Car too weak to redline in 1st, but idles fine. Wtf?

[Ryann]

While on the subject of vacuum gauges, what are the chances that a gauge like this would give me any kind of useful results?

^That would work just fine.

It'd kill me to see you give up at this point dude! You're doing it right.

I've managed to find hidden vacuum leaks quickly and cheaply by taking a car to my local DIY car wash using the water wand to mist the engine with low (low!) pressure.

Oh, and when you did the compression test did the plugs look like you have a lean running condition?

[Earendil]

^That would work just fine.

It'd kill me to see you give up at this point dude! You're doing it right.

Thanks for the vote of confidence. I went ahead and ordered that gauge. It's cheap enough that if it's a throw away gauge, I'll just have some rather expensive rubber tubing.

I've managed to find hidden vacuum leaks quickly and cheaply by taking a car to my local DIY car wash using the water wand to mist the engine with low (low!) pressure.

The last time I sprayed an engine compartment I was like 12, and when cleaning my Dad's car by myself I decided his engine compartment was dirty too. Now ask me how I know what an M20 running on 2 cylinders sounds like ;-)

Oh, and when you did the compression test did the plugs look like you have a lean running condition?

The plugs all looked very similar, and looked somewhere between lean and normal. The dramatic power loss has only been in affect for 30 miles if that.

New clue, that I had suspected:
Last night my friend decided to try and get it from his work (where I've been working on it) to his house. I followed him to keep an eye on it. I watched as he floored 2nd gear trying to make it up a hill, and I tailed him at varying distances. No smell of gas. No smell of anything. No water/oil vapor/smoke. I'm leaning more and more towards vacuum leak or injector malfunction of some kind. The plugs don't look rich, and there is fuel coming out the exhaust.

After making my posts last night, I got too excited and drove out to the car to see about the voltage regulator. I had half a mind to toss the regulator from my car into his just to see what would happen, since I can pull my regulator in probably 2 minutes. I take a look at his Alternator and it has a back cover and no exposed regulator. @#$%. The only thing I can read on it says "Made in France". I couldn't see a brand. Looks like I may have to remove the entire alternator just to figure out what I'm up against here.

I took it for a test drive with the help of my brother. The voltage at idle was 15v, and while driving it varied from 14.55 to 14.9. No as dramatic and mind blowing as I was hoping.

I also checked out his very good looking engine ground strap. I cleaned it up anyway, but that had no effect.

I'd be so very happy if the Vacuum gauge shows me something conclusive one way or the other...

[603Racing]

There are different alternators. There's the Bosch with the voltage regulator right there on the back, easy as pie. Then there's the Valeo that you have to open up to get the regulator out, which may be what's on there.

Sorry to bring up the possibility of the cam again, but did you feel the cam lobes when you checked it out? Also did you very closely inspect the nose of the lobes? The nose is the smaller (a.k.a. lift) side of the lobe. I ask because in the case I saw that has the exact same symptoms you describe (minus the voltage stuff) the nose of the cam was worn down enough to cause the valves to not open as far as they should. They were also open for less duration. His car would not rev past about 4k in any gear.

I hope it's just the voltage regulator! Keep on keepin' on, you have to be close to the solution!

[Earendil]

There are different alternators. There's the Bosch with the voltage regulator right there on the back, easy as pie. Then there's the Valeo that you have to open up to get the regulator out, which may be what's on there.

Thanks! I looked up pictures of the Valeo unit and I'm positive that's what's in his car. We'll end up replacing the regulator, even if it isn't the root cause, there really is no point in risking losing an alternator in the kinds of places the ix gets its self into this time of year ;)

Sorry to bring up the possibility of the cam again, but did you feel the cam lobes when you checked it out? Also did you very closely inspect the nose of the lobes? The nose is the smaller (a.k.a. lift) side of the lobe. I ask because in the case I saw that has the exact same symptoms you describe (minus the voltage stuff) the nose of the cam was worn down enough to cause the valves to not open as far as they should. They were also open for less duration. His car would not rev past about 4k in any gear.

No problem bring it up again. I did not check think to check how worn the lobes were when I had the valve cover off, I was mostly looking for broken pieces, or out of place pieces. The car was running fine one day, and the next the power curve tanked. Without knowing from experience how lobes fail, sudden changes in the power do not seem likely with lobe wear? Also, wouldn't basically all 6 or close to all 6 cylinders have to wear down quickly all at the same time? Even if two cylinder was experiencing a problem it wouldn't prevent the car from reaching red line, right?

[Earendil]

Pulled the voltage regulator tonight. I'm really not sure how it was operational with that regulator... It was so shot.
New one comes Friday, along with the vacuum gauge. More to come Friday!

[kojack]

Had a car that had the same sort of problems after the cat fell apart and clogged itself. I'd try popping the exhaust tubing off the headers starting it and seeing if that clears things up.

[EthirtyIS]

My thoughts would be the cam, which really can't be checked unless it's removed and mic'd.
The injectors, which would also have to be removed. But I would see if you could ohm them out while on the car.
And the cat, which is the easiest. Just remove the cat section of the exhaust and take it for a ride, carefully.
If you would like a set of injectors let me know I have a stock set I'll let go dirt cheap to help your cause, and I also have a set of 19lbs if your friend is interested.
Good luck with your hunting....

[Earendil]

My thoughts would be the cam, which really can't be checked unless it's removed and mic'd.

Yeah, I don't have the tools to check it, or the motivation to remove another cam. I did that once on my car, which was fine for the educational experience. Out of curiosity, what would happen with the cams? Would they become less than straight, causing increased/decreased travel on some valves?

And the cat, which is the easiest. Just remove the cat section of the exhaust and take it for a ride, carefully.

Sadly, the exhaust manifold to header connection lost one of the 6 bolts, and popped loose at about the same time. In an attempt to get the car back to a place where I could test the engine, I slapped some liquid exhaust gasket shit from NAPA on it, added a nut, and sealed it back up. The patch was only meant to hold until I could get a proper gasket in there. But I fear that just "popping it off" is going to require sanding some of that junk off before applying more or adding an OEM gasket.

Also, the last time I ran my personal car with the header off, my car was loud as @#$%. Like scary loud. I can't imagine actually driving it with it sounding like that? I don't think there is an unwelded connection between the exhaust manifold and the cat, but I'll double check.

The injectors, which would also have to be removed. But I would see if you could ohm them out while on the car.

If you would like a set of injectors let me know I have a stock set I'll let go dirt cheap to help your cause, and I also have a set of 19lbs if your friend is interested.
Good luck with your hunting....

Yeah, I'll see if I can't ohm check the injectors. I think this should be possible without removing the intake. Awful kind of you to offer the OEM injectors. PM coming.

[hpde30]

ITS YOUR CAT!

ive seen it mentioned half a dozen times but you keep dismising it. you say you're an engineer, so look at this problem like one. the engine is just an o2pump, it lets air in and it lets it out. in the process of doing that it uses the air to burn fuel. fuel makes the power! If you aren't making power then you aren't burning fuel or getting air in/out of the motor.

You said you switched intakes/maf ect and there was no change, so it sounds like the motor is getting enough o2. You said it drives and idles fine at anything other than WOT, which sounds like you're getting enough fuel. All signs point to exhaust not being able to get out. Its also one of the few things you haven't checked/confirmed.

I know you said its hard to take the exhaust apart, but I think you're going to have to bite the bullet and get it done if you want to fix the car.

[hpde30]

just thinking out loud here, but I wouldn't be surprised if your pre-cat exhaust issues were a result of excess back pressure due to the cat being clogged.

[Earendil]

I have not dismissed the Cat idea, but I have focused on other things do first because the ENTIRE exhaust system is only 2-3 years old. Also, when the exhaust blew out, the driver said it lost even more power. Now if it were a blocked cat, wouldn't blowing a hole pre-cat only help it? Lastly, the hole pre-cat was mostly assisted by a missing bolt, and 2 incorrect ones (small, non-locking). I like to think my engineering prows are not completely off to check for a vacuum leak (easy) before checking the cat (difficult).

So first things first, get the car running at the right voltage, and then we'll see about moving the car to a location where we can run the engine at high RPM without the cat and muffler. It's currently sitting at my friends work, and it wouldn't be good for business to do it there :)

[603Racing]

I missed the part where it did this all at once. A worn cam can happen quickly if there are oiling problems or valves out of adjustment, but not all at once.

Following HPDE's logic, worn cams wouls reduce air movement by not allowing the valves to open properly. A broken cam would make noise.

A bad cat could certainly cause what you're seeing. If the regulator doesn't fix it you need to disconnect the exhaust from the manifold and drive it.

[Earendil]

I missed the part where it did this all at once. A worn cam can happen quickly if there are oiling problems or valves out of adjustment, but not all at once.

Following HPDE's logic, worn cams wouls reduce air movement by not allowing the valves to open properly. A broken cam would make noise.

A bad cat could certainly cause what you're seeing. If the regulator doesn't fix it you need to disconnect the exhaust from the manifold and drive it.

Agreed. I still may be looking at a two part problem though. Assuming the PO wasn't lying to me, and the CAT isn't old, then something must have caused the CAT to fail at such a young age, yes? I'll try and take a look under the car when I see it next, see if I can determine how "new" the CAT is. Those things are usually so beat to shit and dirty after a few miles that it's hard to tell :(
Hopefully I'll see a quick disconnect point as well. Daytime highers are being weird and actually reaching up into the low 40's, and we haven't had any snow yet. This time last year we had a couple feet... This should make me more likely to actually spend some time outside the car wrenching :)

[Ryann]

Pull the o2 sensor! The open hole should let out enough exhaust pressure to make a difference if you've got a plugged up exhaust.

[Earendil]

Pull the o2 sensor! The open hole should let out enough exhaust pressure to make a difference if you've got a plugged up exhaust.

And that sir shall be my next test.
New voltage regulator in, and the car is holding steady at a more sane 14.1v. However this had no noticeable effect in the engine. I attached the vacuum gauge and got a wavering reading from 11-14 on intervals of about 2 seconds, so not likely a per cylinder issue, right?


So that's low, when my own E30 idles at 16. If I add a little throttle it'll start to climb to about 17hg around 2000rpm, but at 3000rpm and my foot near the floor, the vacuum went to zero and stayed there.

I'll have better test tonight, when all the traffic on the roads clears out a bit. I can't for example tell you if the pressure was responding to the throttle position, or the RPM.

Looking more like a plugged cat all the time, aye?

I think we can rule out injectors now.

If pulling the O2 sensor does nothing, I'll make jlevie happy and go get a smoke test. I'm not going to advise my friend do that though until I'm relatively sure that's the issue.