Throttle Response - Duratec

[O.G.]

Throttle Response - Duratec 

I have a problem with my 360R Duratec (180 hp) when opening the throttle. There is a short lag before the power comes in. 

For those who remember carburetors, it would be like the accelerator pump isn't working. This happens from idle and decreasingly so further up the rev range. Sometimes it is accompanied by a misfire or pop sound (too lean a mixture?). 

I originally posted this question over a year ago and got numerous replies saying theirs was the same. Since last year my car seems to have got worse giving rise to some "interesting" moments when applying power. 

Anybody, any ideas? If I require professional help, any suggestions? I live in the Heathrow area. 

O.G.

[ChrisC]

So your ECU/map in the standard 360R using MAP strategy to control fueling, where Manifold Absolute Pressure (MAP) is used to determine the fueling requirements.   The Throttle Position Sensor (TPS) is used to instruct the ECU as to whats required, i.e. acceleration or idle etc.   You could think of the TPS in this setup as an old school accelerator pump, except it work for deceleration as well.   This generally is considered the correct approach where MAP can be made to work, i.e. there is a nice plenum.   It's less optimal with independent throttle bodies for example, where a TPS strategy is generally employed.   

Post build my 360R had exactly the same hesitance during pull away and reluctance to rev.   Since I have Easymap I connected it up and found two things.  

1, The throttle site was way off the throttle position.  I am assuming this might be your problem as well.   It seems the ECU in the 360R is permanently powered, and never resets the TPS resting position.    To reset it you simply have to disconnect the battery, wait 10 seconds or so, and reconnect the battery.   Doing this reset the throttle position to the throttle site on my ECU.   This isnt going to be a problem if you have a battery isolator (and you use it). 

2, Increasing the manifold vacuum during idle.   I had a number of soft bungs, which I replaced with harder silicon items (that fitted better), and I closed the throttle to increase the vacuum at idle a little, making a more obvious change between idle and non idle.  Not to much or it wont idle or cold start well, its all a bit of a  balancing act really.   Remember each adjustment must then have the TPS reset with a battery disconnection as above.

With that my 360R was much improved, not perfect, but improved to the point I not longer thought about it. 

Alternatively you can take the car to someone who can alter the ECU strategy to TPS.         

[ChrisC]

I will add I did the same to a fellow club members 175 Duratec, with the aluminum plenum and transformed its idle and pull away, even though it wasnt the reason we where using Easymap on his car. 

[O.G.]

Thanks ChrisC your extensive reply. The car has just come off a 4 month winter lay up (alright, I'm a Wimp) with the battery disconnected but will give it a go and report back.

For Info my car has that big black plastic inlet manifold with, if I remember correctly, a built in air bleed bypass around the butterfly. Currently the car doesn't start from cold without a touch throttle but idles fine at 900ish after that.

Puzzled by soft bungs, what are they?

O.G.

[ChrisC]

Mine has been SORN as well, I have a few more tasks to complete my winter list, including doing all the work again with the throttle because I had the 420 upgrade done before winter and since then its back to its old tricks. 

You are right about the air bleed.  I thought I could close the butterfly completely with the air bleed, but that started an oscillation that the ECU could not resolve at idle, so I had to settle with a small adjustment from that point.  

What year is your 360R, does it have the 2016+ plenum or the earlier bit more flexible black plastic plenum?

The bungs are located near the butterfly, on the side (engine side) of the plenum. 

The cold starting problems also makes me think your throttle stop needs adjustment, after adjustment my 360 was perfect during cold starts, the 420 is now a nightmare.  

[ChrisC]

For reference what worked on my car was 

TPS at 1.21V,  MAP 0.535 BAR

It started hunting at TPS at 1.06V, MAP at 0.465 BAR, lower than that it was unable to maintain an steady idle. 

Remember the TPS on the 360/420 is fixed position, so no adjustment, this is only adjustment in the butterfly closed stop screw.

These are only my figures, it would be nice to sample a few more cars to build up a "correct" or "best" settings from 360s and 420s that start cold without throttle and lack hesitation when pulling away.   My intension is to recheck my information over the coming weeks. 

[John Vine]

...it would be nice to sample a few more cars...

That sounds a great idea.  Do you plan to include cars with rollerbarrels or is it just for plenums?

JV

[ChrisC]

I will sample any car I can get my hands on, but I need to have the owner’s comments as well, like starting issues, etc.  There is little point if it’s modified or custom-mapped, because it will be unique to the car.   It would be about getting data that would help others get the best from their cars, in a similar way to the much-published 150 Sigma settings.

[Alan Reeves]

I had 420 cams put in to a 175 along with the re map/cams/springs/injectors.

It went for a rolling road finesse with 2 steves ( they had done my undriveable in traffic CSR a few years ago, great).

However after the rolling road once home and a cold start  it was very unhappy to start and probably 20-30 seconds warm up before I could let it tick over.

No hesitation from Steve, back it went to take into account the cold start. Essentially it is an issue doing the re map when you start with a warmish engine.

Its very good now

 

[O.G.]

Just finished a little test drive after some investigation.

I removed the throttle assembly and found the “throttle bypass” went nowhere. It hits a brick (plastic) wall where it’s bolted to the manifold. My manifold is the grey/black very rigid plastic type with big “Caterham” letters on the top. As you say Chris, the only adjustment is on the butterfly, nothing on the sensor. 

As an aside, what is that flatish plastic object bolted to the side of the crankcase with the heater size hose connecting it to the bottom of the inlet manifold.

I disconnected the battery for five minutes. 

Sadly no improvement in anything. Doesn’t start when cold without a feather of throttle but starts OK when hot. Idles at 1050. Hesitant at any rpm when opening the throttle quickly, often with inlet pop.

My car also suffers from severe kangarooing with closed throttle, at rpms below 2000 in 1st & 2nd gear typically when coming to a stop before it would be normal to dip the clutch. Is that connected?

O.G.

[sjl1]

A lot of shared experiences here

First off, that black plastic plate on the engine is the oil breather which vents into the plenum. If you overfill a wet sumped car the oil will vent into the plenum and create smoke, very concerning when you get black flagged at Brands! I am told by Caterham that you can either vent this into the catch tank which will create a lot of oil or simply blank it off altogether, something i am seriously considering

I think i posted on here about my 360r exhibiting lag when the throttle snapped open and my experiences are very similar to others here. Car would start from cold and idle ok after 30 seconds and no signs of kangerooing (which my previous sigma did badly). Recently upgraded to 420r spec and throttle lag is still there but much reduced and much better. Engine starts well from cold but can hunt at idle and exhibits mild kangerooing, no doubt due to lumpier cams. General engine character is much better and i would be loathe to fiddle with it to avoid cost and hassle. Overall i like the Duratec engine, its torquey and powerful and easier to drive than the sigma which felt too highly strung

just need to book some 2019 track days now...

[John Vine]

If you overfill a wet sumped car the oil will vent into the plenum and create smoke, very concerning when you get black flagged at Brands!

That was exactly what happened to me (and at Donington, too), and it tends to occur on fast right-handers due to surge, even if you don't overfill. 

See here for a catch-tank solution. 

JV

[Geoff Brown]

Just fit throttle bodies - extra 10bhp, lots of induction noise, throttle response is instant.........

[ChrisC]

More likely to get black flagged for noise.... 

[sjl1]

Chris, that was my thinking, have seen a few Caterhams fail the noise test at Brands when sporting TB’s. Getting close to the noise limits just becomes a nuisance. Then there is the cost, it was £2k to go from 180 to 210bhp. Not sure i can justify £3k for 10bhp more? Its not exactly lacking in power!

[ChrisC]

I know there is a sweet spot for these 360/420 cars, and I know they can be improved with small adjustments with the throttle stop and vacuum.   I suspect with your car there is something wrong, an air leak maybe giving the MAP sensor a bad reading, an earth problem or maybe TPS problem (maybe the start or a broken wires).

Do you have access (or know a local club member) that's good with Easymap?   Your not to far away if you want to drive over to Essex.

 

[ChrisC]

I would not change to TBs to solve running problems.    I would change to TB's for increased noise, looks and the extra 10bhp providing the tracks I like to visit allow the noise. 

There is one company Track 'n' Road in Rainham  who has the Caterham version of Easymap, so they can change the locked Caterham ECU.   They will be able to change the ECU strategy to TPS and map all the issues out.   You will gain power and drivability.   

    

[SKC]

Hi O.G.

We had a customer mentioning exactly the same comments as you with a Supersport R (basically same car).  We put it on the rollers with its locked Caterham ECU and produced an initial power and torque curve for a baseline.  We then fitted an unlocked MBE ECU and remapped it.  The object of the exercise wasn't to produce more power but to sort out the throttle lag and poor driveability but we did have an initail power figure of 174bhp from an engine (not very old) that was supposed to be producing 180bhp.

The end result was a transformation in throttle response and driveability and an overall top end power gain of 14bhp, the engine now producing 188bhp. 

Caterham are not going to rolling road every car but fitting an unlocked ECU and re-mapping it can have some great results.  Also having the unlocked ECU means if you want to upgrade in the future, you also have the ECU already.  Whilst people are sold are horse power figures, it's generally great driveability and throttle response people notice.

Regards

SKC

[O.G.]

I have decided to bite the bullet, go in big and have the engine remapped by “The Two Steve’s”. The way the car is, it is taking 50% of the enjoyment out of driving. Hope they can fit me in before the Cadwell Park track day.

I will fill everybody in with the results of The Steve’s endevours. . 

Thanks all for your input. 

O.G.