this idle problem is unique, not like most other idle problems

[thrasherx89]

ok so here is the run down

i have a 96 ka24de in my 90 hatch

it was idleing low then reving up to around 1500 rpms and not steady at all

so i checked the maf off a good running ka and it idled the same so the maf is good

i replaced my iacv wtih another that was cleaner and better, that helped alot but didnt solve the problem it still isnt steady (even after opening it a bit)

discovered there was some vaccum leaks from the egr delete so i plugged ALL of those when i took off the manifold to change my PCV

replaced the cap and rotor and had it proffesionally timed

i have NO idea what there is left to do, last thing to do is to change the TPS and im not sure that will even work

any ideas?????

thanks everybody

[i_need_an_s15]

check your o2 sensor....are you running 1 or 2?

[thrasherx89]

im obd 1 i believe, the o2 sensor on the headers?

[blacksrjdm]

No the one on the muffler ...Of course the one in the manifold.

[thrasherx89]

ohh ok just double checking cause i do have an o2 sensor on my muffler

[Didderson]

throttle body needs adjustment.You'll find a very small nut/bolt head on it that stops the butterfly plate from closing too far, let it out a bit more so the tb can close completely. I had this problem with my SR when I bought/installed it.

[blacksrjdm]

No you dont...stop being silly. No one has an O2 sensor at the muffler. What purpose would that serve.

[godofspeed666]

do not adjust the openings on the throttle plate if you do it to much then the iac valve will think you are pushing the gas and can cause it not to operate and may even increase the rpm fluctuation.

Let me ponder on this and ill get back to you.

[Didderson]

No problem god of speed. I know it messes with the iacv slightly, but the idler should be able to handle a completely closed TB. I mean every TB i've taken off a car is completely closed. The little screw thing keeps it from being destroyed when you let it close really fast, so don't back it out too much. Keep em touching when it closes.

[godofspeed666]

That’s correct your IAC valve or idle air control valve primary objective is to keep the engine at the desired RPM at any given load your A/C, power steering etc.

Now on some throttle body’s you may have just a small hole to keep the RPM at a minimum thresh hold each car is deferent ones deferent.

Now let’s say you have have a vacuum leak that is the same thing as the IAC valve opening up more. Make sure the passages that are in or leaving the IAC valve are free from clogging.

Honestly it sound like a vacuum leak or a map sensor problem but im not there so I cant say exactly what’s wrong but if you can find out what’s is not wrong some times that’s just as helpful.

[i_need_an_s15]

what ecu r u using?

[thrasherx89]

do not adjust the openings on the throttle plate if you do it to much then the iac valve will think you are pushing the gas and can cause it not to operate and may even increase the rpm fluctuation.

Let me ponder on this and ill get back to you.

that would be awesome

hmmm maybe the person who owned it before me did adjust the tb and what you told me not to do might already be occurring i will deff check that thanks

[thrasherx89]

Honestly it sound like a vacuum leak or a map sensor problem but im not there so I cant say exactly what’s wrong but if you can find out what’s is not wrong some times that’s just as helpful.

me and a buddy took off the whole manifold and made sure that every vaccum line was secured or blocked

map sesnor? im not sure what that is exactly.

and we have pretty much looked threw everything possible

i only thing left would be the ecu, tps, and maybe what they were discussing above about the tb being adjusted previously to my ownership

[gingerbredman]

You wouldn't have a map sensor if you've got a maf, they both serve the same purposes but they work a little different so.. yeah map sensor's out of the equation.

Starting with basics, make doubly sure you have no leaks along your intake, behind the maf. The hose going beside the throttle body is critical for idle, make sure the hose isn't crimped or anything and is clamped on the fittings.

Question, not that the secondary butterflies or egr removal have any effect on idle, but you had this problem before removing the egr, correct?

..I've never adjusted anything on the TB so I wouldn't know about that, just used the little plastic screw on the manifold to control idle.

[YR240]

Crazy Idea, but, do you have the AC attached and working. 1500 rpm's sounds like what the throttle adjusts to when the ac is on and if you have a wire hanging around making random contact with motor it might could cause the idle to move like that.

[godofspeed666]

im not saying this is the case but you can have a MAP sensor and MAf sensor and they don’t do the same a map sensor or speed density looks at total manifold vacuum and takes this signal and uses it to look at vehicle load the more load the greater the vacuum will be.

The MAF sensor or Mass air flow looks at exactly how much incoming air is passing over the sensor. In either two ways by heating and element and measuring how much amps it takes to keep it at that tempter or by using a heater element and measuring how much the air is heated as it passes throw. More air equals less het

Then you have your throttle position sensor that looks at exactly how much that throttle body is open.

The do this for the most amount of info and as a redundancy

now the computer takes all this info and compares it to one another and acts on this info.

[gingerbredman]

That's precisely why it's fine to run a blow- through setup, because density and temp are .. blah lol let's not get into that here.

Oh, I bet he thought the tps was a map sensor or the iacv or whatever it was. I removed my egr and secondary butterfly actuator thing and left only one vacuum line hooked up which was the fuel press. regulator and haven't had a single issue.

The a/c thing could be something to look at, I'd suggest unplugging the plug on the compressor itself and also taking the a/c relay out and seeing what happens. Wouldn't hurt to anyways.

[godofspeed666]

Just for the info I look at a shop manual and there is a appsolute pressure sensor on a ka24de