GruvyTune

I am really trying to get at this hesitation problem.
I have things tuned to 14.7 AF ratio at idle and part throttle up to the
target lambdas in Romeditor. I then went and put a brand new OEM o2 sensor
in my car and datalogged in closed loop. my short term is well within +/-5%
most of the time and certainly is so at idle or constant throttle cruising
on the highway. The longterm shows no change from zero baseline. I have
the closed loop changeover at the Romeditor default of 790mbar.

Looking at the graph of the o2 sensor voltages they are square waves going
up and down from about 0.1V to 0.8V at idle with a cycle lasting about 5sec
(0.2hz). As throttle is applied but not boosting, and still in closed loop
mode, the freq of the cycles increases to about 0.6 Hz with the voltages
swinging the same 0.1-0.8V. Then when I am on the highway cruising, still
in closed loop (MAPs about 500mbar and about 4000rpm 80MPH) the voltage
swings get tighter and alternate from 0.2-0.8 to 0.6-0.8 and the freq of the
oscillations increases to about 1Hz and the short term changes are tight
oscillations between +/- 5V.

I get momentary hesitations if I come off and back on the throttle very
lightly just as I come back on the throttle.

Does this help out at all. Are my voltage swings normal?

Torin

lucas569

id love to know too, my **** still does this. im untuned though but it seems alot of people were having the same problem...

GruvyTune

Don't even contemplate this problem unless you are well tuned. Running closed loop in an untuned hondata is a disaster and stutters all over the place. better off in open loop. I have it well tuned and have nearly all the hesitation out of it in CLOSED loop. Runs great in open or closed but that silly hesitation is still there in both open and closed. I still get better throttle response in open loop in city driving situations. On highway both are nice and closed loop is giving me great mileage now (my egt's are definitley telling me where my stoich. point is at -- about 805C--I was running about 775C in open loop).

torin

The_Head

Still having the same problem too. @ 3500 RPM in 3rd 4th or 5th the motor will stutter for just a split second then resumes its cruising. I bet Doug @ Hondata will be able to help on this one since you have it datalogged.

93LSivic

Ditto for me. Untuned. I have the same hesitation, wheather its hwy driving or around town. Whenever i lift the pedal a little then depress it a little i get that hickup.
I hope Doug or someone sees this.
BTW Gruvytune, I hope that you sent these datalogged runs to hondata to see what they recommend for us all to do.

I hope this is simply resolved...its starting to get irritating


[Modified by 93LSivic, 1:03 PM 5/11/2002]

SilverLudeSi

Same problem here, especially when cruising with light throttle on the highway.

GruvyTune

I have 15min of datalogging (2Megs) in closed loop with a brand new sensor.
I am going out today and datalog in open loop and try to capture those areas.

It seems in closed loop the hiccup is the car going in and out of closed loop (at least that is what it looks like) but there may be more to it.

GruvyTune

Can you people who are TUNED send me your ROM files. I want to compare. Let me know if you are dyno tuned or street tuned or both.

Send to this email since my hotmail is filling up:

groovy_toones@yahoo.com


Thanks!!
Torin

LEON

I hope someone can help you solve this problem by let's say..... next week!?!

JT

Okay, I was having the same problem as most of you with the hesitation. I was also having an intermittent stalling and engin won't start problem. All these problem started right after I installed the Hondata unit. Well, logical thinking lead me to believe the problem must have caused by the Hondata unit or tuning.

However, after much troubleshooting, I solved the stalling problem by traced it down to a poor connection on the knock sensor. After soldered the knock sensor wiring, no more stalling problem but the hesitation problem persists.

I then followed what Doug said to datalog a few driving session when the hesitation happens. I noticed during certain rpm when the car was hesitating, there were some crazy timing events recorded. I then started to troubleshoot ignition components by disabled the J&S with the same result. The next step was to remove the only add-on ignition component = MSD!!(6AL, cap, and coil). Guess what? problem solved! I suspected the problem might have caused by loose connection but decided not to keep the MSD componets.

When I was having the hesitation problem (it happens almost everyday), it felt like the MSD soft rev kicks in too early or just randomly kicking in. Hope this helps...

GruvyTune

the problem is not really a problem if you keep in open loop. and, if its well tuned, nothing is really sacrificed. I took my car out today and drove around and i hardly get that hesitation. then i went back to my datalog and my o2 sensor tracings look even WORSE!

Does anyone here have any good daalogs of a closed loop rom? Would you please exchange with me???? That would really help me sort this out a bit more. I know doug is looking into this but must have alot else going on. apparently a new rom version in the pipeline but i am not sure if this item was addressed.

torin

GruvyTune

Hah!
way ahead of you. I took out my MSD and went back to stock because i was blowing pocket programmers (3 so far). Only thing I was able to attribute that to was spikes coming through my power supplies. Well, i have a fourth on the way. In either case, my ignition is back to stock and i was surprised that acceleration was smoother (i think i fooled myself into thinking the msd was a great benefit?).

do you have your closed loop datalogs?

GruvyTune

~bump

Doesn't anyone have any datalogs they can send me???
I'm looking specifically for tuned cars running closed loop!

send to: groovy_toones@yahoo.com

thanks

Arturbo

Anymore info on this?

lucas569

actually art i recently removed my vortech fpr and added on an aem fpr and lowered the fp by 3-4 psi (cause im driving around w/ 440 cc's w/ no boost)
and the hesitation is about 95% gone, im guessing because of the bigger injectors the ignition was not able to ignite the fuel coming into the comb. chamber, this is just a guess but its very intiresting.

Trigun

what's your fuel pressure at now?

VaporTrail

today I tried the new techique from Doug on tuning the low throttle rpm maps. The part throttle stuff is pretty damn smooth, especially in closed loop. This is the sweetest off boost car I've done yet, and it wasn't even road tuned. Yeap, did it all on the dyno. It feels 99% perfect.

The_Head

So, do you recommend removing the MSD ignition? I have the SCI, blaster coil, etc.

dustin

Mine runs really smooth, except for that damn hesitation... It looks like it is doing weird things with the timing at the point of hesitation in my datalogs ...

VaporTrail

personally, I find it completely un needed. The only thing I like from MSD is their spark cut rev limiters

GruvyTune

i am working with Doug to figure out the hesitation problem in the gsr.
it appears thatthere are not enough data points in that MAP range. I have adapted an H22a map for use in the p72 gsr. I am fine tuning it tomorrow.

VaporTrail

one thing that might help is moving up the threshold point for the closed loop/open loop crossover.

Also, the new tech page up on Hondata might help.

http://hondata.com/techinjectorsizing.html

It made this new base map I made for a P75 JRSC a piece of cake.

GruvyTune

I thought that may be the issue but the hesitation happens in open or closed loop and I have it set to 790mbar absolute manifold pressure which is way above the 350mbar level where the hesitation occurs.

CovertFI

i have the same hesitation problem, but i am using a fpr, not hondata. every time i feel it going on i look at my a/f ratio gauge and it is lean then goes green and i am fine.

HXMan

I found the cause of my hesitation. When messing with my wiring of my O2 sensors, I didn't connect the ground from the O2 sensor signal to anything. I got the same problem of hesitation with a stock P72 as I got with my hondata setup. Once I wired the ground, problem went away.

*Note* This probably will only work for me, my wiring is pretty messed up. If you want, check that your ground is ok for the primary O2 sensor.