I recently bought a 1992 Celica GT with 250k miles on it. It has a rough idle and a couple other things that may or may not be stemming from the same thing that's causing the rough idle, and I'm just looking for a bit of guidance. I did a search on these forums for rough idle on a 5SFE but it looks like it could be any number of things so I'm wondering if someone could help me narrow it down.
Like I said, it has a rough idle and there is a bit of jerking sometimes during acceleration. The exhaust makes sort of a "put-put-put" or "chirping" sound at lower RPMs and the frequency of the sound corresponds to the engine RPM. I do know of a couple things that could be causing the rough idle and maybe even the jerking, but I'm not sure about the sound from the exhaust.
The cooling fans are hard wired to the ignition so they run constantly, so when it's cold out like it is right now it takes forever for the engine to warm up. Is there a switch somewhere that they are supposed to be wired through? Where would that be? Also, the previous owner did kind of a hack job of putting on a cold air intake and I think I may be missing some sensors, especially because it seems to burn more fuel than it should. What sensors are located on the air intake, or are there even some in the stock airbox itself? And would this possibly be contributing to the rough idle and the jerking?
Also, I do get some vibrations when stopped at idle so I think I may want to replace the motor mounts. Would that do anything to help alleviate the other problems? I'm pretty lost with respect to the exhaust sound, I could make a recording of it though and upload it somewhere if that would help. I'm sorry I know this is a really long post, and I'd appreciate any advice that anybody has. Thanks so much!
Hey, sorry, just an addendum: If anyone has a wiring diagram that includes the radiator fan, that would be extremely helpful. I have the Haynes repair manual but it does not include a wiring diagram with the radiator fan. Thanks
The biggest culprit for a rough idle on these is the idle air control valve, that being said, I had a rough idle as well, with that having been cleaned and it helped some but didn't solve it, I think mine may actually have to do with my MAP sensor as its the last thing that will have any effect on my a/f ratio that I haven't checked out or replaced.
Are you sure the sound is coming from the exhaust? There is a bracket right underneath the engine with a clamp on it, I'd make sure that is attached, as well as th bolts on the bottom of the cat where it connects to the downpipe as I had both loosen on me. Also the heatshields around the exhaust manifold tend to be VERY noisy as well
I have PMed you a link to wiring diagrams since there are a few possibilities.
As for the intake tract, there is one sensor on the airfilter box(the intake air temp sensor), the rest are all on the intake manifold or throttle body. In the PM I have included a diagram as well
The motor mounts could possibly have a bit to do with your sound as if the front and rear mounts are worn the motor could rock about more than it should.
If you can capture the sound, it would help greatly.
I have a very similar problem. Mine only happens when the engine is warm on stutters off the line until 2k and makes that weired chirping noise in the exhaust.
What I have done is unplugged the TPS (throttle position sensor) and I have a high idle 1200k but it fixes the rest, could you unplug yours as well drive it for a bit see how it feels and let me know. Its sounds like we are both trying to track down the same problem. And that would be a nice control to see if unplugging the TPS helps yours as well. Then maybe we can find the real problem
Well the chirping under heavy load/stuttering/ bogging likely is just the exhaust getting moved around abruptly, and probably squeaking against a clamp. Mine does that if I bog the engine down letting off the clutch too quick
Thanks everyone! I got the fans wired correctly now. The intake air temp sensor is actually still in there but the airflow sensor that is on top of the stock filter box is not. I'm thinking I'll make a trip to a junkyard soon and pull the stock intake out of something with a 5SFE, probably a Camry since I don't see to many Celicas in junkyards. Would the one out of a Camry work? Also, I'm looking for the wiring that would plug into that sensor but I don't see any loose wires or connectors anywhere. Where does that particular wiring come out of? If anyone has a picture that would be awesome. I really hope the previous owner didn't just cut it off
And aliened, thanks, I'll try unplugging the TPS sometime soon and let you know what happens. Oh yeah, and I have an mp3 file with the sound I'm getting from the exhaust, I'll upload that somewhere real shortly and post the link.
Junkyards will do you NO good when it comes to the mechanical aspect. I was in a position of trying to find a stock intake hose myself..went around winter, even all the camry's I came across had their hoses gone or were in a complete piece of sh*t state, cracked or taped up. And I can't imagine the camry hoses to work because their's has too many other openings where as the Celica has only 3 openings [one connecting to the throttle body, 2nd to the resonator box, and 3rd to the air filter]..unless you manage to find a way to clog up all the openings.
My hose was cracked on the end by the throttle body, so what me and my buddy did was flip it around to get the end of the air filter clamped to the throttle body, got rid of the resonator box, and taped the living sh*t out of my hose lol. It's temporarily good. I used to cringe to the thought of taping, but my buddy convinced me through desperation and i'm not too ashamed bc it actually is holding up. It's been 2 months and it's still holding up. Gotta retape untill I manage to permanently fix this lol.
Best choice is to make up some sort of a hose yourself using alum pipes. Grab a small one to a certain degree, and then a straight one, connect them all together.
There should only be one sensor on the intake hose or airfilter box. The one on the filter box should be the intake air temp sensor, all the rest lie on the intake manifold or throttle body. I'll try to take a few pictures later
Sorry Rob, you're right, I was looking at a diagram for a different model. The intake air temp sensor is actually still on my intake, so I have all the sensors. Given that, I doubt the intake is the main cause of the roughness and the generally poor way the engine runs. And thanks VanBam, I think I'll hold off on the intake a little while.
To aliened, and everyone else, unplugging the TPS actually does make the engine run and idle a whole lot better! Does anyone know why that might be? Also, here's a link to the exhaust sound (although it goes away without the TPS, except sometimes during acceleration): http://www.filefactory.com/file/ca8b...aust_sound.mp3
Check your egr. Pull the vacuum line from the top of it then use another hose and suck through it like a straw when the engine is warm and lightly. The engine should stall.
Its the hose labled as #2
Next I would clean the egr by pass switch which is the little round piece to the left with two hoses coming out of the back. (Mark the top of the piece with a sharpie so you know what faces up when you screw it back in, also note which hose goes to what side, switching the hoses will cause the engine to run weird.
I would also check the egr module which is the larger piece to the right which has one hose coming in form the left and two going out to the right. When the car is warm unplug the two hose coming out from the right and place your fingers over the holes, you should feel a slight airflow. You can also pop the top off and look at the filter inside.
Next you can check the vacuum ass. In the picture I took there is two but you will only have one. There is a vacuum line coming out of the bottom when the engine is warm remove that vacuum line the car should run different while driving or just stall.
The last thing i did was replace my rotor and cap on the distributor which was like 15 bucks for both.
AND HAVE YOUR TPS PLUGGED WHEN YOU DO ALL THIS. Also when you have done all this unplug the neg side of you battery and let sit for 5 minutes then take it for a test drive.
Let me know if you have any questions
To aliened, and everyone else, unplugging the TPS actually does make the engine run and idle a whole lot better! Does anyone know why that might be? Also, here's a link to the exhaust sound (although it goes away without the TPS, except sometimes during acceleration): http://www.filefactory.com/file/ca8b...aust_sound.mp3
Try the steps about the exhaust sounds like it just trying to keep tune when the car is running rough.
Use a think cloth or heavy gloves, and while the engine is running and you hear this, slide underneath the car and try holding different or moving around spots on the exhaust, if nothing is noticeably moving about/scraping it may be a heat shield. At least, thats what it sounds like to me.
Thanks, both of you! Rob, I will try that as soon as I can and let you know what's up. And to aliened, I will try that but I may not be able to do it until this weekend. Did doing all that help yours run better or is it just for the purpose of diagnostics? Also, I'm going to take it to a mechanic soon to do a compression check (that's a bit beyond what I'm comfortable doing myself) so that may also reveal some things.
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92 Celica GT - Rough Idle
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