babyfood1217

Starting this thread to keep some documentation of what's been going on with our 4runner, and steps taken to correct the problems...

The vehicle is a 2002 4Runner - Sport Edition - 3.4L Automatic

The problem: During a road trip this past week, I noticed the onset of two issues. As of right now, I'm going to treat them as separate issues. If some signs begin to point towards them being related, I'll follow those leads accordingly. As I start this thread, I have yet to doing any sort of work to the vehicle, aside from topping up coolant (ISSUE #1) and checking for codes (ISSUE #2)

ISSUE #1 - I'm losing coolant.
No overheating, ever, at all. The gauge always comes up to under the halfway point, and stays there.During a routine check at a gas station while filling up, I glanced under the front drivers-side wheel well and noticed some splashes of liquid. Wondering where it came from, I popped the hood and looked for leaks. No visible leaks, anywhere inside the engine bay, but I found my coolant reservoir to be almost empty. It's been a while since I checked the level, so I freaked out, bought coolant, filled the res. up and kept going. I kept going as I've had no heating issue whatsoever. The next day, before starting the truck up, I opened the rad cap and found it to be full, but the reservoir had again lowered (not as much, but some.) I again topped it off and continued the drive. The last day of driving, today, I started out with the res. at the "full" line cold, and just now checked (the truck is still slightly warm) and the volume is down between the "low" and the "full" marks. No visible puddles or streaks anywhere.

ISSUE #1 Thoughts - It could be a leak from a hose, the WP, the reservoir, or I'm burning it. I have clean oil, so I'm doubtful the coolant and oil have mixed due to a faulty HG. I feel like with an external leak at a hose or elsewhere, I would be able to see residue or drips. I haven't delved too deep to look yet. I haven't noticed white smoke at startup either. How much white smoke would there be? Is there any other way to tell if you're actually burning coolant? My sense of smell isn't too great, and I feel like I'd have a hard time distinguishing white smoke from water vapor.

ISSUE #2 - There is a very intermittent shudder/stutter. First noticed when using cruise control and gaining an incline in some mountains in Eastern OR. Going up the grade, the truck began to slow. Cruise circuit opened the throttle a small amount to compensate and regain set speed, and when it was enough, cruise circuit a large amount (it was a steep grade.) When the cruise kicked in the larger amount, it stuttered very quickly about 6-8 times before the acceleration happened. I didn't notice rev. changes, and it didn't seem to present itself again. The next day, however, it happened again. Different speed, different rpm's, again on cruise, but it happened and then it was gone. The next day and a half, randomly and about once per hour, the same sort of stutter happened. Sometimes during acceleration, sometimes when steady throttle, with various speeds/rpm's and with/without using cruise control. During all of this, I never got a CEL. Before a 3 hr drive home today, I borrowed a friends OBD dongle and had him check for any stored/pending codes. Nothing logged at all. We parted ways, and I made a point of paying attention to all the details of the drive and the issue so I could start doing some research here. About an hour into the drive, up and down significant grades, and with speeds between 35-60, I experienced a rather significant bout of the stuttering, violent enough to really be felt through the vehicle. During the middle of the stuttering bout, the CEL flashed on for a brief moment, and then went off. Then it drove like normal. I stopped at the next town, and popped into the O'Reillys Auto Parts. Their Bosch code reader showed two codes - P0300 and P0304 - random misfire and cyl. 4 misfire. The CEL light was off, and it was running as normal with no issues, so I continued the 30 miles home. I had only one more noticeable bout of stuttering, with a slight decrease in power, but it also went away in a matters of seconds.

ISSUE #2 Thoughts - This one worries me a little. Coil pack, injectors, MAF sensor, timing issues. Could ISSUE #1 and #2 be related?

My approach, as of right now, is to compile a list of regular tuneup stuff that the truck could use (I've only had it for about 5k - it has 189K on the clock.) I can check off those boxes, and in doing so, maybe eliminate some possible causes of my issues. I also plan on buying an OBD dongle and finding an iOS bluetooth diagnostic app to help identify codes and clear them when diagnosing.

So there you go. The start of my documentation. Road trip over, back to real life. Gah, I'd rather be on the road.

-Chris

fierohink

Issue 2 first, my thought is an injector(s) is going when heat soaked. It may bench test fine cold but when it gets hot it fails.

When those go, it is intermittent but gets worse. Eventually you'll get P0300 plus P030(x) for the individual cylinder that is failing.


Issue 1, have you checked the hard coolant lines that run along the passenger rocker for the rear heater? There are water lines to the firewall for the heater, intake warmer, etc. if you can get a picture of power wash and dry to isolate the leak.

babyfood1217

An injector going was actually one of the first hits that came up when I was scouring this forum and another for matching symptoms. It's further down the rabbit hole, in terms of where I'm going to begin my diagnosing and treatment (starting with basic tuneup stuff, which I'm due for anyway), but it's definitely on that list. I've never pulled an intake off before, but I've found a couple "how to's" on injector replacement/removal. Fun thing is, is somehow I determine it is an injector, I can send them off to Witchhunter, which is in my neck of the woods now! I used them years ago for another 4runner engine replacement, and was quite pleased.

As far as coolant goes, I haven't been able to get under/into the engine or undercarriage and poke around looking for leaks/residue. My gal has needed to use it for some shorter drives across town, so I've been checking the res. level in the morning and at night (when the engine is cold, and again after it's home and when it's hot), and oddly, it hasn't dropped any since the last top up (Sunday afternoon). Hopefully it will be at the same level when she gets home tonight.

Side note, but related, has anyone ever used the litmus-type test strips to test for combustion gases in the coolant? My buddy asked about them and wondered if they would be a good way for me to rule out a HG that could be on it's way out. Again, I haven't noticed white smoke on startup, and I don't think the exhaust smells "sweet."

I just placed an order for a tuneup (denso plugs, NGK wires, Toyota Red coolant, Toyota brand air filter, Toyota brand oil filter) and will pick up the oil locally. I also ordered a WIFI ELM327 OBD reader and will be downloading a diagnostic app to my phone, so I can track/clear codes as needed when diagnosing stuff. First thing I plan on doing is moving my coilpacks around to see if the problem moves from cyl. #4. I only thought about a coilpack going bad was, wouldn't I show misfire codes for two cylinders, rather than just one? I understand it's a wasted spark system, so it seems like two cylinders would be afflicted. Dunno. More reading to come.

-Chris

fierohink

If you have a bad injector, witch hunter won't be able to fix it. It isn't a clogged screen of otherwise faulty issue, it's the windings inside that fail I.e. an electrical component. There isn't a repair or cleaning for that, just replacement.

Good news is you can get a set of injectors off eBay for about $50-70.

babyfood1217

Gotcha. Didn't know that. I guess what Gordon does is more along the cleaning/resealing/spray testing end of things? Good to know, thanks.

-Chris

KZN185W

iTrader: (1)

Issue 1: It is normal for the coolant reservoir to be empty at times and filled at times. when the coolant pressure is high, the radiator cap opens and the coolant flows into the reservoir. If you have filled it to the brim, then the coolant will flow to the overflow hose, resulting into spilled coolant at the left side of the engine bay. When the pressure is low, the radiator cap allows the coolant from the reservoir to be sucked back into the radiator.

http://auto.howstuffworks.com/how-do...r-cap-work.htm

babyfood1217

Thanks for the explanation, though I DO understand how the cooling system works. I realize the volume of coolant will fluctuate, based on temperature, and I understand the dynamics of fluid moving in and out of the reservoir. I have never filled it to the brim, only to the "full" mark when cold. When it is low, causing me concern, the amount in the reservoir is mere drops, well below the bottom of the pickup tube. That indicates to me that even if the engine/coolant temp were changing (cooling down) so that coolant would get sucked back into the system, from the reservoir, it couldn't.

Update: The vehicle has been cautiously driven the past days with senses on high alert, paying attention to things. The stumbling became more pronounced, however the coolant levels has remained fine, with no noticeable smoke on startup, only small amounts of water upon initial startup (it also has been getting cooler in Seattle, so it's easier to notice this.) Sadly, the stumbling got so pronounced/severe the other day, just a few blocks from home, that the CEL came on along with the VSC OFF and VSC TRAC lights. The only other time the CEL came on, it simply flashed and stored a pending code. After tenderly driving the last 1/2 mile home, I managed to check the code and rather than a pending code, it was a confirmed misfire on cyl. 4 (P0304) Only within the last two days, have I had time sit down and do the tune-up items I stated above, so I knew that before anything else was going to be investigated, I wanted to take care of that stuff.

Last night, I drained the oil, and put a new plug crush washer/gasket, a Toyota oil filter, and Pennzoil 5W-30 (took 6 qts total.) I replaced the air filter with a Toyota one, new wires with NGK TE-66, and new Denso plugs (K16TR11) gapped to .043". After these items, My buddy and I hopped in and took my normal commute route, as I know about where I first start noticing stuttering/hesitating. The drive was smooth, and I honestly don't think I felt a stutter at all. It can be tricky sensing the stutter on rough roads, but we drove on enough nice, smooth roads where I feel I would have sensed it had it happened. The stutter didn't throw codes every single time it happened, nor did the tach. always reflect it's occurrence, so I've been focusing on "feeling" it through the pedal feel, vehicle vibration, etc... I noticed nothing on this first drive, but there were still a couple things I wanted to do.

When I get a chance, I will post pics of the spark plugs I pulled out. They look eroded, but not wet or burnt or sooty. Fairly consistent.

This morning I tidied up the wire routing (I swear the TE-66 wireset is a bit longer than what I pulled out.) I also tested the MAF for resistance and voltage per the FSM, and tested the TPS resistance. Both items tested within spec. I wasn't able to do a coolant flush, as I forgot to pick up distilled water to dilute my Toyota Red coolant with, and I opted not to switch the coil packs around at this time. I want to see how this maintenance/tune-up affects my situation. If it continues, then I plan to move a coilpack to a different spot and see if the misfire follows, though I still feel like a faulty coilpack would affect two cylinders, not just one. If the misfire continues on cylinder 4, then it's going to be a bigger issue than I want to think about right now.