So recently I just got done putting my car back together, and I did the following:

replaced engine with a JDM model engine
auto to manual transmission
Power FC and datalogit

I have the following mods:

downpipe
midpipe
intake
catback
TB coolant bypass (yes, I adjusted the fast idle cam thing)
full non-sequential
Profec B Boost controller (set at 10psi)
HKS turbo timer
Banzai Block off plates

So, I hook up the PFC, set the AAS screw to a half turn out from all the way in, start the car, let it idle with nothing for 10 minutes, then 10 minutes with the defrost, and then 10 minutes with everything on. The idle hunts from about 800-2000rpms. Turning the AAS in didn't so anything.

So I then take it for a drive, and now get a consistent high idle of about 2300rpms. I check the throttle position sensor voltages and the VTA2 was out of range, so I re-adjusted it until it was in spec. Nothing changes.

So I thought maybe I have some horrid vacuum leak, so I begin spraying carb cleaner in various areas hoping to find something, and found nothing I also checked all my vacuum hoses and found nothing.

So I drove it around again, and it felt like the throttle was applied even without touching the gas pedal, and if given a very light press on the gas pedal that would go away.

So I park it again and with the throttle slightly applied the car would stop idling at about 2300 and start hunting between 1300 and 1900 revs. So I adjust the throttle cable to where with no throttle applied it does the hunting between 1300 and 1900 revs.

But, after blipping the throttle a few times, it would do the 1300-1900 hunt, then hunt between 1900-2100, then back to the 1300-1900 hunt, then stumble and die. Right after the motor died there was this electrical buzzing noise that lasted for a few seconds, and it sounded like it was coming from the ISC.

So I set all the idle settings through datalogit to 0, so that it doesn't use the ISC. This doesn't change anything.

So at this point I am completely confused, and I am out of ideas. Other than the idle and that light throttle issue, everything works 100 percent. I went through and searched on here and most of the time it seems the ISC is the issue, but from what I can tell it isn't affecting anything. Both the throttle adjust screw are fully backed out.

So my question is: Why isn't my car idling properly, and how can I fix it?

 

Unpug the ISC and see if the idle drops.

TB coolant bypass (yes, I adjusted the fast idle cam thing)

Did you just turn the setting screw all the way in? Push down on the level when the car is idling, to see if you have it adjusted enough.

 

So I unplugged the ISC and immediately the revs dropped down to around 1500 or so. After it became fully warmed up, it started to idle around 1100 or so, but after a couple blips of the throttle, it started to hunt from 1200 to 1500, and hasn't stopped doing it.

My current map has the idle settings at 800, 900, and 1000, the deceleration fuel recovery settings at 1250, 1250, and 1350, and all the function selects turned off. Other than that, nothing else has been changed.

The setting screw has been turned in all the way, and playing with the level doesn't do anything.

 

post a log of the problem. Under the monitor window, select "Advance" and "Aux A/D." Make sure your wideband is hooked into your Datalogit and that the AFR display in the software matches the display on your AFR gauge.

 

If you have backed every throttle screw off and you still have a high pulsing idle you either did not adjust the TB coolant cam screw properly or you have a huge vacuum leak somewhere else in the intake between the TB and block.

What exactly did you do to adjust the fast idle cam? Some use safety wire, others remove the spring on the adjustment screw, then screw it all the way in. I remove the assembly completely, but that is beyond the point on this thread.

 

I screwed the adjuster screw all the way in. Attached is a picture how it is on my car.

When started cold, the car initially idles at ~1000 and works its way up to about 1500. Then as soon as the temp. reading on the PFC reaches 79 degrees it starts hunting from 1000-1500.

Any other ideas before I tear off the UIM and re seal all my block off plates and check everywhere for a leak?

 

Okay so after driving it around, I noticed that it was very sputtery at very light throttle inputs, and every time I revved it or put the clutch in when running anything over 1600rpms, it would stumble and die.

I then set the fuel recovery settings all to 1500, and now it just idles at 1600, and still sputter when given very light throttle input. When I lower the fuel recovery settings, it starts to begin hunting from 1000-1500 again.

 

If your throttle plates are all closing completly then air is getting in somewhere else. You have gone N/S, you have capped off all the unused nipples on the UIM, correct? Did you use a coat of RTV or gaskets under the block off plates?

 

I assume that the air pump is still installed along with the air control valve since you did not mention removing it.

Did you run a RECALC with a DL, do you have O2 feedback on or off, do you still have an O2 sensor; even with the hot wax rod all the way in, if you push down on the lever when the engine is cold, do the throttle plates close more; if you have a DL - did you set the cold start retard to 0 for 60C?

 

I forgot to to mention that yes, the air pump has been disabled, and I do not have an ACV.

I have not ran a recalc with my DL.

O2 feedback is not checked

I still have an O2 sensor

I have not tried pushing the lever when the engine is cold. I will try that tomorrow morning.

I have not set the cold start retard to 0.



All of the unused nipples have been capped off.

I used black RTV sealant on all but one of the plates. I used the orange RTV on that one. If the problem isn't alleviated by this weekend I will pull off the plates and re-seal them just to be safe.

 

If you put sealant on the block off plates, then that is not the problem.

Did you ever have your primary injector rail out? There are o-ring seals between the rail and the block, that people have a tendency to forget.

Take the intake elbow off and verify that the throttle plates are closing all the way.

 

Verify that both TPS voltages are in normal range from idle position through fully opened position.

 

What is it suppose to be?
I having issue with idle but not like his, I can't lower it to 1000 rpm before I can lower it to 700 without any issues but after this thread I know my problem like both of u mention to use silicone rtv on the aws and db tb block off plates I just use new gasket or well I guess u learn soemthing new.
Khris

 

You know I had a similar issue and it actually turned out to be my cruise control wire actually got stuck keeping my throttle high and it kept the lower throttle plates slightly open causing a bouncing idle. Just something to check.

 

In the field service manual, it is listed!

VTA1: closed 0.10 to 0.70; open 4.2 to 4.6.
VTA2: closed 0.75 to 1.25; open 4.8 to 5.0.

 

Thanks I haev to admit I was kinda lazy to look it up, anyway I did found my problem of my high idling and it was ASW and It's pipe block of plates I put new faskted thingking it will seal better guess not anyway I put the rtv sealant on it and put everything back together and now it purs at 900 rpm.
Khris

 

The TPS voltages were good, however, I do believe I broke something important today autocrossing it, because after I got done with my last run, the car now idles terribly at 700 or so revs, with lots of sputtering under light to medium throttle inputs, and at WOT. If in neutral and you rev it up it revs fine. There is also blue smoke coming from the exhaust, but I'm fairly certain that is the turbos, as they have or 80k on them.

And I disconnected the cruise cable, so that can't be it.

I never took the injector rail out.

 

Might be worth checking the hose for your map sensor, might have come off.

 

You were right on the money, sir. I can't believe no one noticed that at the track lol.

 

So I've been driving it with the high idle, thinking about the possible issues. Could it be a TPS problem, even though the voltages read fine? The TPS is just a variable resistor right? So if something was up, it would make the largest difference at idle and light throttle, which is exactly when I'm having my problems. Also, the resistance would increase as the temperature increases, which would cause the voltage to increase (assuming the current is constant, which I believe it is), which would cause the idle to increase, which would explain why my idle increases as the temp goes up.

So the car idles at 1000-1100 when cold, so I'm thinking maybe I should get the cold voltage readings, warm the car up, and then adjust the TPS to those voltages?

Or maybe I have the MAP sensor hose hooked into the wrong nipple? Cause when my MAP hose popped off I was idling around 650-750.

I guess I'm just sort of thinking out loud here, but I know it can't be a vacuum issue, cause the very first time I had the car running with the power FC, I was able to get the car to idle fine, but after some hard driving, it started bouncing.

Maybe I should just do the idle learn process again, and see if that fixes it?

 

So I start my car up, and am letting it warm up. And then, all of a sudden it starts to idle really crappy, with lots of sputtering under light throttle loads, and under WOT driving I was getting violent bucking at around 4000 rpms. I switched out the TPS, and that didn't change anything. The MAP sensor was connected the entire time so that can't be it.

I'm now thinking I might have a faulty injector, so when I get some free time I'm going to swap out the injector rails with the ones on my other motor. The motor I have in it now did sit for several months, as it was one of those "lower mileage JDM motors."

Anyone have any ideas?

 

Do a compression check.

 

While on the topic of idle issues... I have a problem with my 93 rex its fairly standard apart from stragiht through exhaust and 2 air filters... When I start it up its grand.. But every1 now and then wen i rev it.. It seems to splutter and back fire or it mite rev then you could lift off and rev again and it would splutter.. Can someone help me please??

 

I went to go compression test it a little while ago, but was unable to do so because I was unable to warm it up.

I started it up and it ran for about a minute or two, and the idle got progressively lower and lower, until finally it just died. After several tries I was unable to crank it over. It seemed like it was flooded or something. However when it was idling at 600-700 rpms, it was pulling about 15mmHg or so of vacuum, and when it finally stalled out, the last reading for injector duty cycle on the Power FC was around 10%.

 

Compression is greater than 90psi on both rotors, so I guess I can rule that out. All the injectors showed about 13.7 ohms of resistance, so I don't think those are the problem. It sounds like a bridgeport at idle. It took several cranks took get the car started, and once it started, it puffed a cloud of smoke. Any ideas?