Hey all! Looking for some input on getting rid of a misfire so I can pass smog test. Just did a valve job on my new to me '89 3vze . Complete head rebuilds, all new exhaust valves, re-manufactured fuel injectors, timing belt, cap, rotor, plugs, etc. Ignition timing is at 10 degrees. Runs surprisingly well. Idle test is good but has a bad no load misfire starting at about 2,025 RPM. All good up to 2,000 and runs fine with a load on it at all RPM's. No trouble codes. High speed smog test requires 2,200 RPM minimum. Any ideas?

The only thing I'm questioning is if a vacuum hose is possibly connected wrong at the intake manifold for the cluster f of switching valves on the passenger side fender. Connected them all back how the were but could have been wrong from the get go. Can't find a solid vacuum diagram for the '89. The only '89 FSM I can get my hands on only covers the 22R.

Any suggestions?

Hook up a spark tester to see whether you have an individual cylinder issue or if it's all of them. Sounds like you have a disrupted signal that generates your spark. Others will know better than I what the circuitry is on these motors. You can get a spark tester at Harbor Freight fairly inexpensively.

Here's a few vacuum scenarios for you to confirm what's what. Hope it helps

Attached Images

     

Thanks Mikekfr...while I was verifying the vacuum connections found the problem. Massive vacuum leak- line from manifold to PCV valve was un-plugged. No more mis-fire. Will see if it passes smog now.

Thanks for your input Mikekfr and Ahlem.