I've a 1.3 Felicia Pacific hatchback that's done 66,000 miles. Two weeks back the head gasket was replaced as the engine had been losing coolant and had much "mayo" on the oil filler cap.

The mechanic had the head skimmed (very light skim). The V belt and tensioner were also replaced.

He said he'd adjusted tappets.

Since having it back there is a loss of power when going up hills. A hill I go up to get home I could climb in 3rd no problem before the head gasket was replaced.

Now, with the new head gasket, I have to change down to 2nd to get up the hill.

The acceleration / running has a lumpiness to it: this was slightly evident before the gasket replacement, but now is worse.

The mechanic will do a leak-down test later this week.

However, is there something else that could be causing this?

I've tried searching the Felicia forum and seen check the 'coolant sensor'. This is what and where?

Thanks

7 hours ago, miyp36 said:

The mechanic will do a leak-down test later this week.

This is the wisest decision given the history of the car. Followed by adjusting correctly the valves clearance.

Based on your description, such massive power loss may be attributed primarily to a compression loss. A restricted exhaust (collapsed cat, muffler, foreign object, etc.) may exhibit the same symptoms.

7 hours ago, miyp36 said:

I've tried searching the Felicia forum and seen check the 'coolant sensor'. This is what and where?

That is the temperature coolant sensor located on top of the thermostat housing where the big hose from the radiator meets the engine. I would forget about it as a probable cause for now.

Thank you Ricardo for your valuable advice,

"... adjusting correctly the valves clearance" is something I'm able to do.

I hadn't considered that a problem with the structure of the exhaust can also make for these symptoms.

I'll check that too.

I'll let you know how I get on.

Appreciated

9 hours ago, miyp36 said:

I hadn't considered that a problem with the structure of the exhaust can also make for these symptoms.

It is not about the structure. I said 'restricted' exhaust. The engine is basically an air pump. Suck, blow. The engine should breathe easily. It's like you put a rag over your nose/mouth when you want to exhale. Not too pleasant...

I had to wait for the mechanic who changed the head gasket to be available.

Today, the compressions was tested and found to be: 1=175; 2=180; 3=175; 4=175

No problem there.

He said that when the head was off he did a "lead-down test" and no problem there.

 

He took it for a drive and noticed the lumpy acceleration and lack of power.

Back at his garage, checking that he'd put everything back right, he noticed that the oil filler cap was loose: so loose that it was bouncing around and rattling when the engine was running. He tied it down thinking this looseness would affect the engine.

Another drive showed no improvement.

He described it as though there is a fuel shortage: that the engine isn't aware of it being under load.

His view is that it could be a faulty sensor. He, however, doesn't have the ability to check the ECU (is that the right abbreviation?) readout.

 

What puzzles me is that before the head gasket work the engine worked better than it does now post gasket change.

Could it be a sensor?

The 'restricted exhaust' does not appear to be the route.

Any suggestions to figure it out?

Does the ECU need resetting after a head gasket change?

Is there a sensor fault that would mean a loss of power and lumpy acceleration?
 

@miyp36 Well, it's {multiple censored} ridiculous that you're having to try and solve a problem that his work seems to have caused, and more so these days that he doesn't have a code reader.

 

You could try an ECU reset, which is as easy as leave the battery disconnected overnight.

8 hours ago, miyp36 said:

I had to wait for the mechanic who changed the head gasket to be available.

Today, the compressions was tested and found to be: 1=175; 2=180; 3=175; 4=175

No problem there.

If we are talking about PSI then yeah, the values are OK. Although I thought you're using the metric system. At least until October 31st.

He said that when the head was off he did a "lead-down test" and no problem there.

It is a leak-down test, from leaking air. But the test is done only with the head on. So there's a problem.

He took it for a drive and noticed the lumpy acceleration and lack of power.

Back at his garage, checking that he'd put everything back right, he noticed that the oil filler cap was loose: so loose that it was bouncing around and rattling when the engine was running. He tied it down thinking this looseness would affect the engine.

If he thought that, then you definitely need another mechanic. Because that assumption is way beyond ignorance.

Another drive showed no improvement. I wonder why...😲

He described it as though there is a fuel shortage: that the engine isn't aware of it being under load.

His view is that it could be a faulty sensor. He, however, doesn't have the ability to check the ECU (is that the right abbreviation?) readout.

If he doesn't have the tools to diagnose an engine issue, he should try another profession.

The 'restricted exhaust' does not appear to be the route.

Really? Who discarded that? The same genius? Based on what test or evidence?

 

My advice is:

1) Put pressure on the mechanic (?) that did the head gasket job to repair your car.

or

2) Find another more competent one that has the tools and the knowledge to diagnose the engine.

 

As for the rest of your question, nobody on this forum can't see in a crystal ball what is wrong with the engine. Without proper testing all we can do is to toss a coin.

Another possiblity of lumpy engine is the crank position sensor located on top of the flywheel.
Sometimes it needs to be a bit adjusted (position wise) or replaced if damaged.
Also lumpy acceleration can be caused by the carbon tracks being damaged in the TB, they are responsible for letting the ecu know the absolute throttle position.
This can be confirmed by a vag-com scanner looking at the two inverse percentages as the TB is moved.
Generally what I do in these cases is start by a complete sensor and TB cleaning and a full ecu reset.