toyota_mdt_tech

Well, the idea behind a flashing CEL is to stop or converter damage will occur. This is from any missfire. Unburnt fuel will take o ut a cat quick. I didnt see new coil in there. With cylinders 2 and 5, I'd be looking at a new coil.

98runner210

thats the first thing on the list. I replaced all the coil packs.

MTL_4runner

That was the first thing that came to my mind as well but I saw he had all new coil packs already (plus the fact that the code went from specific cylinders to random). The next thing that came to mind was either a loose balancer (where the keyway has been worn and timing jumps around) or problems with the timing belt (often caused by a bad tensioner, causing the timing to jump). It could also be fuel related but a quick check on the line pressure should eliminate that as suspect.

Tell me if this sounds like what you're experiencing:
http://www.motor.com/MAGAZINE/Articles/012007_04.html

98runner210

Not really cause I am not haveing drivability issues

98runner210

hmm it really seems to be stumbling when idling at a light. Still no check engine. Guess I will pull the timing cover off. Is it just the upper raditaor hose and a few bolts on the perimeter of the cover?

n4ynu1010

One thing that will cause definate Idle issues is the EGR if it is open at idle , they can stick and cause great problems with drivability , as well as any vacum leaks again and make sure your air tube going to the throttle body is not cracked and all connections to the throttle body and air box are good , idle the truck and squeeze the air tube all over and if it stumbles worse or stalls take a close look at it and you will find a crack .
Alot of the air tubes have like a acordian design in them for flexibility and the tube will crack in between those so you cannot see it and generally you will not hear it either , generally when this happens it will stumble pretty bad upon acceleration of the motor due to the engine torqueing but that is not always the case .
Outside of all the controls (being tested and verifying they are working), Timing (jumped and set) , Timing Belt (installed correctly,hasn't skipped a tooth and tensioner working correctly-no slack), spark timing (correct/verify correct distributor installation), coils (all good if you have pack , coils can check out fine and still fail under a working load), Injectors (ohmed out and or removed and checked for operation/failure),MAF (test and clean),TPS (check with ohmmeter and adj. or replace) , Plug Wires (replace if old and check for leaks/arcing to ground), Plugs (check for bad insulators-will bleed to ground and fouling) , Check Compression to find if you have a bad HG or Valve causing problem and check plug color for burn for hints as well,02 Sensor (bad or open).
You need to systematically eliminate each thing and keep going

98runner210

The 3.4 doesn't have an EGR does it?

n4ynu1010

Not sure to be honest , have a 3.0 but putting it out there in case , I beleive you are right though , I don't believe they do.

mt_goat

Appearantly just the T-100 3.4, I knew I'd seen some with a plate over the exhaust manifold that was used at one time for EGR.

ciscojay

are those the same brand plugs you've used the whole time? You might even want to try and spend a few bucks and buy stock platinum plugs. When I put in my urd kit I purchased and installed the iridiums...ran like ass. Stumble at idle, would accelerate fine but would randomly hesitate...drove me nuts until I realized that for some reason my motor just didn't like running those plugs. Put in some OEM platinums and it was like a day and night difference. Just a thought after my experience.

MTL_4runner

Dale, I have a blockoff plate on my exhaust manifold where the EGR would have attached on my 1996 4runner, but the EGR was only used on the 95.5 T100 with a 3.4L motor AFAIK. No 4runners with the 3.4L motor ever had an EGR valve on them that I've ever seen.

If you did have one you'd see something like this on the driver's side exhaust manifold:

98runner210

It had Autolites when I bought it, replaced them with Splitfire, then pulled those out and put NGK, now that I think of it, they are the OEM ones. So that rules that out. With all 3 sets of plugs I had a rough idle but never a flashing CEL.

n4ynu1010

Unless you have a blown head gasket or bad valve seats then it would have to be your MAF or TPS , do you know if the trk has a aftermarket cam in it ?

98runner210

It's all stock. I pulled the timing cover off and the belt is tight and everything is clean in there. I have a feeling I am going to have to wait for it to get really bad or break down before I find the culprit.

By the way it has to be something ignition related because sometimes it will clear up and run smooth.

rbh261

I have had the same issues with my 98 4-Runner. I have replaced plugs, wires, TPS, O2 sensor, cleaned the MAF, and replaced coolant temp sensor. I ran advanced diagnostics with a laptop and found that the temp sensor was reading high and the timing progressively climbed at idle. I haven't run diag. since, but I still have the flashing CEL. Mine is only on the highway after driving for quite some time. With the cruise set and the RPM at 2400, it will flash every minute or so.

98runner210

Those are my symptoms exactly. If I cruise at 60 mph the light will start to flash after about 10 minutes and then pop up every couple of minutes. If I bump it up to 80mph the light flashes almost constantly.

rbh261

I bought Toyota brand plug wires the other day and installed them. It cleared up another problem I was having between 3k and 4k RPM. I had a hesitation there that is now gone. Hope it takes care of this current issue.

98runner210

Starting to wonder if it is a catalytic converter. I drove my friend's '97 SR5 4x4 and his had more power. If I am driving with my rear window down, it smells like sulphur or matches really strong. I did find a TSB about that though saying it was normal. I wonder if I need a cat or maybe just a newer Tundra.

98runner210

anyone else have anything?

n4ynu1010

If your low on power and all else is good it may be cat , and O2 sensor on some models will flash continuously if you have a serious heat problem at cat .