Cel light with no codes

Honestly older electronics on cars are weird. The car may know it is not running right but does not have a code to show for what is wrong. I'd fix the rough running issue then figure out the CEL. It's air fuel spark or timing. An inside spark tester and a timing gun can check that pretty quick. To check fuel check the rail pressure while it is running. Make sure the FPR is working and check injectors with noid lights. Checking timing would be good. I'd also check for weak valve springs.

 

Hopping I get my hands on fp gauge tommarow if someone’s brings it back to autozone and will see if they have the noide lights as well.
I figured the timing good as it starts right up and not adjustable.
As for the valve springs, wouldn’t that show on the vacuum which at idle is a constant 18-19

 

Timing can change if a tensioner get weak. Valve springs will cause a misfire that gets worse as it heats up or off idle the vaccum gauge will show a big vaccum drop start to hang open. Very common in old 1UZ.

 

Hooked up inline spark tester and noide light 1 at a time and confirmed signal on spark and injector lines.
Hooked up fp gauge and pressure is high. No change when vacume applied directly to pressure regulator.
After shutting down engine, fp dropped after a few minutes to around 47# and held steady for 25 minutes before I released pressure.
How does one check a return line for obstruction before I replace regulator?

 

Take the return line off a blow through it. Should be pretty easy to blow through. Was there any gas in the vaccum line for the FPR? Sometimes the diahrams leak. I generally unplug the vaccum line for the FPR while its running and see if it changes. Should go rich as vaccum decreases. I'd also check your fuel filter if you haven't already.

 

The fpr vacum line runs to a vsv and is only a few inches long but appears dry. I pulled and plugged it. Then tested both withou vacume and with various amounts of vacuum applied with the handheld pump
Fuel filter has less than 2500 miles on it

 

The fuel pressure regulator should have engine vaccum straight from the manifold not through the VSV valve. On your hood there is a vaccum line diagram.

 

Left everything hooked up and warmed motor.
Fuel pressure stayed high around 58-60.
Vacuum stayed 18-19
In-line sparkler thing held rythem
Reved it up a few times to point of bucking and held it there
Spark thing showed definite breaking at each miss. Swapped to #2 plug and same
Vacuum dropped to basically 0 for a moment then held at albeit jittery 12-14 and returned to 22 and back down to 18 in less than a second.

 

Sounds like the ignition coil is going bad. I would test that.

 

Mine is one of the oddballs, underhood label shows for to vsv to a thermostat on the plenium

 

But the fuel pressure regulator should go straight to the manifold right?

 

Nope

 

I reran the fp test after reading another thread. This time I let the pressure jump to 60 then pressed the release button. This bled some fuel through the release bleed hose but also lowered the pressure down into the 45 range and over a couple minutes built back up to well over 50.
I applied vacuum to the fpr but still no change my book said it should have dropped. So guessing the fpr is bad
I also tested the vsv. Air passes at all times including when 12 volts applied(not even a click) so it appears to be bad as well.
So that now gives me 3 things not passing tests

Fp regulator
Vsv
Efi relay

Right now I can only do 1 of these items
Any ideas on which if any would be the most likely or should I chase spark seeing as I can see a break in the pattern with the inline tester.

 

If the distributors wern’t so damn expensive, $400, I would suggest putting a new distributor in her as a test. While they can be “tested” via an ohm meter there is usually a last line in the service manual that say replace with known good unit.

 

Finally got hands on timing light. Timing holds steady at all rpms when warmed up so guessing chain and tensioner are good.
I did replace the coil and no change
I am believing this has to be in the distributor as I notice that same flicker in the timing light that I saw with the inline tester.
Going to have to see what other makes/models may have a dist. That would be interchangeable with mine and start crawling through junkyards to find a wreck that has one.
When you say $400 you must be thinking after market cardone which is what’s in there now from 2011 which was 97k miles ago.
Might go that route but recently took on a 2023 carolla which gave my budget lockjaw.
Will add whatever happens into this thread as I find a lot of useful stuff going back in time .
If this sight ever goes away I will have to sell my trucks as their whole history since 09 will be gone.

 

Not that it was having the same issue, but the wife used to own a 97 corolla. It did the same thing, Started with throwing a code that indicated a distributor issue. So replaced that. Ran good after that, but the code kept coming back. I kept throwing parts at it. It got to the point where the CEL light would come up after a few minutes of driving, and I could check it right away, and there wasn't a code found. Not even in the memory. I replaced the ECU, and it still did it. So the wife say's "lets just take it to Toyota", so we did. I get into the service bay and start talking to the tech. I tell him what it is doing, and everything I have done, and he tells us that is way more than they would do So I sold it and bought her a Subaru...

 

If it weren’t for how well this truck handles in the sand pine trails of the woods and that it has been apart of my family since it had 6 miles on it I would probably wood just sell it for more than what my sister-in-law sold it to me for 18 years ago.
Funny you said Subaru as that’s all my family owns is yotas and subs

 

Yeah, I think owning a Subaru is a requirement in Colorado. Good luck, and I hope you figure it out. Does it run ok with the CEL on?

 

not right now

 

That sucks. Good luck with figuring it out.