Very slow acceleration

[Zephyr]

Just had a visit from a friend who has a 1.9 with the 140 hp.
his complaint is that the car feels as it is struggling to get to speed.
tried myself, indeed the car feels as if it has 60 or 70 hp.
no errors on the scanner, exhaust makes a healthy sound, no frozen pads on the discs, handbrake loose...
It just refuses to rev quickly while in gear.
revs ok in neutral
it does not slip, nor seems to have a worn clutch, differential and gearbox make no grinding noises.

Any ideas?

 

[Mike Fishwick]

Low fuel pressure? Easy to check, and if so, suspect the fuel filter, pump, or pressure regulator.

 

[Lee]

Blocked cat ?

Maybe stick it on a dyno, £40 a run.

 

[Duncodin]

Maybe maf sensor?

 

[colb]

Possible bad Maf, I had similar symptoms years ago, felt like the car was being held back, fitted an oem Maf and it instantly cured it.
If you can view live data with a scanner take a look at what the Maf is doing and also take a look at the fuel trims, if they are high its either air leaks or a bad Maf misreporting what's passing through it.

 

[Trevor /chedder]

Is the cat solid?, a broken one caused this on mine.

 

[Trevor /chedder]

Also I've read that you can disconnect the maf and the car will run a basic map. Easy to try.. pl asw correct me if wrong

 

[Zephyr]

Spent entire afternoon.
checked fuel pressure 3.1 bar.
checked maf reading, idle values, live data, everyrhing looked normal. disconnected maf and oxygen sensor, had a yellow light, but same result. Reset engine light and took a deep breath, lifted the car and banged the catalytic converter, solid. No rattle.
then said know what? Lets dismantle the exhaust. Removed the front bolts, turned it a little as if I could put it on the side and try but could not do it. So took it off completely. Including sensors etc.
started the car, yellow light and a hell of a noise.
took it up and down the block (my neighbors giving me the look). Still very slow acceleration.
gave up and my friend is taking it to the shop tomorow.

 

[Duncodin]

Birds nest in the air filter

 

[Zephyr]

Birds nest in the air filter

Checked the filter box. No silly foam or anything inside. Nor eggs...

 

[Zephyr]

Update from the shop.
No errors on the official diagnostic
Changed spark plugs and cables, no difference.
Replaced MAF and other two sensors no difference.
no leaks.
Cat and such verify ok and even emissions are more or less what is expected.

 

[DomiMik]

That's why I don't like to bring my cars to a shop... "no idea what's the problem? Well then, let's randomly change some parts, customer's gonna pay".

I would recommend to do a compression test, just to make sure the engine itself is alright. Should cost way, way less than what the shop changed so far.

 

[IainP]

What DomiMik said, compression test, with maybe a vaccum test, if it's low, to check the valves are the cause. Compression with oil checks the rings.

 

[Zephyr]

That's a good plan. Wonder why they did not think of it. I have an excuse, I am not a mechanic, but they should have done this in the first place. Thanks.

 

[Zephyr]

Should cost way, way less than what the shop changed so far.

Luckily enough they only charge labor, parts are test fit to check. This was agreed before taking it for "diagnosis".

 

[Duncodin]

I didn't notice any mention of whether this is a sudden problem or whether it's always been like that. I mean was it quicker and now it's gone wrong. Or does the owner just think it ought to be a bit quicker than it is.

 

[Zephyr]

One week ago it had all the glorious power of the mighty M44. At least that is what he says.
Latest info is that they did a compression test and reads ok. Strange thing is that it happens only when the car is moving.

 

[SV8Predator]

Strange thing is that it happens only when the car is moving.

Yes that is very strange. To clarify, it goes like a rocket when standing still?

 

[Zephyr]

No. It revs freely and goes up into the red in no time.
Contrary to when it is moving where it does not pick up revs and when it finally does it seems that something is holding it back.
Maybe I was not so clear about it.

 

[Zephyr]

Just had a visit from a friend who has a 1.9 with the 140 hp.
his complaint is that the car feels as it is struggling to get to speed.
tried myself, indeed the car feels as if it has 60 or 70 hp.
no errors on the scanner, exhaust makes a healthy sound, no frozen pads on the discs, handbrake loose...
It just refuses to rev quickly while in gear.
revs ok in neutral
it does not slip, nor seems to have a worn clutch, differential and gearbox make no grinding noises.

Any ideas?

This is the issue.
Put any gear, car moves and revs dont pick up as they are supposed to. It takes time to climb the scale and acts as if something is blocking the engine to rev. And when it does there is no power like there is supposed to be.