2000 Corolla - No Start

#1
I have a 00 corolla that I recently did the valve guide seals on, while I had it apart I replaced the timing chain and tensioner, when i t was all back together it wouldn't start. I then replaced both can and crank position sensors and it still won't start. It was timed correctly from the info I got offline, I've checked all the fuses and swapped out some relays and no luck, it just puffs through the intake and sounds like it wants to go every few revolutions. Any help??? Thanks
 
#3
YeS I double checked everything... The only thing I did was blow a alt fuse when I dropped the alt wire on the frame twice.... Bad ecu?
 
#5
YeS I double checked everything... The only thing I did was blow a alt fuse when I dropped the alt wire on the frame twice.... Bad ecu?
That could very well have fried your ECU. Which wire did you drop? If it was the negative then you're fine. If it was the positive then you may end up forking out a decent chunk of $$ for a new ECM.

Do not just replace it though. Diagnose your fault.

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#7
Essentially the way to diagnose an ecu is this:

1. Verify your ecu is getting good inputs (using a computer/scantool)
2. See if your ecu is sending good outputs.

If it is getting good inputs but the outputs are bad, then your ecu is bad.

There is no real easy way to test an ecu. It's a case of "once you eliminate the plausable, whatever's left, no matter how improbable, is the answer".
 
#8
I'm, getting engine rpm, 500-600rpms, no spark advance in the graph, throttle is showing 20% to 100% when I step on it. O2 sensors are working. But I'm still getting a popping sound from the intake. Car ran fine before I did the work. Compression is fine when I replaced the valve seals there was only a small hissing leak and could only be heard in the crankcase. I tried another ecu but it didn't make much of a change.
 
#9
Getting any codes?

Usually backfire out of the intake is caused by running lean, bad cam timing, or worn camshaft lobes.

When you replaced everything, did you check and set the valve lash?
 
#10
I checked the lash and they were all within spec. Car ran beautiful before I did the work. I only replaced the valve guide seals cause they were bad on the exhaust side, I replaced everything else after it wouldn't run, so basically I've had this car apart 4 times making sure everything was done right.

Bad camshaft timing..... Could the vvti loose enough oil over a few days cause it to unlock in the wrong position?
And no codes, maf sensor was a used part cause the original got burned up from a bad backfire cause of carb cleaner, I don't like to use starting fluid.

Also the fans come on after awhile of trying to start it, is that normal?
 
#11
I'm not sure what else it could be. If the VVT-i was the issue, I imagine it would idle fine but run worse as engine speed increased.

As far as the fans go, they go off the temperature of the PCM, but there may be something in there to turn them on after enough starting to get some cool air over the starter motor, so it may be normal.
 
#13
MAF will put the car in limp-home mode (still runnable).

There has to be a wire that got tugged on when you were doing the work. I don't see how it could be anything else...
 
#14
MAF will put the car in limp-home mode (still runnable). There has to be a wire that got tugged on when you were doing the work. I don't see how it could be anything else...
MAF will put the car in limp-home mode (still runnable). There has to be a wire that got tugged on when you were doing the work. I don't see how it could be anything else...
Still no luck, I disconnected the battery would that clear the limp mode? Still pops through the intake every few revolutions.... Bad Maf?
 
#15
Turns out after all the work and a years wait the head was warped, valves burnt and lots of carbon built up in the chamber. New top end has been ordered and all parts are ready to go. Thanks for the help guys.
 
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