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SuperNewbie
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Discussion Starter #1
I'm putting this thread in General to gain a wider audience. So all input is appreciated.
I'm currently helping a lady who has a 94 bird with a 3.8 in it. The car has only 64,000 miles on it. It's spent most of its life in Florida and Las Vegas. So the car is rust free and in pretty nice shape overall. Her mother was the original owner so she's pretty clear on its repair history.

So here's what I'm trying to figure out. Currently when you drive the car doesn't really want to get up to speed at all when you apply the throttle. I test drove the car and if you give it more than just a feather on the accelerator it just won't go. Now my 94 used to be like this until i cleaned the MAF. When I cleaned my MAF it was like a whole new car. So I cleaned her cars MAF and the car was way better (the MAF was very dirty). So now a week goes by and she reports to me that the problem is back. So today I swapped her MAF with one of mine that I know works, and she still has the problem.
Anyone experienced something similar?
She's had some other "mechanics" work on the car recently prior to my time with it. These guys replaced the plugs, cap and rotor, fuel pump, ignition module, and ignition coil. I installed new wires this weekend. Basically these guys were throwing parts at her car at her expense in the name of "diagnosing" the problem. I'm trying to avoid that at this point.
The only other thing that is happening that's worth noting is that there is a vacuum leak in the heating A/C system. When the A/C is on and you do accelerate the vents will relax and go to the defroster position. I don't know if this is contributing to the major issue, but I thought I'd through it in here.

Let me know what you think. Thanks in advance!
Gordon
 

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Newbie
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5,650 Posts
Unless the transmission has some serious slipping issues, I'd venture to say it is an exhaust issue. The low mileage means nothing in regards to the health of the exhaust. One or more converters could be plugged up. The vacuum leak isn't that serious if the vents work when the engine has vacuum. It might just be that the line to the vacuum reservoir is broken or the reservoir itself no longer works.
 

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SuperNewbie
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2,869 Posts
Discussion Starter #3
well I drove the car before I cleaned the MAF and it didn't feel like trans slippage. I drove it after I fixed it and the trans seemed very normal.

Are plugged cats usually this intermittent? Whats the normal way to check the cats to see if they're plugged?
 

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SuperNewbie
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Discussion Starter #5
From you original post it didn't sound like the problem was intermittent. A restricted exhaust can let the car idle and run at low throttle perfectly but will rob power big time during heavy loads or at WOT.
sorry I don't want to confuse anything. It wasn't intermittent until i cleaned the maf. Then the car worked well for about a week, and went back to being crappy. So i guess it's safe to say that its constant now.

And as you just described, it can idle and move at low throttle. you can rev it up when its in park but not while driving.

Any good way to test the exhaust that your familiar with? Or is it just remove the y pipe and see if the problem persists?
 

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Newbie
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5,650 Posts
Unfortunately the most straightforward way is to remove it. There are ways to test the pressure in the exhaust system to find restrictions but it's not as simple, and I'm not totally familiar with the whole process.

One more thing you may want to try is unplug the MAF when you are experiencing the problem and then drive it. If it no longer does it, then it definitely isn't the exhaust.
 

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SuperNewbie
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Discussion Starter #7
I was able to look at the car for a few minutes yesterday while I was at work. I noticed that the pigtail that connects to the ignition coil is in bad shape. I ordered a new pigtail for it, as it's missing a lot of insulation and one of the wires is almost severed from the connector.
I have no idea if this could be causing the problem but I'm gonna fix it before continuing on the troubleshooting process.
 

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SuperNewbie
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Discussion Starter #8
In case anyone is interested here is the outcome on this car.

We had a backpressure test done at an exhaust shop and the cats are good.

Turns out that someone else replaced the fuel pump a few months ago. We tested the fuel pressure and it was less than 30lbs.

I dropped the tank and found that the rubber filler tube that connects to the tank was halfway pinched off due to bad installation. As well the vent line that comes down from the filler next wasn't attached to the tank and wasn't really clamped on either. I figure this could cause a fuel pressure problem.

Once I got the pump out of the tank a strainer wasn't installed when the last pump was installed, and there was crap on the inlet of the pump. And the fuel return line that attaches to the fuel pump assembly was p[inched off some too.

I replaced the pump, the strainer, and fixed all the issues with the other hoses, and the car runs really nice again.

I still need to find the vacuum leak that affects the heater/ A/C controls, but at least she can drive again.
 
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