Torched94

I've done a search for days now and I'm still stumped. Trying to find the next route to take. Plugs, Wires, Opti, Fuel Filter, have all been replaced within the last 10k miles. The car is "bucking" hard under part throttle and under load. Seems to be more noticeable once it's warm. Did the fuel pressure check and its erratic when the problem is happening but then seems normal when it isn't acting up. Tested the Regulator and its fine. Any sense of direction would be helpful. Please Help! Thanks.

antfarmer2

my 94 would bog and backfire in the engine when I jumped on it with no codes changed the front two 02s never ran better.

I would look at your pulsater from the pump might have a crack or loose connection. or failing pump.

load up the fuel pump without starting and see how long it will hold. mine is all factory and will hold all night.

Torched94

Yeah it seems to hold just fine. What's weird though is under part throttle when it's acting up, the fuel pressure gauge goes sporadic with each miss. Would that give any clues as to what it might be? Thanks again for your help. Btw the odo is just over 107k fwiw.

ex-x-fire

I'd take a guess at the fuel injectors or wiring, if the pressure is dropping with the miss then it seems that a couple are hanging open.
Also check for a dead spot on the tps.

Torched94

I'm not too knowledgeable in this field so forgive me, but I'm not so sure the pressure is "dropping off" per-say. It drastically increases and decreases within the normal range of acceleration. I wish i could upload a video to show what's happening. The injectors and fuel pump are all original though. How should I go about testing the injectors instead of replacing everything?

Torched94

http://youtu.be/AJ13Sr_moms

antfarmer2

I never put a gauge on mine when it was acting up. becareful when closeing the hood so you don't crack your windshield. I am going with bad 02s. the 94 was setting up for ob2 but still a ob1.I did the front two, I went with bosch 02s about $25 each. the pass side is harder. get the 02 socket set from orielys and use the short one. I changed the knock sensors while I was under there. the only way to do a proper flush. had to run a wire in there to break the crap up and a lot of it. mine was always taken care just never flushed right.

and this is not tossing parts at it. the 02s should have been changed twice already!!!!!!!
the knocks were good but could not bring myself to put back 20+ year old cheap parts. and the new ones come with the right dope on them. very important as is the torque 14 lbs if I remember right. to get the connector off just pinch it with your fingers.

DinoBob

Why is no one suspecting the pump itself? That's what I suspect. I have experience with this issue. I'd pull it out and replace the pump motor itself, and get rid of that pulsator. It can be replaced with a simple length of hose. We tossed the one on my dad's 86 and never noticed a difference.

antfarmer2

I did in my first post. but he said it is holding and the video shows it is bounceing but still up there. dollar to a donut it's 02s.

Tom400CFI

Maybe....fuel pressure should not be bouncing though. Not at all. Something is wrong there; either w/the gauge/set up or the actual pressure.

antfarmer2

but do you think if it is retarding from the knocks it might do that? when mine was acting up I did not do it with the gauge.

Torched94

I'm fairly certain the gauge was correctly installed and managed. The gauge works in all manors it's supposed to except when the bucking starts and once again, there's no sign of this happening whatsoever when cold. I'm fixing to drive to base where they have lifts and see what's going on underneath. I know this may unfortunately point to the opti but I just remembered I actually regrettably went through a drive-through car wash last week and now this has started. At any rate, I'll be back with updates and thanks again.

Tom400CFI

No, I don't think that it should do that, even w/retarding from knocks. The primary fuel system has no "idea" what is going on w/anything else in the engine; the pump pumps...the regulator regulates. The fuel pressure ought to remain stable (w/in the range of vacuum variability of the regulator).

I'm not saying that your advice is wrong; it could very well be the O2's, or KS's...I'm only pointing out to the OP that the fuel shouldn't be doing that, and that there is a issue there...or his test/gauge/hook up is awry.

antfarmer2

when mine acted up it was so bad it had to mess with the vacumme. look like we will just have to wait and see. I hope he picked up the 02s on the way to the base.

DinoBob

That's what I'm saying. I don't care if the fuel pressure is holding under test or not. But if the pump is intermittent while driving this is what you will experience.

Torched94

So I decided against going to base today and since oriellys said it would take two weeks to get O2 sensors(I'm not so sure that's what he meant, but it is what he said) I decided to order some ac delco sensors from Amazon since a friend read somewhere that bosch sensors tend to act a little finicky with our pcm's. I don't know how true that is but another friend who's a mechanic suggested the oxygen sensors or maf might be the culprit, I went with the cheapest option first.

Torched94

This maybe off topic, but does anyone think it's normal for my car to be pushing 235* degrees water temp when it's 60* out? The water pump is less than 12k miles old and I feel the coolant is in good shape but it just seems extremely easy to build heat when the car is running in park. I've read that cylinder heat from faulty injectors can cause high temps. and wondered if this might have something to do with either issue.

antfarmer2

I would pull the top of the radiator shroud off and clean inbetween they are big vacumme cleaners. do not get your opti wet. the fans are set to come on at 228 and 238.
the six 7mm screws in the front are a pita. I used a flat ratchet wrench with ele tape to hold the screws.

antfarmer2

does your car run ok when you baby it easing on the gas then bog and pop when you hop on it?

Torched94

It use to be like this, yeah, but I just made a quick run to pappa johns and the idle is getting worse. All of a sudden it raises and wants to fight my brakes at the light.