jrbucklin

I bought this car not knowing what i was getting into. My question now is will the PGM-fi relay from the original DX car work with the EX 1.6 liter engine that was put in the car?
The #3 cylinder is apparently getting no fuel - the spark plug is tan whereas the other 3 are a normal black color. So I am trying to figure out what is going on. The car has done this since I bought it. Recently the engine light has come on, and a mechanic who knows honda civics said it was probably the PGM-fi relay. The light comes on sometimes,esp in warm weather, and will go off if i stop the car, and turn it off, and then on again. How much does this relay do in the operation of the fuel injection system? I am told it could also be a bad injector. Symptoms are bucking and jerking after i shift, and when i downshift.
What should i ask a shop to do to diagnose the problem?When the engine light was on, the computer did not come up with any codes. I am a rookie when it comes to civics, esp this strange combination. Thanks for any info
Buck

ezone

The relay is exactly the same

and it cannot cause a single cylinder to have a problem while the other 3 don't.

jrbucklin

Hey thanks so much. that is a relief.
Since the spark plug on #3 is brown, rather than the usual color for a spark plug getting fuel from it's injector, that would be the place to start, eh? I do not want to spend too much money, since I plan to sell it, so i suppose I could switch the injector from#3 to another cylinder, and see what happens. Or just have the shop across the street test the engine, altho no code showed up when I took it in, to see why the check engine light was on(the ppg fi relay is having intermittent problems, but now that it is colder in Oregon, not so much) Maybe they could hook the engine on an oscilloscope. Any ideas on diagnosing why the engine is missing, and bucking and jerking? Thanks again, Buck

jrbucklin

hey Mr Ezone,
If you have the time, could you explain exactly what the PPG-fi relay does. Does it just open and close to supply fuel to the fuel pump, or is its function more complicated. Thanks in advance, Buck

ezone

Start with basics.
Compression test?

It's PGMFI main relay. It's like 2 simple relays in one box with a few small electronics inside it.
It is used to switch 12v+ power on for the fuel pump, and for several of the engine components (injectors, IAC, etc.)
If you view a good wiring diagram you could see what the relay is connected to.

jrbucklin

thanks. i think there is a whole service manual in .pdf format online. And, yeah, since the sparkplugs will out anyway, why not do a compression test, unless the garage does a test and finds out the injector on #3 is bad. But it might be a good idea to know anyway, in terms of full disclosure in selling the car.
You seem to know a lot. Are you or have you been a professional mechanic?

ezone

My fingernails might tell people I have a desk job.....