2006 Honda civic needs help!

they tell me this one has a timing chain.

I hope you got a good deal on it. There are a lot of things that should be done.
It would be a little bit of a stretch for me to list them all. I am sure others would have a better answer.
Look in your owners manual. Make a list of everything that was supposed to be replaced by 100K and get it all done at once. I would guess that your looking at $1K to $2K worth of work.

I am afraid the owners manual went bye bye many moons ago! the deal was very good.

Are the denso plugs any good? a lot cheaper than the ngk iridium.

I totally agree with MinInNH

If a timing chain…then nothing to worry about until about 250k miles or more. But it’ll start making noise to let you know it needs changing.

Denso plugs are good.

You don’t need Iridium plugs. Standard plugs work just as well. Iridium and Platinum plugs just last longer.

Replace all the fluids, including brake fluid and coolant with Honda-compatible fluids. Use Honda brand transmission fluid.

There should be a sticker on the underside of the hood.
It will say what brand and part # plug to get. It will likely have Denso and NGK #'s.
Denso or NGK are equally good, just get exactly what the label says.
Change the fuel filter and get the brake fluid flushed.
You might be able to fine an online maintenance guide at honda.com

Considering the situation, this car should have any and all basic maintenance chores performed including a valve lash inspection.

However, before going too deep into this thing monetarily I would recommend 2 things. One is to check for oil sludge/coking problems and the other is a compression test; each possibly being related to the other. The compression test means the spark plugs come out so replace them at that time.
The easiest way to check for oil sludge/coking is to remove the valve cover (this is where valve lash inspections factor in) and to probe the bottom of the oil pan with a wire loop during an oil change to see if any tar like substance is stuck to the loop.

If there are signs of oil related problems and/or compression problems then I wouldn’t get too enamored with the car. The fact the seller was honest enough to tell you they had done nothing to the car may not mean much. That can also be, and often is, a way of saying that they recently discovered an expensive headache and is their way of playing dumb.

If you have a compression test run you should see readings of 180 PSI and above on all cylinders.

OIl and compression not a issue, oil changes were the only service actually done.

You can and should get the entire required maintenance schedule out of a Haynes manual available at the local parts store. You need a reference such as that to start with.

Re: the plug questioo: both Denso and NGK are equally good plugs, but be sure of what you’re buying. I suspect that the price difference between the two you looked at was because one was platinum and the other irrridum. Both companys (all companyes) make the entire range of tips and will list accptable options for the various engines. Irridium is 8 times harder than platinum, and it erodes slower, providing a strong spark longer. It also enables the plug designers to use much smaller diameter center electrodes, which concentrates the spark more. Use whichever one your car came with. The listing should define the OEM ones.

Find an owner’s manual. Sometimes you can find pdf versions online available for free download. Start at Honda’s website.

“OIl and compression not a issue”

I understand that you say oil changes were regularly done. (Do you have receipts, btw?) But unless someone has actually put a compression gauge on it then - all due respect - you don’t know squat about the engine’s compression. So did someone actually check the compression with a compression gauge?

no, but wouldn’t it have either power loss, rough idle, oil consumption, or smoking?

Not necessarily. If you had one with perfect compression and drove that - and then got in one with marginal compression you might notice a power difference. Also very poor compression can give you obvious running issues. But marginal compression is not something you’d necessarily notice.

Its a simple thing to check and gives you a good baseline for knowing about the engine’s basic health. It can also tell you how much you may or may not want to put into the car, as OK4450 noted.

Its not unlike making sure your home’s foundation is structurally sound before you go and spend piles of $$ on a new roof.

An engine can have compression problems with no noticeable to the driver power loss, oil consumption, or smoking problems and the regularity of the oil changes may have something to do with it if there is a problem.
Loss of power can be something that a driver becomes acclimated to, much like shocks getting weak over time. They never notice it.

Hopefully there is not and my point is that the first thing in catching up maintenance are the spark plugs. The plugs are out anyway so test the compression right then and there and put that issue to rest. If the compression is fine then proceed on with other maintenance issues. If its not fine, then the decision arises as to how deep maintenance wise do you go into this car.

OK, I have a compression gauge. I will do the plugs and check compression. I will post the results.

Valve lash should be checked at 15k, then every 30k thereafter. If the valve lash gets too tight, that will cause burned valves.

Transmission fluid change way overdue, use only Honda fluid. Do NOT flush, just drain and refill, easy to do at home unless this is a sealed transmission. If it has a dipstick, then its DIY, no dipstick, sealed.

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Coolant overdue, use any universal “Long Life” coolant. The one that says mixes with all colors. I like a 2:1 mix antifreeze/distilled water. No flush, just drain radiator and block.

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If it came with Iridium plugs, then replace with Iridium. Use anti-seize compound unless the plugs say they have an anti=seize plating. Do not use anti-seize compound on plated plugs. Do not use copper anti=seize on the plugs.

cont.

And finish off with a new air filter. That should restore performance.