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

[jlevie]

Another though... I believe I've read that being a tooth off in the timing belt "won't cause damage, but it'll run like shit". If the belt jumped a tooth, would it keep power down low and go dead up high?

Timing a tooth or two off will affect operation of the engine noticeably, but it will still run.

[Earendil]

Dropped the entire air box and AFM into my car for a quick test. If anything my car ran better, damnit.

I did notice some moisture in the intake boot. Seemed to be coming from the doohickey on the side (where the coolant lines and valve cover hose meet). Thoughts? No noticeable vapor out te back though, so it couldn't be leaking enough to hurt performance that much?

Compression test numbers are in. My $30 gauge doing a dry test says:
134
135
138
129
130
145

Not pretty, but a 16psi difference top to bottom isn't bad, right?
For quick reference, the Bentley gives 142-156 as spec. I've always read that each cylinder being within a 10% range was more important. Confirmation?
I'm pretty sure these numbers are close (within 5psi) of what try we're last year when it was running good.

Looking and the cap and rotor now. Sorry for any bad typos. I'm using the phone again!

[Ryann]

What did the plugs look like? Do you have a vacuum gauge?

[Earendil]

I don't have a vacuum gauge, or a good way of finding a vacuum leak. All of the wear and tear vacuum leak locations look good, but who knows. I'm starting suspect a massive vacuum leak someplace.

Fuel pressure was solid, so could be Injectors.

What's the operating voltage for these cars? Mine idles at 13.6, 13.4 with lights. This car is idling at 15v, 14.8 with lights. And the bugger is I JUST noticed that the lights are flickering ever so slightly, headlights, but the tiny trunk light as well. Electrical gremlins?

I'm going to try one final thing before I call it a night. I'll toss my plug wires and coil into his car (or vice versa) and see what happens.

[Ryann]

I've started using a vacuum gauge to diagnose weird issues, admittedly with marginal success so far.:)

[Earendil]

Update:

1. I put his plug wires and his coil into my car, and my car pulled really strong with them.
   
2. Tossed a spare ECU into his car, and that also didn't return any of the power.
   
3. Pulled each plug wire one at a time with the engine running. With each plug there was a drop in RPM, with a quick recovery. And when plugging it back in there was a small increase in RPM, with a quick recovery. I take this to mean that each cylinder is doing something. No Cylinder was worse than another.

I think I'm down to the following items:

1. Injectors: Extremely plugged? A bank of them haven't failed I don't think, due to the plug pull test.
   
2. Massive vacuum leak. It's not coming from the boot, valve cover, FPR hose, or throttle body. Many other places it could be though.
   
3. Timing belt skipped a tooth... or two.
   
4. Cap and rotor. I wasn't able to visually inspect this one. The bottom bolt has been sunk so deep into the plastic that I can't get a socket to grab it. The Radiator and fan might need to be removed to get at this bolt...
   
5. Electrical gremlins. I don't like that the headlights and trunk lights flicker their light intensity. The flicker rate increase with engine speed, and becomes almost undetectable (by my eyes) at around 2500rpm. At idle it's about 3-4 times a second.
   
6. On the Electrical note, I haven't checked the ground points. I should check the engine ground point (there is just one, right?) and make sure those poor spark plugs are being grounded properly. Wouldn't it be nice if it were this...

I know less about trouble shooting engine internals. But can I eliminate a busted engine with the compression test, clean oil, clean coolant, clean exhaust, and a good looking top end (under the valve cover) ? I'm really hoping so.

I'm just about to give up on this car and tell my Dad to take it to a mechanic. I just hate admitting defeat when I've done so much! I'll check the ground points before giving up, but I don't think there is an easy way to test the injectors, and I don't have a vacuum gauge or smoke machine. I'm also not interested in doing a timing belt change without a roof over my head.

Gah!

Thanks guys for letting me bounce ideas off you, and for all your input. All I need are a few more tools and I'd feel like I can shakedown 90% of an E30 engine in under a day.

Cheers,
Tyler

[Earendil]

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

Any reason these cheap gauges say they are for carbureted engines? Isn't a vacuum a vacuum? Seems like anything that'll read 0-25 in/Hg will work just fine for the M20.
(FYI: Bentley says normal is 15-22)

[325ix]

You guys are funny with your, "heavy ass ix," comments.

[Axxe]

I had a plugged cat make the car loose a ton of power. Then it blew a whole in the cat (it actually swelled and exploded while red hot). Difficult to check though (plug the exhaust at the tailpipes and see what happens, but you have a leak already so might not do anything).

Another thing to check is the AFM, mainly the internal sliding mechanism, where it makes contact with the board.

[Earendil]

You guys are funny with your, "heavy ass ix," comments.

Aren't I? :)

He has other bits on it that make it a bit heavier still. And my 325i is a stripped out track car, which doesn't help my perception ;-)

I had a plugged cat make the car loose a ton of power. Then it blew a whole in the cat (it actually swelled and exploded while red hot). Difficult to check though (plug the exhaust at the tailpipes and see what happens, but you have a leak already so might not do anything).

Another thing to check is the AFM, mainly the internal sliding mechanism, where it makes contact with the board.

Well, the CAT could be wrecked I suppose. But it's only 3 years old, so if the engine was running okay, it shouldn't have torn its self up in such a short period of time.

Also, the exhaust leak is now fixed.

As for the AFM, I stuck his AFM and airbox in my car and it functions just fine, so I've eliminated the airbox.

Maybe I'll blast the fuel rail where the injectors are with carb cleaner and see if that doesn't make it through the seals. I suppose if every last injector was dumping a bunch of air into each cylinder that could cause this issue, right?

[SpecM]

Try swapping ignition coils

I had similar symptoms and it ended up being the coil

Its worth a try

Sent from my Vortex using Tapatalk

[Earendil]

Try swapping ignition coils

I had similar symptoms and it ended up being the coil

Its worth a try

Sent from my Vortex using Tapatalk

Thanks for the thought. I put his coil AND plugs in my beautifully running E30, and my E30 might have even run a little bit better with his stuff. So I'm ruling those two components out.

[Earendil]

For my own sanity and for those that don't want to read through my long posts, here is the short list of good components. If someone wants to know how I know it's good, they can read above.

Known Good components/passed tests

• Airbox/Filter
• AFM
• Fuel filter & pump (Fuel pressure is great at idle and at speed)
• TPS
• Spark Plugs
• Plug Wires
• Coil
• ECU
• Coolant Temp Sensor
• Compression test good

Good newer components, but unchecked.

• Exhaust system. From exhaust manifold is only 3 years old, including cat.
• New within the last 9 months: Intake boot, Throttle body to intake manifold gasket, Valve cover to TB hose, line to FPR, and valve cover gasket.

Out of all of this, I have only found a couple suspect issues, but I don't think they could cause this issue?

• Operating Voltage at idle is 15v (14.5 is spec). I'll have create a hack to test the operating voltage while driving.
• Looks like a small coolant leak into the TB

Left to check before I give up and have a mechanic do things only they can do, or are willing to do.

• Ground Points
• Harmonic Balancer and toothed gear are okay (I read if they start to separate that they will give bad readings at high RPM to the crank position sensor).
• System Voltage during operation (driving)
• Vacuum test (if people think a cheap gauge is worth anything).

Last but not least, if I were a betting man I suppose I would place money on it being one of the following:

• Giant vacuum leak
• Multiple clogged injectors
• Cap and Rotor (which I can't check, see previous post)
• Electrical Gremlins preventing a good spark
• Timing belt having jumped a tooth

[jlevie]

The system voltage at idle (way too high) and the flickering lights suggest a bad voltage regulator.

Several small intake leaks scattered around the engine can add up to a major leak. Small leaks, especially those distant from the head, may escape detection by a visual check or by spraying carb cleaner around. But a smoke test of the intake & crank case will find them every time.

It takes maybe a half hour, at most, to check cam timing. That and the smoke test should be the number two and three priorities with the alternator being number one. Excessively high system voltage can damage the car's electronics.

[Earendil]

I sort of assumed it was "Gremlins", but I've spent the last 15 minutes reading up on voltage regulator problems, and high voltage (not just low) is a symptom! Now there is a repair I know how to do! :)

Now about "checking the timing". The only way I know how to do this is to check the TDC marks on the crank and cam shafts, and that isn't a half hour job if I recall. Is there an alternate way?

And smoke tests... That'll be purely in the realm of a mechanic with the equipment.