Technical Slow picking up

[Goudrons]

There was a vid of the MAP at idle a good while back in the thread. It was only 30 seconds but it did seem to drift up as it continued to idle.

It averaged 41, 42, 43, and it's peak drifted up as well, 44, 45, and 46 before the vid ended.

I would like to see that done again on a graph, see if that's accurate or not. That might point to a single cylinder problem. A valve might stick if it's not run for so long or if it's been a problem that has got worse over time, a valve seat problem.

 

[l33rsk]

There was a vid of the MAP at idle a good while back in the thread. It was only 30 seconds but it did seem to drift up as it continued to idle.

It averaged 41, 42, 43, and it's peak drifted up as well, 44, 45, and 46 before the vid ended.

I would like to see that done again on a graph, see if that's accurate or not. That might point to a single cylinder problem. A valve might stick if it's not run for so long

 

[l33rsk]

There was a vid of the MAP at idle a good while back in the thread. It was only 30 seconds but it did seem to drift up as it continued to idle.

It averaged 41, 42, 43, and it's peak drifted up as well, 44, 45, and 46 before the vid ended.

I would like to see that done again on a graph, see if that's accurate or not. That might point to a single cylinder problem. A valve might stick if it's not run for so long

The first one is the original map sensor and the second two the new map sensor. Thanks.

 

[jackwhoo]

I am still surprised it not timing ?

Sounds like timing

Behaving like timing

Sensor read like timing

The car stood for long periods which is known to cause the timing to jump

How much do we trust the garage actually checked it ?

A lot of people may have checked where they thought the marks should be....
But there is a 90degree crank difference between earlier non-vvt engine and later vvt engine , possibility of cam pulley incorrectly fitted.

I would be checking myself -probably initially by finding tdc using a probe in spark plug hole of cylinder 1 or 4 (whichever more easily accessed)
And removing valve cover to look at valve depression

 

[koalar]

The first one is the original map sensor and the second two the new map sensor. Thanks.

They look normal except reading 40is instead of 20ish

Normally the scale is 0 to 100

If viewed at the same scale it would show a straight line

 

[vexorg]

But there is a 90degree crank difference between earlier non-vvt engine and later vvt engine , possibility of cam pulley incorrectly fitted.

I doubt that would run at all

 

[jackwhoo]

I doubt that would run at all

Hi,

I was indicating how confusion can set in regarding timing marks, there are several pictures/illustrations online purporting to show correct crank position for non vvt engine that are just incorrect.

Cheers Jack

 

[jackwhoo]

Someone had suggested
Looking at map readings while cranking on starter as a way of testing for blocked exhaust/catalyst. Good idea.
Unplug the injectors to stop engine firing(make sure to clear injector fault codes after testing)
Crank on starter , foot off accelerator, video map graph.

 

[Yolanda]

I think the way forward now is to do what was advised previously, and that would be to make sure the valve timing is correct then do a compression test.

 

[koalar]

Someone had suggested
Looking at map readings while cranking on starter as a way of testing for blocked exhaust/catalyst. Good idea.
Unplug the injectors to stop engine firing(make sure to clear injector fault codes after testing)
Crank on starter , foot off accelerator, video map graph.

Would eliminate back firing as a cause of not pulling down much vacuum

We already tested for a stuck valve in disconnect an injector one at a time the random misfire stays the same. I’d be surprised if ever cylinder had the same fault.

 

[koalar]

I think the way forward now is to do what was advised previously, and that would be to make sure the valve timing is correct then do a compression test.

Correct

The OP had been told the timing is correct by a garage

We don’t know how it was checked. Or if the compression was checked

 

[jackwhoo]

A lot of people may have checked where they thought the marks should be....
But there is a 90degree crank difference between earlier non-vvt engine and later vvt engine , possibility of cam pulley incorrectly fitted.

I would be checking myself -probably initially by finding tdc using a probe in spark plug hole of cylinder 1 or 4 (whichever more easily accessed)
And removing valve cover to look at valve depression

With Cylinder 1 at tdc (found by probing through spark plug hole) the Depression of the inlet and exhaust of number 4 cylinder or number 1 cylinder should be exactly the same- easy to do by eye on this engine .

Sorry to quote myself, just saw how I hadn't fully finished post first go.

 

[Yolanda]

It's a bit of a conundrum for the OP as he could be analysing and replacing parts that don't need changing. It's time to get down to the nitty gritty and go bacck to checking the basics.

 

[l33rsk]

They look normal except reading 40is instead of 20ish

Normally the scale is 0 to 100

If viewed at the same scale it would show a straight line

It's a bit of a conundrum for the OP as he could be analysing and replacing parts that don't need changing. It's time to get down to the nitty gritty and go bacck to checking the basics.

Yes I agree the car is now back into daily usage now as my daughter is now using it as her regular drive she has done about a 50 mile round trip today and only got around 38mpg and the miles to petrol station was on 380 and now is on 260 and the fuel gauge has dropped. I know these trip computers aren’t very accurate. So there is definitely something wrong. Also she said it seams to be holding back when you pop it into 5th gear and she can feel her legs shacking when it’s idling. Thanks

 

[Goudrons]

As it's simple, try the crank test.
Try it when the engine is hot.
Stop the engine fueling by pulling the fuel pump fuse, run it until the engine dies, then crank it over with the throttle closed while reading the MAP and O2.

The MAP might be close to what you are seeing already (40+), but if it drops dramatically to 20 or less you're likely to have a blockage in the exhaust/cat that's backing up and causing the air intake pressure to increase when it's running.

The effects of pumping all this air should show on Bank 1 Sensor 1 O2.
When it was running it was showing rich and the fuel trim was at max negative, but as it's no longer fueling you shouldn't see it rich anymore and the O2 should respond to that.


If you are still getting the 40+ MAP reading and the O2 is responding the correct way to all that pumped air when cranking, then it's likely a "pumping" fault.
The engine physically isn't sucking air in properly.
Why?
There are many reasons for that and not every test will identify the problem, though one might.

If the timing between crank and cam is out by a tooth or two on the belt, that would effect all cylinders, so a leak down or compression test should spot this.
But you would also spot it if you visually checked the valve timing.
You could do this by setting one of the pistons to TDC (squeeze) and check there are gaps between the cam and the buckets underneath on both valves on the cylinder. If the cam is pressing on the valves at TDC, the valve timing it out.
(remember the piston reaches top twice on a normal 4 stroke cycle, you want the top on the squeeze stroke, if you set it at top on the blow stroke the exhaust valve will be open)

If one cylinder is failing, you won't spot that checking the value timing, though it would show up on a leak down or compression test, so that might be the logical test to try next and you wouldn't need to remove the cam cover at this point.

As written before, a leak down test is a bit more controlled.
You pump air/nitrogen into each cylinder at TDC at a set pressure and time how long it takes to leak out.

A compression test is a little less controlled and it also relies on crank speed, which may or may not be even as you move between the cylinders, but it should spot a problem with one or all cylinders are bad and you know roughly what the compression for your engine should be.

You can buy a cheap compression tester for less than £20 these days, which is less than an hours labour at the garage.

 

[l33rsk]

As it's simple, try the crank test.
Try it when the engine is hot.
Stop the engine fueling by pulling the fuel pump fuse, run it until the engine dies, then crank it over with the throttle closed while reading the MAP and O2.

The MAP might be close to what you are seeing already (40+), but if it drops dramatically to 20 or less you're likely to have a blockage in the exhaust/cat that's backing up and causing the air intake pressure to increase when it's running.

The effects of pumping all this air should show on Bank 1 Sensor 1 O2.
When it was running it was showing rich and the fuel trim was at max negative, but as it's no longer fueling you shouldn't see it rich anymore and the O2 should respond to that.


If you are still getting the 40+ MAP reading and the O2 is responding the correct way to all that pumped air when cranking, then it's likely a "pumping" fault.
The engine physically isn't sucking air in properly.
Why?
There are many reasons for that and not every test will identify the problem, though one might.

If the timing between crank and cam is out by a tooth or two on the belt, that would effect all cylinders, so a leak down or compression test should spot this.
But you would also spot it if you visually checked the valve timing.
You could do this by setting one of the pistons to TDC (squeeze) and check there are gaps between the cam and the buckets underneath on both valves on the cylinder. If the cam is pressing on the valves at TDC, the valve timing it out.
(remember the piston reaches top twice on a normal 4 stroke cycle, you want the top on the squeeze stroke, if you set it at top on the blow stroke the exhaust valve will be open)

If one cylinder is failing, you won't spot that checking the value timing, though it would show up on a leak down or compression test, so that might be the logical test to try next and you wouldn't need to remove the cam cover at this point.

As written before, a leak down test is a bit more controlled.
You pump air/nitrogen into each cylinder at TDC at a set pressure and time how long it takes to leak out.

A compression test is a little less controlled and it also relies on crank speed, which may or may not be even as you move between the cylinders, but it should spot a problem with one or all cylinders are bad and you know roughly what the compression for your engine should be.

You can buy a cheap compression tester for less than £20 these days, which is less than an hours labour at the garage.

Ok thanks if you can point me in the direction please of the compression tester? Also I will find out which and where the fuse is for fuel pump and try that test I should have access to the car probably Thursday wether depending as it’s Being used regular now which should do it some good in the meantime after standing many years.

 

[Goudrons]

Ebay or Amazon is your friend for a compression tester.
A basic tester should come with a couple of fittings for different sparkplug sizes, like
Amazon product ASIN B07BKWPPDR
To test is easy.
Pull the fuel pump fuse and take all the plugs out.
For safety sake, stop if firing as well by pulling the coil wires.

Screw the fitting/hose into a sparkplug hole, open the throttle fully and crank about 10 seconds.
Record the reading.

Do this with all 4 cylinders.

As this test relies on crank speed, stating a target pressure can be a bit difficult.
All 4 should all read roughly the same, no more than 10% difference and I seem to think a decent engine should be 200+psi, give or take

 

[Yolanda]

Good advice there. I would also have the throttle wide open when cranking to get maximum compression all though this not a must.

 

[Goudrons]

You might have to do a compression test a couple of times with a good battery to get a worthy result.

Interpreting the result right can point to the problem.

1. A result like this.
Cyl 1 = Normal
Cyl 2 = Low
Cyl 3 = Low
Cyl 4 = Normal
Points to something between two cylinders.
It could be both have broken rings or valve springs, but it's more commonly a sign a head gasket has gone.

2. A result like this.
Cyl 1 = Normal
Cyl 2 = Normal
Cyl 3 = Low
Cyl 4 = Normal
Points to a problem with just one cylinder, perhaps a broken valve spring or worn valve seat.
It could be the gasket has just let go on that cylinder.

3. A result like this.
Cyl 1 = Low
Cyl 2 = Low
Cyl 3 = Low
Cyl 4 = Low
Points to something effecting all cylinders, like the valve timing is out or a really worn out engine.

4. A result like this.
Cyl 1 = Normal
Cyl 2 = Normal
Cyl 3 = Normal
Cyl 4 = Normal
Is, er normal and a worry as you haven't yet pinpointed your problem.

The thought others have is you will get a 3. Low, Low, Low, Low reading, so it's then a matter of checking the timing properly.

1 and 2 problem would probably need the head to come off.

4 and we're all stumped again!

 

[koalar]

As it's simple, try the crank test.
Try it when the engine is hot.
Stop the engine fueling by pulling the fuel pump fuse, run it until the engine dies, then crank it over with the throttle closed while reading the MAP and O2.

The MAP might be close to what you are seeing already (40+), but if it drops dramatically to 20 or less you're likely to have a blockage in the exhaust/cat that's backing up and causing the air intake pressure to increase when it's running.

I thought we already tested, if we increase the revs it pulls more vacuum.(number decreases) If the exhaust was plugged the vacuum should decrease(numbers increase)

The effects of pumping all this air should show on Bank 1 Sensor 1 O2.
When it was running it was showing rich and the fuel trim was at max negative, but as it's no longer fueling you shouldn't see it rich anymore and the O2 should respond to that.

Thought we had seen the O2 respond to extra oxygen. If we unplug an injector we have a reduction in the -100 stft to just above 0

If you are still getting the 40+ MAP reading and the O2 is responding the correct way to all that pumped air when cranking, then it's likely a "pumping" fault.
The engine physically isn't sucking air in properly.
Why?
There are many reasons for that and not every test will identify the problem, though one might.

If the timing between crank and cam is out by a tooth or two on the belt, that would effect all cylinders, so a leak down or compression test should spot this.
But you would also spot it if you visually checked the valve timing.
You could do this by setting one of the pistons to TDC (squeeze) and check there are gaps between the cam and the buckets underneath on both valves on the cylinder. If the cam is pressing on the valves at TDC, the valve timing it out.
(remember the piston reaches top twice on a normal 4 stroke cycle, you want the top on the squeeze stroke, if you set it at top on the blow stroke the exhaust valve will be open)

If one cylinder is failing, you won't spot that checking the value timing, though it would show up on a leak down or compression test, so that might be the logical test to try next and you wouldn't need to remove the cam cover at this point.

As I have been saying since page two of this thread

As written before, a leak down test is a bit more controlled.
You pump air/nitrogen into each cylinder at TDC at a set pressure and time how long it takes to leak out.

A compression test is a little less controlled and it also relies on crank speed, which may or may not be even as you move between the cylinders, but it should spot a problem with one or all cylinders are bad and you know roughly what the compression for your engine should be.

You can buy a cheap compression tester for less than £20 these days, which is less than an hours labour at the garage.

Offers still there I can have a look for you I am near Crewe

At the moment we are going round in circles