Code 16 on a '91 Civic

This problem has been driving my nuts for awhile. I've changed the injectors. What happens is that the check enigine light comes on (the code 16) and if the car is idleing for 5 minutes it starts smoking,
floods out and dies. Sometimes it'll die at a stop sign too. No amount of cranking will clear it and allow it to start. If I pull the wires to the injectors it'll clear the flooded condition and start right up. I hate to replace the ECU and find that the condition is caused by some sensor. So, I guess my question is; is there some sensor that can cause this problem and what's the test proceedure for the sensor. BTW, it's a 1.5l DPI engine.
Thanks for any help.
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Try a google search. Lots of answers and checks. Search "Honda Civic code 16"

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chuck wrote:

Code 16 often indicates a failed main relay. The main relay is located under the the dash at the far left side by the coin tray and it controls the fuel injectors. A relay failure is quite common with a car of this age. A common problem with the relay is cracked solder joints and some people have success resoldering them. I chose to replace mine with a new one from Honda as the contacts inside the relay were pitted like an old set of distributor points. Note that a new relay will run you about $40 or so.
Eric
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A bad main relay will not set any trouble codes, the main relay controls the fuel pump and when it fails the car will not start, usualy when it gets hot outside. This is not the problem Chuck describes. Sounds more like a fuel pressure problem.
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Actually, if just the right solder location cracks, the Main Relay CAN set a code 16. http://www.tegger.com/hondafaq/mainrelayoperation/badmainrelay.html
However, this will be accompanied by a no-start, not a flooded condition.
OP has not stated the trim level of his Civic. I suspect it is below an Si, in which case it has dual-point throttle body injection.
I agree with Grahame here; check the fuel pressure. That is a good place to start. Certainly a better one than replacing injectors; Keihin injector failure is extremely rare.
Also, the OP has failed to indicate whether the problem occurs on a cold start or when hot. This is important. Is the cold-start injector (the upper one) still spraying fuel after five minutes of idling? Has the OP tried pulling ONLY the connector for the UPPER injector?
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Yes, it's a DPI.

The fuel pressure checked ok.

I beleive this to be the problem. I don't think it's a leaky injector. I guess my question should be; What will cause the ECU to power the upper injector when it shouldn't be powered? A temperature sensor? Will this cause a Code 16? BTW, I did check the wire harness and cleaned the ground wire at the thermostat too.

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Pull the connector from the upper injector. See what happens.
How old is your thermostat? Have you tested the ECT sensor for correct resistance?
If the ECU is powering the upper injector inappropriately, it may have been fooled into thinking the engine is too cold. Is there any overfueling problem with the engine stone-cold? Or only when hot?
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Grahame wrote:

in my experience, it does set a #16 on this vehicle. i've had no less than 5 [yes five] 88-91 dpfi hondas with this problem. new/resoldered relays fix it every time.

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On Mon, 13 Aug 2007 19:08:57 -0700, jim beam

I have a 91 Accord. Would you suggest replacing the relay on a preventive basis? I have no symptoms and want none.
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On Tue, 14 Aug 2007 07:43:05 -0400

Why not locate the Main Relay, then purchase a spare to keep available for if/when it does go? Once you know where it is, replacing it is a pretty quick task...
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I checked this. 40psi at the fuel filter with the vacuum hose disconnected.
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chuck wrote:

i don't think code 16 is your problem* - here's what i think is the clue:
"I've changed the injectors."
with the throttle body injection, the injectors are deep set and have 2 or 3 o-ring seals on them. on reinsertion, if you didn't grease properly, i think you snagged one of the o-rings and now you're leaking fuel into the t.b. you'll have to re-pull the injectors and check.
but this begs the question of why you pulled them in the first place - is this a california vehicle and do you have a hesitation problem?
* - code 16 is usually a main relay problem. it happens on hondas this age. either re-solder or replace as a matter of course. it won't affect your injectors with the symptoms you describe.
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The O-ring that generally gets torn/folded is the one that goes into the fuel rail. This results in fuel leakage into the engine compartment; dangerous and smelly.
The seal that goes between throttle body and injector is an air seal only. They are much larger and are harder to damage.
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Tegger wrote:

but there is no fuel rail on the dpfi - all the workings are housed within the throttle body.

see above. i'll email you the diagram offline.
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I see the diagram, thanks. The DPFI injectors are somewhat different from the port-injected ones. I also see I had it backwards which injector was the main one. It's the UPPER injector that is the main one, not the lower.
However, it is not obvious how the O-rings shown could cause fuel leakage if torn. The ones that are indicated on the diagram appear to be air/vibration seals, performing much the same role as the big rubber rings that are used in port injected cars.
Two questions:
1) Where is the fuel inlet? There should be a third (much smaller) O- ring where the top of the injector goes into the fuel connection, should there not?
2) Does the auxiliary injector supply fuel through a pintle on its end, or does it instead somehow supply fuel through the drilling that angles up from its body?
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Tegger wrote:

the fuel circulates in passages in the throttle body and enters the injector through ports between seals 1 & 2 [iirc], if you're counting from the narrow end. if seal 1 is munged or missing, you're getting substantial leakage into the throttle air passage.

there is a 3rd ring iirc, at the thick end. mainly a dust seal i think. can't recall for sure - the injector i have is at the bottom of the parts bin.

through the injector end. technically, that's not the "pintle" - that term refers to the trumpet shaped protrusion on the end of the injector pin that forms the spray pattern when the pin moves to open. a lot of diesel injectors don't have pintles.
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I went to the wreckers today to get some trim parts. Wandering around, I had a peek at a few Civics with DPFI. It was an education, that's for sure.
On one vehicle, I removed the lower injector to have a look at it (couldn't break the screws loose on the upper one due to poor leverage and bad hammering angle; I didn't bring enough tools).
I see now what you mean. The fuel line goes into the throttle body, not the injectors. On the injector I pulled, there is a series of narrow rectangular screened "windows" arrayed around the injector between the two O-rings. These admit fuel through the screens. The outer O-ring is quite thick and robust, and, I would think, hard to tear.

The injector I pulled had a shallow green plastic "trumpet" surrounding the nozzle and pin. Would this not be the "pintle"?
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