Missfire on Idle after timing belt replacement

francis.guthrie · Oct 2, 2024

I've just had my timing belt installed and the garage have told me that my dephaser solenoid has snapped. They have not been able to get a new part in time so they've given me the car back with the broken solenoid fitted. The bottom half of the solenoid had snapped and they have only fitted the top half of it. The car seems to drive ok but on idle it is running very rough and tappy. Am I ok to drive this until I can get it back to the garage or am I going to do further damage to cams/dephasers etc?

Poopensharten · Oct 2, 2024

The whole job will need done again, worse than that, its not good practice re tensioning a belt🥴

francis.guthrie · Oct 2, 2024

The Chubby Pirate said:
The whole job will need done again, worse than that, its not good practice re tensioning a belt🥴

Is it not a case of putting a new solenoid in?

hopgop1 · Oct 2, 2024

Wouldn't have thought the dephaser solenoid would cause rough running? I'd be worried they've not timed it correctly either, I'd want them to sort it all before driving it personally.

francis.guthrie · Oct 2, 2024

hopgop1 said:
Wouldn't have thought the dephaser solenoid would cause rough running? I'd be worried they've not timed it correctly either, I'd want them to sort it all before driving it personally.

Unfortunately I've already driven it home. Seemed ok on higher revs just rough idle. No fault codes either

Brigsy · Oct 2, 2024

Id be concerned about oil flow to the cams/dephaser with snapped solenoid. I wouldnt be driving it myself, suprised the garage let you take it.

francis.guthrie · Oct 2, 2024

Brigsy said:
Id be concerned about oil flow to the cams/dephaser with snapped solenoid. I wouldnt be driving it myself, suprised the garage let you take it.

I suggested that they put the snapped part back in but they were more concerned about it getting stuck. Regretting that now

Brigsy · Oct 2, 2024

It sounds like they have had a go and possibly messed it all up. Id be getting it checked by a specialist to check the cam timing is right and pulleys are torqued correctly.

Martin_172 · Oct 3, 2024

^^ this.

I would have absolutely no confidence that the process has been carried out correctly. And your miss fire on idle sounds like it's most likely timing related, I bet there's good old tipex involved here!

Got a pic of the solenoid? I don't understand how it's snapped? Unless they mean snapped the connector off it with the slip of a ratchet or somthing??

francis.guthrie · Oct 3, 2024

Martin_172 said:
^^ this.

I would have absolutely no confidence that the process has been carried out correctly. And your miss fire on idle sounds like it's most likely timing related, I bet there's good old tipex involved here!

Got a pic of the solenoid? I don't understand how it's snapped? Unless they mean snapped the connector off it with the slip of a ratchet or somthing??

Photo taken from the Internet but its the metal casing thats snapped along that red line.

DaveL485 · Oct 8, 2024

The dephaser, as I recall, uses oil pressure to phase the inlet cam 16 degrees over a certain set of driving parameters including MAP reading, throttle position etc etc - so the cam position naturally should be fine for idle - ie it should NOT run rough or badly even with that solenoid broken. I would be checking the timing is right, immediately. Its a fairly rudimentary setup on the 1*2 in that its not fully variable, the phasing of the cam is ON (16°) or OFF (0°). True VVT is a PWM setup that would be able to vary the cam phase from 0° to 16° and any value in between.

Additionally I dont believe you need to remove the solenoid to do the belt or change the dephaser pulley so why were they messing with it?

Ask them to explain the process they used to set the cam timing, write down what they say and transcribe it here - theres a fair chance they havent done it right.

francis.guthrie · Oct 8, 2024

DaveL485 said:
The dephaser, as I recall, uses oil pressure to phase the inlet cam 16 degrees over a certain set of driving parameters including MAP reading, throttle position etc etc - so the cam position naturally should be fine for idle - ie it should NOT run rough or badly even with that solenoid broken. I would be checking the timing is right, immediately. Its a fairly rudimentary setup on the 1*2 in that its not fully variable, the phasing of the cam is ON (16°) or OFF (0°). True VVT is a PWM setup that would be able to vary the cam phase from 0° to 16° and any value in between.

Additionally I dont believe you need to remove the solenoid to do the belt or change the dephaser pulley so why were they messing with it?

Ask them to explain the process they used to set the cam timing, write down what they say and transcribe it here - theres a fair chance they havent done it right.

A new solenoid has been fitted which has greatly improved it but its quite lumpy on idle still. I'll be taking it somewhere else to get it fully checked over. They took the solenoid out to take the cam cover off as it was leaking.

Darren S · Oct 8, 2024

francis.guthrie said:
A new solenoid has been fitted which has greatly improved it but its quite lumpy on idle still. I'll be taking it somewhere else to get it fully checked over. They took the solenoid out to take the cam cover off as it was leaking.

Whereabouts are you located?

I'd definitely be taking it to a local'ish specialist, sooner rather than later.

shanks · Oct 8, 2024

As above , Bite the bullet and take it to a specialist. Mickpm@ diamond if you are round Nottingham/ midlands.
Last thing you need is for it to go bang

DaveL485 · Oct 14, 2024

Lakeside Service Centre in Redditch can also do these properly, good mate of mine and I lend him my dephaser tools when he gets one in.

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