Huge backfires on idle + running on 3

[Greeny.]

Ok, so I left my car at work over the weekend and just swapped back to it today as ive been away. Started it up and it sounded like it was running on 3, was hoping it would clear as I assume something has just got damp leaving it outside over the nasty weather we have had over the last few days. Obviously loads of people leave their cars outside but mine is normally garaged so I would assume something has got damp as it was working 100% fine when I parked it in the same location on Saturday morning!

Basicly on idle its popping huge backfires without me increasing the revs, I managed to drive it home, pulling away in first also gives me a s**t load more backfires... probably wouldnt be as bad backfire wise on a standard system but with a Yozza race system and a de-cat they sound like gun shots lol!

Whats best to check first? I really think this is something damp related, or at least hope so. Its dark outside now obviously so will have a look over the weekend.

 

[Beef-Mc]

Lambda?

 

[James.f]

Spark plugs would be my first port of call,

 

[Greeny.]

Spark plugs would get effected by leaving the car in the damp for 4 days?

What are the symptoms of a faulty Lambda?

 

[Dangerous_dave]

moisture in your leads / coil pack

 

[Hutchie]

rag the funk out of your car and see if it clears itself, i can be a coil has gone (coinsidence?)

 

[Gttnutter]

I had this issue just a few weeks back..1 minute all was fine, done some work on a 5 then an hour later started up to come home and it sounded like a 12 gauge shot gun! I couldnt/didnt want to drive it home.

I changed the coilpack to no avril

then found it had sh%ite plugs in it so changed them and the leads at the same time,

My betting is either a lead has broken down or plugs as mentioned

 

[Greeny.]

They are the factory NGk's fitted which have covered around 10k in 2.5k years, no sure on the leads, probably been on there for years tbh. Ill have a better look at it over the weekend Cheers guys!

 

[Gttnutter]

They are the factory NGk's fitted which have covered around 10k in 2.5k years, no sure on the leads, probably been on there for years tbh. Ill have a better look at it over the weekend Cheers guys!

Yes mine where oe renault leads so suspect age did come into the issue, absolutly horrible misfire though...made me jump once or twice for sure!!

leads is your cheapest 1st port of call

Take it no lights come pu on the dash? mine didnt throw anything up and i checked it with no faults found on my obd reader

 

[Greeny.]

Started fine this morning after being in the garage overnight

 

[st3ve]

Thats crazy! What could it be? Not every 172 is stored in a garage!?

 

[Greeny.]

Must of been something that can get damp easy so... anything then?

 

[172Ben]

Earth of the battery maybe, this was my problem on monday when it was stupidly cold and it got damp inside.

 

[Daniel]

I'll bet Coil pack, HT leads, Plugs.

In that order.

 

[mini-valver]

If it does it again, pull the leads off 1 by 1. The one that makes no difference to the running of the engine is the cylinder that isn't firing. To rule out leads, swap it with a working one and see if the miss fire moves cylinder. If not, do the same with the plugs.

You'll be able to rule them out easily before you throw parts at it.

 

[richy22]

I love Dan really

On a side note dan mine "once" did this in similar circumstances...left to stand in the rain for a week started rough as hell (funny as I had the yozza on as well) and as you say it sounds like a blooming gun!

Gave it a a bit of a thrashing down the road it it was fine...never did it again and I never found out what caused it (water somewhere id imagine)

gave it a quick blast

 

[MarcoB]

Italian tune up needed thats all.

 

[dave1980]

I had this issue just a few weeks back..1 minute all was fine, done some work on a 5 then an hour later started up to come home and it sounded like a 12 gauge shot gun! I couldnt/didnt want to drive it home.

I changed the coilpack to no avril

then found it had sh%ite plugs in it so changed them and the leads at the same time,

My betting is either a lead has broken down or plugs as mentioned

totally agree, had the same on mine back in the snowy weather. changed coil pack/plugs (renault wanted for £140 for leads so they were last resort).
actually had to pull over as i couldnt get up a hill it was so bad. RAC checked it and the ecu was picking up intermittent missfire.

once changed disconnect the battery so that the ecu resets itself then should be all sorted.