Hesitation on the highway

[95gsrturbo]

ps-- havent tried this yet but have been told that if i swap the ECU EEPROM and just tell the chip that its going into a p28 and leave every thing else the same it will solve my problem. this being because there is no secondary runner to be found in the p28 program. -- the issue then remains that I will lose WHP because the short runners will not open (nothing controlling them) unless i do it manually in which case i lose gas milage from loss of the long runners

catch 22!

[Jaker]

Your short runners will always be open if there is no control. That is the nature of the beast. Honda designed the system to require the ECU to "close" the runners at low RPMs, and release them to open at the ECU controlled rpm.

[RedTeg95]

Looks like we are not the only ones with this problem. I'm convinced that my A/F is fine but I will try the suggestion in this thred on HT...

http://honda-tech.com/zerothread?id=550794

Wish me luck.

[Blown Si]

I have a p28 with the JRSC Big Boost Map. I have the stutter between 3500 and 4500 rpm while at a constant freeway speed. I plan to have some datalogging done in the next few days. I'm told that this map is perfect for my setup and should'nt need any adjustment. My setup consist of a JRSC, 11 psi pulley, RC 440's, IHE, Adj Cams set at 0. I have the evap purge solenoid unplugged. Could this be the reason? I'm fairly new to Hondata and new to this issue. Please advise if anyone has a solution or recommendation. Thanks

[95gsrturbo]

redteg95-- i noticed you are fromATL in the HT thread-- where and who tuned the car-- if you tell me ED ill flip.

that means youre on TI too-- lol
anyhow still cant fix the prob and its relaly annoying-- going on 5 months now ans still cant fix it.

some one mentioned the EVAP any ideas HONDATA?

here are some links to other ppl having the same issue
http://honda-tech.com/zerothread?id=550794
http://www.team-integra.net/forum/displ ... readPage=2

any help is appreciated

[MayhemSi]

I have had the same issue on my car. I have P28 with s100b on my 00 Si. Basically the EXACT things you are mentioning with the stutter at the same rpm range, same throttle ranges, and same vaccuum readings as well as the same flicker on the A/F to lean for just a tiny split second on the stutter. Anything that can be figured out would be great.

[hybridsol]

For those of you looking for an answer, we haven't found one yet...

About the A/F ratio onthe data logs, it is from the STOCK sensor, you know, like when the A/F light show goes back and fourth? There is no way to know exactly what the A/F is reading, as I sid befor, it's too quick for the wideband I have, and no one around us has an FJO or Haltec (sp?)

We think it occurs when the TPS is enough to go from closed to open loop, it "forgets" where it is on the map.

Keep updating as we go...

[Hondata]

OK, there are a couple of points that we can add:

1. Some air/fuel monitor devices upset the o2 sensor signal to the ECU. If the o2 sensor is a old, or the meter is not a good design, the impedance of the meter pulls the voltage down and the car will run rich.

2. The part throttle tuning is critical at crusing speed at about 10 inches vacuum. When in open loop you should not see the a/f ratio go above 15.0:1, otherwise you'll get a flat spot. The jerk you are feeling is problem when the car switches from open loop back to closed loop.

3. When running in open loop there was a bug in early versions of the software where the ECU still read the o2 sensor under some conditions. Make sure the ROM is up to date, and disconnect the o2 sensor as well if you want.

4. With some fuel pump & fuel pressure regulator combinations the fuel pressure will have a minimum level which it will not drop below. It is important to make sure that fuel pressure is above this minimum level at idle so that the fuel pressure rises by the right amount when you disconnect the vacuum line. Normally this is about 8 lbs fuel pressure. Otherwise you have run out of adjustment for the diaphram in the fuel pressure regulator.

5. JR Superchargers (I know this does not apply to you) have a caracteristic where there is a big spike in manifold pressure when the bypass valve shuts (usually just as you go into boost). In some cases the ECU will retard the timing and you'll get a flat spot just going into boost. The solution varies between tuning and playing with the bypass valve.

What we suggest:

1. Remove the a/f monitor.
2. Tune 2000-4500 rpm at part throttle open loop until it is all between 14.0 and 15.0:1 a/f. Datalog in closed loop and make sure that the short term and long term adjustments stay within +10% to -10% Long term adjustment should be 5% or less.
3. Try changing the closed loop disable pressure to a lower value.

Just looked at th
e recordings. In r31.rec at about 52s you can see a problem. The short term mixture adjustment goes to -20% - which will probably cause a glitch as the ECU decides something is wrong and corrects the mixture. The problem is that the o2 sensor voltage is staying at 0.8V when the throttle was closed, whereas normally it will drop to 0v. This would suggest that the very first fuel row is too rich, or the o2 sensor resonse is slow. Since you're using 550cc injectors, I suspect the first rows are a little too rich.

Hope that this helps and you resolve the problem.

[RedTeg95]

Thanks, I will give this a try.

[RedTeg95]

Oh btw, how do I check the version of the rom?

Thanks

[hybridsol]

Well...

We tried a bunch of stuff for like 4 hours on the road, using the Tech-edge WB and the emulator.

Nothing worked.

We tried lean (~15:1) then rich (~12:1). I should point out we were running right off the MAP, that is open loop, and we could repeat the problem consistantly over and over.

We tried changing the "tip in" setting, that didn't seem to do anything.

I can say that the problem is very consistant at 10" Hg- exactly when the stock ROM switches between open and closed loop at part throttle...

Our next trick is to try the exact same map, but with a P28 ECU. If that clears up the problem, well then I think we're on to something...

Sean

[hybridsol]

I'm going to reply to each of these for the record...

1. Some air/fuel monitor devices upset the o2 sensor signal to the ECU. If the o2 sensor is a old, or the meter is not a good design, the impedance of the meter pulls the voltage down and the car will run rich.

The o2 sensor was repleced with a new unit. We did not disconnect the A/F meter because we were using the wide band

2. The part throttle tuning is critical at crusing speed at about 10 inches vacuum. When in open loop you should not see the a/f ratio go above 15.0:1, otherwise you'll get a flat spot. The jerk you are feeling is problem when the car switches from open loop back to closed loop.

Yes, I agree, but we did not see a difference when running lean, in fact the blip seemed more pronounced at lean conditions

3. When running in open loop there was a bug in early versions of the software where the ECU still read the o2 sensor under some conditions. Make sure the ROM is up to date, and disconnect the o2 sensor as well if you want.

We don't know how to check this

4. With some fuel pump & fuel pressure regulator combinations the fuel pressure will have a minimum level which it will not drop below. It is important to make sure that fuel pressure is above this minimum level at idle so that the fuel pressure rises by the right amount when you disconnect the vacuum line. Normally this is about 8 lbs fuel pressure. Otherwise you have run out of adjustment for the diaphram in the fuel pressure regulator.

You may be on to something here, but he's used both a stock FPR and the AEM unit (on now), them problem occured with both. That is what we thought the problem was originally.

1. Remove the a/f moni
tor.
2. Tune 2000-4500 rpm at part throttle open loop until it is all between 14.0 and 15.0:1 a/f. Datalog in closed loop and make sure that the short term and long term adjustments stay within +10% to -10% Long term adjustment should be 5% or less.
3. Try changing the closed loop disable pressure to a lower value.

Just looked at the recordings. In r31.rec at about 52s you can see a problem. The short term mixture adjustment goes to -20% - which will probably cause a glitch as the ECU decides something is wrong and corrects the mixture. The problem is that the o2 sensor voltage is staying at 0.8V when the throttle was closed, whereas normally it will drop to 0v. This would suggest that the very first fuel row is too rich, or the o2 sensor resonse is slow. Since you're using 550cc injectors, I suspect the first rows are a little too rich.

We tried tuning with the stock O2 first, which was difficult to say the least. Changing IATs and water temps kept us from getting consistant results (short and long term adjustments). Using the wide band showed the map was very consistant at +1/-1% over the area in question.

The stutter occured consistantly at different RPM's, but always between the same two map columns.

Sean

[RedTeg95]

Okay here is the latest on this long journey. Thankfully it has come to an end. So Hybridsol and myself have been fighting with this on and off for a few months now. So I called Hondata directly and spoke with one of the techs and explained the whole story. He suggested that we try adding timing in the area we are having issues on the map. So today we did. We found that it helped a little bit but the problem was still there. After more adjustment of the timing we found that we could not make the problem go away. So we moved to our final test. We swapped out my P72 ECU with Hybridsol's P28 ECU. We converted my map over to the P28 and took it on the road (minus all the timing changes I just spoke about). That solved the problem!!! No more hesitation!!! So now this raises other questions. Is this a Hondata issue with the P72 ECU or just an issue with my P72 ECU? I wonder if this is a Hondata issue because of others who have described similar issues. I will post the P72 and P28 versions of my map in a day or so. My hope is someone can take a look and maybe confirm this one way or another. As for myself I probably will be shopping for a P28 ECU this week.

Thank you for your assistance.

[MayhemSi]

My vehicle runs a Hondata p28 with the built in obd2b connectors and s200b and still has the same thing even after several hours of partial throttle tuning with an FJO wideband and St00pid tuning the car. The hesitation will not go away. We have added fuel, pulled fuel, advanced the spark to obscene levels, pulle the spark timing back... doesn't matter. we ran it in both closed and open loop modes with the same results. The hesitation will not go away. The car has new plugs, new wires, the hondata setup is only a few months old, the o2 sensor has less then 10K miles on it... This hesitation is driving me crazy.. Anyone else still unable to get rid of it?

[Hondata]

Last week I looked at a Civic which had a hesistation. Sorry, no magic solution but a big improvement from changing a number of different bthings. There are a number of things on that car which still need attention.

http://www.hondata.com/techhes.html

Most people will find their problem is solved by adding ignition advance and a little bit of part throttle tuning.