Cerebra 4.5

[Crispy4377]

Hi looking for help, I have recently bought a 1998 cerebra 4.5. Was running fine but now when I start it up tick over is around 1100rpm but it gets warm very quickly and then the tick over rises to over 3000rpm the temp gauge goes to 95 but the fans don’t kick in. It is booked in for the problem but not till September. I am nervous to drive it as I don’t want to wreck her. I am new to TVR’s having always wanted one and advise would be most appreciated

[colin mee]

Maybe air lock. Colin

[ukkid35]

You'll need to check for air leaks around the throttle manifolds, and also do a full throttle setup as per the WSM

Don't risk it overheating, especially as you're not familiar with the car

[Ice_blue_tvr]

Big fuse caused similar issues with tickover on mine.. Apparently the low voltage plays havoc with the ecu and caused the idle to raise to over 2000rpm.

Fans not kicking in may be due to the real temps not being what the gauge says?

Have you got rsajp or something to read the ecu outputs? You'll see the temperature and voltage it's seeing directly.

[CerbWill]

Crispy4377 said:

Hi looking for help, I have recently bought a 1998 cerebra 4.5. Was running fine but now when I start it up tick over is around 1100rpm but it gets warm very quickly and then the tick over rises to over 3000rpm the temp gauge goes to 95 but the fans don’t kick in. It is booked in for the problem but not till September. I am nervous to drive it as I don’t want to wreck her. I am new to TVR’s having always wanted one and advise would be most appreciated

Whereabouts in the country are you? I wonder if a local owner with some (decent) DIY knowledge and some software (there's a few versions, original TVR for Win XP, RSAJP/RSiAJP for Android/iPhone, or EvoOlli's new Windows software) could assist. Ukkid's diagnosis is most likely.

Ice_blue_tvr said:

Big fuse caused similar issues with tickover on mine.. Apparently the low voltage plays havoc with the ecu and caused the idle to raise to over 2000rpm.

Did whoever fixed it explain how that works? I'm wondering how a low voltage would affect the readings the ECU sees. It could affect the throttle pots if the 5V Vref was affected, and TP values affect ignition timing. I've limped my Cerb along (looking for somewhere to stop and trying to work out what the newly occured problem was) with a failed alternator twice and both times it developed a tendency to not idle at all as the battery drains.

Ice_blue_tvr said:

Fans not kicking in may be due to the real temps not being what the gauge says?

Have you got rsajp or something to read the ecu outputs? You'll see the temperature and voltage it's seeing directly.

For the benefit of the OP who is eveidently a new owner this is quite right. The dual gauges often overread. In addition there's no way you can set the engine up without software of some sort.

[Byker28i]

This site might prove helpful.
http://tvr-cerbera.co.uk/

Something simple that could be looked at like return springs on the throttle? Cable slipped off the semicircle cable run near the throttle body, throttle pots misaligned. trying to guess why it just started...

Location would be good if another owner could assist with diagnostics software and check the obvious stuff

Edited by Byker28i on Thursday 5th August 10:07

[ukkid35]

CerbWill said:

For the benefit of the OP who is eveidently a new owner this is quite right. The dual gauges often overread. In addition there's no way you can set the engine up without software of some sort.

Also when the engine does overheat, the temp gauge can become very erratic, and can drop back to 80C, possibly because the temp sensor becomes uncovered

If the engine overheats the head gaskets become vulnerable due to pinking, even under light load

[Ice_blue_tvr]

CerbWill said:

Ice_blue_tvr said:

Big fuse caused similar issues with tickover on mine.. Apparently the low voltage plays havoc with the ecu and caused the idle to raise to over 2000rpm.

Did whoever fixed it explain how that works? I'm wondering how a low voltage would affect the readings the ECU sees. It could affect the throttle pots if the 5V Vref was affected, and TP values affect ignition timing. I've limped my Cerb along (looking for somewhere to stop and trying to work out what the newly occured problem was) with a failed alternator twice and both times it developed a tendency to not idle at all as the battery drains.

It was the guys on the Facebook group that explained it.. I don't remember exactly.. Something along the lines of low voltage to the ecu and/or injectors resulting in incorrect firing/opening times leading to a lean condition which raises the idle.

[Crispy4377]

Wow thanks for the info. Lots of reading to do. I will let you know how I get on and if I find the issue

[Byker28i]

Whereabouts are you? Might be worth a post on the Cerbera forum, plenty of experienced owners to help out if required.

[Crispy4377]

I live in Stafford

[gruffalo]

I have had similar a couple of times, it was nothing more than the return spring on the throttle and the poor way it is implemented.

Make sure the throttle is returning all the way would be my first place to look.

[ukkid35]

gruffalo said:

I have had similar a couple of times, it was nothing more than the return spring on the throttle and the poor way it is implemented.

Make sure the throttle is returning all the way would be my first place to look.

Also consider installing a long return spring available from Joolz