Hesitation I can't get ride of ... help!

[R13]

Well, I had mine solved (hesitation/misfire), but after changing the VC gaskets it has reared its head again. It is actually much more pronounced at idle this time around though, but still intermittant.

So:

Plugs: new
O2 sensors: new
coolant temp sensor: new
speed sensor: new

I tried disconnecting each coil, but then it just goes from missing some of the time (every 3rd/5th/etc. cycle), to missing all of the time. I have sourced a good coil that I will swap into the loop tomorrow to see if I can narrow it down. After that though, I'm not quite sure which direction to take. It misses at idle and has a very pronounced hesitation below 3k rpm, but above that, runs normally.

I will update this again once I've completed a more thorough check of the coils tomorrow. This is a great thread though :biggrin:

 

[enkrypt3d]

Well, I had mine solved (hesitation/misfire), but after changing the VC gaskets it has reared its head again. It is actually much more pronounced at idle this time around though, but still intermittant.

So:

Plugs: new
O2 sensors: new
coolant temp sensor: new
speed sensor: new

I tried disconnecting each coil, but then it just goes from missing some of the time (every 3rd/5th/etc. cycle), to missing all of the time. I have sourced a good coil that I will swap into the loop tomorrow to see if I can narrow it down. After that though, I'm not quite sure which direction to take. It misses at idle and has a very pronounced hesitation below 3k rpm, but above that, runs normally.

I will update this again once I've completed a more thorough check of the coils tomorrow. This is a great thread though :biggrin:

Replace all the coils not just one.

 

[R13]

The point is that I can swap the good coil in for each of the existing ones and see where the problem is. If doing so does not correct anything, then there is no point dropping the coin to replace the coils if it is an injector, relay, etc. that is the actual problem.

Update forthcoming this evening hopefully.

::EDIT::

rear bank, driver's side coil (the one that I had suspected) seems to have been the culprit. swapped in known good coil, and all is right with the world.

Also, as an FYI: Autozone "duralast" coil packs are designed in such a way that they do not fit under the plastic covers, so they may be cheap, but they will not fit as a permanent solution. They're probably crap anyway, but that is all that was handy

 

[NSX-SA]

I had the same problem tried everything finally switched to fuel pump to constant 12v all fixed. I have a switch behind the passanger seat (RHD) so i can change the voltage when its switched off the hesitation is back and even the idle is a bit rougher.

 

[enkrypt3d]

I had the same problem tried everything finally switched to fuel pump to constant 12v all fixed. I have a switch behind the passanger seat (RHD) so i can change the voltage when its switched off the hesitation is back and even the idle is a bit rougher.

Wow that is interesting.. so your fuel pump is running at full speed all the time? Does that use more fuel??

That would make me think you need to get your injectors cleaned and balanced...

 

[NSX-SA]

Yep it uses more fuel but the hesitation is gone.

Thats why i put the switch in when i go for a road trip when im just cruising i switch it to normal and get great fuel economy around 770kms on a tank.

 

[enkrypt3d]

Yep it uses more fuel but the hesitation is gone.

Thats why i put the switch in when i go for a road trip when im just cruising i switch it to normal and get great fuel economy around 770kms on a tank.

I would still look at your injectors..... This is just a work around IMO... The car doesn't require a switch to make it run smoothly

If you have to, replace the injectors or send them off to have them cleaned and balanced. Its actually pretty cheap its just the down time that sucks.

 

[Daedalus]

Yep it uses more fuel but the hesitation is gone.

It won't use more fuel than it's supposed to use. The fuel pressure regulator keeps the rail at the right pressure independent of the pump...normally. If the pump needs to be run at a higher voltage to keep adequate fuel pressure, then I would suspect the pump or something in the resistor ciruit is faulty. If the pressure is too low at idle, you can bet it's really too low at low-voltage off idle (e.g., cruise), and possibly under some 12V conditions (WOT?). Verify with a pressure measurement. You can also measure the pump's resistance and/or its amperage if you know the new pump numbers. The FSM also specs a minimum flow rate of 11.3 ounces in 10 seconds @ 12V.

 

[NSX-SA]

I've done this mod to 3 other nsx's all have fixed hesitation problems after increasing HP via intake, exhaust and headers.

I have a fuel new pump to go in i will doing it in the next week will let you know if it makes any difference.

 

[enkrypt3d]

I've done this mod to 3 other nsx's all have fixed hesitation problems after increasing HP via intake, exhaust and headers.

I have a fuel new pump to go in i will doing it in the next week will let you know if it makes any difference.

thats fine if you want to upgrade your fuel jump... for higher HP gains...

If there is a problem then it should be fixed. My car runs great

There's no reason to upgrade the fuel pump if 1 or more of your injectors are dripping. Why not actually diagnose the real problem rather than band-aiding it?

 

[NSX-SA]

This is my spare engine both benefitted with this mod.

Are you saying all 4 cars have the same problem.

Are you aware that the fuel pump go's to 12v when v-tec cuts in anyway because of the extra power produced so all we are doing is boosting the fuel pressure at lower rpm to deal with low rpm hesitation.

I also have a fuel pressure regulator with a guage. The last dyno session showed fuel pressure was dropping at high rpm that is why the pump will be changed.

Just because your car works fine dosent mean all cars are equal.

 

[enkrypt3d]

This is my spare engine both benefitted with this mod.

Are you saying all 4 cars have the same problem.

Are you aware that the fuel pump go's to 12v when v-tec cuts in anyway because of the extra power produced so all we are doing is boosting the fuel pressure at lower rpm to deal with low rpm hesitation.

I also have a fuel pressure regulator with a guage. The last dyno session showed fuel pressure was dropping at high rpm that is why the pump will be changed.

Just because your car works fine dosent mean all cars are equal.

I'm talking about YOUR car not ALL cars... I'm trying to help you diagnose a problem. Not going to try and change your mind if you don't want to hear it.

If you don't want to hear my input from my experiences, then fine. You can't immediately discount my suggestions because you don't know what I know.

I guess the fact that I had this same issue and had my injectors cleaned and balanced for about $150USD and the problem was gone afterwards... The car ran better than it had ever run before. I had a few other things done at the same time like timing belt and water pump but this was the major one...

If you are getting hesitation it can only be a number of things:

Electrical (spark plugs / coils / main relay or other electrical problem)
Fuel delivery (fuel pump / filter / clogged fuel line / fuel rail or injectors or some other fuel related issue)
Or Mechanical (which is usually pretty rare to cause this type of problem)

 

[goldNSX]

Are you aware that the fuel pump go's to 12v when v-tec cuts in anyway because of the extra power produced so all we are doing is boosting the fuel pressure at lower rpm to deal with low rpm hesitation.

Please remember that the fuel pressure is raised above 4.2k rpm, not in VTEC. Good input though but if you observe low rpm hesitation which goes away with bypassing the fuel pump resistor with a switch the resolution would be changing the fuel pump and not installing a switch as the fuel pump seems to deliver less fuel than specified below 4.2k rpm unless there are other (electrical) problems.

 

[R3DLINE]

does this hesitation includes the fact that the rpm is gaining quickly but the mph is not accelerating? Or is that the clutch? There isnt a smell of a burning clutch so can this be the same issue?

 

[R3DLINE]

does this hesitation includes the fact that the rpm is gaining quickly but the mph is not accelerating? Or is that the clutch? There isnt a smell of a burning clutch so can this be the same issue?

 

[R13]

Most of what folks are referring to in this thread is the car stumbling at low RPM under (in my case) significant throttle input.

If the RPM is climbing smoothly with no stumble or jerkiness, but the car is not accelerating, that is almost definately a clutch. That said, i am surprised that you wouldn't be able to smell it.