Jub Nub Posted September 11, 2007 Share Posted September 11, 2007 has anyone ever had this problem: you're driving along in 2nd or 3rd, like 25 or so, holding your foot steady in one place on the pedal, and your car starts bucking and surging like it does when you kill it at a stop light, but your going like 25 or so and it goes away when you give it some gas? its like the car only wants to accelerate or slow down, no in between. does that sound like a tps problem? or would it be the auxillary air valve (which i dont have a clue about?) its a mpfi turbo on a high-comp bottom end, dr 5sp 3.90's. its done it since before i built the engine. oh it was an automatic when i got it. if anybody reads this whole thing and can help that would be cool. thanks Quote Link to comment Share on other sites More sharing options...
2K4 STI Posted September 11, 2007 Share Posted September 11, 2007 Mine does the same thing 87 RX EA82t Seems like the throttle is either on or off no in between Quote Link to comment Share on other sites More sharing options...
mcbain455 Posted September 11, 2007 Share Posted September 11, 2007 I just picked up an '86 GL-10 wagon, 5sp turbo MPFI, 120K mi. I have noticed the same thing. Based on my experience with a spectrum of 5sp. cars, from brand new to 120K mi. and small to large displacement, my assessment is that if you feel this in anything above 1st gear, you're looking at a new clutch in the near future. This is kind of hard to accept for me, because I have a meticulous set of repair records that tells me the clutch has less than 40K miles on it. That being said, I have never had a fuel-injected 4cyl this old so I would like to be told that I'm wrong. I read a description once of why this is acceptable at low revs in 1st - it had something to do with the fact that miniscule changes in throttle position are translated into perceptible jerking motions because of the narrow(?) gear ratio. Ben mcbain455 Quote Link to comment Share on other sites More sharing options...
85T-REX Posted September 11, 2007 Share Posted September 11, 2007 Ben, welcome to the forum! My '85 does the same thing. That just means it's anxious to run. One of my family members had an '86 Charger turbo that did the same thing. That's what the dealer told him too. It may be correctable but what fun is that? Nothing to worry about, just keep it tuned and under boost. That's when it's happiest. rex Quote Link to comment Share on other sites More sharing options...
4WDFrenzy Posted September 12, 2007 Share Posted September 12, 2007 I had a similar problem with my GL-10 before my wife got us stuck over here in Okinawa. I searched the forum and many of the more experienced guys pointed to the fuel pump beign the potential problem. So I changed it out, and guess what? The surging went away. I am not saying that the same thing that was wrong with mine could be the problem with yours, but if you are still running the OEM fuel pump that came with the car, you might try changing that out first. Also, if you have the money to invest in a Walbro high pressure pump(255lph), do it. I had to buy an aftermarket replacement from Autozone, because at the time it was my daily driver.But one of the things I have planned when I get back, is to replace it with a Walbro unit. Patrick Quote Link to comment Share on other sites More sharing options...
2K4 STI Posted September 12, 2007 Share Posted September 12, 2007 Does the Walbro 255 for the WRX fit the EA82T gas tank in a 87 RX? I might upgrade now just to see if that cures the problem.Plus i wanted a better fuel pump anyways. Quote Link to comment Share on other sites More sharing options...
Gloyale Posted September 12, 2007 Share Posted September 12, 2007 Does the Walbro 255 for the WRX fit the EA82T gas tank in a 87 RX? I might upgrade now just to see if that cures the problem.Plus i wanted a better fuel pump anyways. EA82 fuel pumps aren't in the Fuel tank. Might be a really tricky retrofit. Get an external style pump and it should work fine. Quote Link to comment Share on other sites More sharing options...
mrdeep2001 Posted September 12, 2007 Share Posted September 12, 2007 I had a similar problem with my GL-10 before my wife got us stuck over here in Okinawa. I searched the forum and many of the more experienced guys pointed to the fuel pump beign the potential problem. So I changed it out, and guess what? The surging went away. I am not saying that the same thing that was wrong with mine could be the problem with yours, but if you are still running the OEM fuel pump that came with the car, you might try changing that out first. Also, if you have the money to invest in a Walbro high pressure pump(255lph), do it. I had to buy an aftermarket replacement from Autozone, because at the time it was my daily driver.But one of the things I have planned when I get back, is to replace it with a Walbro unit. Patrick Did you test it at all, or did you just swap it out? Jub Nub keep me posted b/c I am having the exact same problem. My car was doing the exact same thing, except now my car seems to lose power around 2000-2500 RPM Quote Link to comment Share on other sites More sharing options...
mykingcrab Posted September 13, 2007 Share Posted September 13, 2007 me tooooooooooooo..... its got better since its driven more,but still exists. you might read both threads:burnout: http://www.ultimatesubaru.org/forum/showthread.php?t=75533 http://www.ultimatesubaru.org/forum/showthread.php?t=64610 there is also a thread somewere about great replacemernt FORD fuel pump,anyone got the link? thanks let us know, i think its a world wide mystery.:cool: Quote Link to comment Share on other sites More sharing options...
mrdeep2001 Posted September 13, 2007 Share Posted September 13, 2007 me tooooooooooooo..... its got better since its driven more,but still exists. you might read both threads:burnout: http://www.ultimatesubaru.org/forum/showthread.php?t=75533 http://www.ultimatesubaru.org/forum/showthread.php?t=64610 there is also a thread somewere about great replacemernt FORD fuel pump,anyone got the link? thanks let us know, i think its a world wide mystery.:cool: I just want to make sure that the pump IS what is bad. I want to try and test it first. Ford F150 fuel pump early 90's there is an intake pump and an inline pump closer to the engine. you want the one closer to the engine. "Ford inline fuel pump works; Napa part number 2P74028." courtesy of misledxcracker Quote Link to comment Share on other sites More sharing options...
Cougar Posted September 13, 2007 Share Posted September 13, 2007 Fuel pumps are one of the possible areas for this trouble. I would first check the throttle sensor for a bad spot on the wiper contact. One thing that could be done to rule out a dirty TPS sensor contact connection is to watch for voltage fluctuations on the wiper connection of the sensor using an analog meter. Quote Link to comment Share on other sites More sharing options...
mrdeep2001 Posted September 13, 2007 Share Posted September 13, 2007 i apologize for my ignorance, but what do you mean by the wiper connector? The plug that connects to the tps? Mine has 4 wires on it. Quote Link to comment Share on other sites More sharing options...
Cougar Posted September 13, 2007 Share Posted September 13, 2007 No problem on the lack of knowledge. The TPS sensor is basically a variable resistor. The wiper part of the sensor is the piece that moves up and down the resistor. There is a reference voltage across the whole resistor and as the wiper moves up or down the resistor the voltage changes. The voltage changes are fed to the ECU to show the accelerator changes. Problems can happen when the wiper moves across a bad or dirty area of the connection. Quote Link to comment Share on other sites More sharing options...
mrdeep2001 Posted September 13, 2007 Share Posted September 13, 2007 ah ok i knew the voltage would vary as you open up the throttle, just didnt know the mechanics of what was actually going on Quote Link to comment Share on other sites More sharing options...
4WDFrenzy Posted September 13, 2007 Share Posted September 13, 2007 Did you test it at all, or did you just swap it out? Jub Nub keep me posted b/c I am having the exact same problem. My car was doing the exact same thing, except now my car seems to lose power around 2000-2500 RPM No, I didn't test the old pump at all. I just swapped it out with the new one since at the time, my wagon couldn't be down for long periods of time, considering it was the only car we had at the time. But like I said, after swapping the pump out, the problem went away. Quote Link to comment Share on other sites More sharing options...
4WDFrenzy Posted September 13, 2007 Share Posted September 13, 2007 EA82 fuel pumps aren't in the Fuel tank. Might be a really tricky retrofit. Get an external style pump and it should work fine. No retrofit required. All you have to do is get the universal pump kit. It supposed to come with the brass fuel fittings for the inlet and outlet of the pump. If you can't find one, just order a Walbro pump kit(high pressure style) and go to the autoparts store and get the fittings, which should net you under $5 for the fittings, depending on you locale. Patrick Quote Link to comment Share on other sites More sharing options...
4WDFrenzy Posted September 13, 2007 Share Posted September 13, 2007 No problem on the lack of knowledge. The TPS sensor is basically a variable resistor. The wiper part of the sensor is the piece that moves up and down the resistor. There is a reference voltage across the whole resistor and as the wiper moves up or down the resistor the voltage changes. The voltage changes are fed to the ECU to show the accellarator changes. Problems can happen when the wiper moves across a bad or dirty area of the connection. I second that. Since the TPS sensor is already on the car, you might want to check it first. I forgot to mention that I checked mine before getting on the forum and having a pump change recommended. Now if you have a bad sensor, be prepared for a bigger shock, since they aren't exactly cheap, brand new. When I checked at the loacal AutoZone in Wichita Falls, TX, they were singing somewhere to the tune of $200 plus for the stupid TPS sensor. I don't know if prices have fallen since, but I was so happy when I found out that my TPS wasn't bad. Patrick Quote Link to comment Share on other sites More sharing options...
2K4 STI Posted September 15, 2007 Share Posted September 15, 2007 Where is the stock fuel pump? Quote Link to comment Share on other sites More sharing options...
Cougar Posted September 15, 2007 Share Posted September 15, 2007 Under the car near the right rear wheel area. Quote Link to comment Share on other sites More sharing options...
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