v4lu3s

I run an s300 on an 89 crx. Street tuned. Recently noticed stuttering. Monitoring sensors i see TPS % changing on its own while driving. I turn the engine off and TPS is rock solid.

Tb is from an Integra, the tps has one cracked ear. I'm going to reflash the program. Should tps be replaced as well or should a look for something else.

OneBadTurboCRV

Take a datalog and pull up the sensors tab. Watch for voltage fluctuations. Use a DMM or even datalog (worst case) and very slowly increase throttle angle. Watch for any blips or dead spots in the TPS output.

You may need to take voltage readings from the TPS input (5v) reference voltage. I actually had that atmospheric sensor go bad on the passenger kick panel and I lost power to the TPS on a EF of mine. It definitely doesn't sound like your issue, but who knows.. just sharing my weird experience.

If you don't feel like troubleshooting, just throw a $30 sensor at it and see what happens. They can definitely fail or even come bad right out of the box. From the sounds of it, yours had previously been shocked in some way anyways.

v4lu3s

I'm too cheap to throw parts and money. Right now i have only been looking on the android app and seeing (while driving) TPS % rapidly fluctuate while I'm cruising at 7 to 25 % range, it will vary about 15% which causes AFR to rapidly fluctuate and stuttering. With the engine off it cycles smoothly with no variation.
I will definitely hook up the laptop and look more closely. I have read about old Honda tps's having dead spots due to wear and age and only acting up while subjected to engine vibrating while running and driving. I would rather confirm than buy parts until it stops...

v4lu3s

Well everything looked good so I went and re-uploaded the program. The 48 mile drive home was flawless...guess it was just software.

OneBadTurboCRV

Yeah, there are definitely glitches in SManager / S300 from time to time even though they never get talked about... I have learned to just upload the tune multiple times anymore. Well at least you figured out the issue and it was a free fix.

turbohatch96y7

iTrader: (15)

S300 has flaws?


Omgz

Omgz

Ongz

v4lu3s

Lol yeah I'm glad it wasn't parts since Christmas has me watching money closely.

S300 also throws o2 sensor codes coasting down in gear on cold days.

Unlike Crome though the engine runs, it idles evenly, and it doesnt randomly stall when going back to idle. And no-one from Hondata has ever failed to reply to tech or licensing emails like happens with Crome, or told me they don't want my business like Neptune....

And considering i have put nearly 30k miles on the street with only the o2 code and this tps misread I'm pretty happy with decent power and 33mpg combined on mild cam and compression while driving like an *******.

spAdam

iTrader: (1)

Sounds like a wiring issue to me. Are you using an ECU jumper harness? New custom harness? 25 year old factory rats nest? Any combination of more than one of those three?

Plug in your laptop, key on, and start jiggling wires around while watching your outputs. I'm not 100% convinced that you've found your problem yet (it might just be dormant).

v4lu3s

Original harness, though when I purchased the car I took the harness out and cleaned as well as re-wrapped most of it (I have built swap harnesses for almost 15 years, the hardest being an MPFI engine wired into a 78 Civic automatic). When I had it apart I cleaned all terminals, soldered/heatshrinked in repairs where there was heat damaged wiring (coolant sensors under the distributor) and replaced or extended plugs to better reach the new sensor locations as needed. That still does not preclude something else going on there of course.

I do have a jumper harness, however it was purchased from a reputable seller/brand (Tom at Lightning Motorsports). Still could be a problem, but have not had one in the 12 years I have bought from him...but there can always be a first.

After several uploads and tweaking of the map I did not see any fluctuation on the 50 mile drive home, however later during the day while moving only with the engine running I did have a few barely noticeable stumbles (had both the laptop logging to touch afr with a new header and the android app monitoring sensors) and saw a fluctuation of about 1-3% in throttle angle. So I suspect you are probably right that there is more to it.

I might swap the original TPS from the original throttle body in, the TB on there now is a junkyard one that has obviously had the tps replaced due to the damage to it externally.

spAdam

iTrader: (1)

I only asked because I had a similar issue (TPS & MAP fluctuations) that ended up being loose-ish pins in the adapter harness at the ecu side. I replaced the knockoff ecu plugs shells with originals that I scavenged from the junk yard and my issues went away.

Keep in mind, when looking at the data, that you don't have perfect resolution in your logs. If Hondata is using an 8-bit number for their 5V signals (they most likely are), you get 256 discrete numbers, each one is 5V / 256 = .02V or 100% / 256 = .39%. If you're right on the edge of one step or another it might look like more jumping than it really is.

v4lu3s

The resolution makes sense Original fluctuation was ranging from 8 to 15% most of the time which was causing wild AFR changes (11 to 17 in less than a second). Now it is down to to less than 2%...the throttle angle range it occurs in is also where freeway and side street cruising occurs which could lend itself to a worn spot on the potentiometer leading to the poor resolution...

SVE ECU0800 OBD0 to OBD1 Conversion harness for 88-91 Honda Civic - CRX is the harness I am using, at work tomorrow I will definitely pull it out and take a look to make sure pins are still snug. I have used these harnesses about a dozen times with no issues but anything electrical can fail.