experimenting

[Kyromoto]

ok so if anyone read my post yesterday my RPMs spike real high on start up (about 3k) then it drops to a stall. I was able to modulate the throttle enough to keep it from stalling but it still spiked every few seconds. so today i check the ICS with my ohms tester and it was good. then i replaced the fuel filter (cause it looked bad anyway) and the RPMs still stayed the same. finally i got frustrated and just started tinkering. i pulled the throttle cable back a little bit farther. just barely beyond the point of contact on the TB. Then i pulled the BISS out just a little bit and between both of those i can get the car to idle just fine. now the problem is sometimes when i accelerate the car wont stop when i let off the gas till i hit brakes and force it to stop. does anyone know whats going on so i can get the RPMs to be normal, and when i accelerate to make it stop when i let of the gas? by the way only somtimes does it feel like the TB gets stuck open not always.

Thanks guys. you've been alot of help



Jeff

 

[absolute_DSM]

Holy crap, thats not safe. Sounds like you have a frayed throttle cable if it wont stop accelerating after you let off the throttle.

 

[Kyromoto]

yeah it scared the shit out of me the first time it did it. but it only did it twice maybe 3 times so i dont think its the cable. the cable based off looks looked fine. i think it has got to be a fuel supply issue or my TB... but i cant diagnose it. ive rechecked everything and it all hooked up and working so im really confused... has anyone had anything like this happen before?

 

[absolute_DSM]

You wouldnt see a frayed cable. They can easily fray inside the casing and cause exactly what you are describing.

I would disconnect it from the TB, and play with it making sure it doesnt stick at all.

 

[Kyromoto]

o ok. should it slide in and out of the covering easily?

 

[snowborder714]

Yes.

 

[Kyromoto]

ok thanks. ill go look at it right now... what else should i look for if my throttle cable is in good condition. what else could cause this?

 

[Kyromoto]

the throttle cable is fine. ive checked everything people have said to check. ive rechecked all vacuum lines, all are ok. im so confused. seriously does anybody got anymore ideas whats wrong with my car? ive driven it and itll drive fine. but the idle is still crazy. either its spikes and stalls. or just stalls. unless im actually giving it gas

 

[absolute_DSM]

Terry's Talon Troubleshooting Tips #3 - Fast Idle (aka. Idle Surge)
Work with that for your idle surge.

But the TB sticking open is not good at all.

If you have cruise, did you check every cable? And make sure the actual cruise pulleys arent binding.

 

[Kyromoto]

do you mean cruise control? and no i dont have that. and look for if the Throttle cable is bending? is that what you mean?

 

[Kyromoto]

1. The idle switch is depressed (foot off the gas)
2. Too much air is getting through the throttle body (ISC stuck open)
3. O2 sensor registers lean mix (too much air)
4. ECU adds fuel to achieve correct mix
5. RPMs increase due to increased fuel/air supply
6. At 1500 RPM the ECU goes into decel mode and cuts fuel (*)
7. With only air coming into the engine, the RPMs drop rapidly
8. At 1200 RPM the ECU turns the fuel back on
9. Goto 2.

well for 1 my car shoots up way higher then 1500 rpm. it shoots up around 4k.
my car also doesnt just kick back in at 1200 it only stalls. if all it did was surge between 1500 and 1200 id be happy. but it spikes to 4k then stalls

 

[absolute_DSM]

Yes I meant cruise. That takes a lot out of the equation.

Is there anyway to get a vid of this? Internet mechanics can only go so far.

 

[Kyromoto]

yeah. ill try and get a video of it tomorrow. its to late now. but i really appreciate your help. this is crazy confusing

 

[Kyromoto]

http://youtube.com/watch?v=7FXULJwNu-g

ok this is the link to the video. i don't know how to just attach it to the forum but here it is. I hope you can figure it out

 

[snowborder714]

Have you taken your uicp off and played with the tb plate yet? Is there any sticking? Is it closing the whole way? Is the throttle cable adjusted?

 

[Kyromoto]

I dont know what the uicp is. I have adjusted the Throttle cable a bit going from barly contact to just barly applying pressure to the throttle. and I wasnt able to look for myself because my grandma cant climb into the car due to the roll cage and all. so i cant tell if the TB is sticking. until i get some 1 else to start it for me i cant really look at it at the same time.

 

[turbosax2]

How / when did this start happening? Have you taken your uicp off to make sure the throttle body plate is acting normal when you're on and off the gas pedal?

Anybody think a bad ecu could cause this?

Edit: Too slow....

uicp = upper intercooler pipe

Take the uicp off so you can see into your tb (take some pics for us), sit inside the car and just mess with the gas pedal while your Grandma looks into the tb and watches what the tb plate does. Have her take a video of the tb plate while you're messing with the pedal inside the car.

That's pretty cool your Grandma helps you out!

 

[Kyromoto]

yeah she is the only 1 who could help me. cus i obviously cant start the car and make a video cause it just stalls. ok so tomorrow take a vid of the TB with UICP off so you guys can watch it open and close? with the car on or off?

 

[turbosax2]

yeah she is the only 1 who could help me. cus i obviously cant start the car and make a video cause it just stalls. ok so tomorrow take a vid of the TB with UICP off so you guys can watch it open and close? with the car on or off?

Do this with the car off. You're just checking to make sure the tb plate opens and closes fully without binding anywhere. If the plate is getting stuck for some reason, that is a problem.

 

[Kyromoto]

ok thanks. ill check that first thing tomorrow. that is if the rain goes away... grrr weather in socal pisses me off. im so close to finishing my car and the rain always comes when i want to work on it

 

[turbo addict]

I would say the throttle is sticking. Also look to make sure that there is nothing that is getting in the way of the throttle. I had a wiring harness that was getting in the way of the throttle and holding it open.

 

[absolute_DSM]

Wow, I just watched the video, that is nuts! Sounds like a wind up toy.

I dont think the TB could getting stuck open enough to get to 4k+ like that by just pumping it a little to get it started.

This may be an electrical issue like turbosax2 mentioned. I really cant see it getting stuck far enough open to hit 4k by just pumping the gas lightly. Correct me if Im wrong.

 

[Kyromoto]

yeah i agree with you absolute. i barley touch the throttle and it climbs way high and it used to crash back down but now it doesnt. so i have no idea. im gonna take off the UICP and double check the TB but i cleaned it real well before i put it on and dont think its sticking. if its electrical what would cause this? and how come this didnt happen before my engine overheated and warped?

 

[Kyromoto]

ok well during the slight break in the rain i went out and played with the throttle cable and TB and took the UICP off to watch it closely. I couldn't get a camera out there because it keep sprinkling and didn't wanna get it wet. But no matter how hard i tried to find a way to get it stuck open it just kept closing right away. So if it is sticking open it is only while the car is on. not off. Any other Ideas??? I have an appointment next week for the DMV where I got to bring my car to get registered and i really want to be able to fix it in time to get the Registration done. thanks guys. you have helped alot so far.

 

[turbosax2]

Do you have any friends that you can "borrow" electrical parts from? You can start testing the electrical components one by one by swapping the known working parts onto your car. I'm not sure which parts are 1990 specific.