Technical I need help with the torque specs throttle body to the intake manifold (Fire 1.1 engine)

[dirksan28]

Hello everyone,

I’ve been experiencing a rough idle and spontaneous revving when the engine is hot.

It appears the throttle body wasn’t seated tightly enough on the intake manifold.
The three bolts (see image) were only torqued to 4 Nm.
I then increased this to 7 Nm, which eliminated the issue for about a week.

However, during reassembly I noticed that after one turn of tightening they felt loose again.
Either the threaded inserts in the plastic intake manifold are no longer holding, or everything settles again (meaning the green gasket is getting compressed).

I’ve searched quite a while for the proper torque spec but haven’t found anything definitive.

I also discussed with Perplexity, which first suggested 20 Nm but then, after pointing out the plastic inserts, settled on 5–7 Nm:

- The intake manifold on these engines is made of plastic, so the throttle body bolts should be torqued carefully.
- The recommended torque for M6 bolts in plastic intake manifolds is usually between 5 and 7 Nm to avoid damage.
- This value matches workshop recommendations for similar Fiat FIRE engines in models like the Lancia Ypsilon 1.2 Fire Evo II and the Fiat Palio 1.1 MPI, which use the same engine block and intake tract.

So my questions to the experts here:

• are the 5–7 Nm from the AI plausible?
• what torque do the three bolts receive according to the manufacturer?

I would be very grateful if someone could help me with my questions and give me a hint.

Best regards
Dirk

PS: This photo is for illustration purposes only and doesn’t come from my own project, as the throttle body is already reinstalled and I didn’t have a picture at hand.
@atakan123123 I hope it’s okay to reuse this image from here.

 

[ZaphodB]

I'd wager it's def. something less than 10Nm.

I'd also take AI answers with a pinch of salt, so stick with your 7Nm for now.

I'd suggest some loctite 243 (oil tolerant&not too strong) in the threads, retorque to 7 and check again in a week to see what's occured

You might have to carefully helicoil the manifold threads if they've deteriorated/stripped.

 

[koalar]

Proper torque is 8nm

Not that critical, snug is fine