Hey guys new to the forums and 1st gen 4runners. I just got this 86 4runner Turbo SR5, it's in great shape and the engine has been recently rebuilt. I hear this diesel like sound coming from my engine at low RPMs, I notice the turbo boost doesn't kick in until past 2k RPM. The gauge shows the turbo boost properly, I'm assuming there is an exhaust bypass for when the engine is below 2k rpm, is this where the sound could be coming from? it runs great and idles perfectly other wise. I really would like to get rid of that noise.
Thanks in advance.

I don't know a lot about the 22RET but I'd start with checking the timing and trying a tank of premium fuel. Next I'd try to figure out if that motor has a knock sensor and if it's working.

I see this is your 1st post so welcome and

It sounds the same with 87 or 91 octane. I'll check the timing, any one know how to check for a knock sensor?

Welcome

I don't get it PICS of what? I'm describing a sound.

We understand,

BUT we are 4Runner junkies and want to see what other peoples trucks look like, especially the rare Turbo trucks!

What kind of noise are you hearing? Clank. Clank, Clank?
From what you said about your turbo boosting, it seems like you have a stock CT-20 that is in fine shape. I think your noise is the typical top end Toyota sound. I am going to rule out timing chain since it was recently rebuilt and I am assuming that the rebuilder knows how install the timing kit and which oil pump bolts go where. You may want to warm up it and double check your valve lash. While it is warming up check to see if the sound you are hearing gets quiter/goes away.

(Nice name btw.)

Hi TurboSR5, Thanks I dig your screen name too! It sounds like you've got a lot of experience with the 22RTE. I really like it, the power just surges when the turbo kicks in. Which is when the Diesel like sound either goes away or is muffled by the turbo & high engineRPMs and fast flowing exhaust.

So checked the timing, it at 5 degrees BTC. While under the hood I couldn't really hear the diesel like sound, but I could hear it while in the drivers seat, I'm thinking exhaust leak because the pipe in front of the muffler is sleeved in and clamped. I also looked in the Hayens manual for the location of the knock sensor if it even has one, but couldn't find anything about it do you know where it is? or if the '86 turbo has one, which I think it should. I'll look in the manual about the valve lash, I couldn't really hear the noise while I was under the hood, but that may be because of the fan blowing. Thanks, will keep looking.

BTW topdown4runner thanks for explaining about the pics, I'll get a better one later.

Definately check that exhaust, I didn't know that you had power problems while under boost, a leak sounds very likely. Also check your charge pipe rubber elbows for cracks or leaks around the clamps. Do you know what condition the turbo is in?
Your knock sensor is low on the passenger side of the block, under and to the rear of your oil filter.

Good Luck

I don't have problems with the boost, in fact everything is great when the boost kicks in. The turbo seems to be in good shape and the rubber and clamps on the charge pipes look new.

I think have this sound narrowed down to two reasons.

1. exhaust leak from the flange behind the catalytic converter. (new flange, old pipes)
2. Valve train noise. (my other car has HLAS, so I've never had to do a lash adjustment, the manual makes it seem easy)

It's the combination of both of these noises MAKES that diesel sound.

Thanks for the info on the knock sensor I'll make sure it's working properly.

Sounds like your well on your way to getting a handle on things.

The valve adjustment is very easy, very little can go wrong there.

If you aren't getting a code for the knock sensor (if you have checked for any stored codes) then you should be good to go in regards to that.

No check engine light, but I'll see if there is any stored codes. BUT I did notice something odd, there is a slight mis at 1900 RPMS, it immediately drops to 1700 RPMS and up on reaching 1900 RPMS drops again. BUT THIS ONLY HAPPENS IF IT'S REVED SLOWLY IN PARK, and if you push the gas it reves past with no problems. NO hesetation or missing in drive at all. this only happens in park and only if it's reved slowly up to 1900 rpms. There's a video on you tube of another turbo 4runner with the exact same condition.
YouTube - Factory Turbo 4runner revving problem
any clues?

I don't think it is anything to worry about, the fuel mapping of your ECU is probably to blame. The computer sees the engine revving up and under load your turbo would be spooling up so spark advance and fuel would be metered differently at that engine load under boost. Since there is no real load on the engine in park your getting the results of a boosted loadout while not under boost.
I could be way off, that seems likely in my limited experience. If you want to dig really deep into this stuff I highly reccomend you join me and the other RTE fanatics at 22RTE-Trucks.com

Okay, found more exhuast leaks, this one is the gasket after the turbo.
Thanks guys.

I've got the same thing going on with my turbo runner. Sounds like an exhaust leak and you can only hear it when you step on the gas. It doesn't really make the noise at all when it idles. I gotta find my exhaust leak now! Finding this thread makes me feel better already.