hi, I am looking for any help you could give me.

 

when ticking over the revs on my Octavia 1.6 jump up and down. sometimes low enough for the engine to stall.

 

I was told by a local mechanic that I needed a new throttle body.

 

the throttle body was replaced as well as the hose connected to it.

 

this seemed to slightly cure the problem for a few weeks but its back again.

 

both lambda sensors were replaced last year for its MOT.

 

thanks in advance.

 

 

Does it also do it at light throttle openings too?

yes, but only when the engine is hot

Ah ok, that probably not throttle body related then..

what engine code is it?

Could it be an airflow thing? Check pipework and connections to SAI. I had a hose pop off the SAI once and idle went bananas, EML came on though.

the hose that connects between the throttle body and the air filter had break in the small pipe. the hose was replaced at the same time as the throttle body.

 

Not sure what other hoses to check or where to find them.

Could it be an airflow thing?.

Yes it could be, but we need to know which engine type it is really, some Octavia's had the early 8v engines from a polo, and they don't have sai or an airflow meter.

From memory, I think there is a breather pipe near the airbox on the 1.6 that can perish and cause these symptoms.

don't have docs at hand but the only code i remember is 1u2, if this is any help. car is a 2002 Octavia 1.6 ambiente

That could be an AVU engine code, in the boot by the rear panel in the spare wheel well should be a bar code sticker, and the code should be listed there.

 it is AVU, thanks for the tip where to look

also, when the engine is hot, it seems to be taking in too much petrol, runs perfectly when cold, as if the air/fuel mixture is wrong.

 

I replaced the air filter and spark plugs about 10 days ago, but still the same.

 

the breather hose was the one that was broken, the full hose was replaced.

there is also a smell of petrol when the car sits idling for a few minutes when hot

As you appear to be experiencing several symptoms that seem to have an airflow type profile, I would be inclined to suspect either the intake temp sensor which is built into the mass airflow sensor, or a faulty injector.

 

As the cost of these are quite expensive to guess at, I would suggest a VCDS scan to see if any codes are present first, and then some basic logging of the airflow sensor to see what gives.

 

When you replaced the other items, were they new or used units?

 

I see in your first post you had 2 lambda sensors renewed, was this for an emissions fail?, if so was it for high co or hydrocarbons?. how many miles on the clock?

throttle body and hose were new from europarts, spark plugs and air filter were from TMS.

 

Car was plugged into a snap-on diagnostic machine when the throttle body was replaced and there were no faults listed.

when I bought the car it had 78, 000 miles. I checked the service manual and the timing belt was due for replacement at 80, 000 miles.

 

had timing belt, pulleys and water pump replaced a week later.

 

Told the mechanic to plug it in to see if there was anything else needed.

 

fault codes for the lambda sensors showed up.

 

faults were cleared and car was taken for a drive.

 

plugged in again and faults reappeared, so they were replaced.

The snap on machine can come in many guises, some can do the same logging as VCDS, (the megabucks version) whereas the smaller versions are too generic and don't quite do the same job.

 

It may be that the sensor is failing rather than failed, so will not return a code, which was why I suggested the logging so you would get a reasonable indication of what is what.

 

Plenty of members on here do this for beer tokens (if you were closer, I would log it for you) see who is near you who might help you out.

 

Just read your last post, do you know what the actual lambda codes were at all?, did he record them on the invoice at all?.

I will try the local scrap yards and try to find an air flow sensor, is there any other car that uses the same one as finding a petrol skoda is like finding hens teeth.

 

4 scrap yards in my area and none of them have seen a petrol skoda Octavia never mind have one.

Your car is unusual in that the air temperature sensor is built into the maf, rather than 2 separate sensors, so it must be from a similar vehicle I'm afraid, although the same engine code in a VW, Audi,or SEAT would be ok to use.

 

You could also run some injector cleaner through to see if it is a sticking injector if it helps - could be a cheap cure, with not a big financial outlay to try.

I don't have a clue what the codes were, I will ask next time I see him.

thanks for the help, I will visit every scrap yard in the area tomorrow and post how I get on. May help someone else with similar problems.

The reason I asked about the lambda codes is that some codes indicate a heating element failure, whereas other codes indicate failure of the sensor itself, which may have been the start of this problem starting to form so the info would have been useful to either rule in or rule out excess fuelling problems.

checked online, can buy an after market air flow meter for around £60. original part is £116. not sure if I should buy second hand or new.

what I was told at the time was the inside part of the lambda sensor on the back of the engine had failed, don't know if that's any help, I don't know anything about them.

Just before we go down the replacing things route, what temp does your gauge read when warm?, what colour is your coolant temp sensor?, Green or Black, as this also controls fuelling by temperature too.