Joshm88

Right, I wouldn't normally post up for help on a forum I tend not to be too active on but I've tried ek9.org and others to no avail.

Details worth mentioning:

EJ8 Civic coupe (UK model)
J's Racing 1.8 stroked B16B (12.5 compression)
J's Racing ECU (VTEC = 5500rpm, idle 1100rpm, cold start up 1500rpm)
J's Racing 68mm TB with new TPS sensor and MAP sensor
Brand new OEM thermostat
Buddyclub low temp fan switch


The issue I'm having:

On cold start up the car idles high at about 1600rpm, and after being driven the revs hover around 2000rpm when the car comes to a stand still before dropping back down to 1600rpm. Even when the car reaches temp, the idle never drops from 1600rpm, and the car seems to be running fairly rich (could be due to the ECU deliberately over-fuelling).

If I turn the engine off and back on once it's reached temp, it sometimes struggles to start - as if it's been flooded - but other times it starts perfectly. Idle will be around 1100-1200rpm, sometimes 1300rpm, there is very little consistency considering it should be 1100rpm bang on.

At no point does VTEC engage, the engine will rev all the way the redline but no VTEC. The idle issue has been an ongoing problem since I dropped the motor in, I attributed it to IACV as I was experiencing a lot of rev hunting, so I replaced it. Rev hunting is now gone, but with this apparent temperature related idle issue remaining? VTEC used to work fine, it then became intermittent, and now works once in a blue moon, it worked once in the past 3 months?! (I restarted the car after putting petrol in, idle hit 1100rpm bang on, and VTEC engaged, next day....same old story, no VTEC).

I am really struggling with this now as I am running out of ideas of what's causing it.

So far I have:

Replaced IACV
Replaced and checked Coolant Temp Sensor (the ECU one, not the dash one)
Swapped ECU with oem EK9 ECU in full working order
Replaced OEM thermostat
Fitted low temp Buddyclub fan switch
Checked for Vacuum leaks
Replaced the Distributor (whole) with one known to be working
Checked ECU for CEL codes (only get code for Electronic Load Distributor, it's still wired into the loom but EJ8 does not have ELD).
Removed, checked and cleaned VTEC solenoid, nothing but oil in there! VTEC solenoid engages when fed from the battery, so it is working.
Fitted HKS Circle Earth kit
Checked ECU pin out voltages for various sensors with multimeter


Nothing has made a difference. It's also worth noting since the engine is JDM it has no FITV.

I've not seen anyone else experience this problem in any of the threads I've read, so any ideas?! All help appreciated.

TaffetaEj6

any cel's when the problem is present? Damn seems like you've done alot to fix the situation. Before i read you replaced iacv i was gonna say clean that possibly for idle issue. As far as no vtec, check wiring from solonoid and other wiring leading to harness that has to do w/ vtec. Oh and no more redlining w/ no vtec. Your pistons will hate you

Joshm88

Yeh don't worry I try to keep it well below crossover rpm! ELD CEL is always present, when the car is cold and warm, and no other CEL's appear. I've checked vtec solenoid wiring, thinking of changing the entire loom to be honest as so far I've come across nothing.

What sensors does VTEC depend on? As far as I understand it, it reads the oil pressure off the oil pressure switch on the back of the block, and engine coolant temperature off the CTS underneath the solenoid assembly? Is there anything else?

Also, I unplugged the CTS (ECU sensor not dash) started the car when cold, it started fine but idled fairly high around 1800-2000rpm. Did the same thing with the car up to temp and it wouldn't fire, just flooded the engine. This is normal right?

Going to swap my throttle body with an EK9 one tomorrow, even though the TPS and MAP sensors are brand new, the J's TB is a bit sticky. Can't see it being related to my issue but I'm starting to try anything and everything!

I'm running Hondata intake manifold gasket, still using stock intake manifold bolts, but like I said no vacuum leaks anyway so can't see that being related either.

Former User

Is the throttle cable adjusted too tightly? It should have as much as 1/2" of slack.

Have you tried to adjust the idle speed?

If you unplug the IACV, what happens to the idle speed?

If you remove the air intake system, does blocking the port leading to the IACV with your finger substantially lower the idle speed?

Did you properly calibrate the TPS?

frankenghia

sounds like the tps is out of adjustment/calibration.

Joshm88

Throttle cable is fine, definitely 1/2" of play in the cable when the butterfly is shut.

I have tried to adjust idle speed using the screw on the TB, made it slightly lower but not substantially. Didn't affect the cold start issue, no VTEC and idle is still inconsistent - sometimes 1100, 1200 or 1300rpm after restarting when up to temp.

Unplugged the IACV whilst running and the car died instantly.

Also unplugged the CTS once the car was warm, tried to restart and the engine just flooded. I've checked the resistance in the CTS itself on cold start up and it reduces as the temp rises.

TPS voltage is fine 0.5V at idle, 4.8V WOT. The TPS came with the throttle body from J's as they come complete with MAP and TPS sensors, OEM units. Surely this means it does not need calibrating if the voltages are correct?

Removing the air intake tomorrow to check idle when blocking the IACV port, will update with results!

Former User

The two IACV tests I mentioned should tell you whether the ECU may be receiving sensor information that causes it to make the IACV increase or change the idle speed. The drop in idle speed after unplugging the IACV is consistent with this idea.

Have you tried bleeding the cooling system?

Is the ignition timing set to spec? You need to use a timing light to check.

Yes, the TPS is fine.

Former User

Did you follow the idle adjust procedure detailed in the service manual for your engine?

Isn't the spec idle speed around 700 rpm for your engine?

Joshm88

I am pretty sure that when adjusting the idle speed the IACV was not unplugged. My mechanic did this whilst I was at the garage troubleshooting the problem and picking up a new CTS. From reading up I've seen that you should get the car up to temp, then unplug the IACV, then adjust idle? (source: http://i639.photobucket.com/albums/u...cture_5764.jpg) However, I also read that Honda say unplugging the IACV typically causes the rpm to drop by around 400rpm but in some instances the car can die......which is a bit confusing?

Ignition timing was done at my local performance garage, I trust it was done correctly. I have however swapped the distributors over with one out of a friends EK9 today so I need to re-check the timing. I marked the distributor location as accurately as I could and made sure the rotor arms were in the same position.

How would ignition timing be causing my problem? Would this not only cause an issue if the timing was say a tooth out on the belt?

Haven't bled the coolant system yet, rad hose isn't pressurising. However I did notice that the reservoir level was a little low, and coolant was full only 100 miles ago? Can't find any leaks so I'm a bit unsure as to why that was, I've since topped it up. I was under the impression that an air lock or such in my coolant lines would only affect idle if I had a FITV? However it's something worth checking I will do it tomorrow!

Joshm88

Yes, spec idle speed is around 700rpm for the B16B, it is the J's Racing ECU that ups it to 1100rpm, I am pretty sure all JDM aftermarket ECU's up the idle to around 1000rpm.

Former User

The idle set procedure depends on the specific engine and ECU.

Changing the ignition timing will affect the idle speed. You can see this for yourself if you turn the distributor while the engine is idling.

Air trapped in the cooling system may cause the ECT sensor to misread the coolant temperature, which would obviously affect the idle speed. Is there white smoke in the exhaust or gas bubbles in the coolant?

Joshm88

I have noticed a bit of white smoke in the past, typically on cold start up when outside temperature has been low, or when it's been wet. I have a decat on the car, and thus attributed it to water/condensation in the exhaust, as after being driven the smoke disappears. Recently there has been no smoke at all. As for gas bubbles, I haven't noticed any. Would both of those not indicate a headgasket problem?

I checked the resistance in the ECT sensor as the engine was warming up from cold start, it appeared to be working correctly.

I will conduct the IACV tests you mentioned tomorrow along with bleeding my coolant and report back.

Thanks for all the help!

Former User

This does seem to be the case.

Yes

I agree. I was just saying that an air pocket in the cooling system could make a good ECT sensor misread coolant temperature, thereby causing idle problems.