increasing loss of acceleration

[packratjohn]

92 SE has been doing great. New problem recently, loss of acceleration. Car starts and runs fine when cold, like first time in the morning, 80 on the highway, no problem. 25 mpg, too. After about 20 minutes, I start getting slight loss of acceleration. I can hold speed, but not accelerate. Gets worse gradually to the point I can't get it over 20 mph and 2K rpm. I can pull over, shift into neutral, and the car will usually die. Little hard restarting, but does restart, then will run fairly well for a few, normal accel up to 70. I can barely make it up a hill when it's bad, and dare not drive in traffic. 20 mile drive to the shop yesterday, died out twice, fortunately plenty of warning.
For routine maintenance, and trying to solve this:
New plugs
New fuel and air filters
replaced coils (but not the distribution plate under them. Doing that today)
new plug wires
Replaced cam sensor magnet (see other post - worked great)
Catalytic converter? no, had shop completely cut it out of the system, it looked fine and nothing changed.
Fuel pressure - possible, was 39 psi at idle, didn't have long enought hose to test while driving.
What about fuel regulator? Too expensive just to try it as a test.
Nothing throws a code, last code was the 41 solved by the cam sensor.

Any other ideas?

[J Wikoff]

Your fuel pressure sounds low. Should be a few/several psi higher at idle. You can test higher load pressure by taking the vacuum line of the fuel pressure regulator at idle. Also, a couple minutes after turning the car off, take that line off again and smell for fuel in it.

When I had very similar problems, a new regulator helped, but didn't alleviate it entirely. Then eventually it got worse, and a new fuel pump solved it.

[LakevilleSSEi]

Fuel pressure regulator I don't think would do that, but good to replace if you've never replaced it. Your starter will thank you on warm restarts eventually.

My guess would be the ICM. Or distribution plate, had something kinda similar on my old SSEi and it was coils for me, but yours are good, so I'm going with the ICM. Tho timing and conditions sound right for the cat getting hot and plugging off.

[packratjohn]

Update, 7/712

Changed out "distribution" plate under the coils. I did this at work and the car flew home, 42 miles, not a hitch.
Then today, okay as usual for about 20 miles, then started acting up, same as before.
Let it cool off and replaced the fuel regulator with a used one from a junker. No help.
I'll have to find a way to test the pump while having the problem. Hope to do that Monday, gotta resolve this.

Forgot to ask... is the coil distribution plate i refer to actually the ICM?
If not, where is the ICM?

[J Wikoff]

Yes, that's the ICM.

Drive it around, get it all warmed up and acting up, then test the fuel pressure at idle with the vacuum line pulled off the fuel pressure regulator.

[packratjohn]

Will do, but not right away. Shop is 20 miles in the other direction.... For some reason my boss won't give me the day off with pay to tinker. I've been replacing old crumbly vac hoses as i encounter them. Wish I were more of a mechanic. Anyway, thoughts:
EGR?
PCV?
vacuum leak?

Remember, this car runs like a rabbit for 20-30 minutes (miles), then will gradually start losing acceleration. At 60, you kick it to pass and it'll falter, maybe lurch, trying to do what I want. From that point on it only gets worse. That last overpass before my exit (40 miles into the commute) is a real challenge. Sits in the parking lot for 8 hours or so, then repeats the performance on the trip home. It's a fun car to drive when it's running right.
Still no codes. I'm thinking of reading them anyway in case I missed one. (I'll use my high tech paper clip scanner).
I do appreciate all the input, and I do try these things out. Some require shop help though.
I'll probably replace the PCV today "just 'cause". Probably never been changed. Done.It was dirty, but rattled normally.
Thanks again, guys and/or gals.

[J Wikoff]

Yours acts just like mine did when the pump was getting weak. The warmer it got, the less fuel it could push. If you could borrow a live data scanner, you could watch the fuel trims rise as it gets warmer, if that is indeed the problem. The fuel pump is the only cause I have personally experienced. And I've read others have a similar issue because of coils or the ICM. 39 psi at idle is too low, and is not a real good sign.

[packratjohn]

FINALLY got around to replacing the fuel pump and problem solved. Accelerates like it should. Haven't run through a full tank of gas yet, but suspect I'll be okay. I'm happy getting 23 or better on what I consider a full size car.
I did have to replace tank straps (bolt stripped, so cut straps and replaced)
Had to replace a few other small parts, mostly due to rust.
I did replace the PVC valve during the process, and have a few spare parts now.
Thanks for all of the input and thought!

[Bob Dillon]

Notice any difference at different fuel levels? The fuel pump is actually cooled by the gasoline in the tank.

I'd say if the car was OK at or nerar full fuel level and got worse as the fuel level decreased, as above, your pump's going out. Is it making more noise?

[packratjohn]

First thing I noticed was the fuel gauge is different, as if it's "synchronized" differently. It used to stay above full mark for a long time, now it falls off quickly. Just takes some getting used to.
No additional or different noises.
Fuel economy after a 200 mile test was 23.9 mpg, so no real change there.
Haven't run it down low yet, but will advise if that makes a difference.

[packratjohn]

Update - over two months, and not a hitch. Starts perfectly, accelerates the way it should. Still getting around 24 mpg with 200K miles. If only the body were perfect... (I mean the car's, not mine) Fun to drive to work, and fun to tinker with.