98 OBW loss of power

[joediesel]

Hi All,

I have a 98 OBW which has lost so much power over the past week it's become pretty much undriveable anytime I'm in the vicinity of an incline.

The car idles fine, has a little hesitation when first applying the gas but then revs up fine.

When driving it shifts fine and the rpms increase correctly, the only thing is it has to keep downshifting to get up hills (or accelerate on any grade) until it basically gets down to 1st and 2nd gear and you have to keep the car floored to get it to climb the hill at 15-20 mph.

I'm not getting any check engine lights.

I'm not getting any pinging (thinking of the knock sensor).

I just did the timing belt in the fall and it has passed our state emissions with out a problem.

Prior to changing the timing belt I changed both catalytic converters (didn't realize the timing belt had jumped teeth until I posted here) so those "should be" fine. O2 sensors are originals but I'm not getting any codes regarding them.

 

I changed the sparkplugs, the old ones looked fine. No noticeable improvement. I did not change the wires since they are fairly new NGKs.

 

Real gas mileage has decreased over the past couple of weeks, not sure if it's because I've had to pump that much more gas into it to go or if it's a sign of it's problem.

 

I've got a Scangauge II and readings for gallons/hr have stayed the same at idle (slight improvement with new plugs). Other readings seem to be ok but I don't have a baseline to judge against.

 

One odd thing I do note is that the voltage seems to be low at 13.6-13.7 but it definitely has been enough to keep the battery charged and running everything.

 

I'm now at a point of uncertainty on what to try next. I don't want to just throw parts at it without reason.

 

Any thoughts from others?

 

Engine is a 2.5 out of 96 with unknown mileage. Auto transmission.

THanks,

Joe

[davebugs]

I have witnessed this be the alternator. Loose high RPM's first and keep loosing more of top end as you drive.

 

Hard to tell it from clogged fuel filter or clogger cat. But perhaps a load test on the alt and battery would help diagnose.

 

Sure cheaper than everything else you've done.

 

What plugs did you install. ALthough bad brand/model of plugs usually isn't RPM related.

[joediesel]

Thanks for the quick reply Davebugs.

 

The plugs were NGKs as recommended here.

 

I was also thinking of the fuel filter but it revs fine, to get up hills I'm basically doing about 3k rpm.

 

When you say the alternator can loose the high rpms do you mean that it can't hit them or that the car doesn't perform when achieving high rpms?

 

I checked my other vehicles (Chevy, Honda and VW) and all their voltages are above 14 at idle. I don't have access to another 98 OBW to see what the standard is on that. Is 13.7 so low that it would cause performance issues yet still maintain a healthy charge on the battery?

 

Thanks

Joe

[davebugs]

I believe you are correct and the voltage may be low.

 

I diagnose it by symptoms rather than my multimeter that I'm definately a novice at.

 

A chain parts store should check the alternator for you for free on or off the car.

 

And if you haven't done a fuel filter they are less than 20 bucks and easy to do.

 

Good on the NGK plugs.

 

And I mean that it just won't get into the higher RPM's. When it kicks down it does for seconds but then starts loosing the high RPM's again.

[joediesel]

I had actually started to take the fuel filter out with the thought of just testing a straight thru connection on it but the hoses are very solidly attached to the filter. I'll go out and give it another try.

Thanks,

Joe

[john40iowa]

Those hoses are very hard to remove. Someone here posted about a tool for just this purpose, but I can't remember the name. You might try the auto parts store.

[davebugs]

Hose clamp pliers. VERY handy for lots of things.

 

I have a good Sunnex(sp?) set and a cheap Harbor Frieght set. The angle at the end is different. IIR the good ones are bent much more.

 

You can also take a pic and some PB and get the pick in there and hit it with some PB then slide the pic around the nipple.

[nipper]

Chain parts stores are useless to test Alt. Simple teste, everything on, engine rpm 1800 rpm, voltage should be 13.5 to 13.8 volts.

 

this sounds like a clogged cat to me, since it seems to be a power issue and not a sputtering issue. Get yourself a cheap vacume gauge and :

 

http://www.classictruckshop.com/clubs/earlyburbs/projects/vac/uum.htm

[davebugs]

True "changing" cats is much different from installing new cats.

 

2 things come to mind.

 

How far do you get before this happens?

 

And try it at night. If a cat is the problem they usually glow a nice cherry red if you drive it long enough and easier to see at night.

[jp98]

I'll have to agree on either the fuel filter or the cat. I know it isn't a Subaru but I had a Chevy pickup that when the fuel filter became cloged it would not pull its own weight. You could rev the engine up as high as you dared while it was sitting still but head up a hill with it and you might as well get out and push it.

[joediesel]

Latest update.

I changed the fuel filter today, yep the hoses are a major PIA to get off but I took the suggestion to squirt some PB Blaster in there and it did help.

 

Unfortunately that didn't help the problem at all.

 

The cats were changed for brand new ones from Rock Auto. Of course that doesn't mean they couldn't have failed also. Before changing the timing belt in the fall these new cats had glowed red a couple of times themselves, not sure if that would have adversely affected them.

 

I've got my wife swinging by Harbor Freight to pick up a vacuum tester so that I can hopefully rule out the cats (or blame them authoritatively).

 

The alternator is still an unknown.

The voltage does not rise above 14 volts and after taking it for a test drive with the new filter it had dropped to a constant 13 - 13.2 volts. I've got the Scanguage set to read voltage constantly and it's just not getting up there. It's hard to fathom that it would be causing this problem but stranger things have happened.

If the cats test out OK I'll next look to the alternator.

 

The other items further down my list are the knock sensor and ignition coil. Since the engine seems to run well without misfires and no pinging plus not throwing any codes I'm not really thinking those items should be an issue.

 

Any other thoughts would be welcome.

 

Thanks,

Joe

[987687]

I'd be kind of surprised if low voltage would cause it to run bad.

The alt completely failed on my 96. I had quite a long drive home, so I turned everything off and just kept going. My scangauge was reading 10.4v when I made it home, but ran just fine, had it's full power.

[davebugs]

I have seen a knock sensor cause this but it's always set a code or a "pending" code.

 

I've never seen a coil or ignitor do this myself. They seem to work all or none of the time - not RPM related.

 

The cats glow red when they are getting too much crap trying to go through them and they plug up. You may have killed the new cats.

 

For cats if you can try this. Start the car up and immediately try and hit the high RPM's clinb a hill, whatever BEFORE they get very hot. COmpare that to how it performs after warmed up.

 

Other than that I think we gotta wait to see what else you find. I'm not sure how you test cats with a vacuum tester. Explain that one to me please. Always interested in learning something new.

 

Alternator is still a possibility - stupid as it sounds. I've been stranded twice with the alternator issue and several folks here have has the same thing happen and an alternator solved the issue.

[Rooster2]

I experienced what you are having with two different cars some time back.

 

On a VW, car just ran badly with no power, and instrument panel gave out crazy display readings. Turned out to be the car battery had a bad cell, so voltage was low. However, I was surprised there was enough battery power to start the engine.

 

Second car had a plugged cat converter with broken cat media, so exhaust flow was terribly restricted. The car would idle just fine, but could not get engine rpm above about 1800 rpm. Top speed was limited to about 45 mph. I could hear the cat converter rattle at an idle, before trouble began. This was telling me that the cat media had broken loose inside the cat, which eventually plugged the exhaust exit at the end of the cat.

 

Hope this info helps!

[joediesel]

It was the catatalytic converter(s)!

 

Davebugs,

My plan to test the restricted cats was based on another post I had read which said the vacuum should drop while holding a constant 1500 RPM if the exhaust is restricted. Also, a few posts back in this thread Nipper had posted a link to http://www.classictruckshop.com/clubs/earlyburbs/projects/vac/uum.htm which gave some diagnostics based on vacuum readouts.

I just jumped online and found this article: http://www.all-catalytic-converters.com/techtip2.html which gives the test procedure:

Another test, using a vacuum gauge, is to measure the engine vacuum at curb idle and at 1600 RPM. If engine vacuum is 21 inches at curb idle and 15 inches at 1600 RPM then there is a good possibility your catalytic converter needs to be replaced.

That article also gave me another test procedure, take out an O2 sensor and run the car.

Sure enough, I popped out an O2 sensor and ran the car down the road and back, it's a little loud but all the power is back.

 

Now I just have to wait for it to cool down and in the morning I'll put the original cats back in the car (yes, I've still been holding on to them since the fall). Since I had removed those thinking they were bad but it was actually the timing belt having jumped a few teeth that caused my problem then I'm guessing they are still good and will be functional. All it'll cost me is about 30 minutes to swap them in.

 

Thanks everyone for the help.

 

Joe

[davebugs]

Thanks for the links to the procedure to in essence test cat blockage with a vacuum check.

 

Well, atleast you do have it diagnosed.

 

Bummer that you ruined new aftermarket cats. I don't know if they'd be returnable and they aren't worth much in scrap (OEM's are).

 

Hope this solves your problem.

[nipper]

Do not get eastern cats, the fail quickly, and i doubt you did anything to kill them. Cats can even handle oil burning.

[MilesFox]

knock sensor

[joediesel]

Final verdict:

I replaced the "new" front cat with the original Subaru cat I had taken out in the fall (@ 170k miles) and it solved the problem. Once I took out the cat I could hear the rattle in it, the interior was completely dislocated and bouncing around in it.

 

Thanks for the help everyone.

Joe

[nipper]

:banana:

[Robert Harik]

:banana:

 

lol