I removed the distributor as well, only to find out that I’m missing a bolt. I … don’t even know how that happened. That is probably why I’m leaking from there. I cleaned everything up and I’ll look around locally for new bolts. It must’ve been when I had the valve clearance adjusted because that was when I noticed the alignment marks on the distributor/valve cover. They must’ve removed it then. Geez.
I think the plugs look fine for an old engine. In the pic they do not look drastically different, and none stand out.
If significant amounts of oil were going into one or two cylinders, the end of the plug would be wet and shiny when you took them out. Hard to miss.
Going back to the beginning, how is the idle now? I think you said it was running fine after you put new plugs in, so if new plugs made the difference, I would just drive it.
Any signs of oil leak on the bottom of the engine, like the lowest point of the transmission, the sides of the oil pan?
On a 4-cyl engine, >300K miles, lower compression, or uneven combustion is to be expected. Your rings are probably normally worn, but not seriously damaged or broken.
On most older cars, if the compression is even across the cylinders, the absolute number is not as significant as the difference between a dry and wet compression test (wet being where a bit of oil is sprayed into the spark plug hole b/f you run the second test).
A professional mechanic may have done a leakdown test with shop air and a calibrated gauge, and actually measured how well the valves and rings seal, but that takes time (meaning $$), and they probably would have told you.
looks mint. jam em back in and recheck in 1k
…
Local places don’t have the bolt. I’m going to run to Home Depot to see if they have an equivalent. Once I put that on, I’ll put the plugs back in and drive it around locally today to see how he runs.
Replaced the distributor bolts, cleaned up the cap/rotor, reinstalled spark plugs and he’s running great. I let him idle for about 20 minutes after resetting the ECU. Re-started a few times. Did some high revs, no issues.
I’ll keep monitoring. I drive about 500 mi a week so I’ll check the plugs again this weekend. Thanks for the support!
The past two afternoons, I’m seeing the rough idle returning, but it is no where near as bad as it was before, and it goes away after about 30 seconds.
It’s like what I posted here a few months ago:
Do you look at the initial idle speed just after start, and does it follow a normal warmup cycle?
Are you experiencing the problem only on a cold start, or also on a warm start (restart)? The last sentence in the linked earlier post was confusing me.
In other words, let’s say you drive the car until the temp has stabilized (warm air from the cabin heater), and after you stop and turn the engine off, wait about 30 seconds and start the car again.
That’s actually hit or miss. After running for a while, if I were to shut it off, wait a minute, and start it back up, sometimes it would start right up running strong, other times it would be rough.
[QUOTE=N FUL FX;2321662]That’s actually hit or miss. After running for a while, if I were to shut it off, wait a minute, and start it back up, sometimes it would start right up running strong, other times it would be rough.[/QUOTE]Did you try disabling the fuel pressure regulator solenoid valve, in case it is malfunctioning on start? It is easy to do, the connector is close to it on the firewall, and all you have to do is unplug the connector (or bypass the vacuum line). It is intended to give you a better start with a hot engine, but on a cold or warm start, the engine should start fine without it. On the other hand, if it is not working properly, it could affect a cold start.
I’ll give it a shot.
have you checked/adjusted base idle? if not, try that. follow the procedure to the letter
I’m about to check the spark plugs now and the fuel pressure regulator solenoid valve.
I also want to mention that my MPG has gone down considerably the past few fillups since changing the plugs. Unsure if that has to do with the usual drop for the winter fuel mix.
??
your mileage could just be winter blend. has the ambient temp decreased much there since doing this? was the car running any differently after swapping plugs?
The FICV checked out fine (checked it while I was around that area).
I didn’t see any difference in checking the fuel pressure regulator’s operation.
Spark plugs look similar. No oil anywhere.
I have not been able to replicate the bad idle. I think I need to just stop everything and check it out next time it happens.
Welfare: I haven’t checked the base idle. It seems to be normal though, including what I experienced today. On some mornings before I leave for work, I get the rough idle, which soon remedies itself as the RPM gets gradually increases (on its own, NOT through me pressing accelerator).
the ecm will adjust to try and maintain 750rpm. so you won’t even know base idle is out. symptoms are typically a rough or hunting idle.
super easy to check: start engine. disconnect iacv. if idle sits at 500rpm, you’re golden. reconnect iacv, clear code, and allow idle relearn
Yes I have the hunting idle, but rarely.
I’ll try that one out. As of today, car is running fine.
[QUOTE=N FUL FX;2321899]Yes I have the hunting idle, but rarely. …[/QUOTE]There is a lot that can be just marginal on older OBD0 and OBD1 cars with no error codes, and the car can still run fine. We have the added complexity of design for low emissions and higher fuel economy, without the error reporting of OBD2.
The FITV is a mechanical device, 25 years old, with I think at least one plastic part inside, and besides that, the heat sensing mechanism is similar to a cooling system thermostat, and we all know those have to be replaced sooner or later. So, it may be functioning just marginally at this point. This may account for the occasional hunting idle. Sooner or later, you just have to replace it, just like a thermostat.
O2 sensor can be fouled, and not sending out the correct signal even after the engine is warm. I don’t think this always generates an error code on cars with 1-wire sensors which have no heater. So if you are used to new cars and expecting an error code for a bad O2 sensor, you may not get it. I think the older O2 sensors lasted 80~100K miles. A marginal O2 sensor has an effect on mileage b/c the ECM will run open loop much longer than its designed to do. (Welfare or someone else who knows this particular car better than I do can perhaps be more accurate here) I think some cars may never generate an O2 sensor error.
MAP sensor may be getting old too, or there may be a small leak and dirt inside the MAP sensor vacuum line. I’ve seen one on another car where a line was dried out and did not seal, had a very small leak, and over time, the vacuum sucked dirt in through the leak. We replaced the vacuum line because it broke while doing something else, and noticed it was essentially plugged inside.
it’s not so much that the o2 won’t allow closed loop (single wire are almost rarely in closed loop anyways). it’s that the readings will be skewed. a contaminated o2 will nearly always read lean (causing a rich condition). what allows the possibility of closed loop is the temperature of the element. i believe it’s roughly 500*f IIRC. that temp is rarely reached in the cars exhaust stream. never at idle. and closed loop is not initiated near or at wot. this leaves a pretty small window for the single wire o2. and that was the reason a heater circuit was instituted. the element can now reach operating temp within about 30 seconds of key on.
tbh, i don’t think i know these cars specifically all that well. but pretty much all manufacturers of any given era will run similar, if not identical, systems. inputs are almost always the same. the only real variance being speed/density vs maf. only the control devices will vary. take a nissan of the same era. it will use like 3 different valves to maintain a smooth, set idle at operating temp. while honda uses just one. there is reliability in simplicity. that is a honda trademark right there. one of the reasons i’ve always appreciated the engineering behind them.
while we’re on the topic of different manufacturers, if you haven’t already, i urge you guys to check this book out:
http://books.google.ca/books/about/Crash_Course.html?id=H9kzkTz9IpMC&redir_esc=y
now i don’t read many novels…at all. could probably count the number i’ve read from beginning to end on one hand. but this book is nothing less than enthralling.
they actually reference honda motor co a significant amount throughout it. how they broke through to the american market from a small engine and motorcycle building company. the first japanese automaker to set up a plant in the us. at the time, a tiny company in comparison to huge players like toyota and nissan. it was that underestimation that allowed them to rise up and level the playing field. paving the way for other japanese automakers to follow suit.
its just so cool to find out why things are the way they are today. and what led them
there. history
starting with people like the dodge brothers and henry ford. the mergers between automakers.
i can’t even scratch the surface. just check it out. you won’t be disappointed