Peugeot 307 NFU jerking and shudder

[vrsgaraza]

Hello all,

I have Peugeot 307 NFU 1.6 16v petrol from 2002, car is okay but I have a strange problem that I can't fix, so maybe, you can help me.

So, problem is car shudders on low throttle or maintaining speed around 2000 rpm in first 3 gears, 4th and 5th all is fine. Sometimes on idle, rpms jump from 800 to around 1100 when A/C is on, and in all occasions if I let go the throttle while driving and want to engine brake, the car dives and jerks like it has bad engine mounts. Car behaves much better (2000 rpm shuddering-wise) when I introduced it with massive vaccum leak on the inlet manifold (discconected the vaccum line going to LPG system).

Things I noticed: Lexia said I have lean mixture ( that is the only error ) but I can smell on tailpipe it is working a bit rich, I have cracked exhaust manifold on cylinder no.2 before the first O2 sensor and I have a cracked fuel tank because fuel leaks if I put more than 40 liters of fuel. Car behaves a bit worse when running on LPG, but all the problems aboive are the same.

Things I changed:

-MAP new

-Throttle body (electronic throttle) and calibrated

-Coil pack, second hand, Valeo,

-New spark plugs, Iridium, suited for LPG use

-Engine mounts

-PCV pipe

-Checked with smoke machine for vacuum leaks, all good

-Deleted LTFT/STFT

-Discconected O2 sensor, first one, for diagnostic purposes

-Discconected MAP, no change

-Pluged vaccum line for EVAP. no change

-Checked grounding wires, all good

-Checked cylinder compression, cca 15 bar all for on a dot

[mickthemaverick]

Is your car switchable between LPG and petrol and if so does it have the issues whichever fuel you use?

[vrsgaraza]

Yes, it is sequent type LPG, and it has same problems on both fuels, only a bit worse when running on LPG.