where did my smooth 4.7 go? Engine Surge

This thing ran like a top. I mean sitting in the drivers seat you wouldn't know it was running, you might try and start it again. NOW it surges at all RPM's.

And this happened all at once after I wrecked the thing, long story....

But there is no visible or invisible reason for this running condition, or excuse for that matter, well maybe...

The only thing I can find on this forum is from 2nd gen owners talking about flex fuel pumps.

This is a 2005 4.7 liter with 160k and it was/still is a good running truck but has this damn Surging in the engine which can be seen at the needle.

When driving the Surge is more noticable at creeping speed and seems to trip the ABS at slow stops. I pulled both ABS relays but still get the whirring noise from the dash at slow stops and some hard stops on dry pavement.

It pulls against the brake at stoplights and the surge is noticable on accereration and lower RPMs while driving. kind of like a ship rocking front to back, yet I can open it up on the highway and it runs like a banshee.

Has anyone experienced this problem in a first gen???

I think I pulled an evap code but it could have been from messing with the lines. I cleared it and it hasn't returned.

New gas cap, no smell of fuel around filler area, no visible damage to canister or lines, vsv solonoid makes audible clicking as if switching back and forth, don't know if that's normal but 4.7 sequoia doesn't do it... those things are like 124 bucks, I'm beginning to ramble.

Thanks all, this site is great.
Jack

 

Clean the maf. Make sure there's no disconnected vacuum lines.
Did you pull the ABS relays or the fuses? I've always heard people say pull the fuses not the relays. That's a whole other can of worms if you want to get ABS working again.
How bad of an accident was it?

 

That sounds 100% like a vacuum leak. Mine did the same thing. It would drive fine, but would idle like shit and surge in D at a stop. I had a cracked intake manifold gasket. Pop the hood and listen for hissing.

 

Welcome to the forum. 1st two places I'd look are basically what these guys posted: Air intake related stuff (MAF, TB, manifold) and vacuum. I'm more inclined to lean towards the TB sticking open, and/or the computer getting bad MAF readings making the TB stay more-open.

Only way to be sure would be to take live readings, but at 160k, it wouldn't be an unreasonable decision to install a new OEM MAF. That's one part I wouldn't necessarily go aftermarket with, but apparently the OEM was a rebranded Hitachi, so maybe Hitachi is OK. If I were you, I'd start here. Pop the neg batt cable off for 10min after.

BMF posts a legit concern with the intake manifold. Things get jarred in wreck. Without knowing what type of wreck it was, what speed etc. it's tough to say.

 

It could be the brake booster, causing both the vacuum leak / surging, and the loss of brake assist. Or that could be the other way around.

Easy to pinch or cap the vacuum line to the booster and see if the idle smartens up.

 

@Jack Sprat can you post clear, sunny pics of both sides of your engine bay, like one diagonal from the front passenger corner aiming back to the booster, and one from the front driver corner aiming back towards the glovebox part of the firewall? Can't hurt to have several eyes making visual check of things.

 

Need more info on wreck. What was damaged/replaced?

 

Thanks for the responses all,

To give some more info, my truck is a 2005 access cab with the 4.7. I ran it off the road at pretty high speed - fell asleep.
managed to replace the hood, headlights, radiator, bed, fenders. It didn't push the engine or smash the fan.

I had a shop do work on the suspension. They replaced a lower A arm and straightened the front sub-assembly. Maybe they didn't get the alignment right, but it drives straight, no pull except slightly left on hard braking.

This running condition - the surging was noticeable but slight after the wreck. It has been more noticeable since; pulling at stoplights and tripping the ABS module behind the dash despite having taken out the relays. didn't try pulling the fuses. I feel like the intermittent pulling/surging while slowly stopping is what trips the ABS module.

I have examined all the vacuum lines carefully, anything coming off the manifold.
Someone said there was freeze-out plugs on the charcoal canister that can fail. There was no visible damage to the canister or connections. I thought I had an evap code but cleared it and it hasn't returned.

I guess I'll start into the throttle body cleaning, maf cleaning, spark plug and coil examination, pcv valve check etc...

But yeah, a vacuum leak would seem logical... the brake booster thought is interesting.

Baffled as to what else could have been jarred loose or broken to cause this.

I'll try to post some pictures of my tricolor tundras engine bay.

Appreciate it.

 

Yeah, pull the abs fuse and see what happens. I don't see the two issues being connected, but you never know. I have my abs fuse pulled for a different reason.

 

Don't discount the mileage and/or age on it and what happens when you take a front impact. That damn engine will run forever, but there's a magnitude of things that have likely exceeded their life expectancy (in years), the MAF being one of them.

On the booster thing, some of these trucks do have a vacuum line from the booster to .... the intake? I think.

Anyway, I can't help but reiterate how helpful it may be for you to share a few bright, clear, sunny pics of the engine bay so everyone can put their eyes on it. Someone is bound to see something out of place, it's worked in the past.

The lack of codes is curious.

 

Any luck?

 

OP was last seen Mar 2. I doubt we'll get an answer.