Hondata

i too get this problem of the ecu wanting to lower the target idle to 650 when i have it set for 750. I set my fast idle screw as outlined to 450 with the iac unplugged and then no matter what i set the iac to it keeps idling down without any electrical load on the engine to 650 or so which is annoying. if i turn my heater fan on it goes up to 750 where it belongs.

any ideas??

Ok the latest....

Well I went, and again failed.
330 ppm on HC
1.2% CO (normal)

My engine is a year 2000 B18C1 with a [mild]ported head, I/H/E, and Skunk 2 intake.

New changes:
Stock injectors back in
Installed Crane Fireball HI-6 ignition and LX92 Coil. This thing rocks. MUCH better than MSD. Multiple spark below 3000RPM
New distr cap
New distr rotor
New iridum plugs
New IAC valve
New PVC valve
Stock fuel rail
Changed ROM to account for 240 cc injectors
New O2 sensor
Checked timing at stock setting.
Cam gears set to stock
Changed ROM to closed loop.
$735 total parts plus 2 days work after work.

It runs REAL smooth now (still at 669 RPM)... A/F gauge bounces between rich and lean at idle...

with the lights on, this brought the idle up to 800 RPM. Compression checks in at 200 psi. I'm going to take it to a shop to see if they can figure it out...

Sean

Anyone please feel free to give anything I could try to get it through? A new cat mabey?

but your o2 sensor should be keeping you relatively stoich and the cat is supposed to do the rest as far as meeting standards.

So, like I'd replace the converter (but I don't have one to give you sorry)

Yea, that's what I was planning on doing... and...

I was going to take the car to a shop with a exhaust system analyzer (sp?)... the guy there said it could be many things, to much or too little air at idle, etc... but my engine decided not to live any longer and siezed up on the way home from work. I haven't opened her up yet (I will this weekend) but it's depressing to say the least....

I will end this thread now, as it serves no purpose for me. (selfish bastard aren't I?) BUT I will say that the Hondata system is a tremendously great product. I was able to solve many tuning issues and head scratchers along the way, not to mention the look of the guys at the track when I pulled out the laptop...

Conclusions:
1) Hondata is way awesome
2) There does seem to be a problem with 670 RPM idle with P28 ECU's. This will not effect anyone unless you are runnig 310+ injectors.
3) Turbo, NA, or SC, you need a wideband O2 to tune

Peace,
Sean

i have a 93 vx hatch with a 2000 b18c1 in it and im haveing the same problems. i have an bouncing idle that is really bad and some times when i start the car the idle jumps up to about 3 grand and doesnt come down. my tach doesnt work either we have check everything and i dont know what the hell i wrong. we havent messed with the timeing or anything like that we just put the engine in and started it up and it runs like shit. im starting to get to the point i just want to sell the damn thing but ive put to much time and money into this car to get out now. somebody please help before i push the car off a cliff and start over

Ahh.. well I'm back. I booted the B18C1 block I had (it was evil) in favor of a B20! Did the old B20 VTEC thang and am ready to rock...

I am still getting the "target idle" of 620-669 RPM after warm-up. Only now the car runs MUCH smoother with little or no bouncing. I must have had a compression problem agrivating the situation...

I used my base map and adjusted it for the larger displacement...

Lessons:
1. CHECK or REPLACE the PCV valve! It's evil and and does bad things
2. ANY vacuum leak will cause havoc with the idle
3. The AIR bypass screw needs to be adjusted if you have a cold air intake
4. Set the TPS sensor to read 0.45-0.47 VDC. DON'T BE LAZY
5. Air bubbles and coolant probelms will agrivate other idle probelms

Hondata- Any ROM mods for the P28 "targe idle" problem?

Sean

i had the same problem i posted a reply under "what do i do about this idle problem". it was the tps on the throttle body the whole time. now my car runs great after changing the throttle body out about 4 times we finally got one without a messed up tps sensor. now it idles perfect.

when you say messed up TPS... do you mean it did not function at all (no voltage reading)? the voltage was off?

To correct the "target idle" problem... Doug (from Hondata) sent me a rom that worked great! The idle stays at 800 PM with no problems. COOL! Now if I could just figure out my other problems....

Thanks Doug!

Sean

BTW- if anyone wants it to try, just e-mail me, or Doug, I guess...