98runner210

I noticed that I have a flashing Check Engine only after driving on the freeway for a while (speeds 60-80mph)

Scanned it and got Misfires in Cyls 2 & 5

Here is what I have done:

Replaces all coil packs
New Plugs (NGK Dual electrode iridium)
New Wires (NGK)
Fuel Injection Cleaning (BG 44K)
Intake Cleaning (BG)
MAF Cleaning
Took and and cleaned throttle body and IACV

Still have the flashing CEL but only on the highway and it scans as Multiple Cylinder Misfire

I tried searching but didnt find n e thing.

Any ideas?

MTL_4runner

When it comes back with 2 cylinders like that it usually means it's the coil pack or plug wire that's bad. Only thing is that you seem to have recently changed all those. Your next step is going to be checking the fuel injectors to make sure they all OHM out ok.....you're looking for a resistance of 12-16 ohms across the coil on each one.

98runner210

I don't get the misfire code for specific cylinders anymore. Just a random cylinder misfire code now. P300 i think

GOH10 Runner

x2 on checking the fuel injectors

98runner210

I would think I would feel something if it were an injector. Also, if I had a bad one I would think it would misfire on a specific cylinder. I wonder if it is a crank sensor or timing issue.

MTL_4runner

The FSM says it could be any one of the following:

*Ignition System (plugs, wires, coil packs)
*Fuel Injectors
*Fuel line pressure
*EGR (unless you have a T100, you don't have one)
*Compression pressure
*Valve clearance out of spec
*Valve timing (usually means timing belt problem)
*MAF
*Engine coolant temp sensor

I'd check the fuel injectors, fuel pressure and timing belt.
Also put in a set of the stock Denso plugs to ensure that isn't your issue.

98runner210

What do you think about not feeling any missing though when it is flashing? It's running smooth.

MTL_4runner

Most people can't feel engine knock either unless it's severe.
Start eliminating items and narrow the list for yourself......leave no stone unturned.

n4ynu1010

My 2 cents worth ...................
I am assuming that since you have the coil packs that your timing is cam or crank triggered .
If so and you are getting a random misfire and you have replaced all that you have I would be looking at the spark timing sensor/trigger on crank or cam , they are known to do this and drive people mad and cause them to replace all of thier ignition system components , the only way I have seen this diagnosed even somewhat reliably is to idle motor and tap on sensor and see if you generate a miss/code .
Other than that , outside of injectors failing randomly (not likely) and considering you have replaced everything else .....that is where I would look for your problem.

98runner210

i am starting to think a cam or crank sensor too. From what I have seen working on cars is that usually don't throw a misfire code unless it is severe and something you would definitely feel. I am a part time mechanic too. I am ready to drive this thing off the Grand Canyon. I love my 4Runner but everytime I have an issue it stumps everyone and is never an easy direct diagnosis and fix.

98runner210

anyone have any ideas why this problem only surfaces on the highway?

MTL_4runner

It could be, but it wouldn't be a bad sensor (that would show a code too), just poor mounting. You should pull the front off the timing cover and check to make sure all is correct because when the code starts out specific to certain cylinders and then becomes random, that's usually a sign that it's getting worse.

Yes I too used to be a professional mechanic and I've yet to have a stock motor problem that truely stumped me.
As long as you follow some sort of system of elimination, you'll get to the bottom of your issue.

n4ynu1010

I have seen many crank/cam trigger/sensors that were intermittently bad and acted up primarily under load conditions that never generated a code for the bad trigger/sensor .
You have to remember the ECM doesn't always see a intermittent problem as a failure , it is designed to report/detect failures of some sort , it could be a mounting problem true so check it out but if all you say is good/new , no serious vac leaks , all connections(electrical) , base timing is correct then I would replace the booger .
The only other thing I would look hard at is injectors but being random kinda rules that out for the most part , do you drive the truck all the time , have seen this problem surface with excessive condensation/moisture in gas tank but usually shows up as a miss/stumble throughout the operating range and not just highway.

MTL_4runner

On 5VZ-FE motors?

I'm not sure I'd buy that.
You need an oscilloscope to check the output anyway, so that's out of the realm of 99% of the DIY types.

98runner210

btw it has rough idle but has had it since i owned it

n4ynu1010

If that is the case have you tested your MAF,TPS,IAC and EGR ?

98runner210

my friend tested those and i cleaned them. When driving with the rear window down it smells like matches really strong. I read a TSB saying this is normal due to the sulphur in the gas. I was thinking a clogged cat?

n4ynu1010

If cat was clogging I am sure you would have some codes (one would assume) but that would affect performance more so accross the board with being more sluggish higher rpms , could be a factor but at the same time if you have a problem in the motor with abnormal emissions then the CaT will produce a strong odor , you just need to take a close look at all of your controls(emissions,PCV,air,idle) and verify all is good , you have replaced everything else it seems , unless you have a bad electrical connection or ground and all else is good then your down to injectors failing somehow or that crank/cam trigger is starting to show its age - and that is the most common sympton - Random Misfire.
Like the previous post stated some of the components can not be tested with what we have in a shop , few mechanics have a oscilliscope at home hehehe
If your cat was that clogged up you would be suffering a rather noticeable power loss I would imagine so that may be reaching.

mt_goat

My 2001 5VZFE has done the same thing only on the highway a few times, but it was always just after I tried to retard the timing by more than 6 degrees with a piggy back controller (FTC). Mine were not the random codes though, they were for specific cylinders like P0301 or P0305, something like that. As long as my timing isn't retarded more than 6 degrees it never does it. Not sure that will help you but I thought I put it out there.

98runner210

I figured if the cat was clogged I would know it by a severe loss of power etc.
I looked and crank sensors are about $80.00 and cam sensors are $140.00. I hate to drop anymore money without knowing. I'm sure most of us have been there though. I have 73K and original timing belt. I wonder if it is getting slack.