Engine Management fault codes

[Zomerset]

I bought myself a C110 to see what was causing my engine management light. Its been on for a long time now, and I have not noticed any obvious major issues driving.

I have 3 codes. 7B Activation MAP cooling, which I understand might well suggest a new thermostat.

The other two are E4 Fuel trim bank, permissible range exceeded.

Are these things to be worried about? And are they going to need sorting pre MOT?!

 

[mrscalex]

Learnt something new there. I always thought the thermostat had an electrical connection purely for the DME to monitor temperature. But it turns out the DME can actively control the thermostat.

Replacing the thermostat is an obvious start point. But googling the error code it would seem it is not always the fix.

 

[NZ00Z3]

New thermostat needed

The Fuel trim codes are telling you that you have vacuum leaks. Now that you have a scanner you can test it out.

Vacuum leaks can be confirmed by looking at the fuel trims with a hot engine at idle. If any are > 8% then you have vacuum leaks. Rise the revs to 3,000 rpm for 30 seconds and if the short term fuel trims reduce, it is if confirmed that there are vacuum leaks.

 

[colb]

Fuel trims exceeding limit like that is allmost certainly down to air leaks check for split or holed rubber pipes on engine its adding fuel from seeing unetered air in the exhaust making it think its running lean

 

[Zomerset]

Thank you folks. I will get looking at hoses, and investigate thermostat replacement. I suspect I will be out of my depth, but its a starting point!

 

[mrscalex]

Thank you folks. I will get looking at hoses, and investigate thermostat replacement. I suspect I will be out of my depth, but its a starting point!

I would say the challenge here is in pinpointing the fault. Changing out likely affected rubber is actually quite straightforward. Always start with the 2 big pipes that exit the back of the air box and go to the throttle body. Flex them around. You’re statistically likely to find something here. The thermostat is more involved but plenty of how tos around. It’s worth changing the water pump at the same time.

Can you check fuel trims on a C110?

 

[colb]

I am in Newport south wales if you need to smoke test it to find leaks, your forum name suggests your not that far away. I'm back in the Uk Tuesday

 

[mrscalex]

I am in Newport south wales if you need to smoke test it to find leaks, your forum name suggests your not that far away. I'm back in the Uk Tuesday

I didn’t want to volunteer @colb but he sprang to mind straight away. This is a brilliant offer @Zomerset . Vacuum leaks are his thing and he’ll sort you out. I wouldn’t think twice about taking up the offer

 

[Oddly Godly]

I had an engine light come on mine due to fuel trims. It was the air hose between the MAF and the engine. Where there is a consitinard offshoot about an inch thick. I replaced both hoses every now fine. Some leaks are harder to find. Just about every Z3 will need the hoses between the MAF and the engine changing at some point due to the age of them.

 

[Zomerset]

Thanks all- and particularly @colb . Very kind offer. I will do a proper inspection of all my hoses etc and if I see nothing obvious, I may well be in touch.