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Hestitation/VSV/Idle Timing all related Issues?

Old 08-21-2018, 08:20 AM
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Hestitation/VSV/Idle Timing all related Issues?

Hi,
Apologies for the strange post title- I have been battling my 4runner for a few weeks now and can't seem to find a good answer to the issue I am having

Here are the problems:
I just replaced my HG and am having trouble making the engine run correctly. It starts right up- high idle around 1500 and then drops down to 900. At idle the engine is a little rough but not bad
I have a hesitation/sputter at 1500rpm and 1800rpm which goes away past 2000 rpm
This started AFTER about 10 minutes on my test drive.
The timing is off at looks to be about 25 degrees Before TDC
My distributor is turned all the way to the left so I cannot adjust the timing any further
The engine feels a bit sluggish and I hit 3000 rpm at about 50 mph so I know there is a timing issue.
When I jumper the pins to set the timing it does not seem to impact the timing which points me to the TPS
I have a Code 71 which has popped up twice while test driving- I have been pulling the positive terminal on the battery to re-set the code to try to figure out the problem

What I have done so far:
Verified the timing marks on the Cam Sprocket are at TDC and timing tensioner is tight.
- BUT I know my crank pulley mark is off by 5-8 degrees so I set TDC on the crank by making sure that cylinder 1 was at the top of the stroke
I had to re-do the HG bc I put them on the wrong side (oops...) so I know that the 1st time I put the dist in it dropped right in and sat at the middle of the adjustment screw
I know the dist is NOT 180 degrees off
- WOULD the engine still run smoothly if the crank was say 1 tooth off of TDC and the CAMS and dist were set at TDC?
IS there any way to fix this aside from pulling the entire timing belt and starting again?
I rotated the engine by hand 2 full cycles and the cam TDC marks came right back to where the were supposed to...

Any tricks for how to figure out if the crank is one tooth off while the cams are set at TDC?

I have replaced the TPS and re-set it to FSM specs as per the rockcrawler write up. It was working fine before I did the HG the 2nd time and when I jumper it would change the timing- now when I jumper it the timing does not change.
The check engine light comes on when I jumper the terminals so I know that part is working
I also unplugged the TPS and the engine runs rough so I also think that it is working correctly.
I am going to test voltage at the ECU for the VTA pin this am...

Code 71 is showing a problem with the EGR and I have not put a vacuum test on the lines yet.
I have reviewed all of the line diagrams in the FSM and checked for vacuum leaks with brake cleaner several times and can't find any leaks.

I THINK all of the problems are related but am at a bit of a loss for where to go next.

Any thoughts on what to tackle or address 1st? I really need to get this truck running today or tomorrow at the latest... as it is getting shipped to Peru in 1 week...

THANKS!











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Old 08-21-2018, 10:12 AM
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Originally Posted by rbNW View Post
... The timing is off at looks to be about 25 degrees Before TDC
My distributor is turned all the way to the left so I cannot adjust the timing any further
The engine feels a bit sluggish and I hit 3000 rpm at about 50 mph so I know there is a timing issue....
If the distributor is off by one tooth, your timing will be shifted by about 28. This is an easy mistake to make. Pull the distributor, and reinsert it following the FSM directions. Then you should be able to set timing.

Originally Posted by rbNW View Post
... - BUT I know my crank pulley mark is off by 5-8 degrees so I set TDC on the crank by making sure that cylinder 1 was at the top of the stroke...
Yow! if the crank pulley mark is off, that almost certainly means the annular rubber ring in the harmonic balancer has failed. It's just a matter of time before you throw the outer part of the HB through the radiator. You need to replace the HB.
Originally Posted by rbNW View Post
...Any tricks for how to figure out if the crank is one tooth off while the cams are set at TDC?
Check compression. If cam timing is off by any significant amount, compression should suffer.
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Old 08-21-2018, 10:21 AM
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Start with the distributor. It's not in where it should be, it's off a tooth or it would be near center of the adjustment range.

Next is the throttle sensor, IDLe switch/signal is out of spec. If the adjustment is loose it's not coming off IDLe until late, to tight and its setting a code without moving the throttle.


The hesitation is the ECU cutting timing because it senses pre-ignition.

YMMV..
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Old 08-21-2018, 12:10 PM
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Thanks guys!
I re-set the dist and as you both suggested it was indeed off by a tooth- hesitation is gone and seems to run smooth. I left the timing around 12 BTDC.

I replaced the rubber on the HB which is how I know it is oof by 5-8 degrees... so hopefully it won't come flying off... I had a tough time getting it back on to the new rubber ring.

Using a jumper on the pins didn't seem to move the timing by much- maybe 4 degrees at most- but I check the voltage on the diagnostic port for the TPS and it was reading the TPS so I believe that means the TPS is set correctly at least with regards to adjusting the timing.

Really appreciate the fast replies and insight. Hope to know enough soon to pay it forward!

Thanks,
rbNW is offline  
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