I recently did a throttle body/EGR cleaning and installed P2R throttle body and manifold spacers but now check engine light is on and the idle speed bounces from 1000 to 2000 and back at idle. I triple checked all the hoses and sensors were connected and changed the IACV sensor but no help.

Could a bad MAP sensor be causing this?

I also forgot to get an additional manifold gasket when getting the manifold spacer so there is a gasket missing beneath the manifold spacer. Could this be causing a rough idle?

Any other thoughts? Thanks

 

Chances are that something happened during the recent work.
If ya triple checked everything, then get the codes read ....as they may help ya narrow down the problem.
A gasket could be improperly positioned and causing a vacuum leak. Also make sure that the coolant level is up in the rad.

 

So it's not the MAP sensor. I got a p0505 code which is Idle air control malfunction. Since I just replaced the IACV I know it's not the sensor itself. Can the lack of a manifold gasket cause this? Any other ideas?

 

Does it idle rough only when the engine is cold? Or does the problem persist once the car's warmed up too?

 

Sometimes it idles fine when the engine is cold. It always becomes erratic when the engine is warmed up

 

My bet is on the gasket..

The reason I asked is because I recently cleaned the EGR on a 2000 Mustang, and after doing so it idled really rough and stalled a couple times until the engine warmed up and any excess water I wasn't able to dry passed through.

 

You have a vacuum leak somewhere. Get a spray bottle and spray water around the IM when the car is idling poorly.

Car should bog down when you spray water near the leak. Once, you find the location of the leak, you'll know what to fix.

Probably the gasket you didn't use. They are there for a reason.

 

Check the throttle cable adjustment there should be some slack on it.
Post back with the fix if possible.

 

so I replaced the manifold gaskets and still having the same problem. Any other thoughts?

What I have done so far:

Cleaned egr ports/throttle body
installed manifold spacer with 2 new OEM gaskets
replaced MAP sensor
replaced IACV sensor
checked throttle cable slack
bled the radiator in case an air bubble got in there

 

Which manifold spacer did you install exactly ? part# if possible

 

First thing to do is check the top plate gasket on the upper intake manifold. It fits both ways, but only works one way.

2nd, get a spray can of carb cleaner. Attach the straw to it and with the motor running start spraying around the intake manifold, throttle body etc. If there is a vacuum leak your rpms will change and in that area is your issue.

 

Are you still showing any codes?

 

Let me know what you figure out, cause i'm going through exactly the same thing and have changed exactly the same thing minus the map sensor and i had changed out all my motor mounts. The next thing i was going to try and changing is that solenoid that runs to the mounts, from researching apparently the ECU controls it and grounds it out at certain points to release the air from the mounts, could be getting stuck and holding it in. Not sure just my theory from researching.

 

Don't know the part number but it's the p2r spacer which many are running on here. My next step was going to take it off and see if that's what's doing this but I just took it to a shop instead.

 

I installed the top plate gasket with the shiny side up. . .pretty sure this is the right way?

Tried spraying carb cleaner around TB and manifold and idle didn't change. Not sure if it's a vacuum leak since the idle actually does go down when I stick my fingers in the throttle body and cover the hole in there.

 

Yeah but I gave up and dropped it off at a shop this morning. Of course when I talked to the mechanic the first thing he said is its probably the IACV. After I told him I just replaced that he said it may be clogged Egr ports, but I just cleaned those out.

On the way there my check engine light turned into a check engine light, VSA, and ! light.

 

Will do. I don't think that solenoid would cause this though.

 

i get a slight rev to about 1.5rpm's when coming to a stop on mine as well.

 

You can install the shiny side up but can be both ways (Left and Right) and only 1 way is good.. this is what he ment, obviously you wont install the dirty side up but you can surely install it on the wrong side (L/R).

 

Report back when you come up with a solution.

 

Oh I see what you mean. Yeah the busier looking side or whatever its called with more outlets is placed toward the driver's side

 

Hook up a scanner with the ability to see Throttle position, it should be near 9.4%.

I can easily make my Rpms jump up and down when warmed up by keeping the Rpm at 1100 until it does it, in my own TL no Cel or anything.

 

Using the OEM diagram helps, shows the curves to the gasket and which way its suppose to go, thats how i matched mine.



Did they ever find out what the problem was??

 

I havent had this problem on my acura but i chased this issue on another car before I found it to be the crank sensor. Yes this sounds stupid, but it was giving me vacuum codes. Might be worth investigating.

 

does anyone know if the OP found the problem? i got the same issue

 

i'm with ya buddy, have a 99 too and have changed and double, triple checked stuff and still idle issue. everyone on here is extremely helpful but takes patience with are cars.

 

If ya replaced the IAC valve, cleaned the TB and EGR stuff....then maybe check the fuel pressure.
Could be a leaky injector or possibly an electrical issue, IDK. But normally it's a vac leak.