Yet another "part throttle hesitation" thread

[jun1or]

At the title states, I haven't been able to get rid of this part throttle hesitation that happens only at less than 1% TPS. Happened after I installed a skunk2 Intake Manifold. I'm sure it's something I can easily fix if I tinker more. Flame on!

Notice Hesitation in datalog at 3.008s and 9.855s where injector duration is 0ms for about one full second. I'm sure it's something simple, but I haven't figured it out yet.

TPS shows 0% at that point, but I assure it is not 0, it's 0.4%. I believe the TPS sensor is good, but datalog cannot pickup that low of TPS angle. I could be wrong and maybe I do have bad TPS, but it works perfect otherwise.

What I've tried:
- Scaled TPS min/max angles on TPS tab.
- Adjusted idle duty cycle down on idle tab.

Thanks in advance,

Mike

[jun1or]

I should follow the rules when posting problems!

When reporting any s300 problems, please include:

- the calibration (as an attachment)
- a datalog of a problem (as an attachment)
- what sort of vehicle you have
- what sort of ECU you are using
- anything about the car which has been modified from stock which may affect the ECU (don't include what sort of rims you have nor stereo etc).
- a specific description of the problem


1991 CRX Si, 1994 B18c1, P06 ECU, S300
I/H/E crower stg 1 cams, skunk2 IM

[Hondata]

Three things I would try:
- Lower the TPS overrun cut off from 1% to 0.5%
- Smooth out the ignition timing on the low speed cam below 2000 rpm in the first 5 columns. Sometimes this alone causes the car to jerk back and forward, especially in first gear.
- Check and re-scale your TPS - it seems very low throughout the whole datalog, and I see it going to -0.3%.

A trick with the TPS is to create a value display, then edit the 'ValueFormat' to #0.0 This way you can see the TPS to 1 decimal place in the datalog.

[jun1or]

Three things I would try:
- Lower the TPS overrun cut off from 1% to 0.5%
- Smooth out the ignition timing on the low speed cam below 2000 rpm in the first 5 columns. Sometimes this alone causes the car to jerk back and forward, especially in first gear.
- Check and re-scale your TPS - it seems very low throughout the whole datalog, and I see it going to -0.3%.

A trick with the TPS is to create a value display, then edit the 'ValueFormat' to #0.0 This way you can see the TPS to 1 decimal place in the datalog.

Very good info. I'll try these methods and post results.

Thank you.

Mike

[jun1or]

Three things I would try:
- Lower the TPS overrun cut off from 1% to 0.5%
- Smooth out the ignition timing on the low speed cam below 2000 rpm in the first 5 columns. Sometimes this alone causes the car to jerk back and forward, especially in first gear.
- Check and re-scale your TPS - it seems very low throughout the whole datalog, and I see it going to -0.3%.

A trick with the TPS is to create a value display, then edit the 'ValueFormat' to #0.0 This way you can see the TPS to 1 decimal place in the datalog.

Problem SOLVED, thank you for your suggestions.

The solution was to rescale my TPS. I had marked 0.8% as the minimum, when actuality it needed to be 0.4%. If you click read value a bunch of times, once in a while it will move up or down. In this case I needed to capture the smallest value.

Thanks again,

Mike

[jun1or]

New problem and I just hate making new threads. I don't want God to kill more kittens, plus maybe Hondata subscribed to this thread :)

Short but sweet, here goes: I let off the throttle under normal part throttle driving conditions and about exactly 0.5 seconds later, car jerks forward a bit as if I blipped the throttle for a split-second. Car jolts a bit even though TPS is zero. Haven't figured it out yet.

Please ignore the wideband values in this datalog, my sensor (or ground wiring) is bad. Again IGNORE lambda values please.

Notice at exactly 3seconds, I have 0%TPS and still injector duration. Is this normal, or is this my problem?

TIA,

Mike

[Spunkster]

it may be your overrun cutoff values

http://www.hondata.com/help/smanager/tp ... uel+cutoff

[jun1or]

it may be your overrun cutoff values

http://www.hondata.com/help/smanager/tp ... uel+cutoff

Hey Spunkster, that was quick!

I thought so too! So I changed from 1 to .5 and back to 1%

I'll play around with a bit more. Not sure which direction to go...

[jun1or]

it may be your overrun cutoff values

http://www.hondata.com/help/smanager/tp ... uel+cutoff

That would be another beer I owe you.

Changed "Overrun fuel cutoff" duration from 600ms to 200ms, now it's smooth as ever. (0.5% for the throttle percentage)

Well I hope my ramblings help others, should they stumble upon this nit-picky stuff.

Mike

[V-Spec race development]

Will this apply to backfiring when you let off the throttle? I was street tuning the other night and noticed that it backfire when i let off the throttle. any help on this? thanks in advance.

[Spunkster]

It may, but that all depends on why it is back firing.

[V-Spec race development]

Spunkster, thank you for the respond. Do you have an idea why does it backfire when you closed the throttle or in decelaration? I never have an issue like this before in all the cars I tuned except for this particular car/tune.