new ca18 problem

[Chris859]

Ok, I just got done sorting out most of the driveability issues on my ca. I thought I was done for a while - and a new problem started. The car idles fine most of the time, but every now and then it will start idling at 1500rpm. Regardless of engine temperature, driving conditions, etc. My initial thought was a vacuum leak, I checked out all of my hoses and whatnot with no luck - not to mention the engine still pulls 16-18in of vacuum at idle(the same as before the problem started). I narrowed it down to what is doing it, but just don't know WHY. The high idle is being caused by the iacv being stuck open by the ecu. If the car is idling high, and you un-plug the iacv, the engine will die. For the most part the engine idles as it should - 1300-1400 cold, and 900 hot... Asside from the random times it decides to idle high. Any suggestions greatly appreciated... I'm not at my wits end yet, just looking for some input

My current setup:ca18det (obviously)stock ecustock turbostock sidemount intercooler255lph pump3" exhaust10lbs boost

------Recently changed/adjusted-Timing-Tps (was way mis-adjusted)-Hooked up intake butterflies (were left unhooked by previous owner)-New fuel filter-New intake filter-New o2 sensor (been on for about 200miles now)-New temp sensors - both gauge, and ecu sensors

[Chris859]

On a side note - Does anyone have a tried and true method for adjusting the maf? It is possible that the previous owner messed with that as well (considering how far off the tps was, and I know he adjusted that). Only real method in the FSM I could find was using an exhaust CO % reading, and I have no way of testing the emissions. So any input on properly adjusting the maf is greatly appreciated as well! Thanks!

[ca18detpowered]

Sounds like your tps may be adjusted wrong? You gotta get it just right cuz theres a little microswitch in there that tells your car whether to idle or not.

Mine kept being a SOB and not switching, so it would idle at 1500

[Chris859]

I'll check into that and get back to you on here... I just adjusted the tps to the specs in the fsm - but neglected to check if the idle switch portion was functioning properly. Shame on me lol

[Ca_Silvia]

Im pretty sure you can not adjust the MAF at all, it just takes readings thats it.

[float_6969]

Some do have an adjustment on them. They were the ones that didn't have CAT's stock. I don't think any of the motors from Japan didn't have a CAT, but Austrailia didn't get CAT's on some cars, and I think some places in Europe didn't get CAT's.

[Chris859]

You can adjust the maf...it has a voltage adjustment screw - as I said - the factory service manual even tells you how to adjust it, I just don't have access to the testing equipment they instruct you to use.

[float_6969]

Well I'm at work, so I can't check it, but I thought that was only available on the non-cat CA's. I never said it wasn't possible that you didn't have a non-cat CA.

As for the idle problem, I would check the idle switch in the TPS before messing with anything else.

[Chris859]

That wasn't directed at you float, lol it was in reply to the guy above - I actually didnt even see your post when I replied. On a side note about the non-cat ca's... Wouldn't the ca18det's from those countries all be the 4 port heads? Mine is an 8 port... As for the adjustable maf thing - fsm says that IF it needs adjusted, you have to drill out, and remove a plug that covers the screw... on my maf this has already been done, and I can clearly see the screw (which is why im assuming it was tinkered with). None of this maf bs will matter after I get swapped to the larger maf and larger injectors. Money is a little tight right now, so im trying to just get it running as good as it can untill then.

On the tps issue - I just got home from work (9pm), and its like 25 degrees outside and a slight breeze...ill check it out tommorow morning before I go to work . Thanks for the input so far.

[float_6969]

I can't say for sure that all of the non-cat CA's would have a 4 port head, but I would be inclined to think so.

It's quite possible that if that plug is gone, the MAFS has been tinkered with. Regardless, I don't think this would cause your fast idle issue.

[Chris859]

Ok, so... I checked out my tps, and idle switch on the tps. Both checked out within spec. As per the fsm, the idle switch is functioning properly. I even tried adjusting it a little more, with no change in this condition. Warm idle still sits at 1400-1500rpm with the idle control valve connected. With the idle control valve disconnected, I used the adjustment screw on it to adjust the idle speed to 850rpm. Then plugged it back in with the car idling at 850rpm... and went right back up to 1500rpm. Out of curiousity, I unplugged the tps, and idle switches seperately... No change. What im leaning towards I don't like - maybe the wiring harness has a broken connection/wire in it for the idle switch portion. Or maybe something else all together.