Revs dipping when idleing

[kriso]

I've done a search but not found any answers to this...when the car is idleing, usually after driving for a while, the revs drop every now and then to about 600rpm for a second then go back up. I had the MAF sensor replaced at stealers and it seemed to go away but this was also coincided with a remap.

After doing N249 bypass, this seemed to come back. Car is now out of warranty so don't want to go back to dealers really...any ideas as to what this could be? I was thinking throttle body might need cleaning but not too sure how to do this..

 

[st10587]

i have noticed this on my 1.2 since the cold weather has kicked in. no idea what it is but its a git when you go to pull away and its done it and 9 times out of 10 you stall!!!

 

[rashcupra]

kriso ring up the remap company!

 

[MichalR]

That happened to me last summer, all i did was to take off the ERG valve and clean it with some carb cleaner and then take of the throttle body and clean the oil and grime off of it. Never had the lumpy idle problem again!

 

[st10587]

where is the erg valve? how hard is it to get off?

 

[MichalR]

Cant remember where the ERG valve is on the 1.2's but on my 1.4 its just above the manifold cover.
To take it off you just have to disconnect the cable, undo the 2 nuts which will allow the gold pipe to slide off followed by the valve.

The gold pipe goes to the throttle body and is only held on by 2 torx bolts. At the same time i took the TB off to clean that up too.

To clean the EGR valve up i sprayed it with loads of carb cleaner and then rubbed it all down with a toothbrush. Also once you have taken the valve off you will notice a breather pipe with a filter at the end. I found that when you take the filter off and using a compressor blow into the pipe and it opens the valve which allowed me to spray more carb cleaner over it!

It was quite an easy fix too, hope that helps!

 

[st10587]

ok had a quick look, sorry if it sounds a bit stupid but the egr valve is the black round thing in the top pic jus below the temp sensor right? the 2nd pic is that where the gold pipe goes into the bottom of the throttle body?

 

[kriso]

kriso ring up the remap company!

It was happening before the remap. If anything the remap fixed it until I did the N249 bypass! So I'm thinking maybe vacuum leak..

That happened to me last summer, all i did was to take off the ERG valve and clean it with some carb cleaner and then take of the throttle body and clean the oil and grime off of it. Never had the lumpy idle problem aga

I'll give that a go too. I have a can of carb cleaner so will check this and the O2 sensor if I can find it as have heard this might be something to do with it.

 

[Nath.]

maybe the revs drop cos a fan kicks in or somthing

if you have a dodgy altinator your revs will drop a lot more than they should when you flash your lights, move the steering wheel, switch on heated rear screen or put the blower on full

to check your altinator output you should be able to measure 14 volts on the 2 battery terminals on tickover, if you have less than that you have an altinator or maybe a battery problem

 

[st10587]

maybe the revs drop cos a fan kicks in or somthing

if you have a dodgy altinator your revs will drop a lot more than they should when you flash your lights, move the steering wheel, switch on heated rear screen or put the blower on full

to check your altinator output you should be able to measure 14 volts on the 2 battery terminals on tickover, if you have less than that you have an altinator or maybe a battery problem

If it was that would it not be a continuous fault not a intermittent one?

 

[Nath.]

If it was that would it not be a continuous fault not a intermittent one?

depends,,,,,, alternators can have an intermittent output, your battery could have a cell down and only cause problems when the temp drops

who knows mate but it's worth getting the alternator output voltage checked as it only takes 2 seconds to rule it out if you have a nice healthy 14 volts

would a vacuum problem be intermittent ??????

 

[st10587]

hmm will your standard multi meter do it?

 

[kriso]

I just tried the multimeter in the dark and as soon as I connected it, the revs seemed to drop and headlights dimmed like there was a sudden load on it

I'll try again tomorrow I think.

Edit: Should this be AC or DC ?

 

[Nath.]

yes a normal cheep meter will be fine, just stick it on DC volts and touch the probes on the 2 battery terminals

dodgy battery connections could be your problem, have a look at the battery terminals to see if they have any white furr growing on them and make sure they are tight

it's a good idea to remove the battery connections and clean with a wire brush then refit them nice and snug

 

[kriso]

Cheers nathwarr, I will try again tomorrow. Fortunately I have just today wangled the radio code out of a dealer so can now disconnect battery and reset ECU etc. which I have been avoiding for obvious reasons

 

[Nath.]

no probs, let us know what you find mate

 

[kriso]

Checked the volts on the battery when idleing and it was 14.5. Couldn't locate the EGR valve but I will have another look.

 

[Nath.]

well at least you have ruled out the alternator for free mate

 

[kriso]

I have found a load of Seat info and it seems the Cupras (along with some other models) don't have an EGR system, so I can proabbly rule this out. Need to find O2 sensor still...this prob is getting really annoying now.

 

[rashcupra]

mine does this BAD but iput that down to something i put on