First Thread - Need Help with my 87 SR5

[justgio928]

In October I was able to snatch a great deal on two 4runners. I got an 88 DLX and an 87 SR5 together for $900. The 88 DLX is now my daily driver and is doing great just been tweaking a little here and there to try and get more power from it.
The real issue I'm having is with the 87. The man was originally planning on selling the 87 for $1200 by itself but when he went to show it to me it started rough and had a knocking. Assuming that it really was an overnight development what could have gone wrong?!
I have done compression tests on all 4 cylinders and by adding a little oil they all came up to 160 or 170. So I'm assuming the valves and pistons are functioning at least that well. Yes I know that means the rings are bad.
It is running on two cylinders currently. As I drove it home, it would intermittently pick up and accelerate hard and fast then as suddenly as it began it would bog down again and I couldn't get past 2nd gear without killing it.
When I pull the boots on the 2nd and 4th cylinders when the engine is idling, nothing happens. When I pull the plugs after revving the engine a bit the plugs for 2,4 cylinders are wet. If I pull 1 or 3 boots the engine kills.
I took the wireset and used it on my 88 for a day and it ran fine.

Any suggestions or experience in the matter would be greatly appreciated!
Justin
I can add pictures and such as necessary.

 

[Bad_Vision]

have you verified that that the ignition is not failing in those cylinders?
1. remove plug attach plug wire set treads against a ground and turn it over you should see the spark from the plug.
if you have no spark then you wont get compression from that cylinder, if you do have spark then check the timing and make sure its dead on.
If after all that you still have bad compression or cylinder misfire it might be time to rebuild.

if it was a "overnight" thing then i would assume something stupid like ingnition not engine problems.

 

[the_dingman]

I'm pretty sure that bad rings would give you a lower compression on those cylinders.

Start with the ignition system, make sure the plugs are hooked up to the distributor properly, and that everything is in good shape. I think you're just a bit away from having it run fine.

 

[cometobanks]

Im betting on failure in the mechanics of the distributer/cap/rotor or plug wires out of order.

Is the distributer post tightened and not turning as you put the hammer down?

 

[justgio928]

I did do that for the number 2 spark plug and indeed there was a spark. Since it is running on two cylinders though I'm thinking the timing couldn't be that far off. If the timing chain had hopped a link could that have these symptoms?

 

[justgio928]

I replaced the distributor on the 88 for good measure yesterday so I'll try putting it on the 87 and see what happens. But as aforementioned, I tried the wires in my 88 for a day and it ran the same as always.

 

[turboSR5]

My bet is the distributor pick up is corroded or "air gap" is out of adjustment.

 

[justgio928]

Air gap?

 

[turboSR5]

Air gap?

What does the distributor air gap do? - YotaTech Forums

 

[justgio928]

So if the air gap is out of the .008 to .016 range for my 87 SR5 then I have to get a new distributor? Does it not have the adjustment screws as previous models did?