SR20 rich high idle issue after replacing all lines

[LtSlayer]

I'll start from the beginning

s13 sr20det black top E5 ECU code

Ok so my motor had a vacuum leak i couldn't track down for the life of me. The logical answer to me was to replace every line and gasket which did work but now i have new problems, a much worse one. I didn't delete anything and don't leak any coolant as well.

At start up I'm at about 1250 RPM which is normal for my car. Then it jumps to 1500 and after it's warmed up, it rests around 1750. The car idles extremely high but once it's moving it drives very well and maintains healthy boost levels as well as AFR throughout the powerband.

I know everyone reading this is thinking the IACV but that was never removed from the manifold and I retained it's lines.

The next likely culprit is a vacuum leak but my car idles rich and even has slight backfires so vacuum leak is not likely especially after all the lines have just been replaced.

Another likely culprit was the coolant temperature sensor but switching this only made this whole probably that much more confusing, the car started and rose to a similar idle but was now running very lean.

Can anyone propose any other ideas?

also does anyone know the torque specs for the intake manifold runners? i got the intake manifold torqued to 13 but couldn't find any information on the collectors that run from the log to the block, thank you

[LtSlayer]

anyone? I'm in a bit of a bind and running out of money to throw at it, I'm sure it's something small.

[S14rebuild]

Have you check maf voltage at idle and at idle rpm (900-1200rpm)?

Any idle adjustment when maf is unplugged?

Bother to take off the ivac and clean it out?

Check vacumm leak with brake cleaner(hear idle surge when leak is found)

Check pcv valve for proper operation..

Throttle body working properly, no carbon build up on plate

Just a few things to look at

[LtSlayer]

Originally Posted by S14rebuild

Have you check maf voltage at idle and at idle rpm (900-1200rpm)?

Any idle adjustment when maf is unplugged?

Bother to take off the ivac and clean it out?

Check vacumm leak with brake cleaner(hear idle surge when leak is found)

Check pcv valve for proper operation..

Throttle body working properly, no carbon build up on plate

Just a few things to look at

I don't have my voltmeter down here and i will check the idle adjustment after I reinstall my fuel pressure regulator. I didn't clean the IACV because I've heard it was complicated and didn't want to open it up if it was functioning well as well as me not having the gasket for it. I also couldn't find any vacuum leak. PCV valve is 2 months old, throttle body was cleaned prior to reinstallation.

I'll check out the MAF when I get my voltmeter down here and if i cant figure it out I'll take off the IACV and thoroughly clean it. I've heard that feeding it fuel injector cleaner can clean it well but i fear hydrolocking the motor. I have about 500$ left to make it reliable again as I'm not working at the moment but worst comes to worst I can afford an IACV as well as a MAF. Think it could be the ECU or wiring?

[S14rebuild]

With out testing/checking i cant say its one thing or another


U can pull off the iacv and spay out the inside with carb cleaner, break cleaner.... use a small screwdriver to walk the valve open and closed. Make sure it moves freely. Reinstall valve with gasket or rtv.

Invest in a multimeter(amazon for like $15)

Do some basic voltage tests will help eleimate/solve ur problem.

Fo shits and gigs, disconnect the battery and unplug the ecu.... makesure its clean and no corrision, reinstall ecu plug. And battery and see if that helps.

[LtSlayer]

Originally Posted by S14rebuild

With out testing/checking i cant say its one thing or another


U can pull off the iacv and spay out the inside with carb cleaner, break cleaner.... use a small screwdriver to walk the valve open and closed. Make sure it moves freely. Reinstall valve with gasket or rtv.

Invest in a multimeter(amazon for like $15)

Do some basic voltage tests will help eleimate/solve ur problem.

Fo shits and gigs, disconnect the battery and unplug the ecu.... makesure its clean and no corrision, reinstall ecu plug. And battery and see if that helps.

I have one back home and I'm getting there somehow in a week. Can i slowly feed it throttle body cleaner through the hose that connect to the intake piping right before the throttle body? I highly doubt it's dirty though since it worked perfectly fine before i disassembled everything and I made sure not to touch it. The wax element is sealed away right? I might have gotten a little pb blaster on the paper gasket but I'm not sure this would harm anything.

can a kinked coolant feed or return to the IACV cause this? or if they swapped feed/return? It was really tight as i tightened them down with the log cockeyed before i put in in place and bolted everything down. Can this possible be the problem? I used general purpose fuel hose for this and it's hard to see if it's kinked. There are no leaks.

[S14rebuild]

U can spray a solid 5 sec bjrst kf cleaner in the iqcv tube then reattqch and start the car(apply throttle to help start up) rinse and repaeat. Might not be dirty but the valve is stuck.

As for the coolant hose.....

I have completely deleted coolant hose to my iacv and have 0 issuses idling. Cold start, warm start, all day no problems..solid 900rpm no surging.

Sooo i cant image having them backwards, or kinked causing this problem.




Like 15yrs ago i had an sr setup that ran solid...then just 1 day it started idling high and comen to a stop would just cut off.... i tried everything maf cleaning, swaln out, 2 diffrent iacv, injector seals..etc.. never figured it out..lived with it for like 2 weeks and sold the swap(went rb26) but it drove me crazy i must of pulled the stock intake 10-15 times sorry not tryn to jinx ya

[LtSlayer]

Should I let it sit in there a while? How would the wax respond to temperatures and know when to close/open if there isn’t any coolant to tell it when the car is warmed up? That’s interesting. I’ll clean it when I get a change and see if it helps

[S14rebuild]

Originally Posted by LtSlayer

Should I let it sit in there a while? How would the wax respond to temperatures and know when to close/open if there isn?t any coolant to tell it when the car is warmed up? That?s interesting. I?ll clean it when I get a change and see if it helps

Your asking questions i never bothered to find the answets too. Ive seen others try it n it was no issue, so i did aswell. It worked. Im in south florida so not much temp change.

[LtSlayer]

I meant temperature change in your motor represented by coolant. Once it’s warmed up it doesn’t need the bump in idle.

Another clue in the mystery. Every time I shift there’s rev hang and the exhaust sounds louder. RPM rises for a sec after I Lift off throttle to shift and sounds like a deep rumble. Any ideas on this? Similar symptoms on an unrelated car stated the same things here, IACV TPS and the throttle cable. Any thoughts on that?

[DiscountPirate]

For your original problem how do you know you had a vacuum leak? Off the top of my head from what you describe I would say either vac line or iacv related (check iacv by turning screw while car is running and see if idle goes up and down according to screw adjustment. Most of the things to check have already been mentioned but you can easily check all of them in one day with very little money, such as:
1- if you can't do a smoke test then throw on a vac or boost gauge on TB and check that.
2- iacv is cake to clean. Just take out screw, spray some seafoam in there, put screw back in and start car, tap on iacv if it's stuck, then adjust screw down to idle.
3-TPS...multimeter
4-CPS...not likely but easy to check
5-TB...check flap and cable adjustment for sticking or play
6-lines...since you replaced everything make sure you have everything routed appropriately
7-maf...not likely, test by unplugging while car is running and see if any change
8-cold start sensor...not likely but also easy to test

[LtSlayer]

Thanks I’ll make sure to run down the list, I’ve been very busy with school but I’ll make sure I get around to it as soon as possible. I’ve never heard of a cold start sensor on SRs I’ll have to look for it. By CPS did you mean CTS? I pulled mine and there were some sports that were kind of rust colored but nothing crazy

[LtSlayer]

I believed it was a vaccum leak because my AFR was running lean whenever I asked for power or was above 3k and I could hear the characteristic whistle of a vacuum leak