That old Idle problem... P28/B18C1

hybridsol · Post by **hybridsol** » Sun Aug 25, 2002 10:23 am

OK, I've got the problems.

This one I'll post about the idle..

'93 Del Sol Si with '00 B18C1 with: Skunk 2 intake and ported head, stock TB, 440cc RC injectors @ 55 psi, I/H/E, Alum Flywheel, P28 ECU (original) sent to Payne Technologies for Stage 4 (not running boost yet)

Let me first say the car runs GREAT at any point except at idle, and even then it does run good sometimes. It seems to run worse when hot.

I'm going to try my best to explain the problems...

**Idle**

Problem: inconsistent idle speed- bouncing, steady, wrong idle speed, low idle speed, high idle speed, etc....

What I've done:
Adjusted TPS to zero voltage
Adjusted idle screw per Helms manual
Adjusted fuel at idle speed to read near stoch or rich (per "Injector sizing")
Adjusted timing (on map) so it does not vary around idle speed
Adjusted speed to 800 RPM
Adjusted idle duty to ++ (two clicks plus- it was more stable than minus)
Performed IAC valve check per Helms manual (OK)
Replaced the PCV Valve

Results/Problems
Sometimes the idle is very good, however, sometimes it is not... the idle starts out high, then gradually drops, then drops again- almost like someone threw a switch- and the idle turns to shit. I used to have the car actually stall until it was warmed up during this time until I changed the idle duty setting. I can press on the gas and make the car idle at the proper RPM . With the lights on (at night) the idle will be good or bounces between 1000-1200 (random?).

I have the advance at the distributor set at 20 deg. In the map, the idle advance is set to 24 deg. Yea, I know it's mucho advance, but it's the smoothest at this level. I tried all kinds of other settings, but they either:

1) had idle sumble coming off of a throttle blip

2) idled at very low rpm's (like 500)

Right now the car idles good, except when te lights are on, the I get the 1000-1200 RPM bounce. From a vacuum gauge, I can see the IAC valve trying to contol, but it don't work.

Post by **Hondata** » Sun Aug 25, 2002 9:35 pm

What TPS voltage? It should be 0.45 - 0.50

hybridsol · Post by **hybridsol** » Mon Aug 26, 2002 7:44 pm

TPS voltage is 0.45V per Hondalogger- sorry I should have said "I set the throttle to zero using the volage from the TPS"

I think ther might be something wrong with my TB. I got the engine from a wrecked integra... and the TPS sensor had to be repalced from a doner car, but it reads OK on the logger. I can upload datalogs to my web page and post the links here if anyone wants to see them...

I can push on the throttle plate linkage (to close it more) with my finger and the car almost stalls, like the throttle plate isn't sitting right or something... I have already completely dissassembled and cleaned, then re-assembled both the TB and the IAC valve... but I didn't see anything wrong or bent or anything.

I don't know why this is happening, I put 310 injectors in my friends '95 GSR w/ Skunk 2 intake- we used the STOCK map adjusted for the new injectors- no problems at idle at all, but he's using the P72 ECU.

Sean

pills_PMD · Post by **pills_PMD** » Mon Aug 26, 2002 8:41 pm

i've heard alot of people having this problem when running a b series engine from a p28... especially the ones coming from the michigan area... mine has this same problem

Sonny · Post by **Sonny** » Wed Aug 28, 2002 1:46 pm

Use HondaLogger and see what your Target Idle says. Make changes to the target idle using ROM Editor and start the car with the new program. Does the change make a difference in HondaLogger?

Sonny

hybridsol · Post by **hybridsol** » Wed Aug 28, 2002 10:17 pm

What? "Target Idle" doesn't appear in my Hondalogger software (rev 2.1) on the sensor page. Was there an update?

Anyway, tonight I spent 3 hours trying to tune this out. I'm going to try my friends Stage 3 P72 ECU to see if that helps, I'm also thinking I might have a bad injector...

What I did tonight:
Remove TB and clean
Remove IAC valve and clean
Inspect TPS
Remove idle screw and clean
Re-assemble everything
Set TPS voltage to 0.47V (0% throttle)
Set base timing to 16 deg (stock setting)
Removed closed loop O2
Set the non IAC idle to 480 RPM
Set the ROM idle to 800
Set the map timing at idle to 18 deg
Tried every "duty cycle" setting on idle control in rom editor
Changed settings on idle speed (700 to 900)

Results:
Idle is good after starting, then goes to 600-650 (very rough) with lights off
Idle is 820 and smoother with lights on, but not like stock.
Idle is 780 or so when fan kicks on

Juging from the rough idle and the high HC reading I got, I either have a misfire, bad injector(s), or funky mojo. I don't have an aftermarket ignition system, but I do have Magnacore wires, a new cap and rotor, an platinum spark plugs. I bought the injectors used, but they were supposed to be unused (RC/Lucas 440cc's). I'm going to try new plugs, and send out my injectors if the P72 ECU swap doesn't work. I'll post back my results

hybridsol · Post by **hybridsol** » Wed Aug 28, 2002 10:30 pm

Just found the 2.5 update. Ok so I'm slow. I don't know why I'm using the 2.1 version.

QUICKSILVER RACING · Post by **QUICKSILVER RACING** » Thu Aug 29, 2002 2:19 am

[quote="hybridsol"]What? "Target Idle" doesn't appear in my Hondalogger software (rev 2.1) on the sensor page. Was there an update?

You need a wideband O2 and retune your maps. You need to get hold of a HC tester.

TorinF · Post by **TorinF** » Thu Aug 29, 2002 5:36 pm

i just put a type r tb on my skunk2 manifold. i run a p28 based rom in my p72 ecu. i had no idle probs before and now, i have my idle drop to 625 whenever i stop with no load on the engine. i have my idle set in the rom to 750 and before it used to be dead on. now, i find my target idle actually fluctuates down in hondalogger to low 600s. Why would it do that? I increased the IAC duty cycle a little but that didn't solve anything.

torin

hybridsol · Post by **hybridsol** » Thu Aug 29, 2002 10:28 pm

Well...

Tonight I had a little "test" night... I have an emulator, stage 4, a wide band O2 sensor, P28 ECU (stage 4), P72 ECU (OBD1; Stage 3+boost) and tried different settings on my engine. (skunk 2 intake, RC 440 cc injectors, stock cams, timing set 16 deg TDC, TPS set to 0.47V)...

Test: P28 ECU- set idle speed and duty cycle to various settings, open loop
Result: the Target Idle speed is ALWAYS 669 RPM with the lights off and 800 rpm with the lights on. The idle speed setting had no effect. The duty cycle seemed to work (faster/slower reaction) A/F~14.9

Test: P72 ECU - set idle speed to 750, open loop
Result: Target idle speed stayed at 750 , 800 with lights on. good idle too. A/F~14.5 to 14.0

Test: P72 ECU- set idle speed to 750, closed loop
Result: Target idle speed stayed at 750 , 800 with lights on. Idle became very choppy with injector duration below 1.5 ms. A/F~ 15:1

Test: P28 ECU- set idle speed to 800, open loop, removed IAT sensor and placed in cup of cold water
Result: IAT dropped to 65 deg F. No change in Target idle speed.

Test: P28 ECU- set idle speed to 800, closed loop.
Result: Target idle speed stayed at 669 , 800 with lights on. Idle became very choppy with injector duration below 1.5 ms A/F 16.0- 14.0

Test: P28 ECU- set idle speed to 800, open loop. Drive test
Result: Target idle speed stayed at 669 , 800 with lights on. When the purge valve opened up, the idle began to bounce(with the lights on)

What I'm going to do:
1) Send my injectors back to RC to have them calibrated
2) Keep posting about this problem. At this point in time I'm not real
happy :evil: . I shelled out $$$ for the stage 4 system, and I was told it would be no problem on a B18C with Lucas 440cc injectors. If an injetor(s) is bad, then fine. But why the 669 RPM idle? I'll have to put my stock inectors back in... which means changing the plugs... again.

I have datalogs for all of these situations.
Sean

QUICKSILVER RACING · Post by **QUICKSILVER RACING** » Fri Aug 30, 2002 12:58 am

Have you read this?

http://www.hondata.com/techinjectorsizing.html

By wide band O2, Do you mean FJO or motec. You haven't mentioned much about O2 readings.

Also you could datalog A/F ratio readings. The car might be lean at idle vacuums. the reason for low idle.

hybridsol · Post by **hybridsol** » Fri Aug 30, 2002 10:58 pm

Yes, I did read the post about increasing the injector pulsewidth. It doesn't work at idle, because normally the CAR IS IN FREAKING CLOSED LOOP. On open loop, the car runs rich. Any attempts to lean it out drops the injectors below 1.5ms and the idle flakes out... of course the 669 RPM target idle doesn't help that either...

I had the car re-tested after all my tweaking (above) and it read HC of 350 ppm, which is much better but still failed. I got a 30 day extension....

...and YES I have a wideband 5- wire UEGO sensor from NTK. It works VERY well.

Sean

LOwrestling2001 · Post by **LOwrestling2001** » Mon Sep 02, 2002 10:42 pm

i am running into the same problem you are with my SCed GSR. so exactly what steps would i take to go about solving this? i will need to have a friend or someone with 4b do it since i only have 2b.

Rex · Post by **Rex** » Wed Sep 11, 2002 4:16 pm

I've been wondering, if one is not using all the potential of the 440's anyway, whether things would work better with smaller injectors as far as all the idle weirdness.

Maybe it has nothing to do with nothing, though at idle, I imagine (by comparison to my stock injectors) there's a big ass hole which my car is trying to control the tinest flow of fuel.

Okay, maybe I have the concept wrong, but suppose you're trying to water a houseplant with the same trickle of water through a firehose. It's at the very least awkward, and about the only way you could do it is to hold the hose over the plant and let the water drip down, whereas with the smaller hose, you can control flow much better, and even create a spray pattern possibly.

Okay, someone tell me if I'm way off base.

Also, I'm thinking the worse thing big horsepower dragsters do, is try to idle properly ( though that could just be cams)

hybridsol · Post by **hybridsol** » Wed Sep 11, 2002 10:05 pm

You are absolutely correct. Most pintle style (think of a clicker style pen) injectors become unstable below 2.0 ms. The mechanics of the injector just don't allow the fast shutoff.

I'm not sure if I said it before, but I worked on a Greddy turbo GSR with 310 injectors. The car ran and idled like stock, but the Hp is limited.

However, Lucas style injectors have a disk that moves up and down (think sink drain stopper) very rapidly. 1.0ms stability is not uncommon. At this low flow rate, even larger injectors like 440cc and 580cc can sustain an acceptable idle.

**update**
1. Installed the stock injectors
2. replaced the o2 sensor
3. Reset the IAC control to stock (center) and left the target idle at 750

Both seemd to help the idle was very smooth on open loop, and exibited no cycling in closed loop. I have some ignition upgrades on the way as well. The ECU still has a target idle of 669 rpm, which doesn't seem to work real well at times. I still get an intermittent idle bounce, but I'm suspecting somthing it's related to the brake system. I'm going to install a new IAC valve, and upgrade the ignition system to aftermarket CD multi-spark style.

Sean