93 Camry dtc 12 shifing at high rpms when engine cold, and wandering idle FIXED.
 

93 Camry LE, 2.2l 4cylinder, auto trans, no anti lock brakes, or traction control, non California emissions car.

I bought the car back in Jan. The car only has 95k miles, and I changed the trans fluid, trans filter, timing belt, etc about a week after getting it home.

The engine always had a slight wandering idle like maybe 500 rpm, up, and down at idle. This got much worse over time, and the tach needle would fluctuate, at idle, from 1000 to 1200 rpms

A few weeks ago the transmission started shifting funny when the engine was cold. I did get a check engine light, it turned out to be a code 12.

I gambled a new coolant temp sending unit, as from what I read this was the usual issue with a strange shifting trans before warm up, and it didn't help.

Today, after installing the temp sender, I took the car out for a test drive.

It shifts from 1st to 2nd, at 3500 rpms [outside temp today is around 93 degs], and from 2nd to 3rd at 3500 rpms.

After driving the car for approx ten minutes it shifts fine.

I was thinking about pulling the pan, and the shift solenoids, and cleaning them with carb cleaner, just in case some debris worked its way into something.

The car looks to be in immaculate condition for its age with the original paint/interior.

Also, I have rebuilt several transmissions, but I don't think the internals of the transmission are at fault here.

Update: I found out how to get the obd1 codes, and was able to pull codes 12, and 41.

Code 12 deals with the distributor, and 41 with the tps sensor.

I tested the tps sensor, and passed all of the tests so that is not the problem.

I pulled the neg battery cable, and left it off for about 5 minutes, then reconnected it.

Now the engine light is staying on [it used to be intermittent], and all I'm getting is code 12. The engine will hesitate when cold from a stop.

I'm guessing the hesitation, and transmission shifting issue are hand in hand, as in the hesitation of the engine is causing the transmission to shift late. Also it don't explain why the engine runs just fine after its fully warmed up.

From what I've been reading the coils on these cars go bad, but it would seem that the engine wouldn't run at all were this the case.

Code 12 is an issue with one of the pickup coils in the distributor, the air gap for the coils or ECM.

Pickup coil will change with distributor temperature. Perhaps a coil is out of spec when cold and in spec when hot.

Does the distributor have built in ign coil or external?

I'm pretty sure its internal.

What is the air gap specs for the coils. I will check tomorrow...........thanks.

What you're saying does make sense as its definitely temp related.

Internal coil distributor cap has only 4 high voltage connections and these are for the plugs (no 5th wire for the external coil).

Air gap 0.008–0.016 inch.

Pickup coil resistance.
Between terminals G+ and G- of distributor plug
Cold 185-275 ohm
Hot 240-325 ohm

Between NE+ and NE-
Cold 370-550 ohm
Hot 475-650 ohm

Hot is 122 to 212F

When facing the distributor/plug outlet from the drivers side and looking towards passengers side. Terminals from top to bottom are NE+, NE-, G-, G+.

Check ign coil resistance.

Primary connection
Cold 0.36–0.55 ohm
Hot 0.45–0.65 ohm

Secondary
Cold 9.0–15.4 Kohm
Hot 11.4–18.1 Kohm

Check coil body for cracks and signs of arcing.

Make all resistance readings are stable and don't start to climb or drop with continued taking of a reading.

Ok, I'll give it a checking out this afternoon.........thanks.

Yep, it was the coil that was bad.

I had a fun time trying to get those four screws holding the coil to the dizzy housing as they were all on the bottom of the housing facing the transmission.

It would have been easy if the dist wasn't locked up [it wouldn't budge so I couldn't turn it]. I did spray some penetrating where the dist meets the head so maybe I can free it up for future, possible issues.

The old coil had a crack in the epoxy, and was arching on the metal tab of the coil.

I took a drive down the road, and the engine ran much better. I was amazed it made so much difference.

Today the NGK plug wires came in, and I installed them, and here is where the problems started.

The car would bog on gear change at the same exact place it always did just down from my house.

I tried pressing the plug wires more firmly on their connectors, but nothing seem to work. I also received my new fuel filter so I thought maybe its a fuel issue so I install it, and yep, same problem with the bog from a stop, and wandering idle.

Great job! Thanks for posting back with the fix.

Well, it did the same thing again this morning. I had to drive my wife to town for some errands so I took the Camry just to make sure all was well.

I was telling my wife what a great mechanic I was for fixing the car, and as soon as we hit the same spot in the road the problem happened again.

Its always at a stop sign about a 1/4 mile from my drive. We turn right, and go up a very small grade [maybe 10% grade, or less].

After the trans shifts from first to second there is a bog. I can floor the throttle, and the engine won't respond. Then very gradually the car will pick up speed until its going all out.

Only does this when its cold. After its warmed up there is no problem.

I checked the idle sensor [I think that is what its called] under the throttle body, and took it all apart about a week ago, and cleaned all of the carbon off the little barrel looking part { I filled it up with carb cleaner, and let it sit for about two hours]. I also moved said part left to right until it was moving very freely, then reinstalled it.

Like I said the plugs tested good [hot, and cold], the old coil was bad, and replaced with NGK coil, new dist/rotor, and now new NGK plug wires.

Oh, and the temp sending unit was replaced last week.

I'm still getting a code 12 even after clearing all of the old codes.

Might be something I have to just live with. The only thing left to change is the dist pickup, and the ignitor.

Did you replace the distributor?

When engine is hot, any bog issues when just revving the throttle when car stationary?