Hiccups while accelerating

S

sergio2305

New Member
Hi everybody, my beloved 1.4 Petrol A2 started to hiccup intensely while accelerating, as soon as I press the gas pedal, making the car nauseating to drive. I suppose it's either the spark plugs or its coils(?). However, this issue doesn't always manifest and when it does its present as soon as I turn the car on and does not come up while driving. I always had the lambda sensor faulty causing a check engine light, I never got it repaired cause the technician told me it's an expensive common issue and it was going to resurface anyway. Moreover, the EGR valve was blocked as the car tended to shut off especially while reversing. The injectors where cleaned not long ago. Does anyone have any suggestions? I think its the spark plugs (or coils) but I can't understand why the issue isn't always present in that case... (maybe the ECU has to be reprogrammed?)
 
If you care that much about the car, you need to find a competent mechanic rather than returning to that technician. "don't fix it because it'll go wrong again anyway" is some of the worst advice I've heard in a long time.

Have they established if there are misfires as well as jumpy throttle response? That will direct diagnosis towards whether something in the ignition system needs to be looked at or if there are other issues.

Having the Lambda in good condition is essential - and should not be skimped on : it needs to be an NTK / NGK original one for best performance.

NGK LZA11-V1 Oxygen Sensor​

Not replacing this can result in your catalytic converter being ruined as well as affecting other components due to running rich and causing EGR and associated pipework into the throttle body to get clogged up - all of which will be a lot more expensive, and the car will be compromised on emissions, fuel economy etc.

What you're describing regarding pogo-ing during acceleration sounds like the throttle body isn't working terribly well - is the idle lumpy?

An awful lot of the above issues could probably be resolved by doing some proper basic maintenance - and I should clarify - I'm not an expert mechanic but managed to do pretty well all of the above jobs stepwise on our neglected 1.4i (AUA) over the past 5 years.
 
Robin_Cox said:
If you care that much about the car, you need to find a competent mechanic rather than returning to that technician. "don't fix it because it'll go wrong again anyway" is some of the worst advice I've heard in a long time.

Have they established if there are misfires as well as jumpy throttle response? That will direct diagnosis towards whether something in the ignition system needs to be looked at or if there are other issues.

Having the Lambda in good condition is essential - and should not be skimped on : it needs to be an NTK / NGK original one for best performance.

NGK LZA11-V1 Oxygen Sensor​

Not replacing this can result in your catalytic converter being ruined as well as affecting other components due to running rich and causing EGR and associated pipework into the throttle body to get clogged up - all of which will be a lot more expensive, and the car will be compromised on emissions, fuel economy etc.

What you're describing regarding pogo-ing during acceleration sounds like the throttle body isn't working terribly well - is the idle lumpy?

An awful lot of the above issues could probably be resolved by doing some proper basic maintenance - and I should clarify - I'm not an expert mechanic but managed to do pretty well all of the above jobs stepwise on our neglected 1.4i (AUA) over the past 5 years.
Click to expand...
Thanks so much! I’ll take the A2 to a more professional technician and ask about the misfires as I don’t have the diagnostic tools. The idle is stable. The throttle body was cleaned by a different technician last January. The lambda sensor that you’ve indicated is the one under the hood? I’ve changed that one last year (the car drove absolutely the same anyway), the previous technician told me that there’s another in the exhaust which I wasn’t able to change. (Sorry for my bad English I’m having some difficulties translating from Italian :) )
 
Another possibility is ingress of air causing the engine light. In a worst case this could be caused by small holes or cracks in the intake pipework as well as around throttle body.

Is there any oil seepage visible around the oil cap on top of the engine? There is a rubber seal under the cap that can become hard so it no longer seals completely, and this is a cheap and easy replacement that can solve some AUA / BBY problems.

Our car's spark plugs and cords needed to be replaced - I found that there were 4 non-identical plugs and the cables looked very poor. The AUA single coil pack was also heavily compromised with cracks and shrunken insulation so sparks were escaping to the block. This was much worse in cold and damp weather, which may explain the sporadic nature of your experience if there is some exogenous condition that contributes to the symptom.
 
Update: I took the A2 to a more serious technician and I told him your suggestions. Turns out that the alternator sensor was faulty causing problems to the whole ignition system, luckily it was a cheap fix and I hope it will last. He also canceled the error that caused the check engine light but after a day or two it came back, I can’t remember correctly but I think it’s the lambda sensor in the exhaust system (not the one in the engine bay). Should I get it fixed? The car now runs smoothly and it’s a pleasure to drive.
 
Is the error a faulty post cat lambda sensor, or is the lambda sensor flagging up that the cat is not working effectively?
Probably best to replace the lambda either way. Cheaper than a new cat.
Mac.
 
You must log in or register to reply here.
Back
Top