Misfire and troubleshooting

[macrosaga]

Hello friends! This forum doesn't seem very active (I suppose there aren't many folks driving 2nd gens nowadays)

Tldr: changed plugs,wires,cap,rotor.adjusted valves. Noticed scoring on cam. Misfire got worse than before changing parts.

I have an 85 accord, carb, 5 speed. It has been my nonwinter daily driver for delivering pizzas for 4 years now.

In my younger years I've owned a few 2nd gen civics and done a fair bit of work on them. I'm not mechanically naive. However there is enough difference with this accord as well as my aging body that I've pretty much given up on working on it myself. In the 4 years I've been driving it I've had all the normal maintenance done as well as some bigger things like replacing the rack and pinion, timing belt/water pump, oil pan gasket etc.

Brings me to last week. I noticed I was losing power/rpms going up hills on the highway. Upon further attention there seems to be an overall lack of power after shifting gears, almost like the carb needs a second to adjust the mixture.

My buddies brother is a trained mechanic and was recommended to me to help weld some exhaust and troubleshoot codes on a Nissan xterra. I drove my 85 accord out there. When I was leaving and started the car he said "sounds like a misfire, bring it back next week and we'll look at it."

We changed the plugs,wires,cap,rotor.
Valve cover gasket and adjusted the valves when the cover was off. The inside of cap was heavily burnt (surprising it ran at all).

The valves were quite out of spec and we noticed scoring on the cam. The car has 215k miles on it btw.

Adjusted the valves to factory spec (intake .005-.007" exhaust .010-.012)
put everything back together and was a much louder valve ticking. My buddy said he thinks whoever adjusted them last tightened them up to take up the slack from the cam (something along those lines). He snugged them up and we put everything back together again and the valve noise is reduced but now the slight misfire has become pronounced.

We double checked that all the vacuum lines were good. Replaced a couple but overall they looked good.

Upon driving it home (up and down steep wisconsin glacier hills) i had to downshift to 3rd gear to get up hills id normally take in 5th. Unless I was in a lower gear it would stutter and almost lurch.

My buddy is more familiar with cars that you can scan, in fact he's convinced that the carb 85 accord has some sort of ecu. He wants to call honda, I've told him unless its a pgm-fi it shouldn't have an ecu.

He's also thinking there is some sort of idle-air valve equivalent on the carb and or a cold start system or something that isn't blending the mixture right.

I told him I'd post here and maybe get an answer. If we've changed the plugs,wires,cap,rotor what would be causing the misfire? Valves out of adjustment? The scored cam? Where do we start?

[Oldblueaccord]

After the valve adjustment I would do a compression test.

It is possible the cams too worn to open the valves correctly.

[macrosaga]

Oh wow, a reply! Wasn't overly hopeful. I'm kind of in a weird predicament...the mechanic I have helping me is younger than these cars but has been trained in the military on "wheeled vehicles" as well as having gone to more than one mechanics schools after military. He knows sound theory on how engines run, just hasn't really worked on 80's vehicles.

That said, he also said we should do a compression test next before jumping to conclusions. So if we find bad/low compression what would be my best course of action? Obviously a head gasket, but there could be leakage at the valves too right? I know that a good shop should be able to lap the head and grind the valves but should I be looking for a whole new head assembly with valves and cam? can the cam be repaired or would i need to find a new one (that might prove difficult). If so what should I be on the lookout for? I'm 99% that it is an "ES2" motor (85 US accord carburetor 5 speed). My buddy would be capable of doing a motor swap but if I went that way I'd want to keep it as simple as possible (bolt in).

After some quick research it looks like the ES3 came with the pgm-fi. would one of those heads bolt on my block? I would need all the fuel injection components/accessories at that point too.
the 2nd (or is it 3rd) gen preludes had an A20A3 engine that had fuel injection as well. I think those will bolt in as well maybe?
If I went with a fuel injected motor how good are the ecu's at calibrating the mixture and how well are the codes (do they point to actual failure points/sensors or is a vague "air/fuel mixture" type code)? I absolutely hated the code chasing from an obd1 system.

If I can get rid of the misfire I'd like to either get the carb tuned properly (I feel like it shouldn't have to go through the cold start cycle on a hot summer day). Either tune the carb or put a weber on it. I've heard that can work but I also feel like alot of people have trouble with tuning webers. Well, I feel like I'm getting ahead of myself here. These are cool cars, I love old Hondas ; I hope I can keep this one on the road!!

If anyone has any suggestions or just wants to say hi that would be great! Thank you

[macrosaga]

Oh wow, a reply! Wasn't overly hopeful. I'm kind of in a weird predicament...the mechanic I have helping me is younger than these cars but has been trained in the military on "wheeled vehicles" as well as having gone to more than one mechanics schools after military. He knows sound theory on how engines run, just hasn't really worked on 80's vehicles.

That said, he also said we should do a compression test next before jumping to conclusions. So if we find bad/low compression what would be my best course of action? Obviously a head gasket, but there could be leakage at the valves too right? I know that a good shop should be able to lap the head and grind the valves but should I be looking for a whole new head assembly with valves and cam? can the cam be repaired or would i need to find a new one (that might prove difficult). If so what should I be on the lookout for? I'm 99% that it is an "ES2" motor (85 US accord carburetor 5 speed). My buddy would be capable of doing a motor swap but if I went that way I'd want to keep it as simple as possible (bolt in).

After some quick research it looks like the ES3 came with the pgm-fi. would one of those heads bolt on my block? I would need all the fuel injection components/accessories at that point too.
the 2nd (or is it 3rd) gen preludes had an A20A3 engine that had fuel injection as well. I think those will bolt in as well maybe?
If I went with a fuel injected motor how good are the ecu's at calibrating the mixture and how well are the codes (do they point to actual failure points/sensors or is a vague "air/fuel mixture" type code)? I absolutely hated the code chasing from an obd1 system.

If I can get rid of the misfire I'd like to either get the carb tuned properly (I feel like it shouldn't have to go through the cold start cycle on a hot summer day). Either tune the carb or put a weber on it. I've heard that can work but I also feel like alot of people have trouble with tuning webers. Well, I feel like I'm getting ahead of myself here. These are cool cars, I love old Hondas ; I hope I can keep this one on the road!!

If anyone has any suggestions or just wants to say hi that would be great! Thank you

[ShiRen]

The forum has several active members... But we all have 3rd gens.

Your mechanic is right... Test the compression. If he is actually worth the job he is doing he can probably even figure out if/why it has low compression without even taking it apart. Yeah the valves can absolutely leak... But so can the rings.

Idk anything about the old engines, but the first thing I do to check if parts are compatible is compare the gaskets on rock auto.

I would definitely Weber swap it if you get it worked out. It's going to be way more reliable, a lot simpler, and perform a lot better than early 80s fuel injection

[macrosaga]

Figured I should update. Found out that the manual was indeed correct in saying to rotate the crank counterclockwise (my mechanic thought that would be bad).

Once we rotated the crank counterclockwise and readjusted valves this old car purrs like a kitten.

Now we're on to getting the carb to do all the cold start stuff its supposed to so I don't have to sit with foot on the gas pedal until its warned up.

I feel especially lucky that while my mechanic is younger than the car at least he likes leveraging and has been heeling out about how it all works. I got no problem with that at all! When everything is done and set hopefully I will have w a better understanding of how all the carb components work!!!

[ShiRen]

Yeah I don't know of a single Honda 4 cylinder that spins the right way around until the s2000 came out. As for it being bad to spin it either way... Not really, unless this was an engine that has some really tight valve timing and has the variety of tensioner that will introduce slack when turned backwards, and only the latter is probably true for your engine. I'm never afraid to turn an engine backwards a few degrees if it will save me a lot of pain.