Technical Feels like someone taps on the brakes, hard starting as well?

[koalar]

Oh happy days! We've got more symptoms.

Put your foot down, nothing really happens, then slowly creeps up. Fine on crusing, fine, but try to overtake or speedup.

Assuming the scan tool is reading this right, the red trace should be close to zero,

-50 LTFT isn't right, the engine control unit ECU is using a known good parameter for load and rpm then measuring the 02 sensor seeing it's way too rich and taking fuel away

There's a few possibilities, either the ECU is looking at the wrong parameters, because on of the sensors is reading wrong


The O2 sensor is reading rich causing the ECU to take fuel away

It doesn't look like a crank sensor error

If the O2 is reading wrong the spark plugs should show a lean condition

You can swap the O2 sensors over, they can be a pig to undo, but post and pre cat ones are the same part

One symptom of a O2 sensor reading rich is very poor performance due to the fuel taken away

 

[BigAdam]

WELL!

Bottom O2 is stuck as hell, so I got 2 new ones on the way, then I shall use brute force and ignorance (maybe a big pipe wrench too) to remove the bottom one.

 

[koalar]

It was only a sugestion at this stage

Post a photo of you plugs

If they look lean is a very good chance the O2 is reading wrong

I am surprised it's not tripped a code yet

Which makes me think the scanner might not be reporting correctly, although torque pro has never steered me wrong on my cars

O2 sensors come out best hot, something a run under load at high revs is enough

Normally I use a 22 mm ring spanner and a blow torch


Be careful though, it's not unknown for them to round off

 

[BigAdam]

22mm. You genius!

Got the o2 swapped around and heres a spark plug

 

[koalar]

Hard to tell on those plug, it's not cut and dried diagnosticely

Looks to me like sometimes it's running right, the bottom thread sooting up slightly, and the running lean and hot and burning off and glazing


It does depend on the fuel used but these are more like what I would expect

Not my photo

 

[BigAdam]

Well having swapped o2 around. No coughs or problems on way to work. So see how home goes.

But man. O2 number 2 reads some WACKY stuff

 

[BigAdam]

OKAY.

I thought I got it with the o2, but no.

But it is a lot better, and i have a better understanding of what is happening.

The car is shutting off at speed, but as I'm in gear, gets bumped started back to life.

Two times I've been sat idle, and the car has just died. Started right back up.

Tried jiggling the hell out of the key, but I'm now thinking it's the old ecu wiring plugs need attention.

So Saturday, going to jiggle and wiggle things.

 

[koalar]

What the idle feels like from inside the car, smooth, or a bit of a vibration, lumpy

What's the power like

With the O2 swap round what's the plugs look like

At idle ared the RPM constant or do they sometimes hunt up or down

Don't go mad moving thing around, it a valid technique to find and intermittent fault, but can also introduce faults that weren't there originally


Same you didn't have you scanner connected as it died at idle, if the voltage or RPM went instantly to zero we would have a starting place

 

[BigAdam]

"What the idle feels like from inside the car, smooth, or a bit of a vibration, lumpy"

Smooth. No blips. No putting. Just nice.

"What's the power like"

Same as ever. Same with mpg. No change.

"With the O2 swap round what's the plugs look like"

They didn't look bad before. Looks about the same now. Car doesn't fall flat on its arse anymore.

"At idle ared the RPM constant or do they sometimes hunt up or down"

Nice and smooth. If it wasn't for the shutting off its a perfect car.

 

[BigAdam]

In pure hope, I've slapped some new plugs in

Here the old ones. Redder ones are two middle cylinders.

 

[BigAdam]

Well thats not fixed it.

Tho its more noticeable now.

So that's my idle in toruqe app. And you can see in the blue circule where i was govong it the beans, how it dipped a bit (in yellow).

Car. Y u no work correctly.

 

[BigAdam]

Okay.

Ecu wiring wiggled. No change.

New coils. No change.

I'm out of ideas.

 

[koalar]

Plugs look a lot better

They have lost the white ash from the outer electrode

Black soot on the first thread


What are the O2 sensors voltages look like graphed now

From cold

Engine off

Intake pressure and temperature

At idle what the intake pressure now

Fuel trims long and short are still taking fuel away

 

[BigAdam]

Oh yay. It got worse.

Car hardly drives now.

Now I got a flashing check engine light, hooray. I think mechanic time is at hand.

 

[koalar]

We are making progress

We have an error code which helps

Pre cat 02 readings look better

Post cat O2 are wrong should be around the mid point maybe creeping upwards slightly

Intake pressure and temperatures are these at idle they are all over the place,

Can't see a scale

Nearly 10 rise in 20 seconds is that degrees

 

[BigAdam]

The pressure and air temp where taken while driving down a stright road. Just pootling along while my car coughed and spluttered

 

[BigAdam]

From off to start/idle

 

[koalar]

100 engine off is correct

At idle it should be 29-33 according to fiat

Mine was a tired engine @ 35 so a similar ball park

50 doesn't sound right

What's happening to the engine when the spike occurred

Revs rise, lower or sound the same

 

[BigAdam]

Revs ping pong about. The blip is me revving it to try and settle it down.

Before it got worse

 

[BigAdam]

Motors off to the mechanic tommrow. By the sound of it . They'll try what I've tried already.

But one lives in hope.