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84 Cressida engine bog
March 19, 2010
Hi all, first time to this forum. Hope you can help. My 84 Cressida will not rev past 2200 RPM on an increasingly intermittent basis. It will only reach the 2200 RPM when no more than ¼ throttle applied, anything more results in fluttering (like a rev limiter), backfire or dies completely until you lift back off to that1/4. If and when it does clear out, it’s never 100%. Fuel filter, plugs, cap and rotor have all be changed.

Thanks for any help


March 19, 2010#1
Did you check timing? Look for any possible leaks in vacuum hoses? Other than that it sounds like the carb is running too rich if it has a carb.

March 19, 2010#2
Thanks Toyodave,

Engine is fuel injected but I'll start checking for vacuum and air leaks. Do you know where I can get schematics of the vacuum lines?


March 19, 2010#3
They used to have a vacuum diagram under the hood of the car. Or you can opt to just change out the vacuum lines that you can get to - as vacuum lines are pretty cheap. I agree with Dave, sounds like a timing/vacuum advance issue - usually if the car run perfectly fine but sharply deteriorates when the engine speeds increase, this is almost a sure sign of the vacuum advance not working. Could be as simple as a loose vacuum hose, could be more involved, depending on what happens from that.

That said, there are a number of things that could cause the symptoms you are describing. Could be a dying ignition coil or intermittent power getting to the coil, excessive ground noise (ground loops), wrong gap on plugs/incorrect plug temperature, clogged fuel filter, dying fuel pump, bad fuel pressure regulator, clogged EGR, bad vacuum modulator, induction leaks/obstructions, exhaust system leaks/obstructions, lazy or dying O2 sensor, burt valves, timing jump, bad pickups in distributor, etc.

March 20, 2010#4

A new Coil lead has seemed to fix the problem. Got lucky!



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