Hello, so I've been troubleshooting my truck with no success so far and wondering if anyone could help. When I unplug spark wires at distributor cylinder #1, #3, #4 show no change in engine idle.
New
distributor and cap
Plugs and wires (sparking hard)
Compression tests excellent
#1= 143psi. #2= 132psi. #3= 138psi
#4= 133psi #5= 134psi. #6= 132psi

fuel filter (fuel that came out was dirty maybe clogged injectors)


tested with volt meter
Vaf and Tps and there fine.

Can here injectors firing fine with screwdriver test but maybe there clogged.

When I bought it they said they had someone replace headgasket so I'm thinking maybe they missed a tooth on timing belt or something.

Only code is dreaded 52 knock sensor but I wouldnt think that would cause only 3 cyclinders to fire. Also it still runs rough when I reset ecm before ks throws a code at 1600rpm.

 

Welcome to YotaTech!

Kudos for your careful trouble shooting so far. Your code 52 is most likely due to a bad "pigtail" - the wire from the knock sensor to the connector on the other side of the lower intake manifold. You're going to have to fix that eventually (code 52 dramatically retards ignition timing), and that requires removing the lower intake manifold. THAT requires removing the fuel rails and injectors. So you can send the injectors off for testing, or at least replace the tiny filters in the top of the injectors.

At the same time you can verify the valve timing (position of timing belt), though that is unlikely to be your problem (missed tooth on timing belt should show up as low compression).

Short of all that, have you tried quickly removing the plugs to see if the non-firing plugs are "wet"? Have you tried putting the inductive pickup of your timing light on each plug wire? If the light flashes, the plug is firing.

 

Thank you for the quick reply
When I did compression tests I replaced all plugs , before I did that when I noticed no change on 3 of the cylinders I pulled a plug (old one) and connected it to plug wire and it was sparking hard.
No wet plugs before but I can check again
Found new set of injectors for around $60
intake gasket for around $15
(Previous owner only used silicone so that needs fixed)
I plan on doing knock sensor wiring , I can see were they tried to splice it back together coming out of the head. Been reading alot about that job.
Also this morning I did an Egr/pair bypass to see if that would change anything. Slight increase in power still has issue.

 

With half the engine firing it seems that it might be distributor related as there are two pickups inside the distributor that are talking to the ECM. But in all truth be told I am not entirely sure what these two do. Your distributor is new but hey it might have a bad or marginal coil on the sensor ring that is the crank triggering for the ECM on the 3VZ-E that I do now. When I rebuilt my engine last year I had put on a brand new distributor and cap from O'Reilly's and the cap developed a crack inside of a month. I returned it and got my $200 back and put the OEM back in. So, how does the resistance on the four plug connector to the distributor read. The FSM has values for the resistance needed. My original OEM 1991 4Runner distributor finally just died a week ago at 245K, 10K after the rebuild. She cranked fine but no spark and check engine light was on with no start. Checked the coil and ignitor high and low sides and they were good. But when I got to the distributor the coils in the sensors were open circuit which was a definite problem and why the check engine light was not disappearing. Upon further investigation the insulation around the coils in the distributor were really funky looking almost as though the coil inside had seen a massive current and had melted the insulation and/or potting compound they are encapsulated in. The tell tale sign was this black grool was near one of the sensor coils that had leaked out of it and was on the die casting housing in one of the many pockets. I had to spring for another Superior Distributor from O'Reilly's, fingers are crossed and so far it starts with a flick of the key like it did before the OEM distributor was going south. For about a month or so before last week the engine was turning over a couple times before it would light off and run from a dead cold first start. I think these sensor coils were the issue and finally died.

So this was a no start for me but you have little engine speed change with plug wire pulling which means it is either ignition or fuel related at the cylinders. #1, #3 and #5 are on the NAS passenger side of the motor so my next thought is wondering if the fuel rail is blocked for those injectors are plugged on that side even though the rail does loop around the intake manifold with the pulse damper and the pressure regulator at opposite corners of the fuel rail. I would thread the a banjo bolt by the oil cap for a schrader valve and see what the fuel pressure is doing in the fuel rail. How is the ground wire at the back of the plenum to the fire wall and the one that is on the DS to the area by the coil and ignitor on the inner fender? Those grounds have a direct bearing on the injectors and spark plugs being happy electrically.

In the event that you fix your wire for the knock sensor, sealing up the plenum to the TB and to the intake use Halomar never go hard blue urethane gasket maker. You get a great seal and no paper compression set ever because the paper gasket is not used. Use it sparingly and you won't get lobes of crap like RTV will do to your air passages. The other place to use this or better yet is 515 Loctite gasket maker for more permanent joints is the idler pulley to the intake manifold between the cam-shafts pulleys. Those four screws are seeing a lot of tensional stress in keeping that pulley in the right location when the timing belt is not correctly tensioned properly. Setting that joint with a paper gasket seems rather inadequate.

 

Finally narrowed it down to clogged injectors. Ordered new ones then pulled them today and sure enough!! 3 were extremely clogged

 

Very good I was about to suggest injectors since the misfires were not all on the same bank. That's one dirty squirter there.