used to run great

[32621]

hello to all,i am new to this forum,and i hope to get any help possible.

i have a 92 corolla 4afe,used to run great,until i removed and replaced the
tps,now it stalls when a/c turned on,timing changes from 5 btdc
to 12 bdtc,idle varies from 900rpm to 1300 rpm,what did i do?
can a throttle sensor cause that much problems or am i looking at ecu problems and just happen to hit it at the wrong time?
i have 3 other toyotas and they have run pretty much flawlessly,thank god.

any help is appreciated
thank you,
32621

[teamyoda]

well if your idle surges up and down dramatically (about 300-500rpms) it probably is an ecu problem. your tps should come back to starting position. did you use a new one or one you found at a junk yard? when you turn your ac on it is supposed to up your rpm's because it's taking power from the motor. just like when you turn your wheel all the way one direction with power steering the idle will rise to compensate for the drag on the motor. and sometimes you overlook things as you do mods to your car. check to see that everything is connected right. double check right before the intake manifold by the throttle body and the tps. maybe you bumped the maf sensor?

[32621]

thanks for reply,

the tps is new, the throttle body new(rebuilt),distributor(new)
wires,etc.all new.

i hoping it wasn't an ecu problem,know where i can find
a decent one?

since i have already replaced alot of the vehicles components
i might as well finish it.
thanks again.

[90 GP]

When you replaced the throttle positioner did you simply bolt in place or adjust per service manual? There are adjustments to make with a feeler gauge to set it up properly. Also check the vac line running to the map sensor (on firewall) to make sure it is intact.

[32621]

the first time i r&r the tps i just shadowed where the previous one was,
the second time i had already removed the throttle body and with the tps attached i removed the tps cover and saw how the contact points moved as
the throttle opened and closed,and adjusted that way.
i checked the vaccum line from the map sensor to the intake,when i remove it idle goes down,checked for leaks ,none.
with all the symptoms and the parts i have replaced what do you think it could be?
the idle flucuates,timing marks change when fans starts,car stalls if a/c
turned on,wow,something had to go bye-bye.

i just got my porsche 951 running like a champ,this corolla which has
alot less to the engine has given me more problems.

thanks

[teamyoda]

if the car will start, describe what happens when you WOT the gas peddal. so sit in the drivers and have it idling if you can, then punch the gas peddal all the way. don't hold it just punch it quickly. let me know what happens. because if it hesitates, then that would lead me to believe it's a timing problem. as i have had in the past. also, when the car is idling can you smell unburned fuel from the muffler? it could be timing because if your timing is not correct, when you kick on your a/c it might not have enough power to run both. try this... loosen up your distributor and move it clockwise and counter-clockwise and see if the idle sounds better. you might just have your timing advanced or retarted.

another thing... when you installed your new distributor, did you have the no.1 cylinder at TDC? that is important.

hope this helps

[32621]

engine revs with no stutter at all,
thats what is so frustrating,you can hit throttle and engine revs great.
turn on a/c,put in gear,or fan turns on,runs very irratic.
when replaced dist.,made sure tdc#1 piston and rotor points to #1 post.
adjusted dist. and timing with light last night again,idle smooth at 1000 rpm
10btdc solid,no change
turn on anything to cause power draw,engine starts to stutter and choke,
idle changes,timing changes,weird.
checked vaccuum hoses,leaks,etc.
about to check out ecu/ecm like you suggested.
thanks.

[teamyoda]

make sure when you and if you look for an ecu to get the manual ecu. don't get the ecu for the automatic as it will cause your idle to surge up and down for some reason.

EDIT:

this makes me wonder if you should have your alternator checked. because if you are running ok until the power is drawn that
would point to the alternator. because if your alternator is not putting out enough voltage, when you turn on other electrical things it will take power away from the power needed to fire the spark plugs. or igniter for that matter. I would have your alternator tested. you can do that at napa or schucks. I would go to napa as they have a insane computer thing that tests both ac and dc output.

[32621]

why would an ecu for a/t cause a vehicle with a/t to surge rpms?

i will check the output of alternator,who knows could be,
is the ecu box under the passenger side dash?

thanks again for help
32621

[teamyoda]

Originally Posted by 32621

why would an ecu for a/t cause a vehicle with a/t to surge rpms?

i will check the output of alternator,who knows could be,
is the ecu box under the passenger side dash?

thanks again for help
32621

the ecu for the automatic is designed to change rpms depending on weather you are in P N D R or whatever. for example when you are in N the idle will be about 800-900 or so. but when you put it into drive it will want to bog down. in turn the ecu automatically raises the idle to comp for the load engaging on the motor from the trans. (load against torque converter). so if you have an auto ecu in a manual, the ecu will detect no automatic trans and it will flip out and cause weird idle.

anyways the ecu is right under the ash tray. like if you have a radio it would be right under there. there is some covers you have to take off to get to it with screws located on the drivers side and passenger side about 6 inches up from the floor along the plastic removable panel

[32621]

thanks for specific location of ecu.

my corolla is an automatic will be okay with a/t ecu
if i need to get one which seems like it will be the problem
that should work.
i hope it will.
i really appreciate all the advice.

32621

[90 GP]

Have you checked for trouble codes stored in computer? They may not trigger check engine light. Here is a link on the two digit codes and how to retrieve them:

http://www.troublecodes.net/Toyota/

[90 GP]

Here is basic info on TPS adjustment. It is geared to Celica but Corolla is also listed and the 4AFE was also used in Celica.

http://www.celicatech.com/imagearchi...h/ADJUSTME.PDF

[blb]

Originally Posted by 90 GP

Here is basic info on TPS adjustment. It is geared to Celica but Corolla is also listed and the 4AFE was also used in Celica.

http://www.celicatech.com/imagearchi...h/ADJUSTME.PDF

I agree. You must adjust the TPS per the service manual instructions or you will get the symptoms you are describing.

[32621]

i will check out those links,thanks again,
the engine did throw a code of 51 when i jumped the diagnostic box,
but the manual i have for this vehicle shows 3 different causes
a/c relay,tps,and ecu.
thats confusing.
will keep trying and thanks again,
32621