Misfire

[Mark51]

I have an annoying misfire. Its ok above approx 2.8k revs but anything below that and on idle it misses.

Ive changed the plugs for some proper NGK ones
Tried a new coil pack and HT leads
Run it on the RS Tuner and it comes up with nothing
Also replaced front lambda sensor aswell
been running it on 98 RON fuel and its made no difference

I had an issue with the CAT melting due to a faulty lambda sensor so the CAT pipe is there but has no cat inside. ie, DIY de-cat as i didnt want to pay for a new CAT at the time. I also have a Henk remap, the car performance does alter when i swap maps from the New Henk one to the old one and to the new Renault map they put on but the misfire is still there.

Any ideas?

thanks

 

[Mark51]

Anyone?

 

[Mark51]

bump

 

[bigup7]

I also have a Henk remap, the car performance does alter when i swap maps from the New Henk one to the old one and to the new Renault map they put on but the misfire is still there.

Any ideas?

thanks

have you tried putting your stock map back on car (the one you backed up before putting on henk's maps?)

 

[hillclimb_clio]

having a very simlar problem with my 172 Cup - have you tried the TDC sensor? Didn't work for me but I belive it has for other people - I'm still working on mine - coil pack next for me I think

 

[Fred@BTM]

you melted a cat?

 

[Mark51]

have you tried putting your stock map back on car (the one you backed up before putting on henk's maps?)

yeah tried that, this is when i actually noticed how good the Henk map actually was

having a very simlar problem with my 172 Cup - have you tried the TDC sensor? Didn't work for me but I belive it has for other people - I'm still working on mine - coil pack next for me I think

i was thinking this but would have thought that it would have had problems all through the rev range. can anyone confirm this?

you melted a cat?

yeah mate, you commented on the thread to say that you have never seen a melted one. Apparently it was down to a faulty up stream lambda sensor which meant fuel was been dumped into the cat. Diagnosis from Renault.

 

[Fred@BTM]

get a 2nd opinion LOL!

 

[Mark51]

get a 2nd opinion LOL!

On what Fred?

 

[Mark51]

today is roasting hot and it seems to be worse when its hot, strange>>>??

 

[hillclimb_clio]

I've been told its probably an injector on mine - will find out on Wednesday when it goes in to be checked

 

[JamboM3]

My thoughts would be injector or have you checked the other lambda? Could be causing a missfire. My post cat one caused all kinds of havoc on mine unroll I replaced I. Different car afterwards. Completely changed the drive felt eager faster smoother. Mine was missing every ow and again though not constantly

 

[Mark51]

i would have thought that the sparks plugs would have shown if there was a problem with an injector though?

Jambo - from what ive read the second lambda sensor doesnt do anything apart from through a light up on the dash if its not working properly - can you or someone confirm this?

 

[JamboM3]

That's rubbish I'm afraid it's higely important

 

[Mark51]

hmmmm, would this show on the RS Tuner?

just plugged it in and no errors show

 

[Ste666]

The Lambda sensors are vital as i have just found out, it won't show up as an error if it's just become old and sluggish or contaminated, the ecu will just make changes to fueling to compensate for what it thinks is a correct reading given by the Lambda, i took mine out two days ago to check after tom from JMS told me it might be the cause of a really low rolling road power output........too low to mention on here, anyway when i took them out the pre cat sensor was almost white with silicon contamination, i swapped them over as the rear looked good and instantly my car felt so much more powerful, so just to be sure i went and bought two new ones today.

the rear one does have a role to play, the ecu sends messages to it to make sure the front one is doing it's job properly.

I found this good reading

http://www.lambdapower.co.uk/diagnosis/diagnostic_index.asp

 

[Mark51]

so how would this work with a decat?

 

[sideways danny]

i
Jambo - from what ive read the second lambda sensor doesnt do anything apart from through a light up on the dash if its not working properly - can you or someone confirm this?

That's rubbish I'm afraid it's higely important

Mark is correct, second lambda is just a warning indicator to tell you when the cat isn't working.

I think it sounds like a temp sensor, or maybe MAP sensor. I'd change the coolant temp sensor first

 

[Mark51]

i saw a post from you in a similar thread that suggested temp sensor so was going to look into that.
easy to change danny? do i have to bleed the system after?

 

[sideways danny]

easy enough to change, just need to move the airbox and you can see it. You will need to bleed the system afterwards yes, but it's not too hard

 

[Mark51]

could you explain where the bleed points are and the process for me? it would be mint if you could

 

[Mark51]

bump

 

[JamboM3]

If your just changing the cts then old one off, finger over hole (when engine cold) then bung new sensor in, you won't loose more than 10ml of water/coolant if your quick

 

[Mark51]

i was also thinking of changing the thermostat aswell whilst i was there but suppose that if i dont have to re-bleed the system then i may aswell just change the coolant sensor first

 

[Mark51]

decided to f**k this off and book it into somewhere that knows their stuff. So its going to RS Tuning in Leeds tomorrow afternoon.

 

[northy]

what was it did they fix it

 

[kevin.s]

what was it did they fix it

+1, ive got a miss on mine every now and then and ive changed the leads and coil and checked the plugs and nothing happened. so i was thinking it must be a sensor or somthing.

 

[Mark51]

what was it did they fix it

yes mate, i must have been really unlucky lol. I have previous tried two separate coil packs and neither of them made any difference. Yet when at RS Tuning we tried another and it ran spot on. so got a new one from Renault and its running mint!