First thing: I have a 93 Accord EX 2.0l with an automatic 4-speed transmission. Everything is stock. Car has 125000 original miles, *very* well taken care of.

Recent work done: Timing belt change in 2013 at 80000. The shop (my wife's old shop which 'sucked ***' in my personal opinion) put in a modern Gates belt, rated to 100000+ miles. They changed alot of other stuff in the timing case as well, though a new tensioner pulley and water pump are conspicuously missing from the work order.
I did a half assed tune up about 6 months ago, at 113000; High mileage synthetic oil, plugs, wires, oil filter (changed nothing on dizzy or air filter). Also, not sure how relevant this is, but I overfilled the oil by about a quarter to half a quart - not very much, and I just decided to ride on it (lazy, I know...).
I was due for a new oil change recently and I just did that about 1000 miles ago. Strictly oil and filter, none of the bells and whistles this time. I should point out that I was starting to see my current symptoms before I changed oil and doing the oil change has had no effect on my problems.

Also, note that the car was in a moderate-impact frontal collision after which my wife's same old crappy shop pulled the frame somewhat straight-'er', disconnected the AC compressor (and I would assume the AC wiring but who knows), and tweaked the engine fan so that it rubs against the plastic cover when it kicks on. Anyway, it's been in a crash and was put back together in a fashion which I think the ASE would not approve of...

Okay, so I'll start off by listing my symptoms, then I'll get into the troubleshooting and work that I've done so far.

Symptoms: I have identified 5 distinct symptoms which may or may not be traced back to a single problem. More likely there's a 'couple' individual things wrong...
1) Car won't start if the engine is hot. It will crank and crank and it turns over and putters but just 'will not' catch. I can hear a click when the CEL turns off (not main relay, right?). If I start it cold it starts easy after three or four tries if not first try. However when I start it cold, the engine will flutter really bad, bouncing between about 1000 down to less than 200 rpms (like, almost dying, then catching up, then dying back down). As soon as I put some gas into it, rev it up for a second, then it calms back down and settles into a cold idle of around 1000 rpms. Once the engine gets warm, idle kicks down to less than 400 rpms and sometimes when I try to shift into reverse it will die (due to engine idling down as it's put into gear). Now before all this trouble, the car usually idled at about 600 - 700 warm.
2) Very low hot idle rpms, but decent cold idle rpms pretty much covered in the last paragraph.
3) Car loses ALL power at about 3500 rpms. Doesn't matter if I'm moving, trying to push up a hill or idling in park trying to rev it up. Of course, engine is choking, my first inclination is to rev it really high and try to burn that gunk out of the cylinders / throttle body (you guessed it; I'm a Chevy guy, lol). I can, or could if I were so inclined, literally 'stand' on the gas with car in neutral, revving the engine. Right at 3500, without fail, the rpm needle just bounces, like it has hit the end of the gauge or something. The engine doesn't scream or anything, just kicks back until the rpm needle drops a little, then guns back up... Damn, I wish this had audio, it's way easier to explain if you can hear... Anyway I'll prob need to go into further detail on this issue...
4) I've noticed some strange gear-shifting anomalies: Mostly, if I'm trying to get up to speed, I can't just punch it, I pretty much have to set my foot at minimal acceleration and just slowly build up speed. If I put my foot into it, it'll either kick down to a gear which is waaaay too low for my current speed (not to mention the rpms shooting up to 3500 and not being able to coax another lick of power past that...). If I don't get on the throttle hard enough, it'll shift way too early, especially into fourth, which it shifts into at about 43 mph if I let it, bringing my rpms to around 1200 or so. I'm almost thinking this could be the 'failsafe mode' on the tranny. But then again, I threw D4 codes 1,2,3,8 and 9 and 1,2,8 and 9 all have to do with transmission solenoid something or other A and B. But then again I have one of those 90-93 TCMs (TCUs) which are apparently famous for having faulty solders and resistors so could be that whole thing. Yes, btw, I *have* done my research on all of these issues.
5) pretty trivial following all of that other bad stuff, but I'm getting terrible terrible fuel economy. Maybe 12 mpg. I know if I fix the other stuff my mpgs will go back to normal, but it's a symptom, so there it is...

So my thought process on this whole thing: Firstly, and I know it's stupid to say "oh, I don't want to spend anything to save my car's ***", but my wife and I are seriously about the brokest (not a word) we've ever been thus far. I'm a journeyman carpenter and construction worker, which basically means winters are 'batting down the hatches' in our house. So im trying to do this as cheap as I can, if only in the sense of changing the cheap stuff before I do something nuts like a timing belt swap or something like that.
Ok, so my thought process was, check the distributor, of course, first thing. Then plugs and wires (they're really 'so' new though...). From there I figured, throttle body (especially IACV and TPS), Idle air sensors (particularly the hot idle sensors, I understand there are two), ignition relay and main relay. Now I know that most of my symptoms point to just main relay and "just do the main relay you cheap bastard"... But not 'all' of my issues even sound remotely like main relay symptoms (and it's so damn expensive lol) and that's why I haven't just done that already.

What I've done: Replaced air filter. Non-intensive throttle body cleaning (didn't rip it out or tear it down, just basically did what the throttle body cleaner can says, expose butterfly flap, spray the stuff in there and half assedly scrub the butterfly flap and etc with a soft bristle brush). Tore into the distributor; cleaned all the contacts, wiped up all the scoring - There 'was' the slightest amount of what looked to be very old oil in there. Honestly I feel like this could have even been blowback (as opposed to dizzy inner seal, the way I understood it was that a bad inner seal will just 'gush' out sh*tloads of oil if it's bad. Or is that wrong?). Really, haven't done that much.
In the morning (4 hours from now) I'm planning to do a full throttle body tear down and intensive cleaning, possibly replace TPS, definitely open up IACV to clean that AMD get a new gasket. I was mostly gonna hit this first because it's free, or rather, relatively cheap, and pretty easy and I know I can't screw it up too bad lol. If that doesn't solve my big problems, then I was going to open up the dizzy again, see if there's any new oil inside, check the ignitor module (I'm assuming I can somehow check just for continuity with a multimeter? Idk). If that still fails then I'm gonna pretty much be resigned to spending the rent money on ignition relays, a thousand O2 and temp sensors and tearing open the TCU to visually inspect the solders and etc. I'll probably be pretty distraught and upset if I get past that checklist because I'll either be screwed on a 100$ main relay or screwed on a ???$ timing job...

Anyway does it sound like I'm on the right track? Does anyone have alot of experience on these dang imports? Sorry if I've done something wrong with my post, it's my first post ever (although I have been trolling around for awhile...).
Oh yeah, I threw CEL codes for the TPS, crank position sensor and something else, I gotta check my notes and get back on the last. Those are in addition to the D4 codes mentioned already (7 or 8 codes in total). I have already reset my ECU as well, using the neg cable method and the backup (7.5 amp) fuse method as well.

Please, please, any insight would be GREATLY appreciated. Thanks a million in advance! I will keep this thread updated with work performed and results...

 

I would seriously appreciate 'any' somewhat well-informed input, guys, if you have anything to add... It would be really awesome before I start tearing into this throttle body this morning (in case I need to go to the parts store...).
Not trying to thread-bump, I just know that I tend to be long-winded and it seems like that huge tome that I wrote could be scaring people off... Thanks again!

 

Welcome. You posted in the right place, so don't worry about being a newbie. Only thing wrong with your post is the length. I gotta finish reading and absorbing it.

You aren't in the USA, because our 1993 Accord only gets the 2.2 liter engine.

A definitive list of the error codes will be good. Some of us might know which ones can be caused by the same problems as other codes.

Until then, part of what you describe sounds like the idle control system. Check this out:
https://www.hondaaccordforum.com/for...e-speed-38734/

 

Aaaand now I feel really dumb... I'm in the US, it 'is' the 2.2l. I always call into like motion or auto zone and say 2.0 and they always correct me and I always think, "god I need to remember," and without fail, I end up saying the wrong engine size the next time, lol. Good thing there's only one on that year, huh?

Sorry about the length. "Read before posting" said be as detailed as possible, and I have a really particular set of problems. If it makes you feel better, I tapped that whole thing out on my phone...

So I got my notepad and the error codes I was getting are as follows:
-CEL Codes - 4, 7 and 9
-D4 Codes - 1, 2, 3, 7 and 8

I know, that's what everyone says "set your idle higher". Thanks for the link. I'm just confused because, 'could' the idle just fall out of adjustment like that all on its own? One day runs fine, the next morning all this stuff starts failing on it? I just felt like the idle coming out of adjustment would be a more gradual thing which is why I was leaning more towards like the hot idle air sensors or IACV. But by all means I could 'definitely' be wrong on that. I'm more of a backyard mechanic than a quote-unquote 'trained' mechanic, lol.

So what I took away from that is it's probably a good idea to go ahead with my planned throttle body teardown and cleaning / inspection?

Thanks for the input. I hate to be needy but if that new info brings you to any other conclusions I'd be grateful to hear them!

 

Quick addendum: 'Can' I use silicone gasket maker in lieu of getting an actual replacement Idle Air Control Valve gasket? If that will fly, would I need to use the high-heat gasket maker or could I get away with just the normal blue stuff? Thanks again!

 

Just finished thoroughly cleaning the throttle body and intake manifold. No change in symptoms...

Checked for vacuum leaks and couldn't find any. Ready to set base idle speed as suggested, has to wait until the morning so I have light.

Couldn't tear into IACV, parts (two specialty O-rings - NOT a gasket like I thought) are a week out.

Just an update.

 

I asked for the detail, because we often get "my car will not start, please help" posts.

To save money, I think some basic diagnostics will help you. Do you have a volt meter? We can suggest some electrical tests to try before you go to replace possibly good working parts. I wouldn't mess with the base idle yet.

There is an important engine ground that is on (or next to) the thermostat housing. Unbolt the ground, clean the eyelet and bolt with a wire brush or sandpaper, then reattach.

I recommend pulling the 7.5 amp backup/radio fuse in the engine bay fuse box for about a minute. This will clear engine computer (ECU) and trans computer (TCU) codes. Start the engine. If you get a check engine light (CEL), shut off engine and recheck ECU and TCU codes.

 

I know this might sound like a dumb question, but have you tried bleeding the coolant system? I only ask, as you mentioned the car took a front impact at some point. I only mention this as the IAC valve is operated by the coolant system, as there's 2 hoses attached to the bottom of it. If there's any air pockets in the cooling system, they can wreek havoc on other related systems. Just a heads up.

 

If you use silicone for sealing anything, try to get either of these:
- Permatex Ultra-Grey (that seems to be the same as "Honda-Bond")
- Something that says "Safe for Oxygen Sensors". Silanes released as the stuff cures can destroy the sensor.

Yes, it's more typical for idle adjustment to go out gradually. But not impossible. The base idle thread mentions a few things that are important.
- vacuum leaks (you already checked)
- air in the cooling system (that can confuse the idle control system)

Another thing, your car has a FITV (#8 in the picture) along with the IACV(#15). That FITV has a plunger inside that can get loose & not work right. Search for threads about cleaning the FITV. I've never done it but it's something about taking off the top lid (O-ring #2) and cleaning it & tightening something down in there. Plugged hoses and air inside the FITV can really confuse the system.

A lot of people don't seem to like the process of setting the very low "base" idle with the IACV unplugged. But it's the whole basis for the system working within it's proper control range.

I like all the detail you have in your first post. It's a lot to digest all at once, but far better than just saying "my car doesn't start".

 

I got a strange new symptom. So it was freezing cold this morning (20° F), and when I started the car it actually revved up all the way. I was able to push it to 6000 rpms. Then I let off the gas and it bogged down and died and when I restarted it, it wouldn't go past 3500 again.

Its got me thinking, it must be a sensor that was frozen open/shut this morning, right? I've read somewhere on the internet, this guy was having 'almost' my same symptoms and he said it ended up being a temp sensor that's located on the left side of the block under the distributor. Has anyone heard of that before?