172 not starting

[Matteh]

ok, tried with the spark plugs in the leads... cant see anything, but i can sorta hear a clicking and I can feel the mini shocks when i hold the leads!

 

[Matteh]

also, ive connected it up with no1 on the coil pack going to the gearbox end and number 4 going to the cambelt end

 

[bmh.01]

If you can hear clicking then you've got spark. If you look very closely you should be able to see it.

1 is g/box end correct, you put everything in and tried starting it?

 

[Matteh]

yep, connected it all up yesterday and put the new coilpack in this morning

thing that worried me was my ICV isnt properly bolted on (very loose) and as it was trying to start, the engine sort of backfired and tried to blow the ICV off! (ooo err).


thats not right!

 

[bmh.01]

Nope that won't be helping matters. You bolt it on and tried it? Any luck?

 

[Matteh]

ive not bolted it on properly, no, need some bolts with a smaller head first

shouldn't make a difference though, should it? even with it completely removed it would still run and idle very roughly

 

[Matteh]

think i've sussed it...

the spark plugs were black = overfueling?

cleaned them up and it runs fine but the plugs blacken up -meaning its still overfueling

and I think its due to having no lambda plugged in?

 

[geesus69]

nice easy fix then, get a lambda whacked on and fire it up

 

[bmh.01]

Yep i'd go with that seeing as the lambda is responsible for fueling. Black is over fueling yes, looks like its time to sort a lambda out then!

 

[Matteh]

yep

geesus, the engine just ran!

next question (l love you bmh ) - are the lambdas for the 172 specific to the 172? or can i grab them off a 1.6 or something?

also, should i connect both, or does it really only require the upstream lambda

do i just put it on at the beginning of my downpipe?



wonder if I could've gotten away without spending nearly £100 on a new CPS and coilpack - but i guess its nice to have brand new genuine stuff

 

[Cro]

specific lambda mate, you can get away with only the upstream plugged in, and the other connected but tidied away somewhere. having similar problems myself at the mo after a lambda problem, hopefully new sparks fix that after you having some joy

 

[bmh.01]

There none specific according to dialogys, well the 1.4/1.6 and 172 ones are the same anyway. Haven't checked any others, the 1.2 ones are different though.

You can probably get away without having a second lambda connected at all as its only there the check that the cat is functioning and you won't notice any difference as theres no light to come on the dash in a Mk1 shell.

 

[bmh.01]

do i just put it on at the beginning of my downpipe?



wonder if I could've gotten away without spending nearly £100 on a new CPS and coilpack - but i guess its nice to have brand new genuine stuff

Anywhere on the downpipe should be fine where theres room really. Well if you weren't getting fuel and spark before the CPS then that must have been a problem unless it was just the way you were checking it.

One way is to refit the old coil pack and try again, can flog the spare if the old one works.

 

[Matteh]

yeh, i'll try that

the GSF website says something along the lines of "Lambda probe - all renault except Laguna V6" £42ex

ECP do em for £16

so i'll ring around tomorrow and source one - i'll find a downpipe to cut up so i can weld in the lambda hole too (or just weld a nut on I've heard?)

should be all gravy then!

the clio fired up this afternoon, but gradually got worse then cut out - plugs were black again... so it must be overfueling like a mofo


cheers for all of your help though mate! really appreciate it

 

[Mark One]

if your looking for a lambda for a 172, cheapest I found was a Bosch one from Central auto supplies.

 

[Matteh]

how much?

 

[Cro]

they are round £40 + vat from there, bosch same as OE

 

[Matteh]

installed an upstream lambda today and it seems to be running better.

my spark plugs were caked in soot though.

I still get the occasional backfire (coming out the ICV hole - big flame!!) and it sounds like its running on 3, but im gonna get some new spark plugs (one of them had a bent tip!!) and hopefully that will solve it

the 1.6 ICV that I have seems to stop the engine from running when u offer it up to the hole on the plenum, but again it might be due to bad spark plugs...

these engines are very picky! makes the mk1 lumps seem bulletrproof

 

[bmh.01]

You shouldn't be getting flames back in the inlet manifold surely? You sure its timed up properly?

 

[ditz]

sounds like you have got the firing order wrong mate,,, one easy way to tell.

adjust the throttle cable so its running a tad faster than normal idle,
pull each plug lead off the coilpack one by one (again if you are carefull and the leads arent breaking down it wont shock you) but if you are worried use some insulated pliers.

if you find pulling say number 2 off makes no difference to the engines running, note that down and plug it back in, continue to check the rest of them.
if you then find another lead makes no difference to its running, switch the engine off and swap those two over.

99.9% sure its that.

 

[Matteh]

cheers ditz, i'll go give that a try now

bought some new spark plugs this morning and it fires up easily (still running on 3 though)

and when i rev it, i'm fairly sure i can hear a knock :dapprove:

 

[Matteh]

tried taking the plugs out one at a time and none of them made a difference to the engines running!

i also tried swapping the order (1234 4321) as i've seen a few people state thats how the plugs should go, but it made FA difference

so either the knocking is causing it, or it's timed up wrong (which is odd, as im fairly sure its run properly before)

the only unreplaced part in my ignition system is the HT leads, mainly cause im avoiding spending yet another £100

 

[mini-valver]

Firing order was never inlne in my old cars, but they used dizzy's. You tried 1432 or 1342?

If they were massively wrong it would crank then back fire. Have you got a leak anywhere in the inlet manifold?

 

[ditz]

i still think its firing order, theres no 2 ways about it pulling a plug lead off at a time WILL make a difference esp if its running on 2 or 3 as pulling one strong cylinder off should stop it running all together,
how quick did you have it running when you did this test?

 

[Matteh]

should i attach lead 1 to coil pack 1
4 to 2
3 to 3
2 to 4?


ditz, it was just on idle when i removed the plugs - i removed them for a good 10-20s each and quite far from the coil, so they could not 'jump'

 

[Fred@BTM]

the coilpack is numbered 1,2,3,4

1 is at the gearbox end, and 4 is the other end


1 2 3 4 gearbox

the HT leads should have number on them too (if they're renault OE)

 

[Matteh]

yeh, that's how I've currently got it set up (seemed logical )

 

[alexbleubolt]

its your ht leads, get some more.