Intermittent misfire - I'm gonna scrap this soon I'm at my wits end

[LOCUST]

Hey
Ok I'm this close to giving up.

Car started misfiring badly is undriveable it's so bad.
Here is the history.

Checked ht leads no 1was crushed between inlet manifold and cam. Replaced them it ran fine. Same day problem re occured. After it drove home fine with no issues.

Next day took it out. Same problem just about limped it home.
Changed plugs 1 and 2 were absolutely fooked. Also changed coil pack as it was cracked.
Took it out for a test drive ran lovely. Better than ever.

Today guess what. Drove it started happening again. If I dip the clutch it cuts out. Just about limped it to my parents house. Was running really bad. Wouldn't run just kept dying. Vie changed the whole ignition system. And its showing no faults on the comp.

I cantjustkeep throwing money at it and I'm getting desperate now.

 

[TheEvilGiraffe]

Are the HTs put in the right place now ? Some genius put them point to point on mine, rather than matching the numbers and putting them through the gap on the end where they should be.

 

[Mister_G]

Could be fueling wrong...

I'm sure someone will come by with some better ideas.

 

[LOCUST]

It's a2003 172 btw.

Hey.
Yeah leads are correct. I'm gonna check thelambdas tomorrow.
All the things that I've changed needed changing anyway buthavent cured the problem.
It was running perfect after changing the plugs and coil pack. Put it to bed last night and today the problem is back.

Must be fueling. I'm gonna clean the throttle body tomorrow.

 

[TheEvilGiraffe]

Have you 100% got the right plugs ?! IIRC they are very specific.

Won't be the lambdas. They adjust fuelling, you'll be running rich if they are fubar'd but not misfiring.

 

[LOCUST]

Plugs are identical. Ngk's. Thethrotle body is pretty dirty buti dunno if that would cause a misfire

 

[TheEvilGiraffe]

It shouldn't .... :S

 

[Inferno]

http://www.aa1car.com/library/misfire.htm

 

[bmh.01]

Did you only change plug 1 and 2? Not a full set?

 

[LOCUST]

Sorry should have written that clearer. Changed all the plugs. But 1 and 2 were totally gone.

 

[keirravn]

the coilpacks are often suspect is it genuine renault that you replaced it with? dont know if it matters with the clios but vag aftermarket coilys are poo and only last a few weeks.

also does it go alright under acceleration? not just a tickover fault no?

 

[LOCUST]

The coil pack was off another 172 with no issues.

Been tinkering today before I get it plugged in to the comp tomorrow and it def getting fuel. As I got petrol in my eye as I pulled off the piper that goes to the injector bar.

The map sensor which is new had The o rings perished So i just put a bit of tape round the plug.
Cleaned the throtle body and idle sensor was filthy but made no difference.

Unplugged the lambdas and was the same. Couldn't get them off though.

It sounds very odd like 2 cylinders and idles at about 2000 then drops and dies.

 

[kristian]

My mates cup ran the same when he changed his coil pack and leads, id try another coil pack and leads... Genuine ones only.

 

[gogsie]

Check your Injectors mate!. Sounds like a problem i had last year and turned out to be a dud injector, i got the rest ultrasonically cleaned and checked and it been fine since.

 

[Greeny.]

Do you have an engine management light on? If so just get it plugged in!! I had identical problems and after replacing coilpack, plugs and leads it turned out to be a faulty injector. Could always just pull them out and see if one is dryer than the others? Was obvious which one of mine wasnt working when looking at them.

 

[LOCUST]

No engine manageMention light on.

Ok so plugged in the comp today and no fault codes. But we think we found the problem.
It's either throttle body or pedal switch.
As we tested it and it was eith 5% or 85% open. No in-between. Which would explain why I can hammer it ok.

As we pressed the pedal with the ignition on the butterflyremained closed until the pedal was to the floor then It opened fully.
Se were changing it tomorrow.

 

[Amy R]

Hi Locust

Did that fix the problem - I think I have the same issue.

Got a misfire - changed plugs, leads, coil-pack, o2 sensor.

With the ignition on, the throttle body only opens fully when the throttle pedal is at 100%. e.g.10%, 20% etc no movement.... 100% springs to WOT.

 

[tom130691]

idle control?

 

[franx]

No engine manageMention light on.

Ok so plugged in the comp today and no fault codes. But we think we found the problem.
It's either throttle body or pedal switch.
As we tested it and it was eith 5% or 85% open. No in-between. Which would explain why I can hammer it ok.

As we pressed the pedal with the ignition on the butterflyremained closed until the pedal was to the floor then It opened fully.
Se were changing it tomorrow.

This is normal i think; the butterfly remaining closed until floored with engine not running, ignition on. How did things work out for you ?