I'd like to verify that my timing is set correctly. Previous owner had a shop do the timing belt last year and I'm wondering if it was set correctly. Only reason I ponder this is because of the extreme drop in power I have below 3000rpm. Above 3000 she's awesome, below it and she's slower than cold molasses. The power difference is like throwing a switch. Almost like it's bogging out below 3000 and then once it hits that point it leans out and runs great. Oh, and no check engine lights or lingering codes so I'm shooting in the dark. But figure checking the timing is easy and cheap enough so why not check it.
Checking and adjusting timing
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TheDurk
Elite Member
Ignition timing or valve timing? Two very different things...
Valve timing:
Use a wrench on the crank bolt to set the crank pulley to 0° (top dead center). Loosen coolant hose clamp at rear of top rad hose and slide it forward. Unbolt top timing cover and slide it forward. Look at both cam pulleys and verify marks line up with marks on block.
Ignition timing:
See attached:
Valve timing:
Use a wrench on the crank bolt to set the crank pulley to 0° (top dead center). Loosen coolant hose clamp at rear of top rad hose and slide it forward. Unbolt top timing cover and slide it forward. Look at both cam pulleys and verify marks line up with marks on block.
Ignition timing:
See attached:
Rock_Rat
Senior Member
Almost sounds like your timing isn't advancing the way it's supposed to. If your timing is retarded due to pre-ignition you should hear some backfiring or "popping" sounds if that were the case. What does your Scan Gauge show?
Go with the easy stuff first before you start checking your timing belt marks. I'm sure you've already looked at your ignition coils, cleaned the MAF, a small bit of seafoam, etc... What's your A/F reading? If I recall, it should be around 1453. Keep us posted.
EDIT: Cam marks and top cover is easy stuff as [MENTION=10169]TheDurk[/MENTION] mentioned.
Go with the easy stuff first before you start checking your timing belt marks. I'm sure you've already looked at your ignition coils, cleaned the MAF, a small bit of seafoam, etc... What's your A/F reading? If I recall, it should be around 1453. Keep us posted.
EDIT: Cam marks and top cover is easy stuff as [MENTION=10169]TheDurk[/MENTION] mentioned.
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I've done all of the usual things. Truck runs and drives smoothly but is just a dang dog under 3000. The moment it hits 3000 it picks up immediately. Timing belt marks are easy enough to check and free. If they are off though I'm assuming I'm pulling the front end down just so I can remove the tensioner, remove the belt, adjust the shafts, and start again. The only noticeable thing that seems "funny" is occasionally I'll hear what sounds like a miss at idle but it might just be my mind.
TheDurk
Elite Member
That's to verify the idle speed. That's why it says scanner, and not code reader. In the old days, we used a Dwell-Tachometer.
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gamefreakgc
Elite Member
Usual things, meaning injector cleaning, MAF cleaning, stuff like that? That's where I would start, making sure the air/fuel ratio is good and all related sensors are good. I'm guessing you've also replaced your spark plugs with dual-ground electrode plugs and at least tested your spark plug wires?
Reason why I ask is because my previous Toyota had this issue. Cleaned out the fuel system and swapped injectors and ran much better. Not saying that's a cure all, but didn't have anything to do with timing.
nevada
Senior Member
i would check the valve timing, as described above. it does sound like it may be off a tooth. ive ran into this on a different engine, and it was exactly how you described it. a dog on the bottom, but good power on top. the cam was off 1 tooth.
is the ignition timing even adjustable on these engines? im not sure that it is.
azcat90
New member
Mine was off 2 teeth and still ran.
All of this has been the last 2000 miles:
Maf cleaned
Tb cleaned
Iac cleaned
Plugs replaced with dual electrode
Plug wires replaced
Fuel filter replaced
Air filter replaced
Tps replaced
Seafoamed engine
Seafoamed gas
Lucas treatment in gas
Pcv replaced
Synthetic fluid in rear axle
Synthetic fluid in front axle
Synthetic fluid in transfer case
Synthetic fluid in engine
B&M Trans cooler
Magnefine in line trans filter
New radiator
It does start what I consider hard and takes a while but I haven't tested the battery or fuel pressure. I know the FPR is bad and it'll get changed at the same time I do my valve covers which will hopefully be next month.
Regardless, I'm fairly certain the timing is off on this thing because of the drastic power difference. I just hope I'm wrong because I'm not looking forward to tearing it down entirely just to move it a tooth unless I'm way over thinking this.
Maf cleaned
Tb cleaned
Iac cleaned
Plugs replaced with dual electrode
Plug wires replaced
Fuel filter replaced
Air filter replaced
Tps replaced
Seafoamed engine
Seafoamed gas
Lucas treatment in gas
Pcv replaced
Synthetic fluid in rear axle
Synthetic fluid in front axle
Synthetic fluid in transfer case
Synthetic fluid in engine
B&M Trans cooler
Magnefine in line trans filter
New radiator
It does start what I consider hard and takes a while but I haven't tested the battery or fuel pressure. I know the FPR is bad and it'll get changed at the same time I do my valve covers which will hopefully be next month.
Regardless, I'm fairly certain the timing is off on this thing because of the drastic power difference. I just hope I'm wrong because I'm not looking forward to tearing it down entirely just to move it a tooth unless I'm way over thinking this.
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TheDurk
Elite Member
It's not. It's set by the ECU. But you can check to see if it is working properly per the doc I posted.
nevada
Senior Member
I think it would be a lot easier to just strip it down.
you will have to compress the tensioner anyway. its on the bottom.
since you aren't replacing any parts, you will want to buy a tool to compress it. it will make it so you don't have to remove the tensioner. making the job much easier.
unless of course the tensioner wasn't changed when they did the belt. then I would suggest buying a new one and replacing it. it either case, you'll need to strip it all the way down.
That's kinda what I figured. I'll have to dig out the receipt and see if they replaced the tensioner or not. I know the belt and water pump were just done last year but not the tensioner. I'll probably check everything this weekend and if it is off wait until fall to adjust it. It's not hurting anything and 103* is not pleasant to work in.
Well I finally decided to take the truck in to the shop and have them check the timing on it as well as a few other odds and ends I just didn't feel like screwing with. Sure enough the timing was off by a couple of teeth. Was relieved to hear that the belt and tensioner and everything else looked new so at least I know everything was replaced like the receipt states. Gonna pick it up next Mon/Tues. Kinda excited to see how it drives with the timing set right.
rideexileex
Senior Member
I'm late to the party, and as my suspicions were reading the first page, glad to hear it was the timing. I'll post for future knowledge anyway - The ECU is set to advance timing as much as possible via the knock sensors only after 3K RPM, which explains why it came back to life at that RPM threshold.