87 cherokee xj
4.0
70% sure has a blow headgasket. Combustion entering the watwr jacket.
SparkplUgs look normal
plugbwires in spec
old rotor old cap
never removed the injectors
compression values at 115 to 120 in 6 cylinders
never measured the pump psi yet and the regulator
never smoked tested
iac disconnected
cts in spec.never measured the values at the ecm

Check in my tiktok video to listen the surge and also has a hissin sound. I used carb cleaner everywhere with no luck.. do you think the leak is undwr the heatshield?
https://vt.tiktok.com/ZSPvDhEro/

 

A blown head gasket won't be found with carb cleaner it's an internal leak. Your hiss strongly points to a vacuum leak, which a smoke test can find, even under the heat shield. Check fuel pressure too. Those are your next steps.

 

Check the nuts on the front/rear of the intake. They commonly vibrate loose and suck air in there. First place to start/rule-out.

Also check into the coolant temp sensor and the sensor inside the intake (they get gummed-up). I believe it's the MAP? Been a while.

But yeah if you have a bad H/G definitely need to sort that out.

 

Can you guys consider a vac leak from.thr exhaust to the intake?

I do. But will.be impossible to detec with the smoke.machine...cause is internal but that hissing sound gives me hope is externas.. that hissim sound come from the injector área.. as always i cross finger is under the heatshield.. i will buy the cheap 89usd smoke.machine frrom Amazon.. hope is worth it