Checking ignition in 1990 Honda Civic Si, 1.6 liter.

Whether there is a visible coil or not, there is a coil, AKA "Ignition Cont rol Module". A thermal fault in these devices is not uncommon, and the typi cal failure-mode (after 30 years). About a US$55 part, or so. That being wr itten, do you have a spark when the system is hot? You can verify that rath er easily by pulling any given sparkplug wire (at the plug), installing a s pare plug, grounding said plug and checking for a spark by running the star ter for a few seconds. Or, if you have an old-fashioned induction timing st robe, seeing if it will fire (with the wires connected).

No spark, suspect the ignition module. Good Spark, suspect the fuel filter, fuel pump or fuel system. Old fuel fil ters will often flow fine until the dirt particles pull back into the eleme nts under suction. So one attributes the failure to ignition... A filter i s about a US$35 ordeal.

Be systematic as repair-by-substitution is expensive.

Peter Wieck Melrose Park, PA

Coin? No, but you can still check spark much easier than that. But...

I had friend's Honda do the same thing yours is doing, and it was a bad fue l pump that stiffened up as it ran. Put a gauge on the Schrader valve (fue l rail) and see if the pressure holds.

If the fuel pressure is good and you want to check ignition, pull a spark p lug when the engine is cold (leaving it connected to the ignition wire) and ground the threaded part. Have someone crank it over and watch the spark. Repeat again once the car is hot and see if the spark stays a nice fat bl ue spark or if it's now a weak yellow spark or no spark. If the spark is s trong when the car is hot, it's not ignition.

If it's ignition, you can buy a rebuilt distributor that includes the coil, pickups, and electronics, any of which can cause ignition problems. A dis tributor assy will cover all bases.

A 30 year old car that won't run hot sounds like fuel to me rather than spark.

You can check spark easily so I guess you might as well, but not at the distributor. check it at the plug, or even at the spark plug wire boot.

Remember anything you take apart in a car that old may break either uninstalling or reinstalling. (speaking from experience)

You did check the fuel line for a hot spot that might vapor lock, right?

Check the main relay. It is a well-known failure point in Civics/CRXs of that vintage. I used to have a 90 CRX Si (same engine as the Civic Si), and went round and round with a local shop replacing all manner of electrical components until finally discovering that the main relay was the culprit.

dies-when-warm-2119566/

main-relay-pics-2535047/

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Dave

snipped-for-privacy@gmail.com Jan 29, 2021, 3:23:38 PM (2 days ago)

Haven't found a Schrader valve.

Is it hidden inside something?

Dave Garrett 3:39 PM (1 hour ago)

The Haynes manual has almost nothing about the relay. It's under the dash? In the engine compartment?

Thanks, ... P.

So we have established that it is not ignition, but fuel related? Have you _ever_ changed the fuel filter in 30 years?

Fuel-pump relay failures are seldom (not never) thermal. Once they latch, they tend to be fine.

Peter Wieck Melrose Park, PA

OK

This is just an observation, from a man who has never owned a Honda car

In the normal course of events, if a car starts from OK from cold, and then doesnt want to start when its hot then it might be caused by the mixture being too rich - like as if the choke is stuck on (for those of us old enough to remember what a choke is)

I have experienced this problem a few times on various petrol engines, and its usually something to do with a thermostat somewhere - so maybe something in the system thinks that the engine is still cold ?

My instinct tells me that if its got enough fuel to start and run when its cold (and needs more fuel) then its not likely to be a problem with the fuel filter.

Probably of no relevance whatever in this case, but just may be worth thinking about ...

AT

Patient: 1999 VW Eurovan Camper - VR6 engine. 72,000 miles. Symptom: Started fine. Ran fine for about 20 minutes or the first hill. Aft er which it would get progressively weaker, then stall. Spark at start: Good. Fuel Pressure at start: Good. Spark hot: Good Fuel Pressure hot: Poor. Cause: Clogged fuel filter - OEM to the vehicle, I replaced it in 2012. Spe cs call for every 50,000 miles. Action: Replaced the fuel filter. Problem solved.

Apparently, the within fuel filter when cold (not under pressure) contamina nts will separate from the element and settle at the bottom of the can. App arently, this allows enough fuel flow to get the engine started, even runni ng for a while until the element reclogs and restricts flow.

Hence the suggestion.

Peter WIeck Melrose Park, PA

as I said

Probably of no relevance whatever in this case, but just may be worth thinking about ...

AT

Sorry for the delayed response. Should be under the dash near the fusebox. Here's a thread with pictures that is specific to the CRX but I'm fairly certain that most/all of the info contained within is applicable to the Civic Si as well.

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Dave

On Monday, Feb 1, 2021, 4:32:24 AM (6 days ago), Peter Wieck wrote,

My mother was the original owner and drove it until a few years ago. The fuel filter could have been changed; I don't know. The user manual calls for replacement every 96 Mm (megametres). Will change it now and test again.

Pulled the cable from plug 1 and connected an old plug. With just a little cranking the engine started on 3 cylinders. Ran fairly well for several minutes. The spark was absolutely visible. Yellow rather than blue. As the engine heated it began to falter. Quit after about

10 minutes. Behavour entirely similar to what I reported originally. Three cylinders quit a little sooner than four.

Feb 6, 2021, 9:08:20 PM (10 hours ago) Dave Garrett wrote,

Good thanks. After installing a new filter and testing, will resolder the relay. This car might still be running in 2050. Electric drive conversion kit? Run on ethanol then? =8~)

Thx, ... P.

Without being snarky - and specifically based on your intention for this vehicle to run forever, a truly admirable ambition:

Let's be systematic. a) You have confirmed a weak spark - yellow, and failing over a short period of time. b) You have completed a maintenance task that while perhaps not 100% necessary is at least not a wasted effort - replacing the fuel filter. c) Re-soldering the fuel-pump relay lugs is a good thing, again even if not absolutely necessary in hindsight - although if it cures the issue - all the better. d) Next step would be the ignition control module/coil/distributor system. You may test the coil separately:

Or, purchase a complete assembly with all of it either new or reconditioned. I would hate for you to have to do more than what is necessary to effect the cure. Either way, a weak spark does suggest a coil - about a $15 ordeal from Amazon.

Peter Wieck Melrose Park, PA

You didn't follow the instructions properly. The steps were to look at the spark when it was cold and running well, then looking again after it crapp ed out. By running the car with the plug in the cylinder disconnected, you were pumping unburned fuel into the cat - which is why I worded it as I di d. Pumping unburned gas into the cat is a fine way to melt it down in minu tes. Hopefully this didn't happen.

What began to falter?? The engine, the spark, both?

Mr. Easthope is insisting on an non-linear approach, sadly. Which will lead to needless frustration and many blind alleys.

Let's start over with what we know right now:

a) The fuel filter has been replaced. b) The main relay does not affect the spark. But re-soldering it is not a b ad thing. c) Parsing what was written by Mr. Easthope +/-4:32 am on February 1, 2021, when cold the car presents a yellow (weak) spark, when hot, no spark at al l. d) No spark at all pretty much eliminates a fuel issue as the primary culpr it - and given the new filter, even that is unlikely. e) Leaving spark.

So, in a linear (logical) fashion what could cause a thermal fault that cau ses a weak , then no spark? a) Coil - thermal faults are exceedingly common in coils. If the coil is O EM, that becomes the first suspect. 1. Coils are cheap. $15 or so from Amazon. 2. Coils are easy to install - perhaps 15 minutes on a bad day, with the correct tools and good light. b) Ignition Control Module - not so cheap ($26 or so) and a little fussier to install. c) Distributor Module - From as little as $90 to as much as $200 - and as you suggest, covers all the bases. Requires a certain amount of care to ins tall. I am not sufficiently familiar with Hondas to know if timing is an is sue with a new distributor, or if it is all via the Hall-sensor. There is a Hall Sensor, so I suspect the latter.

Best of luck, Peter! Looks like you are going to need it.

Peter Wieck Melrose Park, PA

I'm not sure that's what he meant!

Here's his quote:

"With just a

"As the engine heated *it* began to falter." That "it" could mean either the spark began to falter or the engine did...

Sequence-of-tense and basic grammar dictate that "it" is the engine that is faltering. After which presumption begins. Therein lies the danger.

Point being that in a technical discussion, words matter. "But you know wha t I mean...." does not apply. All we know is what is written. Mr. Easthope is not pursuing this problem with either rigor or logic. All we can do is b e clear and concise in what we suggest within the limits presented.

Peter Wieck Melrose Park, PA

This UseNet, that will never happen.

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