Eratic idle! and jumping tach

[jerky_lxi]

Ok guys i have a jumping tach and eratic idle. I turn the key and the fan turns on right away. I replaced the fuel pump today and strainer. The car still has a bad idle, but not as bad and still has a jumping tach. I think it may be a vacuum leak, but i dont know how to detect this. Can someone please show me what this could be or tell me how to check if its a vacuum leak.

[jerky_lxi]

hello?????

[zero.counter]

Starved injectors perhaps. Check timing and replace or check the spark plugs for any fouling or detonation. Check the battery's charge level and clean and check the terminals for corosion. Distributor cap may be cracked or rotor needs replacing. Ignition coil may be bad. Try using a different brand and/or octane level of fuel. Check and/or
replace the fuel filters and air filter, pcv valve.
If you insist on the vacuum hose issue then read futher.
A really serious leak can lean the air/fuel mixture out to such an extent that an engine won’t idle at all. An EGR valve that’s stuck open at idle can have the same effect as a vacuum leak. So too can the wrong PCV valve (one that flows too much air for the application), or a loose PCV hose. The rough idle in these cases is caused by "lean misfire." The fuel mixture is too lean to ignite reliably so it often misfires and fails to ignite at all. Lean misfire will show up as elevated hydrocarbon (HC) readings in the exhaust—enough, in fact, to cause a vehicle to fail an emissions test.

Some ways to check for vacuum leaks would be to visually inspect all the vacuum hoses and connections. Look for disconnected, loose or cracked hoses, broken fittings, etc. Hey, you might get lucky and find the problem in a few minutes—or you might waste half the day trying to find the mysterious air leak. Vacuum leaks are often the elusive needle in a haystack. And if it isn’t a leaky hose but something else such as a gasket, worn throttle shaft, injector O-rings, etc., you may never find it using this technique.

A faster technique for finding vacuum leaks is to get a bottle of propane and attach a length of rubber hose to the gas valve. Open the valve so you have a steady flow of gas. Then hold the hose near suspected leak points while the engine is idling. If there’s a leak, propane will be siphoned in through the leak. The resulting "correction" in the engine’s air/fuel ratio should cause a noticeable change in idle speed and/or smoothness (Note: on engines with computerized idle speed control, disconnect the idle speed control motor first).

Aerosol carburetor cleaner can also be used the same way. But solvent is extremely flammable, so don’t smoke or use it if there are any sparks in the vicinity (arcing plug wires, for example). Spray the solvent on suspected leak points while the engine is idling. If there’s a leak, the solvent will be drawn into the engine and have the same effect as the propane. The idle speed will suddenly change and smooth out.

There are other methods for finding the leaks but require automotive shop equipment for diagnosing such problems. More questions? Hit me up.

[jerky_lxi]

Well i just put a new engine into the car with under 90k on it. I installed a new fuel filter, got the timing perfect, installed a new air filter, new fuel pump, new spark plugs, new rotor, valve clearence adjusted correctly, new seals for everything inside engine, cleaned everything inside engine, and has 300k on all this stuff. I think it may be my pcv valve, but i have no idea where it is. I have had to replace one hose that i broke off that was red and attached to something next to the fuel filter, i replaced it with a normal hose from a leftover ecu box, so that may be it? It went from that to the top of the throtle body. I also replaced all fluid inside of the car too.

[jerky_lxi]

Also the tach barely moves every other 5-10 seconds if i am at 4-5k rpms. So the car runs smooth if i am driving at that engine speed. I also replaced the clutch too, so i have dumped some money into this car, and want it to run correctly ARGH!!!