I scanned through the threads but didn't seem to find specific help on my current problem so I thought I'd ask.

I bought a stock 91 n/a last month that didn't run and towed it home. I did a tune up on it and got the engine going and found it wouldn't move due to total clutch wear. I've replace the clutch and started driving it, but it has very low power. It can't redline in any gear and I'm guessing a 0-60 time of about 25 seconds. I owned a 79 decades ago and know what the car should do.

I checked the compression and it is OK (75PSI on all lobes.) I live at 4600 feet elevation and from the shop manual compensation curve that's OK.

The plugs, wires, air filter are new. I've tried setting the timing at spec (5ATDC) and up to 15BTDC, but that doesn't seem to help. Getting good spark on all leading and trailing wires.

The ECU had one error code and found a solenoid was unplugged. Fixed that and no more codes.

I'm beginning to think the cat is plugged and for lack of any decent way to check that I'm considering disconnecting it and driving a short time to test. Is this a good idea in anyones opinion?

What else should I check?

Thanks in advance for anyones help.
Gary

 

well the cats are just four bolts and they are off.... thats a good start. while your at it you can gut those cats and look into a hi-flow when inspection time comes around. also if you want to drive it around with no cats for little bit, dont sit at idle to long, you'll get woosey and nausiated from the fumes. (done it )

 

oh ya bring a zip tie for the tube that runs from the air pump to the main cat, otherwise it will hang down onto the ground when driving

 

if you think your exhaust is clogged, you can try doing this:

- connect vacuum gauge to intake
- raise idle speed to 2,000 rpm or so
- release throttle quickly

the vacuum should rise and then drop down to normal idle level pretty smoothly and quickly.

if it is slow to rise and drop, then you are likely to have a clogged exhaust.

....

What you could also do is remove the oxygen sensor to open up your exhaust a tad and see if it makes any difference (be careful though)

....

Hugues -

 

Hmm - I hadn't heard that one.
I guess it shows that you had a wider throttle opening the sustain 2K if the cats were clogged.

 

ok got a question: @ idle, what should the vacuum meter show? -20 psi or -15?

 

Don't forget to check the port actuators. On my S4 n/a, the combination of a partly plugged second pre-cat (first pre-cat had a big hole in the honeycomb) and a stuck front port actuator was slowing the car to a 12 second 0-60 (as measured by g-tech). After fixing those, I was down to 7.6 seconds.