Idle Surge Culprit......HELP

[braceyoself777]

Just wanted to let you guys know what ups. I was in my auto class the other day and hooked my car up to a Snap-On Solus computer. I hooked the car up becuase when the ignition key is turned to 3.....a check engine code blinks.....OBDI flashes codes thru the SES light. Anyways, we hooked the computer up and it reads that the Throttle Position Sensor (TPS) is out of range. Did I find my culprit? I went thru just about every step of that dianositic test of Idle surge and the only thing I can find is a boost leak by the Emanifold...but that wouldn't cause idle surge....it would cause lost of boost. Just needed some opinions before I buy this $130 part. Thanks.

 

[LoganDSM]

Sounds like a vaccum issue to me double check Biss screw and do a full leakdown test.

 

[mikelv]

Just wanted to let you guys know what ups. I was in my auto class the other day and hooked my car up to a Snap-On Solus computer. I hooked the car up becuase when the ignition key is turned to 3.....a check engine code blinks.....OBDI flashes codes thru the SES light. Anyways, we hooked the computer up and it reads that the Throttle Position Sensor (TPS) is out of range. Did I find my culprit? I went thru just about every step of that dianositic test of Idle surge and the only thing I can find is a boost leak by the Emanifold...but that wouldn't cause idle surge....it would cause lost of boost. Just needed some opinions before I buy this $130 part. Thanks.

Well, I'm not eactly sure what problems you were experiencing here, but it sounds like you were having an idle surge problem? Idle surge can be caused by a number of different things for many reasons. The main concern and most obvious is related to vacum leaks. There are four major causes of idle surge:

1) Dirty Throttle Body
2) Leaking (or missing) Base Idle Set Screw (BISS)
3) Malfunctioning EGR Valve
4) Malfunctioning ISC (Idle Speed Control)

You need to go through one at a time and visually inspect each of these devices to ensure they are installed properly, and no obvious damage is present.
Here is what you need to do to check the ISC:

Remove the ISC from the TB and visually inspect for damage. On the ISC there are six pins. Make sure the car is off and check the resistance between the pins with an ohmmeter. (volt meters at the parts store will read resistance) Measure the resistance between 1&2, 2&3, 4&5, 5&6. If there are any readings above 30 ohms then your going to have to replace the ISC.

You mentioned the concern for the TPS being out of range. Here is a link involving TPS adjustment for a 1G. Sometimes the TPS can be out of range and confuse the ECU as to where the motor should idle.
TPS Adjustment

Depending on your vehicle's condidtion, you make have vacum leaks present. Double check! Make sure you check your injector seals, TB, intercooler pipes, & hose condition, MBC's, BOV's....anything with air passage.

One neat little trick I used was to unplug my front O2 sensor. If you unplug the O2 sensor, you force the ECU to run open-loop mode all the time.
If you unplug the O2 and your idle surge goes away and the car idles steadily, it's a tuning problem. You don't want to run like this all the time (due to poor gas mileage & rich operation) but it will help narrow down your problem. If you had DSMLink or an EMS of some sort, this could be feaible and tunable, but not recommended.

Here is a link explain surge, and what needs to be done to correct it. I'm sure you'll fine everything you need here. Let me know!

Terry's Talon Troubleshooting Tips #3 - Fast Idle (aka. Idle Surge)


Good Luck!

 

[braceyoself777]

Here is a link explain surge, and what needs to be done to correct it. I'm sure you'll fine everything you need here. Let me know!

Terry's Talon Troubleshooting Tips #3 - Fast Idle (aka. Idle Surge)


Good Luck!

Yeah, I've been using that check list and it has been helping. I've checked all vacum lines and everything seems to be legit. We have a vacum pumper at our shop and I've used that to create vacum in the system with the car off so we can hear air leaks....nothing. The BISS isn't the problem either because it adjust idle...and I believe if it were defective....the idle wouldn't change. But I'll be testing the TPS and the ISC as soon as I can. I have those two parts on hold right now at an auto parts store just in case I have to replace both of them. thanks for the help!

 

[mikelv]

Yeah, I've been using that check list and it has been helping. I've checked all vacum lines and everything seems to be legit. We have a vacum pumper at our shop and I've used that to create vacum in the system with the car off so we can hear air leaks....nothing. The BISS isn't the problem either because it adjust idle...and I believe if it were defective....the idle wouldn't change. But I'll be testing the TPS and the ISC as soon as I can. I have those two parts on hold right now at an auto parts store just in case I have to replace both of them. thanks for the help!

It's not that the screw would be defective, a screw is a screw. The BISS has a small o-ring under the head to seal for leaks. If the idle surge is very definate then a small vacum leak wouldn't be the problem.

Is your mod's list updated? What exactly do you have done to the car.

Did you try unplugging the O2 Sensor? If you unplug that, and it idles better you have an A/F problem, which can be realted to the ISC.

Your looking to measure the ISC's resistancce, try that.

You can also unplug the TPS, the car should hold idle at 1500rpm.

If your 100% sure its not vacum, then it has to be one of those sensors or dirty/sticky throttle body.

One more thing to look for. Did you adjust your throttle cable for any reason? Sometimes if the throttle cable has too much tension on it (where it bolts to the manifold) it can leave the throtte plate open slightly at idle, causing surge. Check the tension and check to see if pulls on the plate at all.

Let me know.

 

[braceyoself777]

The throttle cable seems pretty loose to be honest with you and yes, we did clean the TB plate. I unplugged the TPS and it didn't do crap....no idle hold or anything....is that a sign? But I havn't unplugged the 02 yet.....but I'll do that when I can today. But again....when I unplugg the TPS....the idle will not hold...but the surge continues.

 

[Avionixx]

Have you tried unplugging the throttle stop switch? That's the 1-wire sensor on the opposite side of the TPS; basically tells the ECU when the throttle is completely shut and is indirectly responsible for most idle surge issues. Anyway, unplug it and report back.

 

[mikelv]

The throttle cable seems pretty loose to be honest with you and yes, we did clean the TB plate. I unplugged the TPS and it didn't do crap....no idle hold or anything....is that a sign? But I havn't unplugged the 02 yet.....but I'll do that when I can today. But again....when I unplugg the TPS....the idle will not hold...but the surge continues.

Well, this is a sign that the ECU is being messed with by something else besides the TPS. Do a resistance check in accordance with the service manual specs and see if they're within tollerance.

Unplugging the O2 will tell you if there is a fuel trim/tuning issue. If you do that and it continues, then we know your having a problem with the sensors, most likely the ISC.

Have you eliminated your FIAV or done anything of the sort?

I'm going to talk to a few friends and read up a little more, I want to make sure we get you some helpful advice. We'll figure it out.

 

[braceyoself777]

Alright guys. I pulled the o2 plug and that do jack. But we went ahead and put the TPS on SCOPE and noticed that the TPS wasn't putting out anything out on the graph. We went ahead and DVOMed the connector and the full 5 volts came up on the read out. So I'm getting the full voltage but none of it is going to the TPS.....which puts me to the conclusion to replace that POS. Thanks for the help guys....this is why I love this fourm.

 

[mikelv]

That's good to hear man, let us know if that works once you replace it. Glad to help!

 

[Project2G]

My buddy just bought one from autozone for $119.. (TPS)

 

[braceyoself777]

My buddy just bought one from autozone for $119.. (TPS)

Ahhhh damn. I just paid $156 for it on ExtremePSI......its a pretty good price compared to the $200 ones on Partstrain or Kragen.....Damn.....$119?!?! I couldn't find it on the Autozone website.

 

[mikelv]

Ahhhh damn. I just paid $156 for it on ExtremePSI......its a pretty good price compared to the $200 ones on Partstrain or Kragen.....Damn.....$119?!?! I couldn't find it on the Autozone website.

Your getting a bran new OEM one from Extreme, or other DSM shops.

Autozone, NAPA, and places like that sell you cheap refurbished crap. That's why if you buy an alternator from them or something like that, you end up returning and installing it three times before you get a good one.

If you want to save a few bucks go for it, I'd rather have new quality products from Mitsubishi, which have warranty anyway.

 

[Project2G]

Ahhhh damn. I just paid $156 for it on ExtremePSI......its a pretty good price compared to the $200 ones on Partstrain or Kragen.....Damn.....$119?!?! I couldn't find it on the Autozone website.

His username on here is "hopwoodp".

 

[braceyoself777]

Yeah I thought so. Im kind of over the cheap part now. I bought a used head on Ebay and it ended up being back. $250 down the drain. I went ahead and bought a brand new head for aroun $500.....rebuilt and everything. So i just went ahead and bought the OEM product instead of trying to go cheap. I learned my lesson

 

[mikelv]

Yeah I thought so. Im kind of over the cheap part now. I bought a used head on Ebay and it ended up being back. $250 down the drain. I went ahead and bought a brand new head for aroun $500.....rebuilt and everything. So i just went ahead and bought the OEM product instead of trying to go cheap. I learned my lesson

Yeah, I hear ya. I learned the hard way as well. Did you install the new TPS? Did it fix your idle problem? Let us know.

 

[braceyoself777]

Yeah, I hear ya. I learned the hard way as well. Did you install the new TPS? Did it fix your idle problem? Let us know.

Nope....it will get here on Wednesday.....hopefully before I leave for school cause I hate driving back to see if a part was dropped off....and its not there.

 

[braceyoself777]

Alright....I'm alittle puzzled right now cause the car is responding alot better with the new TPS compared to the old one. The car has to warm up first and then the Idle surge would go away. If the car cools down it comes back. But my next culprit is going to be the Idle Speed Control....ISC. Several of you mentioned about it and I'm going to give it a try. I just have to wait for the funds to come thru. Anyways...I'll keep you updated.

 

[braceyoself777]

I went ahead and ordered a used part.....the IAC or ISC was another culprit. We went ahead and replaced it and the car now DOESN"T surge. It will only do it alittle for a breif second but as far as I know, the problem is pretty much solved...I just gotta tie some loose ends. We took out the old unit and rotated the round part at the end and it was loose. The newer unit didn't even move with the same amount of rotational force. But if any idle surge is present and its not a vacum leak, then its either the TPS or the ISC....Mike out.