Misfire Cyls 2 & 5- Injectors?

[mastacox]

Note- I went ahead and started my own "real" thread so I would stop hijacking Bob's LCA thread and my other "fuel injectors wanted" thread...

Soooommmmbeeaaatch. Went to the gym today, took the 4runner. As mentioned up above, changed out the plug wires and switched the coil packs. No code but running a little rough w/ stumbling. Today, fargin' code. Guess which one? Yup P303 and P304 again. So again, this is after I switched the coil packs.

Dude we're having the exact same problems, except I think my misfire is maybe worse because the CEL light is blinkning a lot for me... Things got better for a little after I swapped in OEM plugs, but now the problems are back with a vengeance

I drove to work this morning and the CEL flashed nearly the whole time, so bad that I called up a shop and dropped it by at lunch... of course it ran not too bad on the way over It seems to me I get the most misfiring when it's been sitting overnight and is cool outside, but doesn't get better after the engine warms up. BUT, when it's been sitting in the parking lot at work in the sun, the engine runs better and doesn't misfire much at first. Very weird...

The shop bawked when I told them some of the stuff I have on the car's fuel system, such as the fuel injectors not being Toyota OEM, but they're going to try and diagnose if the injectors are firing correctly and a compression test. The guy was more receptive when I told him I just wanted to try and have them help narrow down where the problem is for a start.

I'm not burning oil so it doesn't seem like I could have a piston rings issue, but maybe valves (although I put remanufactured heads on just 3 years ago). I'm hoping and not hoping it's the injectors; on the one hand I won't have to swap in a whole new engine if it's just injectors, on the other they'll be hard to find. I'm going to have to bitch at Gadget until he sells me a spare or six... I'm willing to buy 6 just to have them on hand for a rainy day at this point!

[Bob98SR5]

ok now to hijack your thread! :P Actually, better that you and i talk about the plugs in this thread than the LCA one.

brian, for a short time i had the blinking CEL light too. when i changed my plug wires it stopped---for 2-3 days. now its back on.

i have the same symptoms: if sitting in colder weather overnight, in the morning it runs like crap. for me though, warming up helps. However, doesnt eliminate the stumbling i feel thru the shifter. and acceleration in 1st and 2nd sucks.

welp, gonna try new plugs now, i doubt this is the solution.

[Seanz0rz]

ok ill chip in with my past issues.

about a year or two after i bought the truck, i had a stumble around 1800 rpm. usually doing about 55 in traffic on the freeway. never got a CEL for that. I replaced the fuel filter, but it didn't make a difference. replaced plugs and wires and that fixed the problem.

no problems until last late winter, when i had a misfire (random and 1 and 4 IIRC). this only occured when the engine was cold. i narrowed it down to it being moist. once the days warmed up above the dew point, the problem went away. that is, until i went through a water crossing much deeper than i expected in mojave. got a misfire again from that. then again in BB doing some puddle crossings. I haven't had a problem since then with it, but as the mornings get colder, i expect the problem to return and then be corrected by new plugs and wires (i am due for it).

I'm not sure that experience is helpful to you, but at least it's here for others.

[mastacox]

Sooo, took the 4Runner to the shop, expecting the worst...

Turns out I have 2 bad coils instead of one I swapped the bad coils for each other and did nothing to troubleshoot! They replaced both and say it runs great now. Pick it up tomorrow

[Seanz0rz]

glad it was something reasonably simple and low cost. could have been worse!

[mastacox]

That's the truth! Better than having to muck with the fuel system

I'm having the shop put in my new Toytec Bilstein coilovers this morning and I pick it up this afternoon. We're going out on a trip this weekend and I don't have time to put them in myself!

[mastacox]

SO...

The new coils didn't fix it. It seemed to be running pretty well when I first picked up the car, but as soon as I pushed it into boost it would start misfiring. Now 2 days later later the misfire is back just as bad as before (and still cyls 2 & 5). I'm calling up the shop to take the 4Runner back and troubleshoot more; might be time for a fuel pressure test and compression test

The symptoms are strange; it seems if I keep the engine out of boost, and go easy on the throttle, it won't misfire at all. But if I push it a little harder it will begin the misfire, and once it starts misfiring it doesn't want to stop. No major jumping or backfiring or anything, just a loss in power, rougher idle, and it idles lean.

Guess it all points to either a fuel or timing related issue... I wonder if my cam position sensor is going bad or something? I need to try driving around with the OBD reader plugged in to see what the fuel trims and timing advance are doing when it starts throwing the misfire code.

[mastacox]

Update-

Looks like I have the problem at least 90% quantified- it's the fuel injector on cyl #5.

I went and visited a tuning shop in Arlington that does race cars in the DFW area. The guy was pretty helpful right from the get go, and we didn't have to take anything apart in the engine yet. Basically I gave him the full rundown of my symptoms and we both agree I've probably got a sticky fuel injector, and since the code is cyls 2 & 5 it's probably #5 since that injector sits under the supercharger at the rear of the engine near the exhaust collector.

SO, he recommended I do a test; fuel injector cleaner and judicious throttle. I told him I had already tried a can of Seafoam fuel injector cleaner in the tank, his response was try again but MORE because he doubted just one treatment would do much So I went and got two large-size Chevron fuel injector cleaner treatments (20 oz ea, for treating 20+ gallons of fuel) and ran them through two tanks driving down the highway this weekend to the Ultra4 National Champioinships in Blackwell. Things have definitely gotten better.

Oh and I mentioned I needed to do some judicious throttle too- the entire drive I wanted to maximize the injector cleaner getting into the sticky injector, so every time it would do some of it's misfiring shenanigans I would downshift and do about 75% throttle to push about 5 psi of boost and dump more fuel. Believe it or not, it worked like a charm haha Driving back it didn't misfire at all!

SO I'm going to talk to the shop again this week, he said rather than "throw parts at the problem" (I love him already) he would prefer to first swap the suspect injector to another cylinder and see if the misfire moves. This would 100% nail down the problem, and if it does then we could get them sent out to be cleaned and flowed.

I'm glad I just gave up on the other "foreign car repair" shop, talking for 30 minutes with this guy (for free by the way) gave me a lot more insight if nothing else to be able to bounce my problems off a fuel-injection tuning guru and see what he thought. They're going to be a bad influence on me though, he's already talking me into dumping the piggyback control system and going standalone instead to get the Toyota ECU out of the mix altogether

[mastacox]

I forgot to mention the guy also pointed out my rough idle starting when cold in the mornings could also point to a poorly sealing injector. If the injector doesn't seal fully over cyl 5 and drips fuel on top of the valve during the night, then in the morning when I start up the fuel dumps into the cylinder and makes it run all rough and rich until it burns it all off. Makes sense now that I think of it...

[Obi..]

Cool to hear. Buy the guy whatever case of booze he wants. Smart and experienced machanics are a rare find these days. Too many "Techs" out there that are only "Screen Reading Button Pushing Parts Changers".