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420A 95 eagle talon 2.0 non turbo idle surging (video) help!

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jazzman170

Probationary Member
9
0
Aug 27, 2016
Porterville, California
VIDEO:
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Vehicle: 95 eagle talon 2.0 non turbo, manual 420A engine

In the video you notice i only hit the gas once and it sticks at 1600 rpm as the idle before going back to normal and then to surging. Normally my car keep's the high idle, it has the high idle of 2k and 3krpm more often than surging like in this video. You can imagine how annoying this is to drive when its at 2k or 3k rpm and im coming off the clutch, or im at a stop light -.- This is especially annoying since if its surging like in the video and im accelerating because of a green light, when cars are in front of me i cant just kinda coast in 1st or 2nd because its surging and shaking the entire engine due to it giving it gas/lowering/gas/lowering. I have to drive fast and idle it coasting behind people sometimes LOL

I have been dealing with this issue for months. EVERY sensor on the car has been replaced aside from crank sensor! There are no vacuum leaks as they have all been found and fixed. The only thing im thinking it could be now is a faulty ECU that is having issues with either the IAC (Idle air control) or TPS (Throttle Position Sensor).

When i had my brother check the wiring, the IAC wire had been siting on something hot and was grounding out (Metal on metal, it melted through the wiring) and looked to have been that way for quite some time as the wire was almost melted through entirely. He cliped out the bad metal and soldered the ends together, taped it up and it changed nothing with the surging.

Sometimes the car is perfectly fine and doesnt surge but holds at 2k rpm, sometimes it holds at 3k rpm, all while not giving it any gas. The day's it does a good normal idle it starts off that way but after driving it for a very short while it starts sticking at 2k rpm and holding. Other times it'l surge up and down.

The other day on my way to work i went to go get fast food and turned my car on/off multipe times as i moved through the line. Turned my car on and got my food, headed out to work and noticed it seemed to be lacking a bit of horse power. The moment i hit 3500 RPM it started kicking back as if i unplugged the TPS. I turned the car off (while going on the road) and turned it back on and hit the petal to see if it got past 3500 rpm or still kicked back but it was good to go again (Aside from the normal sticking at 2k or 3k rpm when idle)

Sometimes (Rarely) my engine will jerk really hard while im driving and it goes back to a normal idle, other times when it jerked it goes back to normal but returns to the high idle or surging idle. I'm not sure if its the computer trying to adjust something and succeeds but then fails or what, but again that rarely happends. Has only ever done that hard jerking maybe 2 or 3 times in the 2 years i've owned it that its been doing this. I'm only mentioning it because its odd

Does this sound like a faulty ECU with something to do with the TPS?

Please dont say to replace sensors, i have replaced the IAC and TPS each 4 times now, those arent the issue. All other sensors are new as well, and under warranty. I even replaced the TPS and IAC after i fixed the melted wire.

Check engine line comes on and off due to i dont have a speedometer sensor plugged in.
What do you guy's think? I'm at a loss. The guy at autozone even said when customers send their ECU's in for a fix, most of the time they get them back and the problem wasnt fixed. I dont know where i can get a spare ECU that is just plug and play for my car and no vendors make/sell new/re-manufactured ones anymore. It seems like my only choice is to give autozone my ECU anyways and gamble. Its not cheap, couple hundred and if it doesnt even fix my issue that would be horrible
 

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sounds fuel related, because this didn't happen until the on/off's in drive thru line. What is the condition of fuel filter and pump? Fuel pressure and pressure to the pressure regulator and is diaphragm good in reg? You could always pull out ecu and open it and look for anything that's bad to eliminate that also.
 
sounds fuel related, because this didn't happen until the on/off's in drive thru line. What is the condition of fuel filter and pump? Fuel pressure and pressure to the pressure regulator and is diaphragm good in reg? You could always pull out ecu and open it and look for anything that's bad to eliminate that also.

Fuel filter and pump are both new, fuel injectors were all replaced and are cheapies (32 bucks a piece) but remanned. I even replaced the plastic tips on them to a more durable kind that doesnt crack as easily. I could have my brother check the injector's once again to make sure they arent cracked?

how do i go about finding out about the fuel pressure and pressure regulator? Not sure what you mean about is diaphram good in reg.

I already pulled the ECU and its FULL of a gel looking stuff that makes it incredibly hard to see the chips, im talking a few inches thick of this gel stuff all through the ecu.

Thanks for troubleshooting with me, i greatly appreciate it.
 
I wonder if the speed sensor not being plugged in is messing with the IAC. Have you ever had the speed sensor plugged in? What's the story there? Why is it not plugged in?

Yea 420a ecus are filled with gel. Don't even bother trying to dig it out. It doesn't come easy.
 
Also have you checked pcv valve and lines?

Yep i replaced the pcv valve (thats it in the picture below right?) about 5 months ago. This new one does make a rattling sound tho, as if there is a bearing inside flying around with the air zooming through it.
It only has the one line hooked onto it so im guessing thats the lines your talking about? My brother and i have sprayed brake/carb cleaner all over this vehicle's engine and havent found any leaks although im tempted to go buy a can or 2 and check again
 

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I wonder if the speed sensor not being plugged in is messing with the IAC. Have you ever had the speed sensor plugged in? What's the story there? Why is it not plugged in?

Yea 420a ecus are filled with gel. Don't even bother trying to dig it out. It doesn't come easy.

I replaced the transmission from my 95 eagle talon to one from a 97 eclipse, the sensor on my original tranny was messed up and needed a rebuild. When the new used tranny came in we put the sensor from my original tranny into this new one. Turns out its not compatible because it makes the engine have small spurts of loss of power in the lower rpm when driving. I'm guessing i need a speed sensor FOR a 97 eclipse now?

We already scrapped the old tranny and sensor so i cant get the one that it came with back. I did try plugging in the sensor to see if it brought the idle back down to normal, it did not :(
oooh lemme get a video
 
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Ok so its not that it backfires, its more like small spurts of loss of power and it shows im going way faster than im actually going. Also after i was driving for a bit, the check engine light kicked on and i felt a loss of power (Had to push the pedal a bit harder to make up for it) and as soon as i hit 3500 rpm it started knocking back as if i unplugged the TPS. I turned the car off while coasting and turned it back on and it was back to normal (aside from the idle surge and spurts of loss of power because speed sensor is plugged in). It also smells bad (same smell as if you unplug tps and full throttle it, that knock back at 3500 rpm makes it exhaust smell bad). Also keep in mind the TPS has been replaced 4 times, so its definitely not a bad tps.I believe the code its throwing IS for a TPS though, so thats why my suspicions are a faulty ECM

Having the speed sensor plugged in made no difference for the idle surging or idle holding at 2k'ish/3kish rpm

In the video, you can actually hear the stuttering of loss of power as im taking off. (This is due to speed sensor plugged in) so im pretty sure we can outrule the speed sensor as a possible cause?

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^That^ sounds like fuel cut.

BTW I wanted to chime since this thread made me laugh pretty good. I have to say, you meet all the criteria to become a dsm owner. :)
Dont take it too hard though, we were all once there. Just takes some time to figure out all of the problems.

I would also make sure your throttle isnt sticking. Ive had that happen to me a few times.
 
^That^ sounds like fuel cut.

BTW I wanted to chime since this thread made me laugh pretty good. I have to say, you meet all the criteria to become a dsm owner. :)
Dont take it too hard though, we were all once there. Just takes some time to figure out all of the problems.

I would also make sure your throttle isnt sticking. Ive had that happen to me a few times.

haha good to know ^_^ i've been trying to figure out this mystery machine for quite some time! I have thrown a LOT of money into it and still cant nail this idle surge issue. If it sounds like fuel cut, are you referring to how its acting with speed sensor plugged in or to how its acting when idle surge? In either case, you think its the fuel pressure regulator? I dont think i've ever replaced it. I just called autozone and they said i do not have it under warranty so that confirms it probably hasnt been replaced before haha. Cost 100 bucks :(

As for the throttle, we put on a spare throttle body that my brother had and it all looked good and clean so thats not it, and the throttle doesnt stick anymore after we removed the cruise control and plugged the vacuum line (which when we did we also saw it had a leak LOL). That was about 8 months ago
 
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Just checked the fuel regulator, its not leaking or has any raw gas in/around hose. Probally couldnt hurt to replace it but for 100 bucks i dunno.

One thing i should mention to everyone, when i start fiddling with the TPS it effects it by either lowering the idle back to normal (sometimes) or raising the idle if its at normal. It seems like its insanely sensative and the slightest of touch can effect it for the better or worse. The tps is on there tight and doesnt budge and the connector was replaced just recently with 1 from a junkyard (clipped and soldered) because this was doing the same thing before hand. I didnt think it was worth mentioning but it may very well be the problem. I can get a video if anybody is interested

VIDEO:
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Just wanted to give an update on this thread. I wont call it a dead thread, I am now the owner of Jazzmans Talon, so this thread has somewhat a happy ending ha. It was the autozone brand Duralast TPS causing his idle problem. That was it. I had Jazzman order an OEM style TPS 2 months ago and after putting it on there has not been one instance where the idle fluctuated. Pretty crazy that a replacement TPS could cause all that trouble. I call a bad design, even talked to the Autozone reps that come to the shop I work at, they said to call a number and they would actually redesign the TPS if its not working. I mean Jazzman went thru maybe 3 of those duralast TPS under warranty, all 3 were bad. OEM was golden. Now, he mentioned the fact that there is now a model year 97 manual trans in the car. Im the one that installed it for him a year ago or so. I really dont remember the VSS since I was tired as hell when I was doing the work. The speedo reads double the speed it should. Im wondering if there is a signal output difference between the 95-96 and 97-99 cars. Im going to start playing around with the VSS stuff soon, but if anyone has any info feel free to chime in! If worse comes to worse I will simply put in an aftermarket speedo that is programmable by distance driving or something, GPS driven is a good route too.
 
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