Engine unstable after general overhaul

[Lesley Fung]

my prob is the engine unstable after general overhaul since it is ok b4 overhaul
at 1st engine can start but unstable n later on the distributor coil damaged

after replaced the coil, engine can start but still unstable, then timing belt was checked n then found that 1 teeth mistake. after done timing belt, then the engine can start n this time better than before but still unstable

all sensor was inspected and in good condition, no check engine lamp

what is the prob?can anyone who driving honda experienced before?

my car is honda civic ek3 with d15b 3 stage vtec

 

[EvolutionZ]

what unstable u r mentioning about? if engine vibrate then change the engine mounting, if engine jerking then check the plug coil and spark plug, if engine dying off while idling check the throttle body, if accelerating felt like jerking...check the petrol pump...etc etc....

 

[^pomen_GTR^]

dirty throttle body also would make idling unstable..

 

[Lesley Fung]

not throttle body prob

 

[g4i8y0t]

Bro, you have to be more specific. What do you mean with engine unstable? Is your engine vibrates a lot or you RPM goes up and down when idling? May I know why you did the overhaul in the first place?

 

[nyantong]

I once performed a top overhaul for a 4G15 which suffered from engine overheat due to a leaking radiator. After removing the head and cleaning all the carbon, replacing the oil seals and regrind the valve seat, I installed the head back. When I started the car, it felt like it had loss of power and was very rough. At that time, I couldn't figure out what was causing it as there weren't any problems with the timing or sensors. So I figured it could be due to a warped cylinder head and I needed to skim and resurface the warpage. Nonetheless, the car was driven for about a week. By the end of the week, the engine was smoother but still felt weak.
I figured it was all down to the warped head and decided to remove the head again and resurface it. After installing the head back, the engine was once again rough! Boy was I wrong. Nothing I did nor replace solved it. After driving again for about a week, the engine became smooth again but still felt weak. So I kinda just settled and figured the rough idling was due to the engine running in and settling down.
Just wanted to share my personal experience although it doesn't really help to solve your problem.

 

[Viosman]

Seems like u didnt check the spark plug. Shall try use other good one to test it

 

[DanzEterna]

try to plug in MUT/diagnostics scan to identify the problem...i think yr car needs a retune...

 

[skyline2m]

Bro, you have to be more specific. What do you mean with engine unstable? Is your engine vibrates a lot or you RPM goes up and down when idling? May I know why you did the overhaul in the first place?

no check engine light
my RPM goes up n down when idling and sometime the engine off suddenly

---------- Post added at 05:43 PM ---------- 6 hour anti-bump limit - Previous post was at 05:41 PM ----------

I once performed a top overhaul for a 4G15 which suffered from engine overheat due to a leaking radiator. After removing the head and cleaning all the carbon, replacing the oil seals and regrind the valve seat, I installed the head back. When I started the car, it felt like it had loss of power and was very rough. At that time, I couldn't figure out what was causing it as there weren't any problems with the timing or sensors. So I figured it could be due to a warped cylinder head and I needed to skim and resurface the warpage. Nonetheless, the car was driven for about a week. By the end of the week, the engine was smoother but still felt weak.
I figured it was all down to the warped head and decided to remove the head again and resurface it. After installing the head back, the engine was once again rough! Boy was I wrong. Nothing I did nor replace solved it. After driving again for about a week, the engine became smooth again but still felt weak. So I kinda just settled and figured the rough idling was due to the engine running in and settling down.
Just wanted to share my personal experience although it doesn't really help to solve your problem.

my engine leaking and the motor oil come out from the gasket between head n block (head gasket)
suspect the block and head was bent and i do go for resurface for head and block and even line horning

---------- Post added at 05:44 PM ---------- 6 hour anti-bump limit - Previous post was at 05:43 PM ----------

Seems like u didnt check the spark plug. Shall try use other good one to test it

not spark plug prob

---------- Post added at 05:45 PM ---------- 6 hour anti-bump limit - Previous post was at 05:44 PM ----------

try to plug in MUT/diagnostics scan to identify the problem...i think yr car needs a retune...

no check engine light and mechanic have check (OBD 1) no need diagnose, just jump 2 wire from ecu but no signal of sensor prob

the mechanic also have diagnose equipment

 

[g4i8y0t]

try check the ignition timing, spark plug and plug cable.

 

[Lesley Fung]

try check the ignition timing, spark plug and plug cable.

checked, even the mechanic have timing light. he said all ignition are ok. not much different from the actual timing.

recently he said the air cond idling valve got prob then i bought a used idling valve but the prob still same

 

[DanzEterna]

try to install toyota FICD see wat happens.

 

[skyline2m]

can it fit into toyota ficd?isnt that need a lot of midification?

 

[DanzEterna]

wait btw wat engine are u using? ficd normally works for toyota & proton cars..not sure bout other makes.

 

[skyline2m]

wait btw wat engine are u using? ficd normally works for toyota & proton cars..not sure bout other makes.

im using honda civic ek3 with d15b engine