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Spyder Heat related idle issue.

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ryan4269

Proven Member
52
6
Oct 11, 2021
abbotsford, BC_Canada
Hey all, just curious if anyone has had experience with a idle issue that’s inconsistent. I start and Idle completely fine, but after 10 or so minutes of driving, it refuses to idle. it has no struggle it just abruptly and instantly dies. If I give it just the slightest bit of gas it’s fine and holds the rpm no problem with my foot on it, though as soon as I release, it instantly dies. I do get a idle control system error code. It seems almost heat related cause when the car sits and cools all is fine the next start. I’m pretty sure it’s not a vacuum leak, I doubt it’s the IAC, someone told me it could be an o2 sensor. Thoughts? I’ll look at the sensors later and update.
 
You've got a code. I would start there.
You won't know for sure what component is the issue without some objective testing.
Idle control changes with change in coolant temp. Naturally it is heat related, sort of.
What is the code? What have you checked physically? Put a meter on anything?
 
I'm with you on the vacuum hose, though I definitely agree if you have a code, follow that up first. My idle issue wasn't as bad as yours, but mine was with the vacuum hose that goes between the air intake and the air intake. From being over the valve cover it takes a lot of heat and I was getting a good vacuum leak there. Easy fix if that is an issue.
 
You've got a code. I would start there.
You won't know for sure what component is the issue without some objective testing.
Idle control changes with change in coolant temp. Naturally it is heat related, sort of.
What is the code? What have you checked physically? Put a meter on anything?
The code was p0505, the 2.4l has a weird idle control setup, I took off a panel revealing a gearbox and a bit of sludge buildup, I cleaned it out and hoping this solves my problem.

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Can you provide some more pictures? I don't know what you've taken apart but I don't think it's the idle control. I know spyder is different but still.
 
I'm with pauleyman. More pics to orient us with where on the engine this is. I have the same engine but I'm not able to match this pic up with what I have and that doesn't look like the IAC. P505 is an IAC valve system fault. The IAC is bolted onto the throttle body on the bottom. It's expensive to replace so I'd test it first. I've attached a few pages from the factory manual that might help. I'd do the basic testing for the sound of the IAC motor running at the bottom of 310 and the coil testing at the top of 311 if necessary. I also included the troubleshooting flow chart for the error code, but I'd do the basic testing first.

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I'm with pauleyman. More pics to orient us with where on the engine this is. I have the same engine but I'm not able to match this pic up with what I have and that doesn't look like the IAC. P505 is an IAC valve system fault. The IAC is bolted onto the throttle body on the bottom. It's expensive to replace so I'd test it first. I've attached a few pages from the factory manual that might help. I'd do the basic testing for the sound of the IAC motor running at the bottom of 310 and the coil testing at the top of 311 if necessary. I also included the troubleshooting flow chart for the error code, but I'd do the basic testing first.

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sorry, this is right under the throttle body. in the pic I have my intake duct off and tape over the inlet. I am assuming the stepper motor is what is to the left and underneath the gearbox in the pic. Thanks for the diagrams but it looks specific to the 2.0, or am I looking in the wrong spot? I'll take more pictures later, but this is the far left of the intake manifold underneath the throttle.

Another question I have after looking at the diagram, My coolant temp sensor, The top sensor with the pigtail is to the ecu correct? and the bottom small one with a single signal wire is to the cluster right. The pigtail for the top one was damaged before me and repaired a little sketchy. Does this sensor play a role in the IAC? Wouldn't I be getting a separate code for it? Just a thought, thank you for your input
 
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If you can provide pics with more detail of the general area I can say for sure. Sounds like the IAC unit since you are saying it is bolted to the bottom of the throttle body. Since it is sealed, I'd say unless the gears are broken, there's nothing in there to grease or clean. Given the P0505 error, it's most likely electrical in nature, but of course that may not rule out a mechanical failure. The testing you want to do is at the bottom of 310 where it mentions the 2.4 engine and where it continues at the top of 311.
 
sorry, this is right under the throttle body. in the pic I have my intake duct off and tape over the inlet. I am assuming the stepper motor is what is to the left and underneath the gearbox in the pic. Thanks for the diagrams but it looks specific to the 2.0, or am I looking in the wrong spot? I'll take more pictures later, but this is the far left of the intake manifold underneath the throttle.

Another question I have after looking at the diagram, My coolant temp sensor, The top sensor with the pigtail is to the ecu correct? and the bottom small one with a single signal wire is to the cluster right. The pigtail for the top one was damaged before me and repaired a little sketchy. Does this sensor play a role in the IAC? Wouldn't I be getting a separate code for it? Just a thought, thank you for your input
It looks nothing like I've ever seen. And no I don't think that's the stepper motor in that pic. I can't see anything. Please provide pics and pics of the part you took off.
 
It doesn't look like the one on my 2.4. I replaced it once and there is no way those big gears are inside that. Here's pics of what you should be seeing bolted under the throttle body. This is the IAC valve that the code you are getting is referencing.

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Sorry, missed your question about the coolant temp sensors. You are right. The larger one is for the ECU and the smaller one just feeds the gauge cluster. Issues with the wiring for the ECU one should throw a code. Again, since you have a code for the IAC valve, I'd focus on testing that and making sure it is okay first and then move onto other possible solutions. The coolant flows through the IAC valve just to warm it up in cold weather. The thermostat not the sensor controls the flow of coolant to the IAC so I don't think the sensor is coming into play here with the code you are getting.
 
The code was p0505, the 2.4l has a weird idle control setup, I took off a panel revealing a gearbox and a bit of sludge buildup, I cleaned it out and hoping this solves my problem.

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This is the standard (early, I think) IAC valve on the 4g64. This picture is looking over the passenger fender at the IAC assembly; the air intake hose (removed) and TV/plenum are right above the picture.

These IACVs have a DC motor; you can barely see the shaft just above the left gear and right below the threaded hole. There's a rev counter (magnet and ?coil) that you can't see and the black gear drives the IAC needle valve pintle.

This system works well until it doesn't. Replacements ARE available but not necessarily easy to find -- especially if this is the early design with bronze parts. It'll probably need to be completely disassembled and cleaned, then lightly lubed if you want to try to get it working.

The later design -- with a stepping motor -- is far better.

Doing the cleaning job the first time I'd put the cover back on, remove the TV and unbolt this assembly from the bottom of the TV to work on it. It is possible to do this in the car but it's a fussy, fussy job and tiny parts can easily get lost. In the models I've worked on the screw that holds the stop for the pintle must be put back by feel -- you can't see it. It's an M3.

If you can find one, replacement is the easy and more reliable way to go.

The air passage down from the throttle bore must be plugged when solvent cleaning the TV. Otherwise the solvent runs into this assembly, washes out the lube, and it will seize up so you don't have a fast idle, 'dashpot' function, and proper control of idle RPM for A/C, etc.

Edit: Having read the comments above let me clarify things a bit. AFAIK there are three designs for the IAC function on 2.4L engines. The earliest one is the one pictured here I think. It has a bronze pintle and a DC motor that drives the pintle; positioning is done by counting pulses from a revolution counter. Then there was a second version of the same thing, functions in the same way but all the parts are plastic and in my experience the life is not as good. At a guess these two designs are on 1G cars; they're functionally equivalent but not interchangeable.

I think the 2g cars got a complete redesign that uses a stepper motor and is both far cheaper and far more reliable. Of course the control circuits would be completely different so the 1g and 2g cars would have to have different ECMs.

These two paragraphs are based on experience with the 4g64 in the Expo LRV. All of those cars are effectively 1g cars -- they never got a 2g and the design ended with the '96 model year which were identical to '95 except for designation.
 
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This is the standard (early, I think) IAC valve on the 4g64. This picture is looking over the passenger fender at the IAC assembly; the air intake hose (removed) and TV/plenum are right above the picture.

These IACVs have a DC motor; you can barely see the shaft just above the left gear and right below the threaded hole. There's a rev counter (magnet and ?coil) that you can't see and the black gear drives the IAC needle valve pintle.

This system works well until it doesn't. Replacements ARE available but not necessarily easy to find -- especially if this is the early design with bronze parts. It'll probably need to be completely disassembled and cleaned, then lightly lubed if you want to try to get it working.

The later design -- with a stepping motor -- is far better.

Doing the cleaning job the first time I'd put the cover back on, remove the TV and unbolt this assembly from the bottom of the TV to work on it. It is possible to do this in the car but it's a fussy, fussy job and tiny parts can easily get lost. In the models I've worked on the screw that holds the stop for the pintle must be put back by feel -- you can't see it. It's an M3.

If you can find one, replacement is the easy and more reliable way to go.

The air passage down from the throttle bore must be plugged when solvent cleaning the TV. Otherwise the solvent runs into this assembly, washes out the lube, and it will seize up so you don't have a fast idle, 'dashpot' function, and proper control of idle RPM for A/C, etc.
Learn something new every day.
I just checked rockauto for an earlier part and this is the pic I came up with. Looks like the OPS unit.
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This is the standard (early, I think) IAC valve on the 4g64. This picture is looking over the passenger fender at the IAC assembly; the air intake hose (removed) and TV/plenum are right above the picture.

These IACVs have a DC motor; you can barely see the shaft just above the left gear and right below the threaded hole. There's a rev counter (magnet and ?coil) that you can't see and the black gear drives the IAC needle valve pintle.

This system works well until it doesn't. Replacements ARE available but not necessarily easy to find -- especially if this is the early design with bronze parts. It'll probably need to be completely disassembled and cleaned, then lightly lubed if you want to try to get it working.

The later design -- with a stepping motor -- is far better.

Doing the cleaning job the first time I'd put the cover back on, remove the TV and unbolt this assembly from the bottom of the TV to work on it. It is possible to do this in the car but it's a fussy, fussy job and tiny parts can easily get lost. In the models I've worked on the screw that holds the stop for the pintle must be put back by feel -- you can't see it. It's an M3.

If you can find one, replacement is the easy and more reliable way to go.

The air passage down from the throttle bore must be plugged when solvent cleaning the TV. Otherwise the solvent runs into this assembly, washes out the lube, and it will seize up so you don't have a fast idle, 'dashpot' function, and proper control of idle RPM for A/C, etc.

Edit: Having read the comments above let me clarify things a bit. AFAIK there are three designs for the IAC function on 2.4L engines. The earliest one is the one pictured here I think. It has a bronze pintle and a DC motor that drives the pintle; positioning is done by counting pulses from a revolution counter. Then there was a second version of the same thing, functions in the same way but all the parts are plastic and in my experience the life is not as good. At a guess these two designs are on 1G cars; they're functionally equivalent but not interchangeable.

I think the 2g cars got a complete redesign that uses a stepper motor and is both far cheaper and far more reliable. Of course the control circuits would be completely different so the 1g and 2g cars would have to have different ECMs.

These two paragraphs are based on experience with the 4g64 in the Expo LRV. All of those cars are effectively 1g cars -- they never got a 2g and the design ended with the '96 model year which were identical to '95 except for designation.
This clears alot of things up, thank you for the detailed valuable information. I haven't been able to find anything on this style of IAC.
 
If you can provide pics with more detail of the general area I can say for sure. Sounds like the IAC unit since you are saying it is bolted to the bottom of the throttle body. Since it is sealed, I'd say unless the gears are broken, there's nothing in there to grease or clean. Given the P0505 error, it's most likely electrical in nature, but of course that may not rule out a mechanical failure. The testing you want to do is at the bottom of 310 where it mentions the 2.4 engine and where it continues at the top of 311.
bit late, but here's more pictures..

Annnd the physical problem, (img_504)
this is behind the white and black gears exposing the driving gear, (top left) and the magnetic pickup as mentioned above. The broken fitting is what the black gear sits in and has the corresponding notches. I guess this question would be best for @waltah what are the chances this could still work with just the 3 points? is it possible its just the sludge and bits of plastic that was keeping this from properly functioning?

Appreciate the help guys.

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Right, I learn something new everyday. I looked this up and it seems 98 was the year they changed this. As I've been looking for parts for my car it seems 98 was a threshold year for a lot of small changes partly due to environmental regulatory issues. The entire fuel filler/evap thing was also changed and everything around the fuel tank changed as well. Looking at what you got there, I'd spring for the new part while it is still available despite the cost. Buying that reliability I think would be worth it.
 
Annnd the physical problem, (img_504)
this is behind the white and black gears exposing the driving gear, (top left) and the magnetic pickup as mentioned above. The broken fitting is what the black gear sits in and has the corresponding notches. I guess this question would be best for @waltah what are the chances this could still work with just the 3 points? is it possible its just the sludge and bits of plastic that was keeping this from properly functioning?
Short answer: Chances this works with damage as shown are zero.

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These are the internal parts that you can take right out. Getting the cover off will almost surely require the torque of a tool like the one shown.

Make sure the gasket is in good shape and properly positioned if you take off the cover plate on a working unit. The cavity is under slight suction and will collect dirt which will be fatal if the gasket doesn't do its job.

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This is the unit with those parts out showing the head of the pintle and the stop lug you have to remove to take the pintle out. Notice the lug on the pintle pointing to about 7:30. When the car starts the pintle establishes its location by screwing all the way in -- the stop lug functions going in, too. Then it backs out to the proper startup setting. I don't think the all the way out stop -- the removable lug at 10:30 -- plays a role in this but it does prevent the pintle jamming against the gears.

With the pintle lug broken off yours has no chance of working right.

The damage you have is very common. I believe it is caused by mis-adjustment of the BISS and throttle plate stop screw so that the pintle is driven repeatedly against the limits trying to get the right idle RPM. The earliest version works the same way but the pintle and threaded part it fits into are bronze and steel -- they can take some beating. Unfortunately that design is not mechanically interchangeable -- the bolt pattern is different and the diameter of the TB differs so even if you could find it you couldn't use it.

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This is the pintle. It's bakelite and does not take much of a beating before it does what yours -- and a couple of mine! -- have done.

Driven by the motor (brass gear at left in 2nd picture) and reduction gears ending with the black gear with the splines on it the tip goes in and out of a hole in the IACV body to adjust the amount of air. The contour of the tip depends on the size of engine and other things so you can't reliably swap between models.

The proper function is the throttle plate stop provides a basic amount of air while preventing the plate from jamming in the bore. The BISS adds a fixed (but screw-adjustable) amount of air needed to get a proper idle under near minimum air conditions -- no accessory loads, hot day, warmed up ... And the IACV adds a variable amount of air needed to obtain the correct idle under the actual conditions -- colder, accessories on, throttle suddenly closed, etc.

Buy a new IACV assembly. Adjust the other air settings on the TB per the manual so that the IACV can function properly. The various logger programs report IACV steps and the specs are given in the shop manual. After initially setting them, tweak the BISS until the steps number is correct. If for example the manual says 2-20 steps then under warmed up conditions on a nice day you'd want it under 10 or so.

Be wary of any assembly sold as working on multiple engines -- 4g64 and 4g93 for example The tip size/contour is at best a compromise. It'll probably work but you may not have enough fast idle for a really cold winter day so your car will die several times before you can get it going.

AFAIK these assemblies are no longer made in Japan. The best ones (quality control) come from Taiwan.

It's not that hard to understand why Mitsubishi blew this whole thing away whenever your vehicle model went 2g. With a stepping motor everything can be in the ECU and the pintle is part of the motor -- a far less fragile/trouble prone system. Plus faster response.

Edit again: The IACV only functions when the throttle plate is closed. And it never provides much air. This is why when you open the throttle a bit the problems seem to go away: You are now managing the air and the IACV -- which is probably jammed closed -- no longer gives you grief.
 
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Short answer: Chances this works with damage as shown are zero.

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These are the internal parts that you can take right out. Getting the cover off will almost surely require the torque of a tool like the one shown.

Make sure the gasket is in good shape and properly positioned if you take off the cover plate on a working unit. The cavity is under slight suction and will collect dirt which will be fatal if the gasket doesn't do its job.

You must be logged in to view this image or video.
This is the unit with those parts out showing the head of the pintle and the stop lug you have to remove to take the pintle out. Notice the lug on the pintle pointing to about 7:30. When the car starts the pintle establishes its location by screwing all the way in -- the stop lug functions going in, too. Then it backs out to the proper startup setting. I don't think the all the way out stop -- the removable lug at 10:30 -- plays a role in this but it does prevent the pintle jamming against the gears.

With the pintle lug broken off yours has no chance of working right.

The damage you have is very common. I believe it is caused by mis-adjustment of the BISS and throttle plate stop screw so that the pintle is driven repeatedly against the limits trying to get the right idle RPM. The earliest version works the same way but the pintle and threaded part it fits into are bronze and steel -- they can take some beating. Unfortunately that design is not mechanically interchangeable -- the bolt pattern is different and the diameter of the TB differs so even if you could find it you couldn't use it.

You must be logged in to view this image or video.

This is the pintle. It's bakelite and does not take much of a beating before it does what yours -- and a couple of mine! -- have done.

Driven by the motor (brass gear at left in 2nd picture) and reduction gears ending with the black gear with the splines on it the tip goes in and out of a hole in the IACV body to adjust the amount of air. The contour of the tip depends on the size of engine and other things so you can't reliably swap between models.

The proper function is the throttle plate stop provides a basic amount of air while preventing the plate from jamming in the bore. The BISS adds a fixed (but screw-adjustable) amount of air needed to get a proper idle under near minimum air conditions -- no accessory loads, hot day, warmed up ... And the IACV adds a variable amount of air needed to obtain the correct idle under the actual conditions -- colder, accessories on, throttle suddenly closed, etc.

Buy a new IACV assembly. Adjust the other air settings on the TB per the manual so that the IACV can function properly. The various logger programs report IACV steps and the specs are given in the shop manual. After initially setting them, tweak the BISS until the steps number is correct. If for example the manual says 2-20 steps then under warmed up conditions on a nice day you'd want it under 10 or so.

Be wary of any assembly sold as working on multiple engines -- 4g64 and 4g93 for example The tip size/contour is at best a compromise. It'll probably work but you may not have enough fast idle for a really cold winter day so your car will die several times before you can get it going.

AFAIK these assemblies are no longer made in Japan. The best ones (quality control) come from Taiwan.

It's not that hard to understand why Mitsubishi blew this whole thing away whenever your vehicle model went 2g. With a stepping motor everything can be in the ECU and the pintle is part of the motor -- a far less fragile/trouble prone system. Plus faster response.

Edit again: The IACV only functions when the throttle plate is closed. And it never provides much air. This is why when you open the throttle a bit the problems seem to go away: You are now managing the air and the IACV -- which is probably jammed closed -- no longer gives you grief.
Thank you so much, I had no idea what it was supposed to look like, it's odd cause it idles a perfect 750rpm and increases/responds with accessory loads, it is only affected when brought a little over operating temp. Would it be a bad idea to temporarily adjust the BISS screw or SAS screw to idle say 900rpm till I get a replacement? Assuming this would band-aid fix the problem. Also would you happen to have a part number or name for this assembly that could point me in the right direction for sourcing out another one? I can only seem to find the stepper motor style.
 
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What year is your Eclipse? For a 96-97 Rock Auto has the following units:
STANDARD MOTOR PRODUCTS AC250
WVE 2H1201

Rock Auto gives a Mitsubishi cross reference part number of MD614698 for these units. I'd check to see what part number you have to make sure it matches. My experience is most of the time it does but there have been exceptions.
 
Yeah, they all are expensive. Looking at Rock Auto's prices, they've gone up a lot since I bought one last (like everything else lately!). But waltah has some good advice and info and I think if you get everything all adjusted as suggested, it should last a long time. And sometimes I've gotten parts from Standard and WVE that are actually just relabeled OEM Made in Japan stuff from companies like NTK so hopefully you get one of those.
 
Thank you so much, I had no idea what it was supposed to look like, it's odd cause it idles a perfect 750rpm and increases/responds with accessory loads, it is only affected when brought a little over operating temp. Would it be a bad idea to temporarily adjust the BISS screw or SAS screw to idle say 900rpm till I get a replacement? Assuming this would band-aid fix the problem. Also would you happen to have a part number or name for this assembly that could point me in the right direction for sourcing out another one? I can only seem to find the stepper motor style.
Since it sounds like your broken IACV is working somewhat It's impossible to say what will happen if you try adjusting other things.

'Not working when a little over operating temp' suggests that the IACV may be fully closing and semi-jamming there. Do you have any sort of logging or tuning software or device that will let you read the IACV steps? If you do that would let you see where the thing is.

Otherwise, what I'd do is (A) Do not change the SAS screw. That appears to be right and making it wrong will cause other issues. (B) Turn the BISS screw in 1/2 turn and see what happens -- restart the engine if necessary. It's possible that the problem started with a BISS setting too far open so the IACV killed itself trying to get the fully warm idle speed down to the correct number -- the thing broke and jammed.

Experiment with closing (screwing in) the BISS in 1/2 turn steps to see if you get better function by giving the IACV a chance to stay open some even when fully warm. If you have the steps info see if you can get it to a few steps open under that condition.

If you're watching steps you'll have to wait a minute or so for the ECM to fully respond to each half-turn adjustment.

This experiment may fail and may even make things worse but if you keep track of how far you've moved the BISS screw you can set it back where it was.

I think a lot of these things get broken when someone tries to set the idle speed higher with the BISS and opens it up. The ECM then closes the IACV, it jams, and those plastic pintles don't deal well with that.

I think it's a rare 1g/2g Eclipse that hasn't been diddled in this way by somebody by this time. I had to crank the BISS in a full two turns on my 95 GS-T to get the idle speed control to work right. It has the later type IACV so it didn't fail, but the idle was way too fast and not stabilized.

Edit: MD614698 is the p/n for my 4g64 Expos. It ought to also be correct for your car but look it up in one of the online catalogs to be sure.
 
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