasing" represent?

From the Easimap panel description (MBE 992 ECU):

"This is the limit checked voltage which takes into account the direction of the throttle pot. This voltage will always increase with opening throttle."

AFAIK, this equates to the "Throttle 1 Voltage Increasing" panel on the MBE 9A4 ECU (which is what I guess you have on a new 420).

As an aside, that "increase" bit has always puzzled me as my R400D (992 ECU) has roller-barrels and the voltage drops when the throttle opens.  That's because the RBs rotate clockwise whereas the standard butterfly rotates anticlockwise.  The direction of TPS rotation can be defined but requires ECU access. 

And yes, if you want to observe what the sensors are telling the ECU, you'll need the MBE cable.  Mind you, they're very expensive now (£192 !!), although Easimap 6 itself is a free download.

By the way, why did you need to replace the TPS?

JV

[AlastairA]

Thanks JV - so if I understand correctly it is simply the TPS voltage reading?

Yes the cable + windows licence + virtual machine software cost is very prohibitive. If it is just the TPS voltage reading then using a multimeter might be a cheaper approach to set it up correctly but then I guess I would be missing the TPS Site information.

When the kit was delivered, the engine pallet had collapsed and the plenum was resting against the side of the van. The TPS had taken the worst of it - although it still worked, the connector had been damaged on both sides, so I replaced the sensor and the cable connector.

[John Vine]

#99:  ...so if I understand correctly it is simply the TPS voltage reading?

Not directly. The TPS voltage is displayed in the Throttle Angle panel.  As far as I can see, looking at my own recordings, the Throttle Angle Increasing panel shows the difference between the TPS voltage and the max voltage (5v).  In my case, at idle (Throttle Site 0.0), the Throttle Angle panel shows 4.66v and the Throttle Angle Increasing panel shows 0.34v. 

I don't claim to understand all these panels.  For the TPS, the important ones are Throttle Site and Throttle Angle.  For a stable idle, the Throttle Site needs to be less than 0.5. 

To run Easimap, your simplest and cheapest solution might be to get hold of a cheap-o second-hand Windows laptop.  Easimap 6 will run on any Windows version from Vista onwards.  But do check that the cable kit is labelled MBE985v --  the "v" confirms that it will work with Vista onwards.

Sorry to hear about the TPS damage.  Presumably CC provided replacement parts FOC?

JV