Flat Spot then Surge
09-29-2004, 09:23 AM
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Flat Spot then Surge
Hi all,
Bear with me as this is actually my first post! I'm not sure if this the most appropriate place to post, but it is of technical nature.
i've been driving my s2k 03' for about 4 months now, got 9k on the clock. Everything has been running sweet up until about 3 weeks ago. Took the car on a 'relaxing' trip and covered a couple of hundred miles. Towards the end of the journey the car became abit juddery. Accelerating (not aggresively) through 2nd from 4'000 round to 7'000 revs is patchy. There doesn't seem to be a marked vtec cut in. I feel a flat spot around 5'000, it catches slightly at 6'000, dies off again for a bit then gives the VTEC feel from around 7'500 onwards.
The dealer suggested i check the oil! Yeah cheers for that, i might not be the most mechanically minded but i think i had that one covered. Anyway, it started to stall in traffic, sometimes not restarting for a while, so i took it back to the dealers. Apparently nothing wrong; re-set the ECU, tightend something up on the battery.
They suggested that it might be the fuel. I always use Super Unleaded (UK) Octane level at least 97. I run Optimax (98) once in a while. They say the fuel from the supermarket would be of lesser quality and may cause this symtom. I've since run nearly 3 tanks of Optimax through and the haphazard accleleration characteristic remains.
I think power output may be down as well, i sort of had a thing with a Fiat Coupe. I can only assume it was a 20v Turbo (220bhp), as it pulled away while i was flat out pushing hard through 2nd into 3rd. Surely i should be looking to at least stay with it or even pull away??
Can this be purely fuel related? I just have the feeling that something isn't right.
Sorry for being so bloddy long winded, i'll try to keep any future posts shorter. Anyway, all you guys keep asking people for more information, so i thought i would oblige!!
Cheers,
James
Bear with me as this is actually my first post! I'm not sure if this the most appropriate place to post, but it is of technical nature.
i've been driving my s2k 03' for about 4 months now, got 9k on the clock. Everything has been running sweet up until about 3 weeks ago. Took the car on a 'relaxing' trip and covered a couple of hundred miles. Towards the end of the journey the car became abit juddery. Accelerating (not aggresively) through 2nd from 4'000 round to 7'000 revs is patchy. There doesn't seem to be a marked vtec cut in. I feel a flat spot around 5'000, it catches slightly at 6'000, dies off again for a bit then gives the VTEC feel from around 7'500 onwards.
The dealer suggested i check the oil! Yeah cheers for that, i might not be the most mechanically minded but i think i had that one covered. Anyway, it started to stall in traffic, sometimes not restarting for a while, so i took it back to the dealers. Apparently nothing wrong; re-set the ECU, tightend something up on the battery.
They suggested that it might be the fuel. I always use Super Unleaded (UK) Octane level at least 97. I run Optimax (98) once in a while. They say the fuel from the supermarket would be of lesser quality and may cause this symtom. I've since run nearly 3 tanks of Optimax through and the haphazard accleleration characteristic remains.
I think power output may be down as well, i sort of had a thing with a Fiat Coupe. I can only assume it was a 20v Turbo (220bhp), as it pulled away while i was flat out pushing hard through 2nd into 3rd. Surely i should be looking to at least stay with it or even pull away??
Can this be purely fuel related? I just have the feeling that something isn't right.
Sorry for being so bloddy long winded, i'll try to keep any future posts shorter. Anyway, all you guys keep asking people for more information, so i thought i would oblige!!
Cheers,
James
09-29-2004, 09:30 AM
#2
Give the "MAP whack" a try:
http://forums.s2ki.com/forums/index.php?showtopic=209708
AND THEN the ECU reset:
http://forums.s2ki.com/forums/index.php?showtopic=183490
(Follow the precedure for CEL reset.)
Come back and tell us if this did anything. If not, then give us any other details that you can observe of this phenomenon. The info the better.
http://forums.s2ki.com/forums/index.php?showtopic=209708
AND THEN the ECU reset:
http://forums.s2ki.com/forums/index.php?showtopic=183490
(Follow the precedure for CEL reset.)
Come back and tell us if this did anything. If not, then give us any other details that you can observe of this phenomenon. The info the better.
09-29-2004, 09:41 AM
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Hello there.
First try the map sensor as xviper stated.
IMO, I am betting this is fuel related.
You may have a lean spot just after VTEC.
Have your AFR ratios checked with a wideband.
Question for you:
What modifications have you done to date?
First try the map sensor as xviper stated.
IMO, I am betting this is fuel related.
You may have a lean spot just after VTEC.
Have your AFR ratios checked with a wideband.
Question for you:
What modifications have you done to date?
09-29-2004, 10:55 AM
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None. I'm having issues with stock, let alone modifications.
I would like to know more about it though, and this seems to be the place to be. If i were going to dabble, i'd probably start with the breathing, maybe a mugan cold air intake. Nothing too serious.
I want to get this suspected 'fuel' issue sorted first though before i consider anything else. I would like to have a garage that i could trust as well as i dont think i would be much use fitting nitrous on my own!!
I would like to know more about it though, and this seems to be the place to be. If i were going to dabble, i'd probably start with the breathing, maybe a mugan cold air intake. Nothing too serious.
I want to get this suspected 'fuel' issue sorted first though before i consider anything else. I would like to have a garage that i could trust as well as i dont think i would be much use fitting nitrous on my own!!
09-29-2004, 12:03 PM
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I had almost the same problem, mine didnt seem as bad. My problem was around 6k vtec wouldnt kick in (atleast it seemed) and as the revs went up it kinda spuddered. I took it to a respected honda dealer and they fixed the problem. It ended up that when i was hitting vtec or higher rpms the spark plug would mis-fire.
Id check the spark plugs and make sure none of them are burnt or loose.
hope this helps, it was bothering me for awhile. It sucks the the S gets sick.
Id check the spark plugs and make sure none of them are burnt or loose.
hope this helps, it was bothering me for awhile. It sucks the the S gets sick.
09-29-2004, 01:09 PM
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I know. I'm a bit gutted really. I've not really had the car that long and i dont think i've abused it. I've driven it how i feel the thing was designed to be driven.
I'm not entirely sure what a misfire would sound like, but i have also notices that the engine does not sound as sweet as it used to, although i think i might be being abit over sensitive!! I wish i was Honda Super Mechanic!!!
Would the spark plugs really need attention after 9k miles?? I suppose one could have worked it's self loose in that time.
It's going back to the dealers next thursday so i'll let you all know.
I'm not entirely sure what a misfire would sound like, but i have also notices that the engine does not sound as sweet as it used to, although i think i might be being abit over sensitive!! I wish i was Honda Super Mechanic!!!
Would the spark plugs really need attention after 9k miles?? I suppose one could have worked it's self loose in that time.
It's going back to the dealers next thursday so i'll let you all know.
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09-30-2004, 04:56 AM
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Im not an expert, but i dont see any reason a spark plug couldnt have come loose.
It wont sound different, you will feel the engine hickup at certain points above 6.
It wont sound different, you will feel the engine hickup at certain points above 6.
10-01-2004, 06:18 AM
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Problem got worse (then better again) acceleration was really flat in lower rev range in 2nd and 3rd gear. Took it straight to the dealers. they recognizred there was a fault, but wasn't sure what it was. The car is drivable, so i'll be taking it in next thursday. Fingers crossed. Otherwise it's going back for good. I knew i should never have got rid of my VW! (Only joking, i love it, but i'm a bit peaved.)