Multiple cylinder misfire

I have a 2006 SR5 with the 4.7 and it's giving me multiple codes. I actually just bought the truck knowing about the misfire that started as #6 misfire. The previous owner had heard a whistling noise and the shop told him he needed an air pump replaced. He had the pump changed and about 1 month later it started showing #6 misfire. He then changed the plugs (Denso Iridium) and coils (Advance Auto cheap coils) and now,multiple cylinders are misfiring.
I'm guessing it could be the intake manifold leaking or maybe a ground wire for the injectors vibrated loose. Part of the problem is the codes keep changing on me until today, currently all the codes are just misfires. Has anybody ran into this type of situation before ? Thanks !

 

I’d start with coils. Only use OEM or Denso coils. All others Chinesium and terrible. RA best place to buy coils. Denso or NGK plugs good.

 

Coil packs are one of those things you don't buy aftermarket. Denso coils, and don't buy from scAmazon or fleaBay or WallyWorld online. Wanna buy online? RockAuto or Summit. Your LAPS won't usually carry Denso.

Did he happen to give you the original coils by chance?

 

I just texted him and asked, he said he threw them away.

 

What a dick. And a moron. But hopefully you got the truck for cheap, replacement coils aren't gonna be cheap.

Whatever you do, don't add to the problem here. Don't get all crazy and start cleaning the throttle body or other crap. MAF is OK, as long as you use a good MAF cleaner (I like CRC brand), let it dry and come to room temp before reinstall.

I'd be checking grounds in the engine bay. There should be a ground (if memory serves) for the coil packs and/or injectors on the drivers side, right about where the valve cover meets the top arc of the timing belt cover.

Speaking of timing covers, I'm realizing you said the secondary air injection pump was replaced. That means the mechanic had the entire intake plenum off and mighta pulled the fuel rail, there's no telling. You've got a LOT of shit to look over.

I can't urge you enough, since this truck is new to you, probably before anything else, to get a 10mm socket, loosen up one of the two timing covers - whichever is easiest - to confirm the timing belt is intact and in good shape, just to make sure that's not what's causing the misfire. I'd actually be checking the timing also. Remember: You have no idea who touched what before you got the truck.

The only way the ECU can avoid misfires is to make sure:

• Timing is correct
• You're getting proper, strong spark at each cylinder - and to that point, if he bought the wrong plugs, or bought counterfeits off scAmazon (which happens often enough) that could be it, so could bad ground, can't get good spark w/o good ground
• You're getting fuel pumped at proper pressure to the fuel rail - you can throw a gauge on to check, only read it while turning the truck over, that's the only time the pump is pumping until engine is running
• You're getting sufficient and metered air ... that is, the MAF is reading properly and doesn't have, say, some rodent-inspired chunks of air filter on it, and the TB is opening/closing

 

The timing belt & water pump was changed 2 years ago. It was running fine, then he heard a noise and a shop told him the air pump was bad and needed replaced. He said he wasn't sure if it was running properly after the air pump change. The first time I test drove it, there was a slight miss. The second time I drove it , it was daylight and I drove it harder and then it started the multiple misfire and its been misfiring since then. I just drove it home tonight, maybe 12 miles, it never completely dies but the idle got down to around 500.

The Denso plugs & coils were bought at Advance Auto.

 

Yeah, but you don't know what they used for TB & WP, it's worth checking. The timing belt is the Achilles Heel of the 2UZ-FE. The fact you just said you jumped on it and it got worse and was misfiring like crazy is exactly what I'd expect with a belt that jumped time, or if someone went in to do the cam seals and forgot one very specic step that would fuck the timing all up.

It's not uncommon in the '05-'06 to hear almost like a shop vac sound for 30-60 seconds after starting the engine. It's the secondary air injection pump (SAIP), it lives under the manifold next to the starter. That's what the shop replaced. To get to it you basically gotta take the top-end of the engine off, which is why I'm saying: There's a ton of stuff they coulda f'd up in that process, and now you get to go over it all

Look, you might be able to learn more about what you just bought, starting over here.

If I were you, the first thing I would do is this:

• Reset all codes, turn the truck off, then remove the negative battery cable for 10-15 minutes (or longer if you want). Forcing the ECU to reset itself, start a re-learn cycle.
• Check all grounds in the engine bay to make sure they're good. That includes the ground at the front of the driver's side valve cover, and the braided ground that goes from the back of the block to the firewall, I don't recall the others.
• Reattach the battery cables, making sure both of the cables and their housings are alright.
• I'd go across every single connector for every fuel injector, tug on their cables to make sure they're nice and snug, and the clips aren't broken. Hell, I'd check all the sensors I see across the top of the engine, anything on/near big black intake manifold, fuel rails, etc.
• I'd check all the vacuum and fuel lines to make sure they're plugged in, in the correct order, in case the shop swapped one or two, especially anything that attaches to the valve cover. If you need another pair of eyes, post some pictures on here of the engine from both sides so we can see the tubes
• I'd pull the plugs, for two reasons: #1 to confirm he actually put in the correct part number!, #2 to make sure they're in good shape, and if they aren't Iridium (which they should be), make sure they're gapped right. I'll almost bet he put in the wrong plugs or they're fouled.
• If all the above is done, I'd try to turn it over and let it run; let it pop some codes. Let us know what the codes are.

If the codes are all misfire codes, the next thing you need to do is - and I hate to say it to you - but you NEED to confirm the timing. You literally have no idea what the person who changed the timing belt did, there's so many things they can screw up that would cause these conditions, and you can never trust a previous owner to be honest with you. They may've done the work themselves, and didn't set timing right. We've had another guy here with that same issue in the past year. Exact same story.

If every bulleted item above is correct, and you are 100% positive the timing is correct, I'd shell out for a full set of Denso coil packs, but NOT purchased from scAmazon, fleaBay, WallyWorld. Replace the coil packs, pull the neg battery cable for 10-15 min, reset codes, and try again.

And don't forget, if you at least get it mostly running, you can always drive it to a stealership and pay them for an hour of diagnostics to figure out what they think is the issue and take the truck back, then fix it yourself.

 

Thanks for all the information. I'll start checking tomorrow. I appreciate the starting points ! I'll definitely follow up when/if I find the problem.

 

That link I left you with - there's a series of links at the top, including your service manual. It will help you isolate grounds etc.

 

Tonight I went through the first check, codes, battery, plugs are Denso Iridium long life. When I started it it was stilling and didn't want to idle. I remember I had an '03 Sequoia that wouldn't idle after the battery was disconnected due to the IAC valve losing it memory so, I drove to the store to get some throttle body cleaner. I cleared the code before I drove back home (7 miles) and checked the codes one last time and had 300,306,307 & P0137 Bank 1 Sensor 2 Oxygen Sensor . Tomorrow I'll clean the throttle body and move some coils around to see if anything changes.

 

Check your alternator output (voltage)...these trucks get really squirrely when the voltage is low. Did you confirm that your coil packs are authentic Toyota/Denso?

 

For the O2 sensor ... advice: Swap the passenger side O2 (which is supposedly good) with the driver side O2 (which is reporting as bad), clear codes. See if the code travels from Bank1 => Bank2. If not, it's the upstream sensor that's actually bad. Either way, replace both sensors on the same physical bank to keep things in parity, trust me on this, we've seen some shit here.

Downstream: Denso 234-4260 (RockAuto link)
Upstream: Denso 234-9051 (RockAuto link)

Don't buy on scAmazon or fleaBay. And remember RockAuto has 5% coupons all day every day, get the code from RetailMeNot and put it into the 'How'd you hear about us' blank at checkout. They'll apply it automatically when the order is processed after-the-fact. Summit Racing is another solid vendor, who is sometimes cheaper than Rock and the less-scrupulous vendors where knockoff products tend to be found.

 

Pull spark plugs and check for .032" gap. If they say Denso or NGK iridium, check if they are fake ebay/Amazon crap. Ebay ignition coils are crap, they will start going out randomly, throw codes for adjacent cylinder sometimes. Learned this from the truck I bought that came with them, I went through a second set that came with the truck. Some were mark ECCP and others nothing. The NGK iridiums that were already in the truck I put another 40k miles on them, still going strong, don't know how long they were in there. If you want to go cheap on ignition coils get the spectrum brand off rockauto been 2 years, 20k miles. Broke them in with a cross country round trip total 90+ hrs w/ 18 hr runs with 4 hr breaks. Have used 3 other sets over last 3 years in other 2UZFE engines no complaints.

 

I've swapped the coils between 6 & 8 and the miss stays at 6, logic tells me #6 injector

The plugs & wires that were changed before I got the truck are from Advance Auto - using Denso Iridium long life plugs - for everyone that keeps telling me the same thing The coils are whatever Advance Auto sells, The original owner threw away the original coils.

I've used Denso parts for years plugs, O2 sensors, plug wires, coils, injectors, etc and will continue to do so.

If swapping the injectors, what are your thoughts on the 12 hole injectors ? Does anyone have the original part number ?

I'll go swap the position of the O2 sensors now and, report back !

 

I agree with this deduction, but also, since you know they had the manifold off and likely the fuel rail, you'll want to verify they simply didn't f-up the seal on the injector, double-seal, or something equally stupid. I recommend swapping injector 6 and 8, see if the misfire follows. I know, crude logic to save some $$ and it ruins your desire to go 12-hole, but ....

Nobody has been able to identify, in reality on a dyno, that the 12-hole injectors actually provide any real-world, tangible benefits. At least not that I've seen. Not even the manuf'er last I checked. I found at least one dyno run on YouTube that showed no improvement last year or year before.

 

I watched a YouTube video by YotaMD that dyno tested the 12 hole this morning. They're test didn't real show any gains, a minimal increase in mid-range, no mention of MPG. The mid-range might be nice but, I rather save the $$$ ! Just checking opinions if injectors are needed.

 

Yeah, I mean ... Injector-wise, I'm admittedly a cheapskate and if it ain't broke, don't fix it

I'm asshole enough I'd swap the cyl6 and cyl8 injector to see if the misfire follows, and if not, well, you didn't just waste money on new injectors, and you've got something else with a/f ratio or ignition with that cylinder specifically...

 

The mid range is where it's at for potentially increased in town mpg.

A dyno usually won't show mpg gains or losses. Not unless you've got a constant load or engine dyno and can track fuel usage under various load conditions. It'd also be a long series of tests. Or someone with a consistent commute and constantly tracking mpg for comparison.

 

I'm aware you can't determine MPG on a Dyno, I was trying to say the owner didn't mention anything about MPGs.

 

I haven't seen anything on here about spraying brake clean (make sure it's the flammable one) around the intake in order to see if you possibly have a vacuum leak from the intake being off.

 

I normally use soapy water to seek out vacuum leaks, same as tire leaks. Spray bottle with a teaspoon of dish liquid.

A lot of people use brake cleaner on every-damn-thing. I prefer not to, because I've seen it do some weird shit to plastics and rubber. I typically keep the non-chlorinated stuff on-hand, and maybe that's why, I really dunno. I've always wanted to ask what others' experience was with using brake cleaner for misc cleaning jobs. For me, it gets used pretty exclusively on steel and concrete (does a great job of blasting stains out of concrete)

 

I had a similar issue with misfiring on my 2000 Tacoma. Like @shifty` said, since they were in there doing all that work to replace the air pump there could be something loose or connected poorly. My problem ended up being a slightly bent pin on one of the injector plugs. When the truck would get warmed up it would start running like shit. Once I found the bent pin in the plug, I just bent it back straight and never had the problem again.

 

Actually, I sprayed around the intake with starting fluid, no changes.

 

I have read this message thread in its entirety, but since my problem is with a basically "new" first-generation Tundra, I am hoping that it does not involve the more serious post-maintenance electronics and related issues discussed in this one. Here is the link to my new posting:

https://www.tundras.com/threads/2004-toyota-tundra-v-8-pick-up-with-random-misfire.129290/

Thank you! MarkT