Cerbera in USA Stall at Idle

[Ben Dutton]

Hello - I have a 4.2 Cerbera that I recently purchased and imported to me over in the USA. It has had the 12k service etc within the last few months. It ran perfectly in the UK. Shortly after it arrived in the US, it has started to stall at idle. The revs will drop to 900, 800 and then it will cut out. Starts right back up again when I restart it. Drives perfectly. I had been a little too careful with the car - keeping her below 3000 RPM. As I started to give her more life (4000+) she has got much better. Also better since I turned the AC off. Looking for some guidance if possible please. Idles around 900RPM. If I tick her up at around 1000RPM when stopped she won’t stall. Looking for any thoughts please on solutions. Not sure if I just need to drive a race car like a race car or increase the idle RPM on the accelerator setting. No warning lights on and goes like a rocket. Thank you.

[Billy_Rosewood]

Does it happen after a bit of driving?

My 4.2 would stall at idle due to the fuel rail being heat soaked.

If it was on the move it'd get enough airflow to be ok, but she sat in traffic it'd eventually begin to stall.

Completely cured after I decatted it. Might be worth attempting to heat wrap the fuel rail as a test?

[stuthemong]

You using decent high octane fuel? No idea but may have impact as I think is fuel is a bit different to uk?

Can you get diagnostics on the car, serial connector and have a look to make sure throttle bodies and lambda all OK.

Tbh the fix may be to just screw out the idle screw a bit, 950 idle has been impliments on my old 4.2 car too IIRC

[Jhonno]

You need to get it on diagnostics and see what is going on.. Currently it's very finger in the air.

[Cerbusa]

Thank you. I think it is an issue both when cold and hot. She has been decatted. I will say it is horribly warm over here at the moment - 33 degrees C.

[Cerbusa]

stuthe said:

You using decent high octane fuel? No idea but may have impact as I think is fuel is a bit different to uk?

Can you get diagnostics on the car, serial connector and have a look to make sure throttle bodies and lambda all OK.

Tbh the fix may be to just screw out the idle screw a bit, 950 idle has been impliments on my old 4.2 car too IIRC

I think the fuel is about the same - i added the fuel cleaner / octance booster stuff - i think that may have helped. I will hook up the ECU as soon as i can find a cable over here and see what that tells me.

[Cerbusa]

Jhonno said:

You need to get it on diagnostics and see what is going on.. Currently it's very finger in the air.

Thank you - will see what that tells me.

[Jimm218]

Are you sure the idle adjustment screw/stop hasn't come loose and its just shutting the throttles. Mine has done it before. It is under the throttle linkage on the drives side.

[Cerbusa]

Jimm218 said:

Are you sure the idle adjustment screw/stop hasn't come loose and its just shutting the throttles. Mine has done it before. It is under the throttle linkage on the drives side.

It may have done - she was on the vibrating boat for a week coming over from Liverpool.

[fatjon]

http://tvr-cerbera.co.uk/software.html

This should have you sorted

[ukkid35]

Check that both banks have equal airflow at/near idle

No need to get the diagnostics working for that test

[Byker28i]

Cerbusa said:

Thank you. I think it is an issue both when cold and hot. She has been decatted. I will say it is horribly warm over here at the moment - 33 degrees C.

Heat, fans running, aircon on, all put a load on the system. When in France and 35C plus I found I had to use the throttle to push the revs to around 1200 to keep the alternator chucking out power to run both fans and keep the car cool in traffic.

Diagnostics are an essential. Check throttle pot settings etc, they can move plus look for any faults

This is a useful site, full of details
http://tvr-cerbera.co.uk/

Also early doc by Joolz said:
any stalling problems occurring are either as a result of a fault, or more commonly because the butterflies on the O/S bank are becoming blocked with oil from the breather trap in that side airbox.

On cold start, the ignition timing is advanced which takes care of the cold-start fast idle, and the timing is gradually trimmed as the coolant temperature increases. It's important that the butterfly area is cleaned every service to maintain the idle speed...it shouldn't be raised just by opening the idle speed stop screw since this ruins the relationship between the rate of opening of the butterfly and the expected change in airflow possibly resulting in uneven slow speed running (for each incremental increase in butterfly angle, the rate of change of airflow decreases).

Edited by Byker28i on Thursday 17th August 15:18

[pmessling]

Keep the aircon on. Part of the system cools the fuel.

But obviously adds more load to the engine.

Set the throttles up correctly and try again.

[Cerbusa]

Jimm218 said:

Are you sure the idle adjustment screw/stop hasn't come loose and its just shutting the throttles. Mine has done it before. It is under the throttle linkage on the drives side.

Thank you, I will check.

[gruffalo]

Cerbusa said:

stuthe said:

You using decent high octane fuel? No idea but may have impact as I think is fuel is a bit different to uk?

Can you get diagnostics on the car, serial connector and have a look to make sure throttle bodies and lambda all OK.

Tbh the fix may be to just screw out the idle screw a bit, 950 idle has been impliments on my old 4.2 car too IIRC

I think the fuel is about the same - i added the fuel cleaner / octance booster stuff - i think that may have helped. I will hook up the ECU as soon as i can find a cable over here and see what that tells me.

When you get the lead and take a look make sure both Lambdas are switching correctly, these symptom sounds very similar to when mine had Lambda issues, it got through many of them as there seemed to be a run of them which seemed to be made of chocolate and failed frequently.

I slightly higher idle is also good, the alternator doesn't really put anything into the battery until around 1200rpm, mine is set at 1000rpm.

[Cerbusa]

gruffalo said:

When you get the lead and take a look make sure both Lambdas are switching correctly, these symptom sounds very similar to when mine had Lambda issues, it got through many of them as there seemed to be a run of them which seemed to be made of chocolate and failed frequently.

I slightly higher idle is also good, the alternator doesn't really put anything into the battery until around 1200rpm, mine is set at 1000rpm.

Thank you. The lead arrives today so will let you know what i find out.

[Peter-j8c3u]

Maybe you’ve been too tame with it and sooted the plugs, have you checked them?
You need to be using 93 octane or more btw.

[flyingdutchie]

You're a brave man..... driving an ajp in the usa!

[sixor8]

Peter-j8c3u said:

Maybe you’ve been too tame with it and sooted the plugs, have you checked them?
You need to be using 93 octane or more btw.

I presume you're quoting USA octane rating (AKI)? Your profile doesn't mention a location.

The way it's calculated in the USA is different to Europe (RON). People on holiday often think U.S. fuel is inferior, but it isn't. 93 in the USA is equivalent to 97-98 over here.