Hi guys--

So today I sprung for a TBI fuel gauge at the local auto parts store to test the pressure in my car's system. If you recall, I've been having trouble diagnosing a "no power" problem when I push the throttle down more than 1/4 way...the car just seems to bog. It revs up fine, all the way to the shift point, doesn't misfire at all, just feels like I've got 80hp instead of 130.

Anyway, so I put the fuel pressure gauge on today, and it reads 12 psi all the time. Doesn't fluctuate at all when I blip the throttle, doesn't bleed down when I turn the key on with the engine off. Just constant at 12 psi. This is good news for me in that I don't have to spend hundreds on a fuel pump, but what the heck is my problem?! :want: I also did a compression test, and the readings were great. Virtually no variation between cylinders.

Car has a new fuel filter (FRAM), plugs, wires, cap & rotor, and ignition module (all AC Delco--yes, I bought the nice stuff).

I'm guessing my problem has to be with the ignition, but there's not much left! Do you guys think my ignition coil or pick up coil could be bad? What are the symptoms for these? The car only has 30k miles, and the distributor is clean as a whistle underneath. Car does NOT misfire at all, just has a lack of power when I step on it. Power is normal at below 1/4 throttle.

Any suggestions would be GREAT!

Did I mention that it's getting really friggin cold here in Michigan, so if I can get this fixed sooner, that'd be great...Plus I don't really wan't to have to take the car out on the salty roads--it's in too nice of condition. I have a 1995 Aurora with 170,000 miles (still runs great on original engine and trans)that serves as my winter beater while my Caddies rest under a car port until the salt goes away.

Sounds like restricted Cat converter. Any good muffler shop can verify. Please post year and type of Cad in your profile for future assistance.

I was leaning toward contaminated fuel, but this does sound like a plugged cat. It's not uncommon on these cars. Nice pick carnut.

I thought of that this weekend, but dismissed it. I didn't think they plugged up after only 30k miles, but I suppose it's possible. It is original to the car (still has the AC logo on it), but it doesn't rattle at all. I shook it and it was solid.

I'm still leaning toward some type of ignition problem though. I drove the car around tonight and noticed that if I stepped on it, the "ECON" light on the dash stays on if I'm in diagnostics and the 02 sensor voltage stays pretty low, only if I really press on the accelerator, indicating a rich condition...my guess is that the car isn't getting enough spark at these higher RPMs for the fuel that's being dumped in, and consequently, it runs rich.

The 02 sensor is new, and I've tried switching the MAP out with one from another GM car with the same part # and it made no difference.

I'm going to put a new coil in tomorrow. I've had one go out in a 72 Oldsmobile that I used to have and about 2 weeks before it went out, I noticed the car had a distinct lack of power. The it just wouldn't start at all until I replaced it.

If that doesn't do it, I'll take it to an exhaust shop after I fix the cooling fan relay--right now it's inoperative so I can't really idle the car for that long.

Thanks for the help! Any other suggestions would be great too!

If this is the 85 Deville you are talking about.....???.....

Have you removed the throttle body and inspected the EEFE grid that is below the throttle body for deposits?? The 85/86/87 FWD Devilles had an electrically heated grid below the throttle body to help with fuel atomization when the engine is cold. Possibly that is clogged with carbon from fuel deposits due to the low miles and lack of driving? It might be worth a look.

The cat could still be suspect, also. The cats do not "plug" per se with carbon or crap coming down the exhaust pipe. They overheat, melt part of the ceramic substraight and that restricts the flow. It can happen at zero miles given the wrong set of circumstances...i.e....flooded engine with a lot of fuel washed down the exhaust pipe to the cat before starting. The idea or concept of "plugging" means that the cat melts and restricts the flow of exhaust gases causing high backpressure and poor performance. The exhaust pipe/flow is indeed "plugged" but the cat doesn't "plug up" from junk being fed to it so mileage has nothing to do with it. If the car ever had a stuck injector or other problem like that then the cat would certainly be suspect.

Hey chevelle--

Yes, this is the 85 I'm talking about. So that's what that funny thing is under the throttle bores. It looked clean when I last opened them (a few days ago).

I forgot to mention in my earlier posts that the car seems to have more "pep" when cold, and significantly less when hot...this was another thing that was pointing me toward an ignition problem, and confusing me about the fuel delivery problem, since the car needs much more fuel when cold than when hot.

Actually, when I first start the car and drive around the block, it seems pretty peppy, except if I really step on it (more than 1/2 throttle)--which I don't like to do.

As the car warms up, the performance begins to suffer to the point that it's boggy past 1/4 throttle.

Thanks guys so much for your help. I'm going to try the new coil tomorrow since it was cheap and easy to replace. :hmm:

Just a guess...

Did you check TPS? It may not be working smoothly. And I think when you open the throttle, after some point, the car goes into open loop, so your observation may be fine.

Yes, I checked the TPS and readjusted it to be .5V at min air. It works smoothly.

One more thing never mentioned, does the trans shift at the right times and do you have part throttle kick down? If the T.V. cable is adjusted too long it will shift too early and will be sluggish. Any tranny shop can verify cable is adjusted correctly. Most GM cars of that era had the same type of cable and adjustment proceedure, so a factory service manual from a Riviera, Toro or B body car would help.