93 Corolla computer problem or???

Look for my responses listed after each relevant section below.

How long since the car had the ignition wires, spark plugs, distributor rotor, and distributor cap replaced?

Have you had base ignition timing checked?

It generally runs very well but for a few troubling incidents.

How long was the car parked? 1/2 hour? 1 hour?

It turns over fine but no kick

An engine needs 3 things to run: air, fuel, and a source of ignition at the appropriate time. One or more of those elements is missing.

Start with the easy stuff - check for spark when the engine is cranking. If there is spark, then check fuel.

If there is no check engine light illuminated, it is highly unlikely that any trouble codes will be stored in the ECU's memory. So unlikely that I don't bother pulling codes on a pre OBD II vehicle unless the check engine light is illuminated.

Disconnecting the battery will guarantee that there are no trouble codes, because disconnecting the battery is one way to clear trouble codes.

There is more though. On my way

A flashing OD light means that a trouble code is stored in the transmission ECU. I think the problems are unrelated, unless the car has been in an accident or there are aftermarket accessories installed, like remote starter, stereos, etc.

Hi Ray,

Within the past two months, new plugs, wires, cap and rotor. Also ignitor and coil three months ago when coil failed.

No since it runs great when it runs.

This last time for about an hour. The time it stopped while running it was stopped for several hours while I went for help, called a tow and had it towed home. Next morning it started like there was no problem. Perhaps it is worth noting it has never failed to start after sitting overnight.

I had a passenger with me when it stopped while running and we checked and got no spark.

I understand that. Maybe I'm not being clear here. Today, after the failure to start I tried to check the engine code (by the flashes of the chrck engine light) when shorting E1 and TE1 and noted that there was no check engine light at all when the key is turned on. Then I disconnected the battery for a few min., after reconnecting the bat. the check engine light came on when the key is turned to the on position but shorting the test terminals at that point only gets the OK code, steady blink blink...... I expected that but it seems relevant that the light itself fails. The starter turns over fine and the lights etc all work ok just no ignition. and no engine light.

No, no accident and nothing added. today was the first time for the tranny symptom, drive and 2 were just like neutral and this happened immediately after getting past the no start so I suspected a connection.

Tim O

Were the parts OEM or aftermarket? If the parts are OEM, it is unlikely that they are the cause of the problem but if they are aftermarket, then that is a possibility, particularly the coil and rotor.

Remove the distributor cap and make sure there is no engine oil in the distributor. If there is, replace the distributor shaft O-ring.

OK, that is a big clue. Check the primary connections to the coil, including the primary connections. Make sure the primary wires have good connection and are not corroded.

The main ECU is located either in the passenger side kick panel or behind the glove box. Make sure it is dry and the connectors are good and tight. A loose connection to the ECU or moisture around the ECU cold cause problems. While it is possible that the ECU is bad, the chances that it is bad is something like 1 in a million. They have an extremely low failure rate. Also check the grounds near the ECU to make sure they have a good connection at the ground point.

I think there is a loose connection somewhere or oil or moisture is getting into the distributor somehow. Otherwise, I'm out of ideas, sorry.

"Ray O" wrote

The main ECU is located either in the passenger side kick panel or behind

Thanks Ray, I'll look all that over closely. I still have the original ignitor. The earlier problem turned out to be the coil so I'll swap ignitors while I'm in there.

Tim O

back. It generally runs very well but for a few

dental appointment, it absolutely refuses to start.

if nothing was ever amiss. Once it died while

to a stop. The interesting thing is that when it

engine light, no flashes, no light as the key is

. Today it happened again. Just on a whim I

came on (as it does when you start up) and it

home I lost all forward transmission gears (Automatic)

and off. After six miles it went back to normal.

never had a tranny problem with this vehicle before

new ECU. Any advice or suggestions will be greatly

That sounds just like the kind of thing bad electrical conections might do to me.

With a little luck and the engine running you might find the source by jiggling the electrical wire or conector causing the problem.

If any work was done to the car prior to this problem that would be a good place to start.

GL Dan

I doubt if the igniter is the problem. When an igniter fails, they tend to fail suddenly and completely and will not work even intermittently. A loose connection to the igniter could be a problem, and a coil may have an intermittent problem.

Well I just went through about 5 start/no start cycles in my driveway and I am still befuddled. I thought that disconnecting the battery for a few min. and reconnecting temporarily solved the problem. It seems to but not always, wonderfXXXingful, an intermittant solution. I checked all the connections of recent work, coil, ignitor and plug wires, all good. I looked for bad grounds, nothing. I checked the connectors into the ECU, all shiny and solid, nice and dry under that center console.

The one clue that seems important is that when it isn't going to start there is no check engine light when the key is turned to the on position. If the check engine light is illuminated then turning the key fully to start will fire it right up no problem. Whether it starts or not, the lights, horn radio, cig lighter , rear window defrost all work fine. Just that check engine light. It is also worth noting that but for one time it is always after the car has been turned off that it won't start. Only once while running it stopped and then refused to restart.. I'll Keep looking in here and if I solve it myself I'll post the solution.

Best regards, Tim O

Just for grins, try replacing the EFI main fuse under the hood and keep the one you remove for a spare. make sure the wires going into the fuse box are nice and tight.

I forgot to post my solution, sorry for anyone interested.

I found cheap source for replacement computers on Ebay so I tried that, $50. It was worth it just as a diagnostic answer. Well it wasn't the computer. As I noted earlier the engine light did not come on when the key is turned to "on" when it won't start and that it would come on when it was lit. While checking out the fuse box under hood by the drivers side after a failure while driving I felt a bit of heat in the relays, one in particular, labeled EFI F-HTR. Pushing down on the fuses and /or relays caused this relay to click, engaging and disengaging randomly. When I got home I pulled the entire fuse box apart . There is a set of plug-in connectors to the bottom. At first glance all looked good, very good in fact, clean and shiny. These are well built and protected from the weather with good ( but pain in the butt to disassenble) plastic casing. This was quite disheartening. I left it all for a few days before I came back to give it another look and this time I saw a little bit of green on one of the larger wires in one of the connectors. I gave that wire a little tug and BINGO! it pulled out showing a crusted broken connection. The little spade style crimped- on end piece was gone, just a rumor of copper left there. I figure it must have been something in the metal of this connector itself or perhaps there was an impurity present on this connector. I did a little creative soldering , carefully fitted it all back together and it has run well since.

258,861 miles and still running strong and getting near 35MPG. If US manufacturers don't get their heads out of their asses soon we won't have a domestic auto industry at all.

Best regards, Tim O