what does a flashing CEL mean when driving?

[Duane]

So our 99 did this on the highway the other day.
Driving about 70 on criuse and a generally warm day.

The check engine light would flash slowly on and off.
What could this mean?

Should I count the number of flashes as does this mean anything?

 

[raydouble]

So our 99 did this on the highway the other day.
Driving about 70 on criuse and a generally warm day.

The check engine light would flash slowly on and off.
What could this mean?

Should I count the number of flashes as does this mean anything?

It's typically a misfire code. The flashing is usually a indication of pending catalyst damage from unburned fuel.

 

[Duane]

Will the computer have a code in it to check?
or does it just think it has unburnt fuel from a poor O2 sensor or a possible specific cylinder from a known misfire?
I noticed zero driveability problems..no misses or surges etc.

 

[raydouble]

Will the computer have a code in it to check?
or does it just think it has unburnt fuel from a poor O2 sensor or a possible specific cylinder from a known misfire?
I noticed zero driveability problems..no misses or surges etc.

I'm sorry, maybe it's just emissions related. There should be a code stored.

 

[sseaman]

Go by an Auto Parts store and have them read the code if the CEL is still on. They should also be able to print out a vague description of what the code means

 

[Gumby]

96+ the CEL will flash if the ECM detects 150% of normal emissions. It flashes to tell the driver that he or she is potentially destroying the catalytic converter.

It means fix it now. Don't keep driving it.


It will set a code. It could very well be a misfire, but it could be a lot of other things as well.

 

[raydouble]

96+ the CEL will flash if the ECM detects 150% of normal emissions.

Great info, thanks.

 

[Duane]

96+ the CEL will flash if the ECM detects 150% of normal emissions. It flashes to tell the driver that he or she is potentially destroying the catalytic converter.

It means fix it now. Don't keep driving it.


It will set a code. It could very well be a misfire, but it could be a lot of other things as well.

The CEL doesn't stay on when stopped. It just flashes when driving sometimes. We slowed down 5 mph and it would quit.
At any rate thanks for the input Gumby.
Nice to see you bought some newer iron and will bring your knowledge and wit to the 95+ forum.

 

[KayakPanic]

you couls also try and reset the code by disconnecting both the + and the - battery terminals for about 10 minutes, and then see if it is still throwing the code. Sometimes it will stop throwing the code.

I have had to do this a few times on my 96 tacoma bacause of not having $400 for new o2 sensors.

 

[Duane]

Well I had it in at the dealer for an oil change. They checked for codes and said it had pending codes for missfires on cylinder2 and 5 which happen to share a coil pack.
So I have a new one on order, will change it out and see what happens.
more to come

 

[Duane]

Well new coil pack in and no change. Cylinder5 & 2
5 6
3 4
1 2
Front

So yes RayDbl the pending codes brought up were misfire on cyl2 and cyl5.
Gumby.. if the 150% emissions level is being reached then what does the thinking on this? An 02 sensor? a bad injector pushing in excessive fuel? or what does one try next?
Kayakpanic.. so how many 02 sensors on a 3.4L then? one before and after the cat I assume?
One would think the ECM would figure up an O2 code if that was the problem though. Guess it needs to short or open perhaps??
thanks guys

 

[raydouble]

Have a multimeter to test the spark wire between 5 and 2?

Could also be the primary voltage going to the coil pack.

Here is the entire troubleshooting procedure.
http://www.ncttora.com/fsm/1996/SIL/techinfo.toyota.com/ileaf/02toyrm/02toypdf/02rmsour/2002/024runne/di/eg5vzfe/cip0300p.pdf

 

[Duane]

Hey thanks for the link raydbl
I looked through the 1634 page manual via the download link at the top of the 95+ section and I can't find the DI 57 -62 pages that your link points to although it is an 02 reference.

Looks like I might be in for some digging here and to find something simple hopefully somewhere. I don't want to start part swapping and I'm really not thrilled about checking compression or valves... sort of impressed though that these little buggers are smart enough to run up a flag that a problem exists..now to see if I am smart enough to isolate the problem.

cyl2 and 5 codes seems too coincidental to not look to common control/parts. I would think if the ignition lead over to cylinder 2 were high resistance then why would it show a pending P0305 code and not just a pending P0302 code? Seems to make sense if it were shorting on route to cylinder 2 then it may drop the secondary voltage to cylinder 5 and then both codes should show up. hmmm

Thanks for the direction as usual

 

[TheDurk]

Hey thanks for the link raydbl
I looked through the 1634 page manual via the download link at the top of the 95+ section and I can't find the DI 57 -62 pages that your link points to although it is an 02 reference.

Looks like I might be in for some digging here and to find something simple hopefully somewhere. I don't want to start part swapping and I'm really not thrilled about checking compression or valves... sort of impressed though that these little buggers are smart enough to run up a flag that a problem exists..now to see if I am smart enough to isolate the problem.

cyl2 and 5 codes seems too coincidental to not look to common control/parts. I would think if the ignition lead over to cylinder 2 were high resistance then why would it show a pending P0305 code and not just a pending P0302 code? Seems to make sense if it were shorting on route to cylinder 2 then it may drop the secondary voltage to cylinder 5 and then both codes should show up. hmmm

Thanks for the direction as usual

This is a waste spark ignition. This means the coil fires both plugs at the same time when either ONE of them is at top of compression. it is a series circuit, so power flows through the wire to the far plug, then across the gap, through the block, across the other gap and back into the coil. (Or maybe backwards, I forget). So any high resistance in the wire or problem in the coil affects both cylinders equally. A short, however, can bypass either plug, leaving the other one operating.

 

[Duane]

Holy Durk now that made me think.....
I thought they would be a simple parallel circuit with both gaps being jumped. Read a bit online and yup they talk of negative and positive polarity spark. On e link talks of them switching as well so as to not wear out the plugs from firing negative polarity.

I tested my lead over to cylinder 2 and it was at 16.67K ohms..manual says under 25K ohms is good.
The dealer tried a new lead today as well as I thought why not let a master service tech sort it out. Well they made me feel good as they aren't certain yet either..want to try another ECM.

It doesn't seem to stumble or miss just the darn light flashes at highway speed and dropping the load slightly allows the light to stop flashing. Likely simple as most things are... just to know what it is

 

[TheDurk]

Duane, I just read back in this thread, and I don't see that you have tried new plugs, or even looked at the old ones. Did I miss something? Looking at the old plugs is important. New plugs should be double electrode OEM spec NGK or Densos. I can't believe a dealer wouldn't change them first, even with the 302 + 305 codes. As I said, a plug that fails open (rare I admit) will mess up both sparks.

 

[Duane]

Durk
Should have added history on the plugs. New correct Densos were put in about 10,000 miles ago.

So a recap...
- new Denso plugs .043 gap, new wire set, new coil pack on cylinder 5..shared by cylinder 2
- ECM swapped with no change
- compression test on the engine.. results 160 to 170 dry..across the board.

- after the newest set of plugs and ignition wires it set a P0302 now.... so I'll focus more on cylinder 2

--next up... injector and control, coil pack control and possibly cam and crank position sensing.

Fuel or ignition you would think you could feel a miss or something? Wonder if the crank&cam position sensors or teeth on the pulleys are damaged, dirty etc as this might be able to get the ECM thinking there is a problem without there really being one. Just means the measurement is buggered that detects how fast it thinks the engine is spinning.???
At any rate hopefully this can be a learning experience for many at my expense

 

[Duane]

a recap... diagnostic codes P0300, P0302, P0305
NEW-- Cylinder5 coil pack , wire set, dual electrode plugs, good compression


an update... checked back with old favorite independent garage and they subscribe to some service bulletin database service
-- 1 repair was the crankshaft gear key slot worn allowing timing to fluctuate..replaced gear, woodruf key and new belt.

Going after this next Tuesday.... hoping the crankshaft slot is ok and that I haven't damaged the converter from the extra fuel going into it.

 

[Duane]

Well looks like the problem is a loose crankshaft pulley. Pulley and key worn pretty badly with the crankshaft thank goodness looking ok as well as the keyway.
So here is the lesson..if your 3.4L is throwing up a combined P0300, P0302 and P0305 codes this is a definite possibility.

Now I am wondering how common this failure is and why it fails? I think mine failed likely from an improperly torqued crankshaft pulley bolt. spec looks to be
184 ft lbs. Thinking this might be different now .... higher... ??
This IDENTIFIX database service has several confirmed fixes on the crank pulley being loose causing these 3 codes to come up together. It has also been single electrode plugs used and cam timing off.
Identifix

Also interesting that you can buy a $170 kit from RockAuto with belt, idler and tension pulleys and water pump and gaskets. I wonder if the quality of these components are really good? RockAuto Parts Catalog
More Information for AISIN TKT005

Something to perhaps post up RayDbl.
I'll take better pics and post them up.