1995 Civic Engine Pulsates

[quote:9dd0929f16="feruzim"]I got this 1995 Honda Civic (D16Z6; 1.6L SOHC) with about 110,000 miles on it. Got a great deal, but not too long after the engine blew. I replaced the motor by myself (new motor has approx. 50K miles on it), but after firing it up it pulsated. I waited a while and after the engine warmed up the pulsating went away. It would come back when the engine would idle a bit higher so I lowered the engines idling rpm a little bit. This has only solved the problem when the engine is warm and at idle. While accelerating at around 900-1200 rpms in first gear the engine will pulsate unless I give it more gas and push it above 1200 rpms.

The point is, my engine pulsates when cold (cuz its usually running at higher rpms until warm), and between 900-1200 rpms when warm.

A friend told me it could be the temperature sensor. Another friend told me it could be the speed sensor (damaged a little bit during the engine swap), but my odometer and speedometer function properly. So, I'm not sure.[/quote:9dd0929f16]

Hello !!
check the compression on each cylinder, also check the distributor cap, spark plugs and wires.. looks to me like your engine has a misfire... at idle remove one by one the spark plugs wires and see the difference until you find the one its missing..
also check the IAC valve (idle air control valve) and the EGR for carbon build-up ..

let us know..

good luck!

[quote:184a142bb7="fisherman"]Hello !!
check the compression on each cylinder, also check the distributor cap, spark plugs and wires.. looks to me like your engine has a misfire... at idle remove one by one the spark plugs wires and see the difference until you find the one its missing..
also check the IAC valve (idle air control valve) and the EGR for carbon build-up ..

let us know..

good luck![/quote:184a142bb7]

Thanks bro. I won't be near my car until next week, but when I get the chance I'll try it out.

Question: If it is the wires that are crossed, or a misfire in general, wouldn't it pulsate or idle rough even after warming up? Wouldn't the car's performance also lack in horsepower? When I first started it up the idle sounded way off and rough so I switched a couple spark plug wires and it smoothened out. A minute after switching the plug wires the rythmic pulsating stopped. I've barely put 3000 miles on the swapped engine and I took the car to 120 mph farely well (I installed a cold air intake and racing clutch as well). I'm not saying that you're not right, cuz I'm gonna try the plug wires as soon as I can, but that's just a question that popped into my head. If it is a misfire, wouldn't it misfire all the time? Or, is it such a slight misfire that the car only seems to perform just fine?

[quote:a5d5086f4e="feruzim"][quote:a5d5086f4e="fisherman"]Hello !!
check the compression on each cylinder, also check the distributor cap, spark plugs and wires.. looks to me like your engine has a misfire... at idle remove one by one the spark plugs wires and see the difference until you find the one its missing..
also check the IAC valve (idle air control valve) and the EGR for carbon build-up ..

let us know..

good luck![/quote:a5d5086f4e]

Thanks bro. I won't be near my car until next week, but when I get the chance I'll try it out.

Question: If it is the wires that are crossed, or a misfire in general, wouldn't it pulsate or idle rough even after warming up? Wouldn't the car's performance also lack in horsepower? When I first started it up the idle sounded way off and rough so I switched a couple spark plug wires and it smoothened out. A minute after switching the plug wires the rythmic pulsating stopped. I've barely put 3000 miles on the swapped engine and I took the car to 120 mph farely well (I installed a cold air intake and racing clutch as well). I'm not saying that you're not right, cuz I'm gonna try the plug wires as soon as I can, but that's just a question that popped into my head. If it is a misfire, wouldn't it misfire all the time? Or, is it such a slight misfire that the car only seems to perform just fine?[/quote:a5d5086f4e]

Could be...
Make sure that the firing order its correct sometimes the ECU compensate the "weak" engine and this could be the case..

let us Know on the firing order...

Good Luck!

Let me ask you a question. When you replaced the motor and put the new one in, did you by chance happen to have the intake manifold off the engine?

Even if you didn't there is a possibility that the engine behaves this way due to a leak at the intake manifold. The gasket could be bad or even more likely is the possibility that a piece of the old gasket is still on and this causes a leak.

What can happen is the engine computer senses that there is too much oxygen and so compensates by dumping more fuel. The engine does not need the additional fuel and senses a flooding so it cuts back on the fuel flow. This cycles on the engineback and forth.

Thought to think about.