Idle problem....

T-Bone · Post by **T-Bone** » Thu Dec 15, 2005 6:10 pm

I have a problem with it missfiring. when it is at idle it has a missfire, i cant tell what cylinder it is i pulled the plug wire for each cylinder and it just made it worse. if i rev it up and hold the revs anywhere from 1,900 RPM to 2,800 the engine drops down about 3,000 RPM then jumps back up and again and again. when driving once i hit about 3,000RPM the engine hesitates then starts to go up where it should be.

Finder349 · Post by **Finder349** » Thu Dec 15, 2005 6:28 pm

Could be way off but I had read something about Spark plugs and an issue like this. Open the hood at night and look for the sparking. It seems good results have been had with the NGK plugs. Resistance of 10,000 Ohms or less is good. Some plugs have 90,000 (way too much). If this has been going on a while then the plug wires could be damaged.

I am sure that if I am way off that someone will let us know.

Calvin

T-Bone · Post by **T-Bone** » Thu Dec 15, 2005 8:14 pm

thanks for the reply. i am going to check and see if i can see a spark anywhere around the plugs. the guy i bought the car from said that he put new NGK plugs in it. i should probably check the plug gap and make sure that they are good. oh i forgot to mention that the idle speed is normal around 800rpm.

T-Bone · Post by **T-Bone** » Thu Dec 15, 2005 10:28 pm

i just got done checking for anyspark while its dark out and i couldnt see aynthing.

Post by **ARCHINSTL** » Fri Dec 16, 2005 1:51 am

I can't really tell from your wording, but save for the misfiring, are you saying you have an RPM-cycling-on-its-own problem?
Try disconnecting the vac line from the metal tube to the "A" vacuum switch at the switch (the one with the black connector). Plug the line with a golf tee or similar. This worked for me, although I intend to install a functioning "A" switch at some point.
If you have not yet seen it, check out the "Vacuum Line" thread in the early section of Repair Guides; there is a color rendition which makes all of the spaghetti more understandable. The line to which I am referring is the yellow one in the guide. Switch "A" is at 6:00, next to the EBCV.
Again, this may or may not be a solution, but it is worth a try. Also check out my lengthy thread about "RPM Cycling" in the Repair Questions section.
Tom M.

T-Bone · Post by **T-Bone** » Fri Dec 16, 2005 8:56 am

thanks for the reply. do you have a link for the vacuum line page? i cant seem to find it anywhere. the way the engine runs is at idle it has a missfire, i just cant seem to find out what cylinder it is. if you hold the revs between 1900 and 2800rpm the engine will cycle about 2,500 to 3,000rpm (but thats when the car is not driving). When driving once i hit about 3,000rpm the engine will hesitate for a little bit then start to climb in revs like normal.

Post by **ARCHINSTL** » Fri Dec 16, 2005 12:12 pm

T-Bone -
Here is the link. viewtopic.php?t=692
Everyone new to the forum should check it out as well. It is on page 1 of the Repair Guides section. You should also check the undersurface of the car's hood. There is a small diagram pasted there with the particulars of your car's lines. Mine was pretty wrinkled and kinda faded, so I took a digital photo and stuck it in the 'puter and cleaned it up that way.
I dunno about the misfiring, alas. Is it a regular misfire, which would seem that a specific cylinder is missing? Or irregular? If it is a regular misfire, think about a cause that disappears at higher rpm.... I would Google something like "Idle misfiring" or "Toyota misfiring". Possibly something in the advance???
Incidentally, NGK is the way to go on plugs. I was not a believer until I switched from virtually new Bosch to the regular NGK ($6.34 for 4 at Advance); there was a noticeable improvement. Nippon(Denso) was also an OEM, but most people seem to use NGK.
Do you mean that the engine will rev from 2500 to 3000, or that it will rev 2500 rpm when you are in the 1900-2800 range? This would take it to pushing 5000 +/-.

takza · Post by **takza** » Sat Dec 17, 2005 6:33 am

If you have misfiring problems and you haven't done so recently...best bet is new ignition parts...plugs...wires...cap/rotor...then if you still have problems....go from there?

Plug the vac line right at the EGR to see if it's this?

T-Bone · Post by **T-Bone** » Sun Dec 18, 2005 6:42 pm

I have new NGK plugs in. I will have a new cap and wires tomorrow. I hope they fix it. if not then i am going to get a new rotor too. oh yeah, what does plugging the line with a golf tee in the line do? is it because a part goes bad?

Post by **ARCHINSTL** » Sun Dec 18, 2005 8:37 pm

Plugging the vac line to "A" switch prohibits any vac from operating the switch. Apparently my "A" switch (or its connection to the ECU) is bad. The switch affects a fuel cutoff solenoid, the vapor canister, and an air bleed into the carb. With it connected, I got the RPM cycling mentioned; with it disconnected/line plugged, the car runs great.
I still want to replace the "A" switch, though.
It may or may not be part of your problem - how's that for a promise? Just try it and see.
Also pop for the rotor; it's not expensive and will eliminate another item of consideration.
Tom M.

takza · Post by **takza** » Mon Dec 19, 2005 6:05 am

T-Bone wrote:I have new NGK plugs in. I will have a new cap and wires tomorrow. I hope they fix it. if not then i am going to get a new rotor too. oh yeah, what does plugging the line with a golf tee in the line do? is it because a part goes bad?

If you plug the vac line right at the EGR...you factor it out of the equation and can tell if this is the problem area.

You should always replace the rotor and cap together since they wear together.

The plug wires on this car have to be routed just right to keep them away from one another and other metal things where they can ground out.

T-Bone · Post by **T-Bone** » Mon Dec 19, 2005 11:22 pm

i replaced the cap, rotor and wires. it made a huge difference. its idles great now and doesnt missfire. but it still bogs down a bit under heavy accel. it bogs down around 3,000 rpm then it starts to pickup again. i have not tried removing the vac line. i will try to get to that in the next day or so.