Mechanic stumped by my Corolla

Hello all,

I have a 1995 Toyota Corolla that I dearly love(d). On Christmas Eve morning, 2009, it died as my wife drove it to work. Before I had it towed to my mechanic, I tried starting it. It would just turn over, begin to run, then die. I figured it might be a fuel problem, but no biggie.

Six months later, it is still not fixed. My mechanic, a brilliant guy who has worked with my family’s cars for several years, is completely stumped. He spent so much time working on it with no result that he admitted he can’t charge me for any labor.

He got it running, but it runs so roughly and stalls so intermittently that it is truly not safe to drive. He has taped gauges to the windshield connected to various parts of the engine in order to do diagnostics while on the road. No resolution.

He’s taken it himself to five other mechanics - Toyota and/or electrical system geniuses - without any luck. Now that it is back at his shop, he and the rest of his staff have been taking cracks at it during breaks or after work.

Here’s what he’s replaced:

_Fuel relay (this got it to finally start)

_Distributor cap

_Distributor rotor


I’m finally having it towed to my house since he needs the space and can’t spend any more time on it.

However, I can’t believe that this car is unfixable.

Any ideas?



All you’re likely to get here is a long list of things that have probably already been checked. So try to get a complete list of basic diagnostics that have been run on the thing.

E.g. presumably the fuel pressure has been checked? A smoke test or some other similar thing to check for vacuum leaks/intake manifodl gasket? Compression tested? etc. etc.

See - there are tons of very basic things to check out. Save everyone some time and try to get a list. Or send the mechanic here to give a full report.

Fuel pressure is good. Tank is clean and there’s good gas in it. No vacuum leaks. Compression is good. Alternator is fine. New plugs. New spark plug wires.

Every single test he can run comes back good. Only when the car gets on the road does it miss, sputter, and stall. It starts up right away again, but the same behavior returns.

I’m sure he’s a great guy, but what you need here is a skilled diagnostician. He’s replaced parts from both the fuel system and he ignition system. It’s basic troubleshooting to verify proper fuel line pressure, which would eliminate the fuel supply as a suspect, and basic troubleshooting to verify proper spark.

It’s also basic trouble shooting the verify that the ECU is getting a good temperature signal, important to the engine’s getting proper fuel mix for starting.

It’s also easy to verify injector operation.

Lacking proper spark, if that turn out to b ethe case, there are techniques to check everything that goes into providng good spark. In this case that may involve the igniter, the crank (or cam) angle sensor and the cam speed sensor. Thes signals are needed to tell the ECU to fire the sparkplugs.

No disrespect to your current guy, but I think you need a new shop.

PostScript: the fact that it begins to run is good news. It means your timing belt is intact. Verification that the belt hasn’t alipped and the cam timing is correct is also easy with either a vacuum gage or a compression tester. This is another possibility for him to consider.

Right, but I’m saying give a full report or this game goes on and on and on and people tire of it.

Presumably it has spark? Do the fuel injectors actually operate? Does fuel actually make it to the cylinders? Has the timing been checked? What were the actual numbers on the compression test? How do you know there are no vacuum leaks? Etc. Etc.

I never saw the OP mention that the timing had been checked. This problem can be caused if the timing is off.

But as cigroller pointed out, we need a full history of exactly what has been done to the car so that we aren’t just throwing out things that have already been tried.

I want compression test results for the cylinders.
That will also indicate a possibility of belt slippage, taking the camshafts out of phase with the crankshaft, as the valves would be opening and closing at the wrong points, lowering compression.

I would also say MAF/MAP sensor.

How old is the battery?


If it is a carburetor model check the float to see if it is still good, new needle and seat, and clean out the bowl as accumulated debris is one thought, better yet when it gets to your house get a rebuilt carb, my 2 cents, 4 cents equals bad fuel pump, flush gas tank and new fuel filter,

Based on the parts that were replaced it sounds to me like some wild guessing was going on.
A dist. cap and rotor is not going to cause a problem like this unless they are scrapyard bad; and this would generally be due to a worn out distributor in which the dist. shaft has caused the rotor to make contact with the cap.

This car and the systems that make it run are not that complicated.
So at this point has this mechanic even told you what’s missing? (spark, fuel, or compresission?)

Starting and dying could be a sign of a failed ignition switch.
I don’t suppose anyone has bothered to check for simple things like a blown ignition fuse, etc?

My wild guess thought was that the timing belt might have jumped teeth so the timing’s off, I don’t know if that’s possible or likely on this car though.

Maybe the computer’s gone bad.

Get a list of all the things your brilliant mechanic has eliminated as a potential cause.

The 95 may be too new to still use an igniter which was under the ignition coil in older Toyotas. We used to have unrepairable airplanes sometimes that would be fixed when somebody finally got around to following the steps listed in the manual.

Your description of the efforts of many geniuses sounded really familiar. The old igniters used to cost about $350.

The computer was one of the first things he looked at. He installed rebuilt one and there was no change in the car’s behavior.

I agree with Waterboy’s advice about the fuel filter and pump. If the filter hasn’t been replaced yet then do that. If that doesn’t help then replace the pump even though the pressure has been checked ok. If replacing the pump doesn’t help I would then look into problems with the ignition timing. Focusing on the sensors for the timing.

At this point you’ve accumulated a long list of suggestions and one common theme.

The common theme is that your guy is just throwing parts at the problem rather than diagnosing it. That more often than not does not work, and it almost always wastes large amounts of money.

The long list points out that there are a number of different possibilities. YOu need a shop that knows how to do diagnosis and figure out which possibility is correct rather than just replace parts.

Personally, I think you’re best bet for getting this fixed is to find a reputable independently owned and operated shop that knows how to diagnose.

Update: just got the car towed to my house and am determined to fix it.

According to my mechanic, it has compression and gets fuel. Right now, however, there is no spark = flat battery and dead distributor (he took the replacement and reinstalled the old one). My first task is to get a working distributor in it > get it cranking/started > start with fuel filter and pump and work from there.

Just my humble opinion but I’d bet a box of doughnuts this problem is something very simple and what has happened is that the diagnosing started at the back of the book and was worked toward the front.
The rule of Always Suspect Something Simple should be abbreviated and followed first before getting too deep into any problem.

A lack of spark problem should not require 6 hours of guessing much less 6 months.
As to the story about taking this car to 5 other mechanics I can’t say that I buy one bit of that. He may have bounced the problem off someone else during a face to face or telephone discussion and one would think that if he actually did have conversations with 5 people that one of them would have chimed in with something about checking the ignition fuse or the ignition switch, etc.

I’ll see if I can pull up a wiring schematic and give you a color code to check. You can get a cheap test light from Wal Mart and maybe we can help you through this.
My feeling is that a mechanic should have egg on his face when this one is sorted out.

I’ll take that bet. If you win, you may find a few of the doughnuts missing on delivery.

I agree with your post. I just wanted to take a “chance” on a free box of doughnuts. By the way, can you tell me why the driver’s side of my car seems to ride lower than it used to?

I would replace the inline fuel filter, for about three bucks.

Sagging because of too many doughnuts? Time to add spring spacers on the drivers side or a sandbag on the passenger side floor. The doughnuts must always remain. :slight_smile:

A look at the schematic shows the ECM gets power from about 5 different fuses with a 10 Amp ignition fuse being one of them.
With any electrical problem I always check every single fuse as a first step and my opinion is that should be done here.

If all fuses are good then use a test light to probe a black/orange wire at the ignition coil. This wire should be powered up with the key in both the RUN and the START positions.

No power means a faulty ignition switch and while I do not know how the ECM internals are wired (that’s a job for the elec. engineers) it would seem to me that a blown ign. or EFI fuse (15 Amp) could be behind this problem.

I’ll get spacers immediately. Heavy duty ones.

It’s always prudent to check the fuses, but whereas the car is starting and running, albiet roughly and erratically, I’d considered the ignition switch and the fuses a low probability. But, I’ve been wrong plenty of times before, I could be this time too.

My gut tells me this one is going to end up being a fuel deliver problem, but to know will require someone going through the basic troubleshooting. Based on the post the OP’s current guy isn’t doing that.