HELP! I have a a semi bad idle. It fluctuates between 800-1200 RPMs untill the car is warmed up. Then it stays at about 850RPMs. But when I take off in the car it sputters and feels very slow untill about 3500 RPMs and then it shoots off and feels normal, if not, even better than normal. I changed the PCV Valve, IAC Valve, Plugs, Oil, and cleaned the throttle body. All this has happened since I put in another used engine in my car. I checked the timing before it went in, and it seemed good. My idle vacuum seems good. So what else should I check or replace?

Recheck the timing and check the compression. I'd say change the fuel filter, but if this only just started happening with a new motor then I would suspect the motor.


95 Eclipse RS : 5 speed
15.7 @ 87.9mph
Jeep TB writeup - http://www.dimensia.com:81/jimbo/JeepTBfor2gnt.html

check your tps

I still belive the timing is fine but I will change the fuel filter, even though it was replaced less than a year ago. I bought a used motor, but the guy who sold it to me showed me how it ran fine. I was getting a code 25, but I replaced the Idle Control Valve, and disconnected the battery for a minute. Now the cel doesn't come on anymore, but when I do the keydance the code is still in the system. Maybe I should pull the engine fuse to get rid of the code, and see if that helps. Also, how do you know if the tps is bad?

yes i would say fuel filter also. here's my little write up i did on dsmtuners on changing the fuel filter... if you've never done it before.

The fuel filter is located on the passenger side about 8 - 10 inches before the rear wheel and it's about 6 - 7 inches under the car. there are only 6 bolts needed to be taken off. 2 for the bracket that holds the filter on and 1 that secures a break line to that bracket . use a 12mm socket for those 3 bolts. the other 2 bolts are the main inlet and outlet screws. use a 3/4" box wrench for the outlet side, because a socket won't fit up there. use a 3/4" socket on the inlet side. the last bolt is a very small size socket, i don't remember what size, i think it was an 8mm or 9mm socket. this last bolt holds the filter inside the bracket. there will be a real nice bit of gas all over the place if you don't use a pan of some sort to catch the gas. just make sure you take note of the which side is which on the filter when you put the new one in place, if you mess that up your car won't run very well. and if anyone is reading this and is about to go buy a fuel filter then READ THIS: if you have a 95-98 talon, the parts catalogs at most autozone's, advanced auto parts, pepboys, napa, etc. say that you need fuel filter # FF634. i bought that filter before i saw what mine looked like (i have a 96 talon by the way). when i got it home, it was too big, so i had to go back to autozone and have them look up a 96 eclipse to see if it listed a different fuel filter... it did. the correct fuel filter for 95-99 eclipses/talons is #FF611. i hope this will save tons of time for everyone changing their fuel filter. i'm glad i could help anyone out.

My car is a '95 with the fuel filter on the firewall. Is there a good writeup for that? Also, what are the symptoms of a bad fuel filter? I just replaced mine less than a year ago with the NAPA Gold one. Also, the stutter is only at RPMs less than 3500. After that my car runs fine.:shrug

Could plug wires cause the problem? Is there anyone in the Houston area that could help me?

hey, guess what i get sputtering till almost 4,000 RPMS, and i have replaced a ton a crap so far, most likely its not plug wires. does it do it in 1st gear?

I am an automatic and as far as I can tell it does it in every gear except over drive. It feels like my car has to power untill 3500 RPMs and I have a semi "lopey" idle. But I guess hats what I get for when all I ask for is a cheap "running" motor. So it doesn't really bother me too much. I only paid $600 shipped for it. But I still would like to get the problem fixed!

Bump. Can anyone help?

Did you put in the motor and use the sensors that came with the boneyard motor?

Could be coolant temp sensor, especially if it engine temp related.

Could be MAP sensor, check plugs, wires, O2 sensors. Any of the full list of things that the ECu uses to set fuel and timing curves.



Exile Racing Technologies: http://www.exileracing.com
So. All that's left, is... everything - Jesse James

I used all the sensors off my original motor. I checked the resistance between the wires, and they're all good. I just don't see the problem?:shrug

Could my problem be either the map senser or tps, even though I'm not throwing codes for them? Could plug wires be the problem?

why go through this all again. search for, 'anyone having the stuttering problem' or something like that. there is a huge post about this already.

Its not a stuttering problem. I have a semi-bad idle, and my car seems very slow until I hit 3500 RPMs. Then it acts normal again. I replaced the plugs, pcv, crank senser, cam senser, coil, IAC valve, oil, checked the timing, wire resistance is good, cleaned the trottlebody, and I still have the problem.
All this is a different problem than which you guys had.

I would say to try the plugwires. I doubt it is the fuel filter because normally that is a problem that rears it's ugly head the whole time the car is running and is not RPM specific. Now plugwires are generally gonna give you problems in the higher RPMS, but with the list of things you have replaced I would juts try wires. Or if you have any local 2GNTers try the wires off their car. My next suspect after wires would be the coil. Again try someone elses coil if at all possible because I know these aren't cheap.

I did replace the plug wires and coil. It weird how my car acts. Its like my timing is retarded, but its actually dead on?:shrug Maybe the used engine I got had the head milled, so the timing marks would say its fine, but actually be incorrect. Is there someone in the Houston area that I could stop by and show it to?

oh i see... Sounds just like my problem though. my car would be weak as hell till about that rpm range. then it would be fine. i just checked my gap, o2, wires, plugs, bla bla bla, i just switched wires around and pulled some off to see a difference.

^^^Well, did you find the problem, and were able to fix it?

i just changed my plugs. then it went away. then it came back shortly later. so i changed wires. went away. came back once, but i haven't done anything and no sign of it. :shrug

Well, it turns out my probelms have been caused by the timing being off by one tooth. It was fine when I checked it the first time before I put in the engine, so I'm assuming somehow it skipped a tooth without hurting the valves or engine, OR the belt got more tension when it was started for the first time. But anyways, I called around, to see who could adjust my timing. Cause I'm feeling lazy and its raining alot down here. And there is a small shop who will do it for $30 and they said it should take them no longer than an hour. Am I getting a good deal or what? I wonder if they know what they are in for. I did say timing belt, and NOT ignition timing. So I just hope they know what they're doing!