I have a 89 240sx automatic with ka24e engine. The motor was just replaced with a junkyard motor with 30k miles. Once i got it back, there seemed to be some hesitation. Off the line, if i dont give it too much gas, it stutters a bit, but if i give it a decent amount of gas, it seems to be fine. Also, when i get around 2500 rpm's, the power seems to go away, this happens all the way up till 3500 rpms. Once past there, it doesnt seem to have any problems. Does anyone have any suggestions as to what may be the problem? Thanks
Stumble while accelerating - test and check all of the following
Contaminated or low grade fuel. Fuel filter clogged - low fuel pressure. Fuel line clogged - low fuel pressure. Return line clogged - excess fuel pressure. Idle switch sticking off, poor connection or badly adjusted. Mixture ratio adjustment on MAF if fitted. Ignition leads. Fuel pressure regulator - low pressure. Fuel pump - low pressure. Engine temp sensor. Injectors. Plugs. Coil. Ignition amp. Crank angle sensor/igniton pickup. Air fillter clogged. Leaks or faults (if flooded with petrol, mixture will go way too rich as throttle opened) on evap canister purge system. Inlet duct leaks between MAF and throttle. Throttle plate and body clean with full throttle plate movement. MAF - faulty or poor earth in loom. O2 sensor if fitted. ECU - check for codes.
Stall while loading - test and check all of the following
Ignition timing Low idle Idle air AAC blocked or faulty. FICD not opnening or full of crud. Idle switch remaing off.
I've heard lots of cases of people replacing parts at random to fix faults. A common one is to replace the expensive MAF when the fault is a poor earth in the loom - 30min max with a soldering iron, the hard part is finding a technician that can use a volt meter to diagnose it and an auto electrician to do it. But this is the first time I have heard of someone replacing the whole engine! Were you told by a professional mechanic to change the engine? I would advise you to sue them for the cost of the unnecessary work as it failed to fix the problem.
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The problem with the old engine was leaking injectors. With the dealer quoting $850 to fix that problem, and another $1000 to install a new timing chain and guides, i decided to go with a new engine. I found the 30k motor for 750, and i had a friend install it for me, who charged 250. He's been workin on cars for years, ase certified and all that junk, and has a badass Bigfoot Special, so i trust his work. the random replacing of parts might happen anyway, just so i know everything is new. Either way, i'd like to fix the problem first, and then just get other stuff as i feel necessary.
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