I've got a turbo b18c, hondata 4b. I'm doing some street wideband tuning, and I can't get rid of a hesitation I have between 5-6k rpm. After 6 grand, all is well. Just in that range, it hesitates badly. I think its tuning related simply because I don't know what could cause such a specific hesitation mechanically. Anyway, the a/f is right around 12.5 in that range.... any thoughts?

Is the target lambda table in the rom editor software a good one to base my tuning on? (12.5 under boost)? Or should I cange my target a/f?

 

whats your ignition map look like in that area?

 

John... doesn't this sound familiar? It seems to me that ALOT of B18C1 swaps that go boost experience the hesitation in the same place. I did that del Sol recently with a B18C1 swap (GS-R ECU) and it did the same thing.

Small things like re-gapping plugs to .32 to .35 usually don't tend to solve the problem. I'm curious to know if something in the GS-R ECU causes this... something related to the secondaries opening perhaps?

 

I do not have the hesitation you are speaking of...

But, are you sure that your A/F ratio is smooth from before 5k till after 6k? I ask because usually the A/F will change significantly enough after your VTEC crossover point which may give a hesitation. What is your crossover rpm? Make sure that the A/F ratio is as smooth as possible before and after the crossover.

 

I don't have access to a dyno, so my ignition map is the same as the one in the basemap for the stock JDM b18c modified for 550's. I generated boost tables using 0.5 degrees of retard ber pound of boost. The fuel maps seem smooth... right around 12.5 a/f. the graphs don't have any jolts/surges in them.

This only happens at WOT.... also the strange thing is: I first installed the 550's and the standalone before the turbo. Idled like crap (lean), so I simply richened up both fuel tables by 25% and it ran fine. I turbocharged it, and (of course it wa running rich) but this hesitation was not there. strange part: even before I started making changes to the fuel curves, this hesitation gradually started.

Vtec engages at 4900. It started engaging at 4400... and the hesitation seemed to start there. Now, it seems to start at 4900 when vtec hits and last until 6000. A soon as it hits 6k, all is well.

The hesitation is pretty bad... It makes me not want to drive it for fear of blowing something up.

 

Is this overlap related? How is your cam timing set?

 

I have stock cam gears and stock cams.

 

what does everyone think of the default target lambda table given with the romeditor software?

I would consider it to possibly be detonation... but I can't hear it (which doesn't necessarily mean it isn't there), but it gets better afer 6k... wouldn't it not get better it if wasn't detonation (unless I was simply running lean in the hesitation area)?


[Modified by servion, 2:23 PM 10/21/2002]

 

I dont have that problem on my b18c1 swap, but I am running a P28 ECU, not a P72.

 

^^^

 

If you have replaced the GSR manifold with a Skunk or similar, you will need to add ignition timing between 45-6000 rpm. There is a dip in that area due to the torque from the dual plane intake.

Compare the stock P20 and P72 maps to see what I mean.




[Modified by Hondata, 9:49 PM 10/21/2002]

 

my intake manifold is still stock, as are my internals. The timing is striaght off the 269550 map

 

Did you richen up the WHOLE map(s) or just the first few columns (idle/low load)? My guess is that you are WAY too rich at VTEC. How do your plugs look? Look at both maps around that area to see if the high cam map is much different than the low cam map.

 

this is very interesting...... its weird that it starts when VTEC ingages and stops when the secondaries open (6000)........ a/f is just fine between 4900 and 6000?? have you tried leaning out this area and also richening it up?? i also have to street tune ( only v-afc hack) but i feel your pain!!!
BUMP!

 

this is strange... it seems to be getting worse over time (I haven't had time to touch the tuning yet, so nothing has changed) and it starts around 4500rpm... even though vtec is 5000rpm. I can now hear loud popping (I would guess backfire) when I'm, under WOT in that range. Could it be something mechanical?

 

Could be a p72 problem.......butterflies? I'm using p28 and I'ts always been smooth since i converted from obd0. Looks like everyone who's NOT having this problem is using p28....

 

I have this problem too. P72 ecu, skunk2 mani. You think a p28 would solve this? Interesting...Would I need to send the p28 out to get chipped or anything of that nature?

Thanks

 

well, the thing is: when I furst put the turbo on, it didn't do this. This has began and gotten gradually worse over a few weeks. A also ran standalone for a week before turbocharging it, and it was great then too. Without any tuning changes, this problam has developed from nonexistant to a big deal

 

^^^ any help would be appreciated.... fouled plugs perhaps? That's the only thing I can think of that would slowly get worse over time

 

free bump for a good dood...

 

I had the same problem with my b18c1 and p72 setup with hondata. I put my program into my p72 as a p28 and the problem went away. I'm running a skunk 2 mani so I had no problems. Try making your program for a p28 and see what happens.

 

this is getting weird... I've got the fuel curve running me right at 12:1 in boost.... and its not getting better. If I richen it up to amounts like 9:1, then it feels semi-ok, but I cam smell the gas, and I don't htink it's supposed to be running that rich. Could it be somehting mechanical?

 

Hey man, if you want to rule out that it's an ECU issue, we can swap in my p28 sometime and see how it runs. Would that be possible? My b18c1 runs without hesitation (not a swap tho) with a p28 ecu and Hondata semi-tuned basemap. I also have the stock intake mani. Let me know, maybe we can meet up this weekend or something.

Justin

 

the hesitation you are describing is not like the typical p72 hesitation that continues to plague alot of people. Yes, the timing is different between the two but that is not likely to fix that problem. "Leon" is right. getting the A:F ratios to cross over smoothly in closed loop to open loop is important. bring your target lambda down a bit in your lower MAP areas and only run 14.7 in the first 3 columns. send me your rom and lemme see it.

 

Cool.... I emailed you my rom. When you say to bring my target lambda down, do you mean more rich or more lean?