Chokes on idle

[Swivelgames]

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.

[muttpower]

Before changing anything out or dishing out money to a mechanic, I'd check that all vaccumn lines are attached, and that there are no leaks on the intake between the VAF and Throttle Body. You'd be surprised at what a small leak there could do....

[DeadMaker]

Also i would suggest to check out spark plug and spark plug wires..Who knows maybe you are lucky.

[kira_kira]

im currently having a similar problem any help would be appreciated. when i floor it the car will accelerate (with reluctance) up to 3000 rpm then choke out till 5000 rpm (real slow accel and almst no power) and then it bloody damn well goes like its supposed to. i check vacuum lines and sprayed for leaks found nothing. if i feather the throttle it accels kinda fine but still a bit boggy. oh and its burning epic amounts of fuel. any suggestions?

[muttpower]

Sounds like a spark issue...like it's missing at speed.

[Ryan]

There was also an issue with the knock sensor cover plate resonating at certain RPM's giving a false knock signal, cutting power....

Timing is suspect, as is distributor, and intake leaks.

[kira_kira]

well i spray tested the engine for air leaks so now i check dizzy and replace plugs. as for the knock sensor is there a way to check without ripping the intake off? and i may need to replace my check engine light lols it never comes on even tho im using an atx ecu in a mtx car =P thanks for the leads guys much appreiciated ^_^

[Ryan]

yeah, replace the light, and then pull the codes.

[kira_kira]

well i seem to have solved my probs... i put the old k8 ecu back in... didnt stop to think to pair the ecu with the intake... using the k8 intake... yeah.... yay me =P (have u had a v8 today?)