I have a 91 Honda accord with 320,000 miles that sputters under soft normal acceleration and is fine when i either let go of the gas for a second or push it about 25% more and make it rev up. idles ok occasionally ill park it and it will rev up and down about 500rpm i dont know if this is related.
Work Done in last month, plug tube seals, manifold seals, entire distributor, plugs&wires, mostly all new vacuum lines. engine and gas treatment with sea-foam. Bought new fuel filter today haven’t installed it just wanted to jump on here see if anyone has any ideas.Injectors?
The idle speed roaming indicates there’s a problem with the idle air control. Could be a vacuum leak, or could be that the idle speed adjustment screw (if you have one) has been used to correct for a different problem. Check the basic stuff first. Is warm idle rpm within spec? Is idle ignition timing within spec? Do all the devices that are supposed to hold vacuum actually hold vacuum (using a hand-held vacuum pump). Is the egr valve working correctly? Valve clearance ok? Cylinder compression ok?
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The warm idle is actually a bit high 900 its spec is 800 but it just shakes the car to death at 800 its so smooth with the extra 100.I would expect its out of time a little due to the distributor but it didnt do the bogging under acceleration right after replacement it did it a few days later. Ill have to have a shop check compression i honestly dont know how but i do know its not leaking oil anywhere which is usually a good indicator right? how can i test egr?
I have a Corolla of that era. It simply won’t run well unless the warm idle rpm and idle timing is spot on. Adjusting the idle rpm from 800 to 900 to solve a poor idle problem isn’t a solution. You need to find the cause of the poor idle problem. It sounds like you may have some misfiring going on, or serious air/mixture problem.
ok so ive noticed if i adjust the distributor the idle will go back to 800 happily so im going to do that tonight and filter tomorrow since i already got it and im going to either test the egr or just replace it anyway. it seems like miss fire to me as well honestly. may have to just change the timing belt and re time the whole thing but if it was out of time wouldn’t it get worse the more i hit the gas if i step on it its more than happy to go with no surges or miss-fires or anything
There’s two types of timing. Ignition timing which sets the spark relative to the crankshaft; and valve timing, which set the valve opening/closing events relative to the crankshaft. It’s more common to have an ignition timing problem than a valve timing problem.
Not necessarily if you have an ignition timing that is overly retarded. The computer advances the timing when you step on the gas, so it might be adjusting it to where it is supposed to be when you step on the gas. I think the same could be said if you had overly-advanced valve timing. Valve timing isn’t adjusted by the computer (on that vintage), so with it overly advanced it might run poorly at idle, but ok when you step on the gas.
The computer’s algorithm during that era assumes the ignition timing and idle rpm is correct when the throttle is in the closed (idle) position. If ether of those is out of spec, the computer will be confused & isn’t able to compensate.
ok so i will defiantly get the distributor to where it idles at spec and then i will clean the egr i just looked up how and it seems simple. If all goes well it will stop surgeing
A warm idle adjust screw out of spec will definitely cause idle surging. Ask me how I know … lol …
would it just randomly go out of spec on its own? or could all the new parts have thrown it off?
just to be clear its surging at idle and bogging under very low acceleration. I was more curious of the bogging than the idle.
The idle screw wouldn’t normal change position on its own. The throttle valve area tends to clog with carbon deposits over time, and that lowers the idle rpm, and requires the idle screw position be reset, opening the idle screw air passage a little more. But that’s generally a minor adjustment. If there’s a vacuum leak then adjusting ide screw may require a major adjustment to get it to idle at the correct rpm, and that’ method of fixing a vacuum leak won’t usually work in the long run, b/c the idle vacuum leak isn’t constant.
Revving up and down at idle suggests an idle air control motor problem. A throttle plate sticking to deposits in the throttle body can also be involved. A toothbrush, cotton rags, and the correct solvent can clear those deposits, to eliminate one possibility.
I understand. Ok well i have a list of leads to follow now and thats what i needed i was just stumped… Ill be back on here tomorrow to let you know the progress.
Best of luck.
Im out of replies, ok well i only think its that because it ran good with the hose off and terrible unplugged wouldn’t even run really
Turns out its the MAP sensor if you take the vacuum line off the throttle body it resumes normal idle and operation but occasionally stalls out. Its 300 dollars so i got one for 30 on ebay used.
Hold on to the existing oem MAP. MAP’s are rare failure items.
Wasn’t the map i bought a new vacuum box anyway, it seems the problem is most likely a major throttle body leak and hydraulic engine mount vacuum is leaking. Bought new gasket and just plugged the line to the engine monunt