Car is driving itself.. literally. Throttle issue?

[Metallic36]

Alrighty, finally got everything put on.. changed to a 626 mani, blocked off the EGR but still have the tube, then put on a Steedspeed mani. At this point I am getting ready to add a standalone, but not going to until the car runs well on the stock ECU. Not boosting, just driving normally.

So if I go into 2nd, it feels like the throttle gets stuck, and it literally accelerates by itself enough to make me shift into 3rd if I allow it to do it's thing. It will do the same in 1st, and accelerate itself up a hill with no problem.. by itself. I rev it up to disengage it's attitude, then it's okay until it gets stuck again. I checked the little wire on the throttle body and that is okay, but I'm wondering if anything else would cause this and what I need to look for.

 

[sean22306]

I had this issue when I rebuilt my motor. TB have any carbon build up? Mine had some, cleaned it with some carb cleaner so it seated properly and moved more freely. Solved the issue for me.

 

[Metallic36]

Thanks, I'll try that. I didn't clean the TB while I had it off, but I'll do that tomorrow and see. Is it just the TB staying open or ? that is causing it?

I had this issue when I rebuilt my motor. TB have any carbon build up? Mine had some, cleaned it with some carb cleaner so it seated properly and moved more freely. Solved the issue for me.

 

[BOOSTR]

Did you have the issue prior to swapping im?

I had a bad TPS in another car that would cause an occasional sticking throttle.

In addition to trying to clean your throttle plate you might want to lubricate the linkage.

 

[sean22306]

Thats what finally solved the issue for me. My car used to rev also though at idle. Rev up to like 2k then drop and do this over and over and over. Got annoying. This was all after a complete rebuild, forging, 626 mani and a whole mess of new parts so knowing the real issue is kinda hard to tell. I just know cleaning the TB is what finally solved it after about a week of driving it like that.

 

[Metallic36]

Thanks, that sounds similar to what it's doing. I guess it's from the stress of removing the TB and all that stuff. It definitely explains it though.. and it had done it before a while back and I thought it was the timing, the shop fixed it that time though, but for now it looks like I'll be cleaning the TB.

 

[Metallic36]

Alright, I cleaned the throttle body, reinstalled, and it still does the same thing if not a bit worse now. It has to be something with the new intake.. it mostly does it in 2nd gear, it will rev itself up to 3K and if I take my foot off the gas, it continues to accelerate unless I hit the gas to get it "unstuck."

 

[Metallic36]

So far I've found that it may be the IAC valve.. going to do a little research on the TPS though.

 

[GG RACING]

Check if the intake manifold gasket is leaking or throttle body gasket but it for sure sounds like an IAC problem. Try and clean it out and make sure the o-rings or gasket aren't leaking(i don't know how mazda mounted it). As far as checking for leaks I check them they same way I check for boost leaks. Go to Home Depot in the plumbing section and get a rubber cap(it doesn't matter if it is bigger a hose clamp will squeez it down all the way) and drill a hole in the center and put it on the end of the turbo or intake pipe and take your air compressor and attach a sprayer to it and fill your system with air and listen for leaks. If you want to be real crafty get an air tool fitting that screws onto the botton of a tool that you attach the air hose to and find a nut that fits it and two washers, attach all that to the cap and put the hose on it and now you are hands free just dial in the air pressure from the air compressor. And also check the block off plate for the egr to see if that is leaking.

 

[Protege03ak46]

time for an exorcist. lol

 

[TheMAN]

move the throttle body pulley and pay attention to how the cable moves and if it binds anywhere

when I swapped to the FS-ZE intake, the pulley hit the end of the shielded part of the cable and it got stuck at the higher opening ranges... I trimmed the s*** and now works perfectly

 

[Alamo1]

Sub.

 

[Metallic36]

Thanks, I just went outside and had my husband watch it while I revved it up, then I let him rev it up while I watched, the cable moves freely, doesn't catch on anything. Earlier today I unplugged the TPS for the heck of it, actually idled better without it plugged in. Plugged it back in and my idle dropped significantly to about where it was going to stall. I have the TB ordered, so hopefully I'll be able to switch them out and see if it may be either the IAC valve or the TPS.

Also wanted to add that this isn't the first time it's done this.. earlier this year after I had a shop replace the head and install some other stuff, my idle was extremely high. I remember loosening the screw a little bit and that helped with the idle and with it trying to drive itself, I took it to a shop that fixed the timing on it and got it going fine again. Not sure what the issue was with it driving itself that time though.

move the throttle body pulley and pay attention to how the cable moves and if it binds anywhere

when I swapped to the FS-ZE intake, the pulley hit the end of the shielded part of the cable and it got stuck at the higher opening ranges... I trimmed the s*** and now works perfectly

 

[Metallic36]

I switched out the throttle body, definitely a difference. There is still a weird thing that happens when I go to stop, the idle will go up a little and when I push in my clutch it goes back down to normal. Dunno if maybe it did it before and now I'm noticing every little thing. Thank God it's no longer driving itself though, that was freaking awful.