Chokes on idle
Posted: February 20th, 2011, 11:37 pm
I'm having some trouble with acceleration. Much of the symptoms seem like a MAP or MAF sensor, but the problem is there's no CEL (granted, its OBDI).
I was accelerating onto the highway when my car suddenly didn't want to accelerate anymore. "Great"... I figured it was gas, so I pulled into a gas station and filled it up. The gauge was at 1/4 tank, but I figured it might just be a problem with the fuel gauge. That didn't work, obviously.
After starting it up, it had a very rough idle. The engine chokes when giving it too much throttle too quickly, and only hesitantly increases revs when increasing throttle very, very slowly. After reaching around 2500-3000 RPMs, it can typically handle a more generous increase in throttle, but never open throttle unless it's gradual. The higher the RPMs, the more I can play around with it no problem.
I kind of suspected the fuel filter, but after playing with it a bit it didn't make sense. I replaced the fuel filter, and (coincidentally) the idle was a bit more stable. At idle, the car was having no problems due to smothering or lack of fuel. Not to mention the fact that once I got it safely passed the threshold of about 2500-3000 RPMs I was able to rev it just fine.
Anyway, to my utter surprise there was *gasp* no air filter in the intake. What the hell the previous owner was thinking, I'm not sure. I did have it checked out at a mechanic before I bought it, since I was so far away from our shop and it wasn't a very easy task to bring it all the way there for a major inspection before a purchase. The local mechanic did a couple tests here and there and said it looked fine (it did to me as well), so I went ahead with the purchase.
Replaced the fuel pump and fuel filter. Checked the throttle and MAF sensors with a multimeter, and also tried unplugging the MAF sensor and they were fine. I looked inside the intake manifold and there wasn't anything clogging it. And there wasn't anything inside the intake boot either. Oil is clean and full. Any other ideas?
The previous owner took great care of the car and, for a '94, the car (engine and interior especially) are in immaculate condition (save the missing air filter). The last thing I have to add is the fact that it smells and sounds like there's an exhaust leak (since before I purchased it). Since a hole in the exhaust can cause these types of problems for a MAP sensor, I thought this might be it as well. But, although a lot of these symptoms are similar to a faulty MAP sensor, this car doesn't have one so that was quickly ruled out.
I did drive the car home, and, when it let me give it throttle, the engine rev'ed and drove fine. It was getting it above the threshold every time I needed to shift that was a pain in the a--.
If anyone has any suggestions that'd be great. If not I might as well just bring it up to a mechanic and stop messing with it. It's my DD and I use my car for work, so I've gotta have it running soon.
I was accelerating onto the highway when my car suddenly didn't want to accelerate anymore. "Great"... I figured it was gas, so I pulled into a gas station and filled it up. The gauge was at 1/4 tank, but I figured it might just be a problem with the fuel gauge. That didn't work, obviously.
After starting it up, it had a very rough idle. The engine chokes when giving it too much throttle too quickly, and only hesitantly increases revs when increasing throttle very, very slowly. After reaching around 2500-3000 RPMs, it can typically handle a more generous increase in throttle, but never open throttle unless it's gradual. The higher the RPMs, the more I can play around with it no problem.
I kind of suspected the fuel filter, but after playing with it a bit it didn't make sense. I replaced the fuel filter, and (coincidentally) the idle was a bit more stable. At idle, the car was having no problems due to smothering or lack of fuel. Not to mention the fact that once I got it safely passed the threshold of about 2500-3000 RPMs I was able to rev it just fine.
Anyway, to my utter surprise there was *gasp* no air filter in the intake. What the hell the previous owner was thinking, I'm not sure. I did have it checked out at a mechanic before I bought it, since I was so far away from our shop and it wasn't a very easy task to bring it all the way there for a major inspection before a purchase. The local mechanic did a couple tests here and there and said it looked fine (it did to me as well), so I went ahead with the purchase.
Replaced the fuel pump and fuel filter. Checked the throttle and MAF sensors with a multimeter, and also tried unplugging the MAF sensor and they were fine. I looked inside the intake manifold and there wasn't anything clogging it. And there wasn't anything inside the intake boot either. Oil is clean and full. Any other ideas?
The previous owner took great care of the car and, for a '94, the car (engine and interior especially) are in immaculate condition (save the missing air filter). The last thing I have to add is the fact that it smells and sounds like there's an exhaust leak (since before I purchased it). Since a hole in the exhaust can cause these types of problems for a MAP sensor, I thought this might be it as well. But, although a lot of these symptoms are similar to a faulty MAP sensor, this car doesn't have one so that was quickly ruled out.
I did drive the car home, and, when it let me give it throttle, the engine rev'ed and drove fine. It was getting it above the threshold every time I needed to shift that was a pain in the a--.
If anyone has any suggestions that'd be great. If not I might as well just bring it up to a mechanic and stop messing with it. It's my DD and I use my car for work, so I've gotta have it running soon.