Winlight

when I get a CEL in my 96 Civic LX (code 71,random misfire cylinder 1) it will blink at real low RPMs.It happens at around 300 RPMs and then stops blinking but stays on once the RPMs are back up.What does the blinking mean?

Former User

Blinking = severe misfire

Check the plugs, wires, cap, and rotor

Winlight

the plugs,wires,cap and rotor are all brand new.what would cause the misfire to get worse at lower RPMs?

Former User

If the fuel injector is pulsing fuel into cylinder 1, then compression test the cylinders.

Winlight

I have 125 psi in1 and 175-185 in the other 3 cylinders.I put a cap of oil in cylinder 1 and it brought my compression up to 150 psi so I know my rings are shot.but why does it only throw the code at low RPMs?

apexi_rsx

it just repeats the blink it stops and stays solid then does it again. its a server problem is u only have 125psi in one and 175-180 in the rest then maybe check a valve could be burnt . whens the last time this car had any maintenance? usually misfire could because of wires or plugs but ur compression test came back bad. wanna save yourself some money and just take the head off and inspect it. or take it to a shop

EFPhilly

I would try to ghetto leak test it to see if the valve when that piston is at TDC will keep the air in or let it escape. I found out it was just carbon buildup on mine.....not a burnt valve. The compression jump is significant so I would suspect the rings based on the wet test

Winlight

I already know the rings are bad.What Im asking is why does it only misfire at low RPMs and why does it get worse as the RPMs get lower?

EFPhilly

I would start with the plug gapping and checking the plugs for any bad signs (ie detonation)

sounds like something that you haven't done is tried a working distributor....you have changed the rotor, cap, wires, etc.

I also dont see why no one has asked you why your motor is allowed to idle at 300 rpms. If my motor idled at 300 rpms, I know my Hondata would still think the idle was at 1000 and it would cause it to misfire (has happened). I would first try to get your car idling steady at the proper RPM and see if it is easier to control the misfire. :D

Winlight

EFPhilly

I also dont see why no one has asked you why your motor is allowed to idle at 300 rpms. If my motor idled at 300 rpms, I know my Hondata would still think the idle was at 1000 and it would cause it to misfire (has happened). I would first try to get your car idling steady at the proper RPM and see if it is easier to control the misfire.

I would hypothesize, that as the engine RPM is dropping it is getting further away from what it should be. Your car is set to idle at a certain RPM...that is why the Honda manual doesn't say set your idle to whatever you feel like because you ECU will figure it out....it says set to 750 plus or minus whatever; I do not see set idle to 300 or less or let idle drop below this. If your car is idling lower than this and your adjustment screw is all the way out then you have sever IACV issues or vacuum leaks.

If your motor thinks its at 800 RPMS and it is at 300 RPMS I would think it would be drowning the cylinders in petrol.

Winlight

Thank you,this is most likely my problem.
My idle isnt set to 300 btw,it just drops down there sometimes and then throws a code.normally it is around 900

EFPhilly

Okay well you cant just imply information on here. I did not know that.

That would be where I would start looking for the problem. Its not why does it misfire when low rpms....its why the hell does your motor go to low rpms. The IACV should stop it from dropping below a certain point. I would go get another IACV and trying it...(if you have a buddy who has got one buy him a beer and borrow it for an hour)

Winlight

the only friend I have with a honda dosnt have the same IACV as me.Ive been meaning to clean mine but have had to fix so much other stuf I havnt had the time.I guess its time now or buy a new one.

EFPhilly

I wouls start with cleaning it, but a dirty one ususally causes wandering from what I have seen. A faulty one causes low readings and low idle at times. I would start there and maybe adjust the FITV plunger out a hair, if you have one

Former User

A bad IACV would not explain the low compression in cylinder 1. You seem to want to avoid this most important problem but it's not going to just go away. Do a cylinder leak down test to see whether compression is leaked to another location besides the crankcase (bad rings).

EFPhilly

If you are cheap like me

apexi_rsx

with that much carbon good possibility the plugs fouling too but as ron stated above thiers still bad compression in 1 because only gaining 25 psi i believe there's something still wrong. id do a leak down see how that does

Winlight

the reason Im avoiding the low compression in cylinder one problem is because all Im trying to do is get my car smoged so I can get tags.it passes emissions now but what happens is the check engine light comes on when the smog guy lets my car idle on the rollers because for some reason it idles real low on the rollers.If I can keep it from idling so low on the rollers then it will pass.I know Ill still have the low compression in cylinder 1 but I can live with that because Im going to do a swap in July.

Former User

The point is that what you are calling a low idle problem more than likely is actually a dead cylinder 1 problem, which will probably prevent the car from passing a smog test.

Winlight

it passes emissions.I only failed because the CEL came on during the test.

Former User

We're going in circles. The CEL comes on due to bad cylinder 1.

Winlight

yes,but it only happens if the RPMs get to 300 or lower.Im not trying to fix the bad cylinder,Im just trying to keep it from getting to low RPMs so the CEL dosnt come on during the test.