Engine Losing Power

LARRY70GS wrote:

If it is pulling 20" of vacuum at idle, raise the RPM to 1500-2000 RPM, and look at the vacuum. If it starts to fall off, the exhaust is clogged, bad catalytic converter, or collapsed muffler. Check your fuel pressure. Is it up to spec? When was the last time you changed the fuel filter? Use a scan tool to see where the ignition timing is.

It for sure falls off after any throttle is applied. I get 19.9"-21.5" at Park. If I give it any throttle it immediately begins to drop. I will report back once I install the downpipe and cut the cat.

charlieRobinson wrote:

LARRY70GS wrote:

If it is pulling 20" of vacuum at idle, raise the RPM to 1500-2000 RPM, and look at the vacuum. If it starts to fall off, the exhaust is clogged, bad catalytic converter, or collapsed muffler. Check your fuel pressure. Is it up to spec? When was the last time you changed the fuel filter? Use a scan tool to see where the ignition timing is.

It for sure falls off after any throttle is applied. I get 19.9"-21.5" at Park. If I give it any throttle it immediately begins to drop. I will report back once I install the downpipe and cut the cat.

When you open the throttle, it may drop a bit, but then should increase. If it slowly drops off with steady throttle, the exhaust is clogged for some reason.

From what you've said, it sounds like you have a bad Cat. My car was very sluggish but ran fine otherwise, and when we built the downpipe, we gutted the cat as well and it made an unbelieveable difference. Im wondering if this is what you might have been thinking in the other thread? Haha

th3fr4nchi5e wrote:

From what you've said, it sounds like you have a bad Cat. My car was very sluggish but ran fine otherwise, and when we built the downpipe, we gutted the cat as well and it made an unbelieveable difference. Im wondering if this is what you might have been thinking in the other thread? Haha

Really hoping I get the same results! Just waiting for the resonator and clamps to get here and then it's game time.

Easy to diagnose a clogged cat. With engine warm, rev in park. Not to the floor, but give it some quick 3500-ish pedal. If it seems to struggle as RPM rises, it suggests a restriction in the exhaust, likely the cat. If it revs freely, it's something else.

The revs felt and sounded the same at 1-2k as they did at 2.5-3.5k.

A 10 second test with a vacuum gauge will settle this. With an engine at operating temperature, observe the reading at idle, in Park. Open the throttle enough to attain 1500-2000 RPM and hold it steady. The vacuum level should hold steady at about the same level. If you observe the level dropping while holding the throttle open, you have an exhaust restriction.

LARRY70GS wrote:

A 10 second test with a vacuum gauge will settle this. With an engine at operating temperature, observe the reading at idle, in Park. Open the throttle enough to attain 1500-2000 RPM and hold it steady. The vacuum level should hold steady at about the same level. If you observe the level dropping while holding the throttle open, you have an exhaust restriction.

Did that too. My vacuum did not drop. stayed ~20-21 the entire time under throttle in park.

charlieRobinson wrote:

LARRY70GS wrote:

A 10 second test with a vacuum gauge will settle this. With an engine at operating temperature, observe the reading at idle, in Park. Open the throttle enough to attain 1500-2000 RPM and hold it steady. The vacuum level should hold steady at about the same level. If you observe the level dropping while holding the throttle open, you have an exhaust restriction.

Did that too. My vacuum did not drop. stayed ~20-21 the entire time under throttle in park.

Then your exhaust is fine. You have other problems.

charlieRobinson wrote:

Just to remind everyone for the 1,000 time. I'm almost a total newbie to cars.

charlieRobinson wrote:

Never had a misfire and my LTFT is fine. Cat is getting murdered soon, so we'll see if that's it.
My setup can for sure handle a 3.6", no problem.

I don't think you are getting the point. You need to scan your car if you want any helpful information. Do you have a good scanner that can log multiple parameters at once? Do you have any way to adjust fueling or timing? Some WOT scanning logs will help you (and us) figure out if you are lean or rich or too much or too little timing or what.

Go back and re-read modding 101, and pay attention to the parts about scanning and fueling and timing.

Does your BBV work properly?

Don't you dare pour a can of Restore into that thing.

lol

deekster_caddy wrote:

charlieRobinson wrote:

Just to remind everyone for the 1,000 time. I'm almost a total newbie to cars.

charlieRobinson wrote:

Never had a misfire and my LTFT is fine. Cat is getting murdered soon, so we'll see if that's it.
My setup can for sure handle a 3.6", no problem.

I don't think you are getting the point. You need to scan your car if you want any helpful information. Do you have a good scanner that can log multiple parameters at once? Do you have any way to adjust fueling or timing? Some WOT scanning logs will help you (and us) figure out if you are lean or rich or too much or too little timing or what.

Go back and re-read modding 101, and pay attention to the parts about scanning and fueling and timing.

Does your BBV work properly?

Don't you dare pour a can of Restore into that thing.

Yes, I can scan but I can't tune or adjust any parameters.

I will paste a graph WOT run for you guys to check out.

Yes, BBV is fine.

No, I won't use that shit. Just thought it was weird.

Again, the lack of power could all be psychological. You guys could drive my Riv and say it feels fine. I just recall having more juice with my other lower mile L67.

If the question is whether a 150k mile engine will have less power than a 67k mile one, I think the answer to that is 'yes'. Is it a significant amount of power? Probably not, unless you have other issues.

If your rings were truly worn enough to be noticeably loosing power, I'd think you would see some grey smoke exiting the tail pipes during regular driving, and your oil level would drop 2 quarts or more between changes. Notice anything like this?

AA wrote:

If the question is whether a 150k mile engine will have less power than a 67k mile one, I think the answer to that is 'yes'. Is it a significant amount of power? Probably not, unless you have other issues.

If your rings were truly worn enough to be noticeably loosing power, I'd think you would see some grey smoke exiting the tail pipes during regular driving, and your oil level would drop 2 quarts or more between changes. Notice anything like this?

My oil did drop a bit, about half a quart I think. I had to get it topped off last week. I thought it was because of a bad oil pan and gasket, though.

No smoke and nothing else weird to mention.

Burning a little oil is normal for an engine with 150k. If you only lost 1/2 qt, and you can see oil leaking form the pan, I'd think your rings are sealing pretty well.

Do a couple of timed 0 - 60 runs or quarter mile times and see if your performance has really dropped. Post your numbers here and everyone can tell you if your times are correct for your mods or not. The butt dyno isn't always that accurate.

On the highway last night, crusing 65 mph.. i lost power steering, and no power with the gas peddle 0 RPM's. Headlights and radio stayed on. I let the car cool for 20 mins and drove it home.. I have had a cracked radiator for a couple months now and just kept adding water. I didnt add any yesterday and now i hope im not screwed!! Also cracked vaccum lines from the TB that i did try to repair.. but it looks like crap, and i bet its still leaking. ...Noticed a small oil leak, looks like its from oil pan, never noticed it before...Also added half bottle of octane booster to half tank of gas, ANY HELP?? PLEASE!

UPDATE... car wont start until i press gas pedal 3 times. Idles fine but RPM gauge sticks Maybe too much air? Dirty MAF?

Cracked radiator, leaking vacuum lines..... I think you need to take care of these basic and known issues first as you are introducing several variables into the mix by leaving them in place.

Just having bought my 95, I'm no expert on troubleshooting much specific to this model yet, but my experience with cars of this and older vintage are that vacuum leaks can wreak havoc as too many metering systems rely upon those expected vacuum levels to operate normally.

Replacing all the vacuum lines & fittings in an engine bay can be time consuming, but it usually isn't hard. The only tough part is when there is some weird factory fitting that is unobtanium. Sometimes you have to fab something up with other fittings in that case, or visit a wrecking yard.

In that same vein, I plan to replace all of my vacuum lines and fittings this summer. I don't think I have a significant leak, but I can see several rotted lines and some are so hard that they are loose on the fitting. So they definitely are losing some vacuum now, and it will only get worse. After 18 years, no surprise.

Al

Thanks just got back from GM, part 24508742 is going in now, hoses and "T" connecters, also a bottle of seafoam... Hopefully im just out of gas!!

Did the vac line repair, and put 8 gallons of gas and whole bottle of seafoam. Car starts after steping on the gas. Idles fine, Still running hot (cracked rad) Now Im seeing oil leak and boiling by the injectors, is this head gasket?

96rivie wrote:

Did the vac line repair, and put 8 gallons of gas and whole bottle of seafoam. Car starts after steping on the gas. Idles fine, Still running hot (cracked rad) Now Im seeing oil leak and boiling by the injectors, is this head gasket?

Sounds like your Lower Intake Gaskets may have gone? Do you have oil and/or coolant puddling up around the injectors and supercharger? Or is it fuel leaking from an injector that's boiling on the intake?

Dark oil around the injectors and SC...

Yep. It sounds like your lower intake gasket took a poo. I'd actually like to see pictures of it if you could before you go ripping stuff apart. Look all around the supercharger, including the backside. Also, take a light and look under the S/C snout and the throttle body. Follow around where the LIM mounts to the block and look for visible leakage. A bad LIM leak can cause a vacuum leak and bad running conditions.

It puddled up around 2 injectors up front,around to the sc snout and dripping slowly down the backside and down to the oil pan, super sucks!! Im down to $100 and def. not a mechanic but, maybe can get a rad in there this weekend, and do the LIM next week