idle surge

i know this is posted all over but thats why im here all those dont quite answer my question. Im going through the steps trying to find the problem. A little backround. i think i have the worst idle surge of all time. today i started the car and it idled at 800 like i have i have it set on link and then after cruising for about 10 minutes it started to hit 1500-2000 and then 20 minutes later in the 96 degree heat it was idling at 3500rpm with the ac on. It seems to get worse with temperature. I cleaned the throttle body already. checked the ISC and it read 33.5 ohms beween each connector i wasnt sure if that was too high but it was a little hot. Then i checked the biss. The funny thing is that it idles fine when its cool so the biss didnt really need any adjusting. can it back itself out while driving? so no im onto the egr. If the idle surges more based on temp is that more likely the egr or the ISC. sorry that was so long :uhoh:

Had a similiar problem , hook it to a diag machine , ended up being TPS.

wouldnt it show up as a dtc on dsmlink. how much was the tps/labor cuz i dont have a diagnostic machine and does it have to be surging to show up on the diagnosis machine?

wouldnt it show up as a dtc on dsmlink. how much was the tps/labor cuz i dont have a diagnostic machine and does it have to be surging to show up on the diagnosis machine?


Mine surged withouth throwing any CEL's so it fooled the diagnostics a couple times. 250 dollars later after the foolage , I finally got a CEL for it.

The idle bounced about 200 rpm when cold and up to around 450 when warm when it did bounce around. New tps = no problems :) I did it myself so saved on labor / shop costs.

Although I have never encountered this problem, I've read that the drive cycle for the TPS is "funky" and sometimes trips the CEL, but normally doesn't. I would definately pull out the shop manual and test it if you think it might be the cause of your problem.

i did its supposed to measure 3.5-6.5k ohms i got 580 and 1800 so im pretty sure its bad. time to find one :)

If it gets worse as it warms up, I'm betting it's the throttle cable adjustment (linky (http://www.automotiveforums.com/vbulletin/showthread.php?t=336178&highlight=throttle+cable)). In fact I have a 6 pack on it.

I went through the steps i pulled the bracket all the way to the drivers side but that meant i got 15% Throttle at idle so then i adjusted the throttle to give me 0 at idle (while its hot i might add) should i leave the cable as far as it will go and then adjust the TPS to give me 0 at idle. If you you pull the bracket all the way to the drivers side is that physically WOT? What if adjusting the TPS still doesnt get me to 0 at idle?

I'm not entirely sure what you are getting at, so I'm going to ramble on for a bit hoping that something is helpful.

You can't not get to zero when adjusting the TPS. The TPS can get adjusted to whatever you want, seperate from the physical position of the throttle plate. First the throttle plate must be set up properly, then the TPS can be set so the electrical signals properly represent the physical situation.

When you are pull the cable to the driver side, the throttle pedal is on the floor right? This takes two people, or something heavy like a brick. When setting it up this way, understand that there is no possible way to get any more slack at idle while still being able to achieve wide open throttle. You get maximum slack, which means 0% TPS (physically), and then some. This is where I'm confused with your situation.

If you don't physically have enough travel to get full throttle and get enough slack to maintain fully closed throttle plate while at idle, you still have cruise control and the wear in the assembly is screwing you. Either swap in a non-cruise throttle cable if you can live without it, or take a look at the cruise cable junction box and figure out how to adjust it. It's not something I care to try to get into over the internet, but there are cable adjustments on the box. Also be sure nothing inside the car is limiting travel, like the floormat. Floormats will fuck you every time. ;)

Once the cable is set up properly drive the car around until it's as warm as it's gonna get, then have someone operate the gas pedal while you watch the TB. Check the slack with the gas pedal released. There should be some. Try to physically close the throttle plate by hand. It shouldn't move. If it does, it's still porked. Then have your friend floor the pedal. Verify that the throttle plate is fully open all the way to the stop. Try to open it more by hand. It shouldn't move. If it does, it's still porked. Go through the setup again.

If it passes both of these tests when warm, it's set up properly. Once you are certain of that, you can now ensure the TPS is set properly. On a 2g, the TPS is also your idle switch. With DSMlink you can log the IdleSW parameter to see it switching over. When the ECU considers the throttle to be at idle, it will be a "1" (on). When you push in the pedal it will change to a zero (off). I can tell you right now that the switch over will happen between 1 and 2% TPS, so the setup is critical. Also ensure that you have not set it too far "negative," or below zero. It will still read zero, but you will lose % at WOT. Generally a 2g with a non cruise cable (max travel available) that is set to JUST be on zero at idle will achieve 94-98% TPS at WOT.

Once it is confirmed that the cable is setup properly, and the TPS is set properly, you can actually get into diagnosing idle problems, if any indeed still exists. These two things take care of the majority of idle problems, especially for 2g. Same for 1g, but TPS is less critical, and the focus is on the seperate idle switch, also called the throttle closed switch.

you underestimate the efficacy of your rambling lol. That helped, well see this weekend cuz i wont have time tomorrow. So damn frustrating but i guess i signed up for it when i bought it