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Since this is my first post (Been following ECTG for a long time on youtube) I’ll introduce myself in a few words.
I primarily work and tune European auto’s. Its my second job/hobby. I work as an aircraft mechanic for the Coast Guard. Its inevitable that I get requests for other imports for coworkers/friends and that sometimes puts me out of my comfort zone. This particular Honda, more so than most. The bane of my existence; late 80’s to 90’s feedback carburetors…
This 88 Accord has a hesitation right off the throttle. The rpm sags and then seems to accelerate. It also has NO useable power on light to mid throttle or in the lower RPM range. It runs smoothly, no surging, bucking or misfiring. Just no power and that slight stumble right at throttle application. If you push it to have the auto tranny downshift and you get in around 3,000 RPM, it will move reasonably well and pull smoothly and steadily to 5,000 RPM.
This problem he said has been going on for about 6-8 years. Has gotten no better or worse with time.
What the owner has said has been done:
Reman carb.
Fuel filter
Tune-up
He said one mechanic advanced the cam timing!? He said this has been reverted back to stock settings.:blink: I haven’t checked yet.
Some other things I can’t recall now. Some of these things were done 2-4 years ago with no improvement to the problem.He’s had it to a list of various mechanics. Some of them doing shady work and didn’t help the problem. Now I suppose I’m up to bat…:sick:
What I’ve done:
Traced every vacuum line and confirmed it with the under-hood chart.
*The distributor vacuum hoses were crossed
*The choke actuator vacuum hoses were not plumbed correctly
*Some hoses (Maybe 4 total) around the carb were capped off or routed to the wrong areas.
*I noticed when I hook a vacuum pump to the inside choke actuator line, it will move the choke but will not hold vacuum. However, no apparent vacuum leaks around the diaphragm (with carb cleaner sprayed on the diaphragm) Also the choke opens fully and closes with engine temperature.With these corrected, it seemed to idle a little smoother and higher. But the main problems persist.
So with this and any other questions you’ve got for me, perhaps we can get this owner happy. I know there is a lot of older Honda tech guys on this forum, so hopefully that will help. This Honda vacuum system seems overly complex to me.
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If the choke actuator won’t hold a vacuum with the pump
then this is a vacuum leak. even though you sprayed it.
It sounds to me like its a carb problem. sounds like its
not set up right. try putting a vacuum gauge to read manifold
vacuum.also check mechanical timing.Alright. I’ll replace the choke pull off.
I’ll get a vacuum gauge on it see what the vacuum looks like and check the cam timing.
Any info on adjusting the carb correctly? I’ll do some searching and report my findings.
He also said he’s unhooked the PCV valve. Although some lines were unhooked and plugged off, The PCV valve wasn’t. So I don’t know what he’s talking about…
sounds like alot of crossed up things. do you
have a vacuum diagram for the car? A FSM may be
needed here.here is a link that may help you.
for vacuum.;)http://www.justanswer.com/honda/1m9r4-copy-vacuum-system-routing-diagram.html
Yeah. I’m using the vacuum diagram decal under the hood, which looks like the first one in the site you linked. The others below that may be more help as well and I’ll double check to those as well. I know I’ve routed some vacuum lines that were not connected correctly before, or ones that were capped off for no apparent reason. And the cold start and idle is much improved (Don’t have to pump the accelerator pedal before cranking or blip the throttle to clear the idle at first.)
I want to get my vacuum gauge hooked up to it, but it just started raining. Hopefully it’ll let up shortly.
Ordered a choke close valve, though likely not the problem here, is leaking anyway.
The video doesn’t do too much good. I’ll take a look at the float level, maybe its low. It doesn’t seem to be running rich at any time. The choke does open fully within a couple minutes. I haven’t checked to see if it opens more under throttle.
I also want to check some of the other diaphragms on the carb to make sure they hold vacuum. But I don’t think they will be an issue, since the whole carb was replaced as a unit several years ago with no change at all, he said. It certainly looks like it has been replaced.
Thanks for your help!
Had a few minutes to put a gauge on it. got ya’ll some video! Makes things so much easier.
Basically in the video you can see the vacuum when fully warmed up. Holding at 20 inches hg. The needle trembles a bit. I don’t diagnose stuff like this frequently with vacuum, so I’m not sure if thats a huge deal or not.
The accelerator pump seems to work fine. The float level seems okay. Choke is fully open. Choke is fully closed when cold.
The white valve in back chatters when I let off the throttle.
With good vacuum like that, I don’t think I really need to check ignition timing or cam timing, unless perhaps something is too far advanced and hiding a problem… Hmmm….Perhaps the vacuum is a little too high? I was expecting it to be around 18 or lower.
[quote=”college man” post=33007]keep us posted.;)[/quote]
I did! you must have been reading when I posted my last update, lol Check the vid I posted if ya want.
This latest round I hooked up a timing light. I was unable to see the timing marks on the crank pulley. And I’m not sure where the correct mark on the timing cover is.
I saw under the hood to have the trans in gear, but doesn’t tell me to short a the diagnostic connector, so I suppose this vehicle didn’t have that?
I did retard the ignition timing. And the revs seem to be smoother right on throttle application, where the stumbling occurs. But I haven’t driven it.
Yeah, a FSM would be helpful. I have one for a civic/CRX…But its a Haynes. I also have Alldata online.
But I again got chased away by the scary rain. I’ll do some reading on Alldata, figure out where the timing marks are at least.
UPDATE:
Well Alldata was helpful. Found a (very lengthy) procedure for A/F mixture setting and idle speed adjustments. Also found the procedure for ignition timing. The mark is on the flywheel. No wonder I couldn’t see it on the crank pulley. Also it says to cap off both vacuum lines to the dizzy. I’ll get the ignition timing set, test drive it and see how it goes. I’m sure the owner will be happy already, since it starts RIGHT up without touching the accelerator pedal. Doubt its done that in 8 years.vacuum does look good.I did some digging around.I was going to
tell you about the carb sight glass but you found it.when you rev
it in the video.is it bogging or is it just the video? if you rev it
to 2000-2500 rpm. does that sight glass bowl drop or the level stays
steady? also there is suppose to be two fuel filters.one under the hood.
found these links on checking timing.;)http://www.justanswer.com/honda/0i5jx-set-timing-marks.html
http://www.justanswer.com/honda/3uici-set-timing-1988-honda-accord.html
Yeah, I believe you can hear it bog for just a second right when I pull the throttle. It stumbles for a brief second and then picks up.
The float level stays stable when I rev it. I heard some models have two fuel filters. I’m not sure if the owner knows that or not.
The timing was advanced about 10 degrees or more from where it should be. I retarded it exactly to spec with the trans in gear and vacuum advance hooked up. I also checked to ensure the vacuum advance works and holds vacuum. I also checked the other Dizzy vacuum line (#25) for vacuum; when cold it has vacuum, when warmed up it does not.
Test drove it with the ignition timing set to spec. The stumbling right when you press the accelerator pedal got noticeably worse It lacks power throughout the entire RPM range now.
Great, now what!? 😛
check the procedure I sent you on setting the timing.
I don’t think you did the procedure right.check base idle.
car in park.vacuum plugged off to the vac advance.timing light
on white mark.recheck the timing.Yup! I did that part of it too. I checked it first with the vacuum advance disconnected and plugged. Set it at idle to the white mark with the trans in neutral. Then I connected the advance, put the car in gear and checked to make sure the red mark lined up.
First, thank you for your service.
Those old cars can be tricky. Sounds like you found the timing marks, funny where they hid those. That said it seems you’ve had a lot of people in there messing about that weren’t familiar with the car, for that reason I might go back and double check all the vacuum hoses not only to make sure they’re in the correct location but also for damage. Lastly the distributor also has a mechanical advance I believe, if that’s the case perhaps the weights in the distributor re sticking or having issue. it’s been a while since I’ve worked on one of those so I’m a bit rusty.
Awesome to hear from ya Eric!
I have already been through each and every vacuum line. Marked each connection with paint pen as I checked for security and correct routing.
I’ll open up the distributor and see if the weights are free in there. I’m going to remove and inspect the EGR valve/ports as well. It certainly does seem like some sort of timing advance problem by the way it reacts and how it did when I retarded the timing back to what it should be. Do these have any other idle air control? or is it regulated only through the idle circuit in the carb?
Yanked the distributor out. The mechanical advance does not seem to work. If I hold the bottom of the center shaft, the rotor side of the shaft has no advance. No give at all. Also when I twist the shaft freely back and forth a jingling sound occurs inside. Ontop of all this, the distributor was full of the red death powder. Also on the trigger sensor, one of the wires were damaged and slightly and corroded.
Just as a second check I’m going to throw it back into the engine, disconnect the vacuum advance and see if the timing advances with engine speed.
Hopefully this is the remaining problem with the hesitation.
I still have to service the valve cover gasket. I intend to check the cam timing then, since the owner said a mechanic had previously advanced it…A shame a mechanic would even suggest or perform that in this case.:angry:
Thanks for the suggestions and guidance. I’ll report back when I have updates.
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