Ok this is a complete shot in the dark... but does anyone in the santa monica area have free time this weekend and want to help me with an idle problem on my ZC rex.

Can't seem to figure out what the hell it is. It's probably a vacuum hose leak somewhere. I've done searches through this forum and found a lot of info but nothings helped so far. I've had it checked out by 2 or 3 mechanics but none of them were familiar with JDM engines and figured I screwed it up somehow during the swap.

Basically when the engine warms up (about 10 minutes after ignition) the idle starts to bounce. After a little drive time it will rev to 3000rpm up and down to almost shutoff and if it stabilizes sticks at 2500rpm or so.

Anyway if you've read this far maybe you can add some input. If you're feeling really generous and happen to live close by, please come help.

thanks

 

If you pay for my gas I'll drive my rex out there and try to lend a hand sunday/monday. I'm about 1 hour away and I'm off those days. Are you tossing any Check Engine Lights [ie code 7 map sensor] or anything like that? Try pulling the EAVC [back of manifold, has 1 sensor plug and 2 coolant lines running through it] and cleaning it out with some break cleaner, making sure the screen is free of any obstructions or debris. Check your vacuum lines and nipples on the mani to make sure anything with a vacuum is either plugged or has a hose. Mine did this after I had my manifold ported and I came to find out the manifold wasn't properly cleand and the metal shavings and gunk had collected in the EAVC and after cleaning much of the idle problem was fixed. - Darrell

 

Hey whutsup, I can give you $20 worth of gas. That's if you really want to drive this far. I'm reading a code 9, or No. 1 Cylinder Position. Not sure that means anything. I'll try pulling the back manifold tomorrow.

If you have absolutely nothing to do and want to lend a hand, please come on out. Otherwise thanks for the advice. I'll post the results as I go along.

thanks,
-rick

 

damn im away at school.....but i live in sm....well if its still bothering u by may 19th u can drop by my house and i will take a look at it

 

First remove the sensor, then the two coolant lines running to the bottom of the circled thing[I forgot the name at the moment...]. Loosen and remove the two 12mm bolts holding it to your manifold. Pull it out and inspect, more than likely there will be some sludge or carbon buildup on the screen and much more hidden inside. Spray the living crap out of the inside and the screen. Keep spraying until only clear fluid is spilling out then put it back on the manifold. Also, check your 02 sensors condition, if its quite old, go ahead and replace it. More than likely your in need of a new one. Check the butterfly valve inside your TB for build up. If its dirty it might be keeping the TB from closing completely. Clean it out with the carb cleaner or a rag with some gas on it. Check your spark plugs condition, should be nice and brown. Check your grounds, 1 on the thermostat, 1 on the clutch cable bracket on the trans, and the valve cover. Make sure they are making good contact. For the vacuums, you could actually just remove most of them since you can't smog your ZC in cali anyways. Here's a pic of that..



I even labeled them with colors so you can see where they are going, the purple one is just going back onto a plug on the map sensor. Also make sure your coolant temp sensor on the passenger side of the head, beneath the dizzy is functioning correctly. If all this looks good, your idle should be much better if not fixed. PM me if you need more help, - Darrell

 

the flat head screw on the throttle body kind of on the top turn it right to close left to open play around with that but it that doesnt work have the car started stick you finger in the throttle body and theres two holes in there right before the butterfly put your finger infront on them and see if its stops then you have a valve sticking open in the idle position sensor.. try them before ripping it all apart the sensor, it can be a bitch with the motor in the car..

 

Thanks for the help so far guys. I've played with the idle screw before. No help there. I also cleaned out the throttle flap. It didn't have much gunk and fortunately wasn't getting stuck open. Today I tried getting that back sensor off the rear of the throttle body and can't find my 12mm wrench. I'll go buy another one tomorrow along with some more carb cleaner.

What exactly does the coolant temp sensor have to do with the idle? The second mechanic I took the car too replaced the sensor and said it was low on coolant. I didn't understand what it had to do with engine idle.

Anyway, thanks so far. I'll post tomorrow after I get that sensor cleaned up a bit. (I took the old one off my SI engine and didn't see a screen. Is it inside the sensor?

 

phew okay I had a few drinks tonight so I'm gonna make this update short. I cleaned up the EACV sensor on Monday and drove the rex to work and back today. No real noticeable difference but I think the key to my problem is that the engine runs smoother when it is still cold. The warmer it is the higher the idle speed and the more dramatic the fluctuations. (It goes from 0 to 3000RPM in a matter of seconds and continues to cycle unless I throw it into gear.)

If anyone has an idea of something tangible it might be in terms of maybe a busted sensor or completely disconnected tube/shorted connector please add input. I am willing to try anything.

Once again Darrell, thanks for your help and pictures. I haven't checked the O2 sensor yet but I think I remember one of the mechanics from before checked it out. Honda Crx thanks as well. All input, continued and new, is appreciated.

 

LMAO!
had the same problems. unplug the plug from the IACV and swap it with the IAT (driver side of intake manifold) see if it works.... sometimes they get backwords and when block warms up it increase it.

try lowering your idle.... i did it and i thought car was gonna die... but then it ended up fixing it.

also, put a picture up here of your engine bay. might have vacuum lines in wrong(friend had that problem)

there are alot of things that could do it 0.o but IACV / IAT plugs can make it take a dump sometimes

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by godzilla4rilla &raquo;</TD></TR><TR><TD CLASS="quote">(It goes from 0 to 3000RPM in a matter of seconds and continues to cycle unless I throw it into gear.)</TD></TR></TABLE>

So when you put it into gear, the idle stays at 2500? What ECU are you using? Was it auto or 5spd? When you did your swap, did you have to do a MPFI swap? Was the car an Si/DX/HF? Is the ECU throwing any codes? Maybe 6 or 7, sounds like map sensor or TPS. - Darrell

 

Darrell, yeah the idle would stay high when in gear (up to 2k RPM) but I think because the driveshaft is engaged it goes back down. It's like I've got an automatic when it's in first because it wants to go even with my foot off the gas.

The shell is an Si, and I'm using the Si ECU. I've got a PG7 ECU but it seemed to run worse with it. The car has a manual Si transmission. It's still throwing a code 9, which I don't get. The spark plugs are pretty gunked up (charred and black even though I replaced them 1000 miles ago) and I think it's running very rich. I have a little oil leakage in two of the cylinders but a ran a vacuum test and compression test and the cylinders were all within spec, although on the low end of acceptable. I haven't added any aftermarket parts to her because she was going to be my daily driver.

I wish I could check the timing but I don't have the belt cover to reference any marks with. Anyone out there with some pictures of a ZC cover so I can eyeball it?

thanks for the advice so far everyone, I don't have time to work on it until this weekend so I'll post results and a picture of the engine bay when I get through all of the suggestions.

-rick

 

in this pic, you need to have the lines on each side of each cam even with the line where the valve cover and head meet.

[img]http://www.we-todd-did-racing.com/wetoddimage.wtdr/wOTIxMTQ0NnM0MTNkZmQzMXk1NDE%3D.jpg[img]

In this pic, you see the little plastic arrow pointing with a 'crosshair' kind of thing, you would look straight down at the arrow, and when it lines up in the 'crosshair' there would be a line on each side of it and one straight inline with it. The lines are located on the crank, 1 is at 16º[degrees beforetopdeadcenter BTDC] and 3 closely stamped together. [The middle one is Topdeadcenter or TDC] When they all are lined up, your timing should be dead on. Now the problem I think your having is because you might be using an ECU ment for a 5spd car. And also, I believe there is another vacuum line or sensor for auto trannys to keep the car from dying when you shift gears. I would research the auto trannies more. - Darrell

 

thanks for the pics.

I'm not sure I understand the auto tranny part or maybe I wasn't clear. The Si tranny on the DOHC ZC is manual. The 5spd Si ECU I am using is manual too.

 

Halle-frikin-lujah!!!! I think I found a major cause for some of my problems. I spent today replacing any vacuum tube I could find and behold......


the PCV valve was loose, so I looked at the old Si engine and realized that the thing snapped in half!




Modified by godzilla4rilla at 10:48 AM 5/15/2005

 

By the way can you guys double check the vacuum line routing and tell me if it's correct. I used some of that crappy silicone dress up stuff so I could remember which ones were new. Thanks for the help. I'll post more tomorrow when I replace the PCV.

 

More engine bay shots....

 

Ok, after driving the rex around today I still have a high idle problem, but at least no more rollercoaster fluctuations. I adjusted the idle screw as far down as possible and the idle remains running up around 2500RPM. Can anyone provide a picture of how their ZC engine bay vacuum lines look? I have feeling I crossed something or left something open.

thanks,
-rick