any advice - loss of power over 3k revs / no top end....
Discussion
HI guys,
my 1999 civic 1.4 daily ride has gone limp mode and thrown up P0172 (fuel trim error) and P0170 (running rich bank 1) codes. At the same time it now will not go over 70mph (and to be honest 65 is a struggle).
I've reset the codes and it now sometimes throws just the P0170 code, but mainly doesn't give me the eml, just runs gutless.
I've also noticed a whooshing noise as if air is escaping when under heavy load (possibly back pressure from exhaust leaking through a joint?).
I've checked the 02 sensor and this is fine, air filter is clean and clear, car will rev relatively freely when not under load (it is only a 1.4 ) just runs out of puff past 40mph / or over 3k revs.
my thinking now is a blockage in the exhaust - ie a dead cat, any other suggestions before i bite the bullet and buy a new one and spend half a day cursing rusted bolts?
TIA
my 1999 civic 1.4 daily ride has gone limp mode and thrown up P0172 (fuel trim error) and P0170 (running rich bank 1) codes. At the same time it now will not go over 70mph (and to be honest 65 is a struggle).
I've reset the codes and it now sometimes throws just the P0170 code, but mainly doesn't give me the eml, just runs gutless.
I've also noticed a whooshing noise as if air is escaping when under heavy load (possibly back pressure from exhaust leaking through a joint?).
I've checked the 02 sensor and this is fine, air filter is clean and clear, car will rev relatively freely when not under load (it is only a 1.4 ) just runs out of puff past 40mph / or over 3k revs.
my thinking now is a blockage in the exhaust - ie a dead cat, any other suggestions before i bite the bullet and buy a new one and spend half a day cursing rusted bolts?
TIA
Oh dear, the usual clueless advice. The fueling system neither knows nor cares whether the cat is working or not. The lambda sensor is upstream of that and even if there's a second sensor downstream that will only put the check engine light on to let the owner know the cat isn't working but it won't go into limp mode or affect the fueling in any way.
Find the cause of the noise and I suspect you'll find your problem.
Find the cause of the noise and I suspect you'll find your problem.
the sound only comes when at full throttle under load though so a bit difficult to source unless i surf under the car while someone else drive it 
the more power you try to give it, the more strangled it feels so does feel like an exhaust issue.
will report back if i bother to do anything about it this weekend
thanks for the advice so far
the more power you try to give it, the more strangled it feels so does feel like an exhaust issue.
will report back if i bother to do anything about it this weekend
thanks for the advice so far
Pumaracing said:
Oh dear, the usual clueless advice. The fueling system neither knows nor cares whether the cat is working or not. The lambda sensor is upstream of that and even if there's a second sensor downstream that will only put the check engine light on to let the owner know the cat isn't working but it won't go into limp mode or affect the fueling in any way.
Find the cause of the noise and I suspect you'll find your problem.
A partially blocked cat/exhaust will give the em conflicting info on air flow and throttle position.Find the cause of the noise and I suspect you'll find your problem.
I have come across this several times, so please take it from me that this can be the cause of a fuel trim code.
Fuel trim codes can be awkward to cure,firstly a inspection of the induction system for airleaks should be carried out,a garage with a smoke machine to show leaks may be able to help you,is the lambda switching correctly,if it is sticking in the rich position is the airmass meter/map sensor,coolant sensor values correct,fuel pressure should be checked,have had a blocked fuel return pipe cause a rich mixture before,a vacuum gauge on the inlet manifold may show if you have a blocked cat but I would check the above first
This could be an airleak after the airflow meter, any air dragged in here isn't 'seen' by the ECU and so not compensated for, causing rough running.
Check the hose clips for tightness and inspect the trunking for any cracks or splits and also all the vacuum system, the small bore pipes and fittings for cracks and missing parts.
The best way to locate a leak is to have the engine running and warm and then spray lighter gas around each joint in turn. If the engine rev's up you've found your leak.
Check the hose clips for tightness and inspect the trunking for any cracks or splits and also all the vacuum system, the small bore pipes and fittings for cracks and missing parts.
The best way to locate a leak is to have the engine running and warm and then spray lighter gas around each joint in turn. If the engine rev's up you've found your leak.
350Matt said:
This could be an airleak after the airflow meter, any air dragged in here isn't 'seen' by the ECU and so not compensated for, causing rough running.
Check the hose clips for tightness and inspect the trunking for any cracks or splits and also all the vacuum system, the small bore pipes and fittings for cracks and missing parts.
The best way to locate a leak is to have the engine running and warm and then spray lighter gas around each joint in turn. If the engine rev's up you've found your leak.
And if you don't, you'll probably burn your garage down. Check the hose clips for tightness and inspect the trunking for any cracks or splits and also all the vacuum system, the small bore pipes and fittings for cracks and missing parts.
The best way to locate a leak is to have the engine running and warm and then spray lighter gas around each joint in turn. If the engine rev's up you've found your leak.
Win-win.
Mate had a Vauxhall Vectra 3.0 v6 with a similar problem.
His mate said it was running on 4, but I heard it and thought different.
Did a check and found 2 fault codes, one was MAF the other was air temp.
That told me there was an air leak in the system, so told him to take the manifold apart.
Sure enough, there was a fault in the rubber seal which caused it to draw air at that point.
He repaired it, replaced the manifold I erased the fault codes and she ran sweet as a nut and ate lesser cars for breakfast.
That was two weeks ago and still there is no repeat of the MIL coming on.
An air leak throws all manner of herrings into the red dye.....
His mate said it was running on 4, but I heard it and thought different.
Did a check and found 2 fault codes, one was MAF the other was air temp.
That told me there was an air leak in the system, so told him to take the manifold apart.
Sure enough, there was a fault in the rubber seal which caused it to draw air at that point.
He repaired it, replaced the manifold I erased the fault codes and she ran sweet as a nut and ate lesser cars for breakfast.
That was two weeks ago and still there is no repeat of the MIL coming on.
An air leak throws all manner of herrings into the red dye.....
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