Hi Folks,I recently bought a '96 Cinquecento Sporting that I knew to be a non runner(head gasket).The car had been sitting unused since 2003 everything looked solid and reasonably serviceable so I decided to do it up for the Girlfriend to drive.

Prior to stripping the head I had the car running,it had to be towed to get it going.At the time it wouldn't run below 2000 revs but everything appeared to be working but as expected it blew all the water out.It refused to start off the key during another attempt to get it going.Firing on the starter but not getting itself going and occasionally spitting back through the TB, so I just assumed this was the headgasket gone that was causing the problem.

The head was removed and skimmed,new gasket fitted and built back up.New belts etc,water pump, thermostat,spark plugs and radiator fitted.

When I tried to start the car it refused to start off the starter.It was firing then occasionally spitting and popping back through the TB.I automatically thought I'd made an a##e of setting the timing so I re-did it.Again and again,still getting the same result.

Last night,the car was towed and it started immediately.However it still wasn't keen on idling and was sounding rather flat!Upon stopping it it would still not start itself.Towed again, away it went!It was then taken for a run under its own power to see if it would cure itself!It would very nearly idle but just wasn't right.Unfortunately no change upon stopping and trying to start again.

Today,it still will not start itself spluttering and blowing back through the TB.

I have tried another set of coils.

Different plug leads

Even tried the old plugs back in!

Everything tried still gives the same result!

I'm not quite sure what to try next.


Anybody have any suggestions?

Could a faulty crank sensor cause this to happen?

Have you checked the crank pulley the alternator belt fits on as it has a small hole that lines up when you bolt it on, very easy to get it out which means the timing is out by 120 degrees IIRC.

The car will try to start with this but will do something similar to what you describe.

It's unlikely to be the crank sensor, but they can cause the strangest symptoms if the cables have fretted.

I think it's the timing very slightly out.

I've seen similar things on single and twin cylinder engines with poor compression. While I doubt it's the case here, I wonder why you didn't recut the valves, fit new valve guide oil seals and re-set the valve clearances while you had the head off?

I had the same after hg change - had to start for several times, battery going low but than it starts- some backfire shots from TB, very rough sound, couldnt run idle without gas, but after while it cure itself and its running great now-probably because of no oil and petrol in top of engine

you shouldnt tow cinq, your t. belt could slip and thats why not running-check t.belt again

Thanks for the quick replies.

Just to clear up it isn't the crank sensor pick up wheel.It is definitely on it's pin.

Hi Fingers99,When I first heard and seen the pops through the TB, I automatically assumed the timing was out.I tried a tooth each way with no result then two each way with no success.

I had a quick look over the valve gear and it all seemed fine.In hindsight i maybe should have whipped the valves out and given them a going over.Have had the rocker cover off since re-assembly as I thought a valve may have been stuck open.

Do you think a bad earth could cause problems like this?

Could the sensor have failed due to deterioration to the elements?
This car has sat untouched for 5 years.

Diwiak,It did get better after being run for a bit at a fast idle.I might check the timing and get it bump started again.

Thank you

After 5 years almost anything is possible. I think that it runs but won't idle might point to an issue with the idle control valve or compression.

But, if you don't have a spare throttle body or compression tester to hand, I'd be tempted to change the oil, put some fresh petrol in it and try taking it out on a run.

You really ouight to change the coolant and the brake fluid before you do so (if you have not already).

add redex to petrol, this will clean out petrol injector. You might need to remove injector but I'd try and avoid.

Add proprietry gum solvent to oil, change filter after an interval.

flush out coolant passages with proprietary rad flush agent

bleed all the brakes until all the old fluid is purged. Or buy quija board for partner.

Take for long run and leave at tick over with heater on and heater fan on, the ECU needs to be trained again, sit in car for this it may overheat, the fan needs to come on and it may not ...

Change oil in gear box, check drive shaft gaiters are intact.

get MoT etc...

expect wheel bearings to fail in 3-4 months...

Noel

Blow back through the TB is a timing issue. Rather than blindly moving the cam timing set it up properly.

Remember it can be 180 degrees out

Cheers

SPD

i had the same problem as you,

the car would start but would back fire every now and then. timing was one tooth out and i had stupidly not put the crank pick up wheel on the pin, sorted that out and all bril now.

rallycinq said:

Remember it can be 180 degrees out

Cheers

SPD

Click to expand...

Thanks for the suggestion but I have tried this already.

Although somewhat a non believer in the possibility,as I don't see how a Cinq engine management would now what the difference was(it only ever knows the crank position).If the cam marks and the crank marks are set surely it makes no difference.

I did go through quite a few searches on this forum and the punto forum looking for all the common mistakes.Unfortunately it doesn't seem to be any of the usual mistakes.

And for everybody who are concerned about me piling it into a tree due to brake failure I can assure you that the chance of that are minimal.
Firstly the brakes have been overhauled and secondly there ain't any trees where i live!

Okay forgetting about the cam.
If the crank mark is in the right position then the Number 1 piston is going to be in a known position.
Therefore if the crank is turned 360 degrees back round to its timing mark then number 1 piston is going to move back to the same known position.

So if the cam and crank marks are aligned properly,how does it make any difference?

The spark timing comes from the crank position doesn't it.

Please humor David, ease of tensioner, rotate the engine though 360 degrees re-tension, reassemble, start engine.

I think you have to set the pistons on the number 1 pistons compression top dead centre, but I allus disconnect the battery & block the engines rotation - way too difficult for me otherwise.

Noel

ClamHunter said:

So if the cam and crank marks are aligned properly,how does it make any difference?

Click to expand...

the crank is alligned properly, but as has been said, the crank turns twice for every turn of the cam.

so despite it pointing at the mark, if it's on it's second rotation, then it's wrong, 180degrees wrong, wrong enough to blow charge out of the TB.

there's precious little else that can cause that. we're not talking about ignition timing, it is cam / valve timing.

Although somewhat a non believer in the possibility,as I don't see how a Cinq engine management would now what the difference was

Click to expand...

it doesn't, and it doesn't matter. we're talking cam timing.

Noel

I did the procedure as you stated.Turned engine till crank and cam marks lined up.Slackened belt.Took the belt off the cam pulley.Turned crank through 360 degrees then replaced and tensioned the belt.Then turned the engine with a spanner a couple cycles to make sure everything still lined up.
Made no difference.

David I'm not meaning to upset or offend you but I don't believe it makes any difference if the marks are lined up.
I was taught how to work on car engines with points and distributors so ECU and sensors sometimes p!!!s me off as I can't physically see what is going on!

Emlyn

Just to clarify the charge being blown back through the TB doesn't happen on every cycle of the 4 cylinders.It is random that lead me to believe it's not a valve timing issue.

I assumed this was a sticking valve originally but it only occurs when the coils are live.

Thus lead me to believe it was an electrical issue. i.e. sparking too early

Emlyn

The difference is the plugs fire 1&3 together then 2&4 together, you need one to fire on the one compression stroke, not on the 4 compression stroke if you turn through 360 degrees. It is not like a distrubutor where the plugs fire individually. And no I'm not an engineer, or spanner person, I lock engines positively first.

It needs to be correct but you have a 2nd problem if it does not make any difference?

Noel

Ive got my HT leads set up so that 1 and 4 are on a coil together and 2 and 3 are on a coil together.Thats the info i have found on this forum.

Wouldn't that mean that 1 and 4 spark together so if 1 spark is a power stroke 4 is the wasted spark.

Could somebody clarify plug order for me.I did try numerous different orders and swapped LT's over.
At present I have from the coil nearest the bulkhead to the grill i have 1,4,3,2.

Pep0 said:

The difference is the plugs fire 1&3 together then 2&4 together, you need one to fire on the one compression stroke, not on the 4 compression stroke if you turn through 360 degrees. It is not like a distrubutor where the plugs fire individually. And no I'm not an engineer, or spanner person, I lock engines positively first.

It needs to be correct but you have a 2nd problem if it does not make any difference?

Noel

Click to expand...

Thats not correct. the firing order is 1342. so it fires 1(4)3(2)4(1)2(3)

with the wasted spark in brackets.

plugs 4 and 1 should be fired by the rear coil pack, plugs 3 and 2 by the front one.

cylinders are number from the timing end of the engine, with 4 being closest to the coils

reading through the whole thread, i think it's worth changing the crank sensor. they're only ~£20 from a factors. If the cable is damaged, it can cause weirdness. Inspect the cable from it to the connector.