Need help! 4A-FE rough idle..... - Toyota Nation Forum : Toyota Car and Truck Forums

ShadowH101 · 03-20-2008, 12:21 AM

Hello...I've got a 1991 Toyota Celica ST with the standard 4A-FE engine in it. About a month ago, it started to run rough and idle rough on me, especially when stopping at red lights or stop signs. My engine will make like it's about ready to cut out on me by dipping heavily in RPM for a second or two, and then will jump back up and either idle rough at about 750 rpm in drive or will jump between 700-750 rpm in drive. I cannot obviously see a vacuum line cut or off, though I think this is what it is, but does anyone have other suggestions?????? Would greatly appreciate avoiding the auto repair shop!!!!!!

It is Auotmatic, and the car has about 131,000 miles on it...anything that the engine is known to have go out around this time that would cause this? Suggestions please.......

bobbyex · 03-21-2008, 01:37 AM

you might have a misfire or bad air/fuel mixture. any check engine light?

ShadowH101 · 03-22-2008, 11:46 PM

No, no check engine lights..........if there was one, then I would've went and jumped the E1 and TE1 terminals to see what it flashed. I have just replaced the spark plugs with some iridium plugs (NGK, of course), and that gave a little bit of a boost, but it's still doing the same thing. Could it be anything else, and where would be the likely place that I would have a vacuum leak, or rather where is it that the 4A-FE engines USUALLY have this problem??????

wilber · 03-29-2008, 11:00 PM

Could be your fuel filter,try changing it,specilly if engine started doing this out of the blue.

wilber · 03-29-2008, 11:03 PM

Also ,if equiped with a timing belt check to see if any slack in it and if it is still aligned,slack in belt will make it run rough.

Tezmaster · 03-31-2008, 07:59 PM

i have a 3sge engine and i had a similair problem,

but from 1000 rpm to 1500 at idle, the fix was clean the air flow sensor! or to jerry rig it open the top up and move it 3-6 teeth.

ShadowH101 · 05-27-2008, 11:01 PM

I will be doing the timing belt in the next few days ( as I do not know when it was changed last from when I bought the car), so I will go and do that to take care of the belt, the oil leak I have found to be in there (as there is oil baked on the outside of the middle (No. 2) timing cover), and to make sure that my timing is good before I go on in my troubleshooting to make sure that my belt hasn't slipped a few teeth.......and I will keep that MAP sensor idea in mind to check it later and possibly clean w/carb spray...........

P.S: Sorry I haven't been on lately....been busy with things and haven't had time to get on and reply......

ShadowH101 · 05-27-2008, 11:02 PM

I will be doing the timing belt in the next few days ( as I do not know when it was changed last from when I bought the car), so I will go and do that to take care of the belt, the oil leak I have found to be in there (as there is oil baked on the outside of the middle (No. 2) timing cover), and to make sure that my timing is good before I go on in my troubleshooting to make sure that my belt hasn't slipped a few teeth.......and I will keep that MAP sensor idea in mind to check it later and possibly clean w/carb spray...........

P.S: Sorry I haven't been on lately....been busy with things and haven't had time to get on and reply......

ShadowH101 · 06-08-2008, 11:06 PM

Did the timing belt, and found one of my oil leaks and fixed it, which was my camshaft seal leaking down the side of my cylinder head. However, the car still idles like it did before. And a few days ago, I checked on the NGK Iridium plugs that I popped in there 3 months back, and they were RED!!!!!!!!! I couldn't believed it! $40 in plugs gone in three months!!!!! I have to solve this problem, especially with the poor gas mileage I'm getting (it seems) and the price of gas going up past $4 a gallon. Now, I've talked to a few people about my plugs, and they have either said that I'm running hot (even though my car has NEVER, EVER overheated) or I'm running lean (which seems more probable). Any more suggestions would be appreciated. I think my next move would be to scrounge up a few used parts, such as the MAP sensor, from the local junk yard and clean them out and switch them out to try to get a feel for what is going on with my air/fuel mixture. Like I said, I would REALLY APPRECIATE any suggestions!!!!!!!!!!!