14 CUX ECU Still battling!

Ian Anderson · Post by **Ian Anderson** » Sat Dec 02, 2006 4:41 pm

I started a thread on the old forum saying EFI Sucks

Well one of the ideas was to get a replacement ECU and try it (My one could not be read by the diagnostic tool)

Today I fitted the other unit (E bay one and it was taken off a running unit - even said come up and see it running if you want and huge positive scoe!)

The new unit worked and the engine ran and idled (on the original it would not idle once hot) Took it to full temp - radiator fans running and it idled fine and revved cleanly.

Took it for a drive and it is totally shite. At about 1750 rpm (30mph in 3rd) it turns into a kangaroo / bucking bronco so I cannot travel in a traffic queue!) Under acceleraion pulls like a train - pulled off in 3rd with zero clutch slip - last one needed a slipped clutch to torque much improved.

So where to look now?

Could it be that it should be a no lambda system? I am running lambdas and perhaps they are not happy and making huge corrections that end as a kangaroo?

Any help greatly appreciated.

Cheers
Ian

jwriyadh · Post by **jwriyadh** » Sat Dec 02, 2006 5:20 pm

Check your tune resistor, 3900 ohms will make it use the lambda sensors, 470 ohms will instruct the ECU to ignore them.

jw

GreenV8S · Post by **GreenV8S** » Sat Dec 02, 2006 8:22 pm

From the sound of it something is way off, either that chip is wrong for your engine or there's a fault in the system. (There are loads of faults that could potentially cause that sort of symptom.) Do you have any diagnostic equipment and wideband lambda sensing available?

Ian Anderson · Post by **Ian Anderson** » Sat Dec 02, 2006 9:05 pm

Peter

Yes I agree something is way out but I cannot figure it.

I went to 3 tuners with the old ECU and non of them could read the codes.

This new (2nd hand) ECU seems to work better until you are drivin then it's back to kangaroo petrol. But it seems this only happens when trying to cruise and on low throttles 1200 - 2200 rpm

I don't have any diagnosics myself but possibly time to buy a wideband Gunson thingy from Halfords.

Or should I just say F*&$ it and buy a wwbber and manifold?

Oh yes and the date codes are only a week apart for the 2 units! (1490 and 1590)

JW

On the original ECU we started off with the non Cat resistor and it was so rich it burnt our eyes with the fumes in the pen back garden. It was also using about a litre of fuel every 2 minutes at idle! ( about 20 litres to take it to full temp and fans running three times)

Ian

GreenV8S · Post by **GreenV8S** » Sun Dec 03, 2006 12:59 am

Ian Anderson wrote:I don't have any diagnosics myself but possibly time to buy a wideband Gunson thingy from Halfords.

Well worth having wideband sensing available if you're DIYing, but personally I'd suggest you buy a decent one such as the ones from Innovate, Zeitronics etc.

Really the only way to track this down is to read the fault codes, check the sensors, fix the obvious faults so that the system is working to specification, and then fix the map if necessary. This is all quite hard to DIY, the fault code readers are quite expensive (although there's somebody at www.pistonheads.com who hires them out), to check the sensors you just need a multimeter, changing the map is the hard bit and requires a clever person with the right equipment - which isn't readily available. I only know two people with the skills and equipment, so you might struggle to find somebody local.

Richard · Post by **Richard** » Sun Dec 03, 2006 5:19 am

Local LR shops should be able to read the codes easily (and cheaply) enough, no? Sensor value ranges are in the service manual too, IIRC. Map changing is a trickier business, but there are cheap and programmable devices that can alter MAF readings in a useful way - eg, here and here. Of course, you'd also need a decent WBO2 sensor and controller to make the best use of this kind of thing.

Ian Anderson · Post by **Ian Anderson** » Sun Dec 03, 2006 10:13 am

You would think Range Rover / Landrover garage would be the place

2 said unless the engine is in one of our cars do not bring it on site

Local TVR center did not want to know

3rd Landrover Garage said no but the head mechanic was interested enough to want to do it himself - unfortuneately he could not get an old style ECU reader - only the new stuff available.

I alo posted on the Engines forum and it would appear that the cam in my engine (102 from JE) is a bit of a pig to tune and only works above 3000 rpm So perhaps I have been slagging the efi when it is the engine

Ian

GreenV8S · Post by **GreenV8S** » Sun Dec 03, 2006 11:14 am

If you don't mind spending money on it, Mark Adams is the person to fix this. He has cornered the TVR market for fixing and tuning the 14CU[X]. Otherwise I suggest finding an independant TVR specialist near you - they tend to be more accomodating than the dealers.

kev_the_mole · Post by **kev_the_mole** » Sun Dec 03, 2006 12:26 pm

Why not buy a Megasquirt and Wideband? Probably cheaper than Mark Adams and then you can play to your hearts content

Mr. Shurvinton is a nice approachable fellow.

Cheers,

Ian

jwriyadh · Post by **jwriyadh** » Sun Dec 03, 2006 12:39 pm

It would be of benefit to go through the whole of the hotwire system test schedule ”by the book” to ensure there are no faulty components. This can be found by googleing for hotwire or 14CUX. The new ECU should be accessible to standard testgear and allow confirmation of your checks.
This then leaves the ECU as the only possible area with a problem.

There are six fuelling maps in a 14CUX, one limp-home and five dedicated to a type of engine, i.e. 3.9/4.2, cat or noncat. When JE modified the mapping only one of these was altered, I would assume a 3.9 noncat.
The tune resistor is therefore crucial since it selects the map to be used.

If you are really lucky your “new” ECU will have the rom socketed so it would be possible to swop the JE rom into the new ECU.

If you have no success with the above then the options are Mark Adams/Emerald/Megasquirt, keeping in mind that your cam will always present an increased level of difficulty.

jw

ihatesissycars · Post by **ihatesissycars** » Sun Dec 03, 2006 12:57 pm

Have you asked JE about it?

Post by **Coops** » Sun Dec 03, 2006 1:17 pm

kev_the_mole wrote:Why not buy a Megasquirt and Wideband? Probably cheaper than Mark Adams and then you can play to your hearts content

Mr. Shurvinton is a nice approachable fellow.

Cheers,

Ian

so is Richard and Rob nice approachable fellows

(vems)

Ian Anderson · Post by **Ian Anderson** » Sun Dec 03, 2006 4:57 pm

Yes I asked JE and that said trailer the car up and let them strip and check it the re map etc. about £1600 - too rich at the present moment.

Guys at RPI want to swap out a lot and quoted about £980 including a full Mark Adams set of chips - they said if it does not work return the car and they will swap it back! Good idea but 200 miles of kangaroo away! (Said he would get the car to pull of hard in 5th and pull to 170mph)

I have e mailed Dave and he said Megasquirt would be possible but I am Electronics challenged so very wary on that - a Cobra bloke could so the whole megaswuirt thing but is battling with neighours with engines running and also is very limited on garage space (non existant)

Vems how much and can the VEMS unit be made to plug into the hotwire plug? I could probably do that! If so how much and delay in sorting it also do they have a dealership network in SE England?

I really just want to get a decent drive in the car!

Ian

Ian Anderson · Post by **Ian Anderson** » Sun Dec 03, 2006 5:16 pm

Sorry JW

Missed your post

Yes all sensors etc have been tested as per Haynes manual and come out with the corret readings. (they should as it is all brand new kit just not used for 16 years)

Ian

Post by **katanaman** » Sun Dec 03, 2006 5:28 pm

I think you have to face the fact that you either start learning or start paying. I would recommend the first option and it inst as difficult as it first seems. MS and Vems can be bought pre built so you don't have to worry about the soldering. I know you can also get a pigtail to connect between MS and the rover loom with little work involved. I imagine the same is available for Vems but don't know for sure. So connection wise you shouldn't have to learn very much to get it all working.

Next up is tuning it and while there are many maps out there for both systems they are really just a get you started. You will have to learn and understand what does what and why. If you don't then it will be very difficult if not impossible to get your maps right. In some respects going to a carb would be no better as you need to understand what your doing to be able to tune it. Whether or not you want to go for MS I would check out the site and manual as the principles are the same for any system and there is a huge amount of well written easy to understand info there.

There are a good few people around that I am sure will be willing to support you but its a straight equation to what you know to what you pay. The more you know yourself the less you pay plus if you ever change anything you can sort it yourself in minutes instead of relying on other people. Choice is yours.