krytellan

So it's a 94 4runner SR5. Everything was fine... driving down the road and the engine just suddenly stopped running. I coasted to a driveway and it wouldn't start again but is turning over fine.

My limited knowledge leads me to either spark or fuel. Any ideas on where I should start for tracking down the problem?

iamsuperbleeder

do you have any gas in it?




checking spark is the easiest thing to do, especially if you've got a timing light I'd start there

toyota4x4907

Did the check engine light come on?

bugs1961

Sounds like a broken timing belt. Take off the distributor cap and rotate the engine with a wrench. If the rotor isn't turning then it's the belt.

krytellan

Oh yeah. I should mention that I have been having a problem with the speed sensor (speedometer goes out occasionally and the trans will slip out of gear sometimes) and so am days away from fixing that. Chances of them being related are?

And yes, due to above reason light has been on for a while, so no help there. I'll check the things mentioned first and work from there. Thanks for the suggestions guys.

krytellan

Checked for spark from plug through to coil and nothing. Used timing gun and spark tester. The coil checks out as OK as per the Haynes impedence specs. This leads me to a faulty ignition module. Now, before I run out and drop $150 on this module on a prayer, anyone have any last minute suggestions or tricks that will allow me to test this module? I went to Auto Zone and lo... they didn't have the correct plug. Such is my life with EVERYTHING I try to get tested for free.

TOYOTA 1

check the efi fuse.

iamsuperbleeder

just about to say that


15amp fuse under the hood on the passenger side

krytellan

No such save. I so tried, but it's fine. New igniter in order then?

krytellan

Got the ignition module and it's not the problem. Does this mean it could only be the coil? I tested the coil and primary resistance was at .70. The specs say it should be between .35 and .56. Is this check significant enough to indicate needing a new coil?

iamsuperbleeder

it's only about $10 for one; I'd say go for it

krytellan

And... no go. Not the coil either. Looks like Sunday will be a day of staring at the engine compartment of the truck wondering WTF is going on.

GO_BLUE!

cracked/wet distributor? The battery is giving juice, right? Take the speed sensor off the t-case and clean all the ATF fluid out of it (the magnet and around the o-ring and any that may have leaked onto the electronics) and reinstall. My speed sensor died but my Runner kept running.

krytellan

I've already replaced the cap and rotor. I plan on replacing the sensor but not yet. I'm convinced the sensor has nothing to do with this issue.

I have replaced both igniter and coil and that was no help. Yesterday, after taking a look at the distributor and putting everything together, it fired right up. We drove it around a bit and it again died right before my driveway... at least allowing me to coast into it No spark for the rest of the day. A lot of the relevant wiring has small tears in the coating and I plan on replacing that.

The next course of action will be checking the IGT signal from the ECM. My question is that the repair manual says that this should be tested at idle. How do they expect you to do a test for no spark when your car is idling????


After that it's looking for bad wiring, but we've tested most wiring and found no problems. I absolutely hate these kinds of problems.

krytellan

Alright then. I have fixed it and wanted to post this should anyone else have this problem.

When you have no spark and you have eliminated coil, igniter, ECM, distributor/cap, and wiring, it's likely your Mass Air Flow Sensor.

Disconnect your MAF sensor and try starting your car. If it starts for a couple seconds then dies, you have your answer. Wish I would have found this out earlier in my week long mystery.

Thanks for those who tried to offer insight.

Nogarage

Freakin' well done!! Thanks for letting us know. Sure it was a PITA, but when is diagnostics not?? But it's fun, too, plus you're more in control for what happens down the road. Hope you saved the parts you replaced... Also, isn't it nice you didn't start pulling and rebuilding the engine? ?

thook

krytellan.......if you're up for some reading, this page will explain some technicalities for you. When you're reading, only information relevant to vane airflow meters apply......not mass airflow sensors. The two are technically different although a VAFM is still an airflow sensor.

http://www.autoshop101.com/forms/h34.pdf