Hesitation/flat spot problem with Honda Accord
Discussion
Thought I'd make a thread here in case someone may be able to shed some light!
My old 2000 Honda Accord 2.0 (my Dad has it now) has, since I've had it (and has done for years) a slight 'flat spot' at exactly 2,500RPM when under load, noticeable in lower gears, but mostly in 2nd and 3rd. The symptoms are if you're accelerating hard, i.e. WOT from low RPM through the revs, you'll feel a slight jolt as it passes 2,500RPM.
It didn't bother me as it's not THAT bad but my dad is very curious.
We've tried everything we can think of, including:
New plugs
New leads
New fuel filter
My dad took it to Honda who spent 4 hours looking at it (but don't worry, they didn't even charge him an hour's labour) and said that the distributor cap/rotor are fine, all the sensors are fine, all vacuum pipes are fine, nothing appeared on any diagnostic equipment. They don't know what to suggest without spending god knows how many more hours investigating.
It's had pretty much every other consumable part I can think of! Even a new clutch, although I'm sure that's not relevant
We're out of ideas! My only remaining theory is that it's something to do with the engine management and some sort of mapping discrepancy, but I'm not sure what can be done about that.
Anyone?!
Thanks!
Oh, FYI, it's a 2L SOHC 16V VTEC engine.
My old 2000 Honda Accord 2.0 (my Dad has it now) has, since I've had it (and has done for years) a slight 'flat spot' at exactly 2,500RPM when under load, noticeable in lower gears, but mostly in 2nd and 3rd. The symptoms are if you're accelerating hard, i.e. WOT from low RPM through the revs, you'll feel a slight jolt as it passes 2,500RPM.
It didn't bother me as it's not THAT bad but my dad is very curious.
We've tried everything we can think of, including:
New plugs
New leads
New fuel filter
My dad took it to Honda who spent 4 hours looking at it (but don't worry, they didn't even charge him an hour's labour) and said that the distributor cap/rotor are fine, all the sensors are fine, all vacuum pipes are fine, nothing appeared on any diagnostic equipment. They don't know what to suggest without spending god knows how many more hours investigating.
It's had pretty much every other consumable part I can think of! Even a new clutch, although I'm sure that's not relevant
We're out of ideas! My only remaining theory is that it's something to do with the engine management and some sort of mapping discrepancy, but I'm not sure what can be done about that.
Anyone?!
Thanks!
Oh, FYI, it's a 2L SOHC 16V VTEC engine.
I had a 1999 1.8 mondeo which did something very familiar. Except it used to really annoy me as it's flat spot was at about 2,000rpm or exactly at where the revs would sit in 4th gear doing 40mph. My journey home from work used to consist of going up a road with a steady incline with a 40mph limit which was enforced by speed cameras every 100M or so. If I left it in 4th I was constantly having to adjust the throttle because of the flat spot and the other options were to leave it revving in 3rd or labouring in 5th.
Had the car for over a year constantly trying to fix it but could never find the cause. Everything I tried or was reccomended to me had no affect whatsover.
Had the car for over a year constantly trying to fix it but could never find the cause. Everything I tried or was reccomended to me had no affect whatsover.
I also own a Honda Accord, with the F20B6 engine like yours (mines the 170hp version. is yours the same or is it a 148hp model?).
I'm afraid that the flatspot is to do with the mapping on the standard management. The F20B6 is tuned to run incredibly lean below vtec engagement (4250-4300rpm) which results in excellent mpg, but a nasty flatspot. All F20B6's I have drove suffer from the same problem, with some being worse than others.
I looked into getting it rectified too, but the standard Honda management system does not take well to being messed with. While it is possible to alter the standarx tune, it would be incredibly time consuming and expensive. It would be cheaper and more worthwile going for aftermarket management.
For now, i can live with it until i am forced to use Hondata management for when i supercharge it this winter.
To sum up, its not realistically possible to solve it. You will just have to live with it im afraid!
HTH.
I'm afraid that the flatspot is to do with the mapping on the standard management. The F20B6 is tuned to run incredibly lean below vtec engagement (4250-4300rpm) which results in excellent mpg, but a nasty flatspot. All F20B6's I have drove suffer from the same problem, with some being worse than others.
I looked into getting it rectified too, but the standard Honda management system does not take well to being messed with. While it is possible to alter the standarx tune, it would be incredibly time consuming and expensive. It would be cheaper and more worthwile going for aftermarket management.
For now, i can live with it until i am forced to use Hondata management for when i supercharge it this winter.
To sum up, its not realistically possible to solve it. You will just have to live with it im afraid!
HTH.
I would be asking your Honda dealer to check their old technical service bulletins on Honda's extranet.
There was a product update on that generation of accord for throttle body replacement due to a flat spot.
Whether it includes your specific vehicle they can tell just by inputting your VIN.
There was a product update on that generation of accord for throttle body replacement due to a flat spot.
Whether it includes your specific vehicle they can tell just by inputting your VIN.
Howard- said:
Thought I'd make a thread here in case someone may be able to shed some light!
My old 2000 Honda Accord 2.0 (my Dad has it now) has, since I've had it (and has done for years) a slight 'flat spot' at exactly 2,500RPM when under load, noticeable in lower gears, but mostly in 2nd and 3rd. The symptoms are if you're accelerating hard, i.e. WOT from low RPM through the revs, you'll feel a slight jolt as it passes 2,500RPM.
It didn't bother me as it's not THAT bad but my dad is very curious.
We've tried everything we can think of, including:
New plugs
New leads
New fuel filter
My dad took it to Honda who spent 4 hours looking at it (but don't worry, they didn't even charge him an hour's labour) and said that the distributor cap/rotor are fine, all the sensors are fine, all vacuum pipes are fine, nothing appeared on any diagnostic equipment. They don't know what to suggest without spending god knows how many more hours investigating.
It's had pretty much every other consumable part I can think of! Even a new clutch, although I'm sure that's not relevant
We're out of ideas! My only remaining theory is that it's something to do with the engine management and some sort of mapping discrepancy, but I'm not sure what can be done about that.
Anyone?!
Thanks!
Oh, FYI, it's a 2L SOHC 16V VTEC engine.
Is the hesitation from the same coasting speed in 2nd and 3rd gear? At say, 50 kph / 31 mph ?My old 2000 Honda Accord 2.0 (my Dad has it now) has, since I've had it (and has done for years) a slight 'flat spot' at exactly 2,500RPM when under load, noticeable in lower gears, but mostly in 2nd and 3rd. The symptoms are if you're accelerating hard, i.e. WOT from low RPM through the revs, you'll feel a slight jolt as it passes 2,500RPM.
It didn't bother me as it's not THAT bad but my dad is very curious.
We've tried everything we can think of, including:
New plugs
New leads
New fuel filter
My dad took it to Honda who spent 4 hours looking at it (but don't worry, they didn't even charge him an hour's labour) and said that the distributor cap/rotor are fine, all the sensors are fine, all vacuum pipes are fine, nothing appeared on any diagnostic equipment. They don't know what to suggest without spending god knows how many more hours investigating.
It's had pretty much every other consumable part I can think of! Even a new clutch, although I'm sure that's not relevant
We're out of ideas! My only remaining theory is that it's something to do with the engine management and some sort of mapping discrepancy, but I'm not sure what can be done about that.
Anyone?!
Thanks!
Oh, FYI, it's a 2L SOHC 16V VTEC engine.
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