Cel light with no codes

I have another thread started on this but getting nowhere. 95 Tacoma 4wd and 5 speed manual. OBDII, 270k miles. Running rough with no power. Starts right up when cold but is difficult once warm. Cel is lit but my scanner says no DTC. Autozone and Orielys get failures when they scan. Have changed carbon fouled plugs, dist. Cap and rotor. Cleaned and checked egr, cleaned maf and iat. . Pulled and cleaned cat. Checked compression which is high on all cylinders (210 -220 on all) checked vacum 18 at idle but the miss will not let me get reliable readings past that, drops to 8 but returns to 18 at idle quickly.
Without codes I am lost with where to start my next round.

 

Does that engine have a rubber disc as part the harmonic balancer? I've seen those fail and cause lousy running under load to to the timing not being proper.

Fairly easy to check with a timing light if you can't see wobble in the balancer.

Just a thought.

 

You have verified another circuit is not grounding back through the cel light.

Your device is connecting just fine? Just no DTC codes present.

Fuel system problems most times will not trip any codes. Last fuel filter change?

Are you able to read the tests as completed ?

Have you cleaned the truck harness side OBDII plug ever??

Being dirty or corroded can cause connection issues makes it rough when it is not visible to your eyes .

Yet checks out because the meter probe is sharp enough to push through the corrosion.

Ever check if your injectors are leaking? Causing the hard starts when warm.

 

You just might have a unicorn… there were a few 95.5 Tacomas shipped that are actually OBDI and not OBDII. It may have the DLC but the PCM is still OBDI. Look at the sticker under the hood and see if it says OBDI or OBDII compliant.

I had a friend of a friend who could not get his 95 Tacoma to pass smog. He was pulling his hair out. I told him what I told you and sure enough, OBDI. Once the smog shop understood, it passed smog.

 

I was going to mention this but thought the OP knew what system they had.

 

I brought this up to the OP in his other thread. He insisted it is an OBDII truck.

 

This was only due to having codes read in the past.

 

This truck has an OBD 2 DLC ?

 

Not sure what sticker you are referring to. Here are what I have under

 

I am not much of an electrical person so not sure how to know if anything is grounding back through the light. As for cleaning the hook up, I did spray with contact cleaner on both the scanner and truck then plug and unplug several times while battery was disconnected. Tear down for fuel pressure check has not been done in a while, will have to get my hands on a gauge again. But had not delved into that yet this time

 

YO OP
Just picked up mine(for Son) few weeks ago
1996 2.4L 5 lug
Got it for a song, owner said had the ‘hot no start condition’
I did everything you did plus:
Fuel Filter
Installed fuel pressure gauge
Tested FP regulator (passed)

ugh 212k and probably nvr changed

Last up to temp trips(twice),
Got home and started NP
Waited 10mins…..started up NP


FP gauge reading 22lbs running
Which is low IMO
(Gauge is 60yrs old, testing with air compressor this weekend)

every thread I searched here,
80% of the solution/fix is a new F pump or/and injectors
20% of fixes are needed random
Some sensor/FF/pvc valve/etc

I’m sure I’m not out of the woods thou
GL

 

After some more research it appears that there are Tacomas that are not 100% OBDII compliant even if they have the connector under the dash. Your underhood sticker does not say OBDII compliant. Give this procedure a try…

https://www.2carpros.com/articles/t...finitions-and-code-gathering-method-1990-1995

 

Doing that now. CEL comes on and stays on without the jumper but when I do jump the connections, when my vsv starts clicking (green one under plenium in picture) starts ticking the light goes crazy then off.

 

After reading this and since I was under the hood of my "95" today I snapped a pic for reference/comparison. OBD II certified in the lower right corner, also the blurb about being a CA vehicle. Looks like the sticker OP posted is for a vehicle outside CA, and missing "OBD II Certified". Different engine and state, not sure if this is even helpful, but the discussion got me interested enough to have another look a that sticker under my hood.

 

Good catch Looiz!
OP’s sticker doesn’t have and says Canada!

im going read that posted thread ^^
I’m guessing it’s a series on blinking lights (like morse code)
Helped friend with a OBD1 Honda while back

 

Yeppers
That’s it

Looks like you need to put OBD1 ECM in diagnostic mode by plugging in 2 pigtails
Then count flashes

Just to let you know
On older Subaru’s (OBD2 thou)once the diagnostic pigtails connected, all kinds of weird stuff happens……constantly
FP cycles then turns off/rad fans cycle for 30secs then stop/blinking CE lite/blinking cruise control lite
Then repeats
thanks for updates

 

This is a good contribution. It suggests that only the California spec'd trucks in 1995.5 model year were OBDII compliant.

Out of curiosity, does your truck have only a single catalytic converter? Or does it have dual CATs?

 

Cat was stolen and replaced sometime before I purchased the truck in 2014, so I’m not sure what was on there before that. It has a single cat and single O2 sensor.

Requires an evap system pressure test every other year for the smog. According to the tech it’s required for “95” and older, and he always seems surprised that it’s OBD II given the “95” model year.

Now I’m Interested to know how you go about troubleshooting an OBD I Tacoma when the check engine light is on.

 

Well, had some light time this evening and was going to prep for next testing (fuel system).
Was getting ready to disconnect the battery but figured I might as well try one last time for codes and tried both OBD I and II. On OBD jumpers cell stayed constant on until the egr VSV started ticking. Gave it 10 minutes of rapid flashing then gave up and plugged my OBDII in and this time connected to it by by.
I got a yellow light so ,
Does this mean that we are OBDII?
Does this show that the ECU is functioning and that there is an issue in egr system(maybe that clicking VSV)
I tried to pull up the live data but app says no past recordings

 

Starting on easy side first, I am testing distributor.
On the pick-up coil I am using cheep multimeter set to ohm settings ( no sub settings just says 20-200 ohm) Haynes shows should be 85-275 but my meter shows .250, 253(that is WITH a period in the front. So wondering if that is a typo in book.
Resistance on primary and secondary reads correctly at .38 and 13.9-14.6 respectively.
While I was under the hood I also tested the Efi relay
Terminals 3&5 and 1&2 for continuity
3&5 shows none
1&2 show .83 but no beep for continuity (is that acceptable?)
Added 12 volts and got beep or full continuity on terminals 3&5.
Sorry I’m all over the place with this but doing what I can without throwing money at it and saving wrenching for a time when I have the testing equipment on hand.