1991 integra gs, completly stock, approx 270k km, not driven hard until the last 8k km or so.
alright, here’s the deal… i could start my car, but it didn’t climb to the fast idle - it stayed at around 700 rpms, and vibrated a bit. i tried to give it a little throttle to get the revs up, but they didn’t climb too well, and the engine vibrated a lil bit more - nothing too bad, but it didn’t feel quite like normal. the revs didn’t want to go too high above 2.5-3 grand, and the cel came on as i was reving. i checked the code - #5: vacuum part of the MAP sensor. when i took a look at the sensor, i found a small hole chewed in the vacuum hose between the metal tubing leading towards the intake manifold and the T junction at the bottom of the sensor itself (some sort of rodent).
i got some tubing from lordco (automotive parts store)… not actual vacuum hose, but very similar size… i cut it to fit,and put it on to replace the short (approx 3 inch) section that had had the hole before, and also replaced a slightly longer piece that had some chew marks - i forget the name of it (shop manual not handy), but it feeds extra air to the intake to help start the engine, i believe. the car started alright, ran alright… until the engine got warm; when it got warm, the car would bog severly at any more then light application of throttle, as long as it was below 3000 rpm. when the engine was at idle (approx 750 rpm), a quick tap of the throttle would result in the revs immediatly dropping towards 0, then stalling sometimes, or fitfully climbing back to idle other times. sustained wot caused the engine to stall immediatly. very light throttle would cause the revs to slowly climb, and the gas pedal could be floored without consequence above 3 grand rpm. if the car stalled, it was extremely difficult to restart while warm. no cel for this, tho.
my theory was that the lordco hose used wasn’t strong enough when hot (from heat in the engine bay) to resist the vacuum at wot or near wot, and was collapsing, cutting off the sensor and causing the ecu to flood the engine with extra fuel, and that the bad air/fuel mixture caused the bogging.
however, the problem still exists after replacing the lordco hose with proper vacuum hose from an acura dealership (albiet slightly different than the original - thicker on the outside but thinner inside).
i’m thinking the spark plugs could’ve gotten fouled, and i will check them as soon as i can, but i’m looking for other suggestions as well.
