Duratec - Very poor running partial throttle - Update

[Guest]

Hello Blatchat,

 

I wonder if anyone can help diagnose or has any thoughts on this? My Car (Duratec SuperSport) seems to be having some issues that I'm hoping to resolve.

 

The car is nearly new (just passed 540 miles / 7 months old) and is still being run in but today I've experienced some very nasty hesitation/ stuttering whilst driving 20-30 miles or so on the dual carriage way home this evening. The symptoms:

 

- Near impossible to drive on a partial throttle at between 3k -4k revs (60- 70 mph). Trying to keep a constant speed and a constant throttle resulted in much kangarooing. The car felt like it was suffering from fuel starvation and felt like it was going to stall (but didn't)

 

- Applying throttle to try and counter act the lurching resulted in car accelerating OK but there was often quite a hesitation between throttle being applied and car actually reacting to that input.

 

- Very poor fuel consumption. My wife was watching the fuel gauge dropping whilst we were heading home. If the fuel gauge is to be believed (I realise they aren't always that accurate), then we did about half a tank of fuel in about 60 miles!

 

- Car would accelerate seemingly OK on wide open throttle and did not stutter under these throttle conditions

 

- Car didn't start brilliantly earlier today. I had to give it a dab of throttle to get it started and avoid it stalling.

 

I was alarmed enough by these events that when I got home earlier I was scouting around under the car to see if I could identify any potential fuel leaks but I found none. Whatever is the exact cause, the cars fueling is clearly all over the place.

 

Also, Just before packing the car away I noticed that there was a lot of black soot in the end of the exhaust. I'm reasonably sure its excessive and shouldn't be there and I'm also fairly sure I'd have noticed it previously if this was something that had been there a while. I'm assuming therefore that this must be a recent development.

 

I've done some digging in the archives and from what I've been reading, I'm wondering if the lamda sensor is knackered. Some posts from other owners with similar issues that I found included

 

This one here

 

And also this one here

 

What particularly interested me about the second post was the owner talking about having refueled with Shell V-Power recently. As it happens, this is exactly what I have just done (within the last 60 miles or so) having not run anything but 95 octane fuel in it to date. Could it be something in the Shell fuel that the lamda sensors don't like?

 

So, do I just take a punt and get another lamda sensor or is there some way of diagnosing better whether it really is this and not something else? Are there some other things that I should be looking at?

 

Thanks in advance,

 

Tom

 

Edited by - tomwoodis on 30 Mar 2014 13:12:18

[revilla]

Afraid I know nothing about the Duratec, but if it was a K Series I'd be looking carefully at the throttle position sensor and it's wiring. May be of some relevance?

[Jonathan Kay]

I don't think that it's anything to do with the change of fuel.

 

I'd start with simple things first. Have you had a good look at and play with the the throttle pedal, cable, and linkages? Can you replicate the poor response when you play with the throttle by hand?

 

Jonathan

[revilla]

@Jonathan - I'm beginning to think you may be stalking me 😬

[Jonathan Kay]

:-)

 

TPS is a good idea!

 

Jonathan

[Michael H]

Hi there

I don't think this is your lambda sensor - that only makes a small difference to the ECU mapping. More likely a MAP or TPS sensor, or even a bad earth connection.

If your car is low mileage and under warranty, then I'd recommend you get Caterham to sort it out for you - I've just had my Duratec upgraded by them, and there was a temperature-related misfire. They collected the car from me, fixed it, and returned it in 3 days. Speak to James Gibson in aftersales.

Mike

[Guest]

Thanks everyone.

 

I had a fiddle about with all of the various connectors that go to the various sensors that you referred to. I also checked the wiring to each to make sure there was no obvious chaffing issues etc. I also pulled one of the spark plugs to see what the state of that was like. It looked very sooty to me given the low mileage. I took a picture of it along with the exhaust.

 

Spark Plug

 

Exhaust tip

 

Before I restarted it though, I disconnected and reconnected the following sensors:

 

- MAP

-TPS

-Lamda

 

I then started the car up. I had quite a bit of black soot expelled from the exhaust but perhaps not unsurprising given what had built up inside.

 

Stuff deposited on the floor

 

I then took it for a run. Partly this was so I could refill it with petrol and see how much it had used and partly to see if I could recreate the problem of yesterday. By my calculations its done about 20mpg over the last 100 miles, 50 miles of which would have been on the dual carriage way under what would normally be favorable conditions.

 

I went for a run down a stretch of the A3 at 60-70 mph on a constant throttle just as before to try and recreate the problem but this time nothing happened

 

I guess in a way this could be a good thing. All I can think of now is that either my disconnecting and reconnecting of the various sensors has got them working again as they should or... I have a dodgy earth somewhere which was presenting itself last night but not today and the ECU was having some problems?

 

I'm guessing I was experiencing 'limp home mode' last night as a result of the ECU not being fed the right data from one of the sensors or something. I guess I will have to keep monitoring it to see if the problem occurs again.

 

The tip of the exhaust actually looks cleaner now than it did this morning too now that I've been for a run so I think whatever was causing it to overfuel must have remedied itself

 

Here's hoping I guess. I'll also ring Caterham next week to see what they think I should do and whether they'd like to have it in to be looked at.

 

Tom

[John Vine]

It would be worth delving a bit more into the wiring to (1) the TPS and (2) the coil-on-plugs. IME, both suffer from fractures (probably due to high-frequency vibration). Have you seen this thread?

 

JV

[rgrigsby]

I've had exactly this on my Duratec when the TPS gave up, luckily I've got the TPS position on my digital dash so I could see it was going to 0 to 100% in the first few mm of throttle pedal travel.

 

 

[Guest]

Interesting, thanks both. I hadn't seen that thread John so thanks for sharing.

 

I'm hoping I don't have to rewire in a new loom!

 

I'll be sure to check out all the wiring to the TPS and the coil packs in more detail in that case. As for checking out the main loom, its covered in some kind of heavily braided plastic sheathing so it will be tough to work out if anything in the loom itself is knackered.

 

Any ideas how one would go about trying to get a digital feed (to a laptop?) to try and identify whether the TPS is indeed functioning correctly?

 

Tom

[Pete - W.Sussex]

And I join those suspecting TPS issues. I had this with my R400d and JV pointed me in the right direction. As he says it might be vibration but I am more convinced it is heat related. The wires are very thin and the covering rubber - it all expands when hot and the wires begin to break then cool and make random contact. The race versions are silicon covered and hence resist the expansion when hot. That's my theory anyway and it might explain why you struggled to have the problem after fiddling with the connections.

[John Vine]

Quoting TomWoodis: 

I'm hoping I don't have to rewire in a new loom!

If you mean the flexi-loom for the COPs, it's actually pretty straightforward. All you need is a crimping tool, some connectors and patience! We're not a million miles apart (Guildford-Dorset), so if you need help, let me know (good excuse for a blat!).

 

JV

[Guest]

Quoting John Vine: 

Quoting TomWoodis: 

I'm hoping I don't have to rewire in a new loom!

If you mean the flexi-loom for the COPs, it's actually pretty straightforward. All you need is a crimping tool, some connectors and patience! We're not a million miles apart (Guildford-Dorset), so if you need help, let me know (good excuse for a blat!).

 

JV

 

That's very kind of you to offer John, will keep you posted on how this one progresses.

 

Tom