theiceman

Hey Guys

I always like to bounce my ideas off other guys ...
Co owrker drags me to his house for coffee and then say oh by the way my kids car is runnning rough can you look at it for me ? what a set up ...
anyway looks like it is runing on 3 cylinders ( 91 civic 1.5 16v TBI , 300,000km )
he says got any ideas? I said yeah , buy a new car ..

I pull the plug wire off number 3 cylinder and makes absolutely no difference. the others cause it to allmost stall out .

he already replaced the plugs so i took one of the old ones stuck it in the number 3 wire and grounded it ... spark .. no problems .. even white. It is TBI so i know the fuel delivery is probably okay as the other 3 cylinders are working.

I walk around the back and hear a soft popping, allmost pfft sound through the exhaust.
My recomendations to him . do a compresion check . maybe even a leakdown as he has a compressor . figure he should be able to rig something up . If you want to go further take the valve cover off and have a look ...

My feeling is he has a busted valve , valve spring or droppeed gude even. Probably exhaust ...

any other ideas ?

BTW when I first got there I did the propane thing around the intake .. stupd me .. should have gone for the wires first ..

can you replace a valve spring without taking the head off ? never done that before ..

KILRWAIL

A leakdown/compression test would be helpful. I'm guessing it's not a valve, since you state it's a 16 v engine. If one's gone the other will still work (like my Mazda). Yes, you have to remove the head to replace a spring, but it's pretty easy. Could be a plugged or broken injector or related elecrical connection, which is worth checking before removing the head. With 300,000 kms, it's likely to need some head work and rings, but I wouldn't start there.

rusnak

I think you are probably correct, Iceman. I would suspect the valve seat and if it were my car, I'd probably pull the head.

whalebird

Those cars eat distributors. It's so common that any parts store will have it. IIRC, pull the cap and look around the base of the distributor for metal fillings and carbon dust. If any, replace the distributor. Again it happens all the time; I know I've replaced half a dozen or so.

gtihop

With 300k on a honda, most likely a valve problem. put air in the cylinder and see where it comes out.

User 4221

That was my thought as well. A weak connection may check out OK on the spark test but may fail under load and temp.

Its a cheep thing to do and probably needs to be replaced anywho...

theiceman

Thanks Guys .. are you talking the whole distributor unit ? then why would just cylinder 3 not fire ? am I missing something? I will definitely look at it closer for sure.
Peter if the valve failed or a chunk broke off and wasn't closing properly you will have no compresion therefore no ignition. That is why i was thinking valve or spring.

Thanks guys

MUSSBERGER

Go to starbucks next time

theiceman

no kidding .. paying the 5.00 for a cofee would have less painfull. But i do admit to being interested in anything mechanical

KILRWAIL

I agree, but the compression test could eliminate that as a source. If a valve is just worn, the other one will still work. Since you've already checked for spark, it seems to me the next thing to check for is fuel, i.e. the injector. If the distributor was pooched, you wouldn't have spark, unless the camshaft position sensor in the distributor is sending spark at the wrong time. Compression test has to be next.

theiceman

Yeah I agree that is the plan, if that checks out then go for the distributor I am thinking from a wrecker. .. it is TBI ( throtle body injection ) so there is only a couple of injectors in the throtle body , an upper and a lower so i am guessing they are okay as the other cylinders are fine. i think P.A has compresion testers on sale this week actually .. allways looking for an excuse to buy tools..

theiceman

Just an update for you guys ... told my budy to go buy a 25.00 compresion tester ..
results

160,160,0,160

well that pretty well sums it up now doesn't it .... busted valve ...

KILRWAIL

So, now we know. It could be worse. What's next?

theiceman

hwe said he is just gonna run the car on 3 cylinders while he looks to get another car. The thing is a POS so I don't blame him . he says it has been that way for a month . I told him to find a buddy with the same prblem and build a V6.

he said befoe he calls the wrecker tho he is gonna pull the head off for a look see...

gtihop

If he is going to pull off the head, he is 3/4 the way to fixing it if it is a bad valve.