Car jerks on gear change

JamesBryan · Dec 4, 2018

For the map sensor it's called Intake Manifold Pressure on Torque app.

Louis · Dec 4, 2018

JamesBryan said:
Voltage wise it looks fine yeah.

I'm not actually sure how fast it should be alternating though, seconds or milliseconds.

Going to remove the new decat section this weekend and pull the engine forward. I'm sure it's not sitting right.

JamesBryan · Dec 4, 2018

Louis said:
Going to remove the new decat section this weekend and pull the engine forward. I'm sure it's not sitting right.

The decat isn't sitting right, or the engine isn't?

Louis · Dec 4, 2018

JamesBryan said:
The decat isn't sitting right, or the engine isn't?

Engine. I remember pulling the engine forward a while back and it did improve gear change etc but then soon went back to how it was.

JamesBryan · Dec 4, 2018

Louis said:
Engine. I remember pulling the engine forward a while back and it did improve gear change etc but then soon went back to how it was.

Loosen the mounts, let the car idle for a bit and it should find it's own settling point.

Tighten back up.

Louis · Dec 4, 2018

JamesBryan said:
Loosen the mounts, let the car idle for a bit and it should find it's own settling point.

Tighten back up.

Not better to pull it forward?

JamesBryan · Dec 4, 2018

Louis said:
Not better to pull it forward?

Depends how yours is tbh.

Give it a go.

bloke · Dec 4, 2018

Lambda isn't bad. You don't need to graph the map, just reading with ignition on and then idle.

Line the engine up, don't just pull it one way or the other.

Louis · Dec 4, 2018

bloke said:
Lambda isn't bad. You don't need to graph the map, just reading with ignition on and then idle.

Line the engine up, don't just pull it one way or the other.

I'll swap the lambda over as I have one and will be jacking up the car anyway and then can compare. Will have a look at the map sensor reading in a bit!

Thanks all

Louis · Dec 4, 2018

Map sensor 14.2 PSI Ignition on
5.5 Idle (relatively cold engine, 1/4 on dial) does jump around ever so slightly 5.3-5.7

JamesBryan · Dec 4, 2018

MAP sensor is working then.

bloke · Dec 4, 2018

what is it in mbar?

JamesBryan · Dec 4, 2018

bloke said:
what is it in mbar?

Well 14.2 is nearly 1 bar, so nearly 1000mbar

Louis · Dec 4, 2018

979 and 379

bloke · Dec 4, 2018

map sensor is bolloxed.

JamesBryan · Dec 4, 2018

Why is it?

I'm sure they're meant to read around that

STEVE.M · Dec 4, 2018

bloke said:
map sensor is bolloxed.

Within tolerance.

Depends on height ASL & temperature.

bloke · Dec 4, 2018

979 is low, normally reads little bit lower than atmospheric on clip.

Louis · Dec 5, 2018

So change map? I do have a spare but made no difference when I swapped it, unless that's fucked too?

JamesBryan · Dec 5, 2018

You could check and see what that reads, but I'm guessing it'll be around the same.

You are well above sea level being up int' hills.

bloke · Dec 5, 2018

Not that high up though??

JamesBryan · Dec 5, 2018

I'll see what mine reads later.

You watch mine will be fucked

Simon998 · Dec 5, 2018

Mine does the same but I think it's just one of the mounts that I haven't changed yet, either the gearbox side or the other little dicky one.

I changed the belt side mount and dogbone mount for new items with powerflex bushes in both and the sloppyness on gearchange still exists. I was told to loosen off the bolts on the engine mount and run the engine for a few minutes to let it 'settle' in a natural spot as there's a few mil of adjustment on them, but when I tried this, the mount didn't move at all unless I engauged gear and rocked the engine that way.

Louis · Dec 6, 2018

Also noticed today when the engine was cold if I was moving off in slow moving traffic then came to a stop. After pressing in the clutch the revs would sit at around 1300 and fluctuate then drop down to 1000.
They also seem to bounce up when pressing the clutch down in slow traffic more than they used to. Almost like it's trying to stop the car stalling which is odd.

JamesBryan · Dec 7, 2018

You got an RStuner map on this?

Louis · Dec 7, 2018

JamesBryan said:
You got an RStuner map on this?

No map

Touring_Rob · Dec 7, 2018

STEVE.M said:
Just get on with it.

I replaced everything with new at 125k miles in August.

Injectors, coil pack, plugs, HT leads, Lambda`s, air & pollen filter, oil & filter.

Has run faultlessly since, and I am now on 133k, same as you.

Another oil change planned for this week.

My lambda didn't throw an eml for quite a while and intermittently even then. The lambda had totally failed and rattled. The car would (several mins after start) hesitate, missfire and bog down with throttle, would then drive fine but use quite a bit of fuel. Was doing 20 mpg where it now runs fine and averages over 30 on the same journey.

Also read of people having air leaks etc.

Touring_Rob · Dec 7, 2018

Louis said:
Swapped the map sensor, no change.

Got a video of the slight popping at idle, this just normal with a non res decat milltek system?

I'll change the lambda when it's not pissing it down! It's on and off which is really annoying

tbf, that sounds no different to mine... if i make a slightly off gearchange the car will jerk nastily, slow changes fine, quick changes fine. Seems to stumble getting back onto the throttle which cases a jerk.

I've only ever noticed this on cars which I've been mapping with the thottle enrichments turned off - they go lean as you get back on the throttle for a short amount of time, missfire (sometimes quite badly) and then return to normal with steady/slow throttle, the jerk feels pretty much the same in mine as that.

Louis · Dec 10, 2018

@JamesBryan did you get chance to have a nosey at your map sensor?

JamesBryan · Dec 10, 2018

Louis said:
@JamesBryan did you get chance to have a nosey at your map sensor?

Ahh no, i'll go and do it now.

JamesBryan · Dec 10, 2018

100kpa with just ignition on, so 14.5psi

38kpa engine running, so 5.5psi

Very similar to yours.

Louis · Dec 10, 2018

@bloke You sure this isn't normal then?

bloke · Dec 10, 2018

what reading are you getting for atmospheric pressure and manifold pressure with ignition?

Louis · Dec 10, 2018

bloke said:
what reading are you getting for atmospheric pressure and manifold pressure with ignition?

Isn't the manifold pressure the same as atmospheric pressure at ignition? Or is there another way to gauge the overall atmospheric pressure through something else?

bloke · Dec 10, 2018

should be almost the same.

STEVE.M · Dec 10, 2018

Louis said:
is there another way to gauge the overall atmospheric pressure through something else?

You don`t have a barometer in your hallway?

JamesBryan · Dec 10, 2018

STEVE.M said:
You don`t have a barometer in your hallway?

I feel like you're putting him under pressure here.

STEVE.M · Dec 10, 2018

JamesBryan said:
I feel like you're putting him under pressure here.

Probably find him in the bar.

JamesBryan · Dec 10, 2018

STEVE.M said:
Probably find him in the bar.

With his mate, Pascal.

Louis · Dec 10, 2018

STEVE.M said:
You don`t have a barometer in your hallway?

I'll call me mam