Ecu going out??

[britdog]

Okay I'm gettin pretty mad because after every fix something else happens to my car. So it idle surges I got use to it. Okay it revs 2k when I push the clutch in an I tap the gas to drop it down and then it idle surges. Okay kinda get use to that to. Then it idles at 4k till I take off and the car drives it self through each gear I put it in. Order a rebuilt throttle body new tps an new iac and the car runs great just adjusted the biss screw a little bit an she did good. But all the sudden after about 3 hours of driving around it goes back to about 3-35k ie till I completely stop and then a few seconds later it drops down and idle surges 1-1500 about 3 times then settles down. I'm stumped please help I look like a fool at a red light at 3500 rpms

 

[LarryJoe]

You tried a boost leak test? That could very easily be a vacuum leak.

 

[FearlessNick]

One thing our cars do is they sense the speed when we are in neutral. So say we're going 25 MPH and were in neutral. Well the computer tells TPS to keep it open just a little bit so we can keep things moving. Ex. Water flow. Then once it senses that we are going 0 MPH the idle drops.

But this does sound related to a vacuum leak. Maybe take some carb spray and just hit your vacuum lines a couple of times. If you notice a RPM change when you spray a area. There is where your leak is.

Hope I helped some!!

 

[ibreakmytsi]

I've seen coolant temp sensors do this, or being low on coolant. X2 on vacuum leaks. Spray on the intake manifold gasket as well.

 

[codym]

OP did you replace the TB gasket when you put the rebuilt one on? That's exactly what mine used to do and the gasket hadn't been changed in a loooooooong time. It was bad.
Check for boost and vacuum leaks if the problem persists.

 

[DSM1G90]

Fiav ?

 

[britdog]

Okay so an update to this it's only doing it when warm. It's snowing here in Ohio and this morning got off work car ran amazing like a new car until it warmed up then it started with the high idle. It does about 2k-3k untill a complete stop then drops to about 900-1k. Left a red light came to the next one and boom 2k idle tapped the gas and it went back to 2k idle unlike before I'd tap it and it would idle surge and go back to a normal idle. Another thing the new rebuilt throttle body I got from my body has the vac lines blocked for te egr but I have not blocked the egr off. Is that a problem? I'm going to take some carb cleaner today and check for some vac leaks

 

[DSM1G90]

You don't need to worry on the EGR -this unit has no effect on your idle issue unless you got the vacuum lines disconnected from the EGR.

I'm still calling it the FIAV isn't doing it correct thing on you....do you have the cooling lines bypassing it, or similar?

but ......

Wonder if your throttle cable is a bit too tight, for it really acts line one, or your throttle plate linkage is sticking on you where carb cleaner sprayed over that might just loosen some gunk that's holding it open...or you got a stop screw, or even cruise control cable (if applied here) isn't returning on you.

Do you know how to adjust the cable? You loosen those two 10mm bolts that holds the cable mount on the int manifold move the mount towards the throttle plate linkage a smidge.

You're supposed to have a good quarter inch of cable deflection between the linkage and end of cable sleeve.

If that's okey, I'd recommend a IAC test, then if that's okey adjust the BISS to get idle speed under control.