Better Explained Situation

[blackrosenova40]

So my engines seems to act scary at 4000 Rpm, gets really loud, and seems to be weak. and I have always been scared to push it past that. Well tonight I finally decided screw it and so I brought it past 4000 rpm.

Idle to 3800 Perfect!

3800-4200 really weak and really noisy

4200-6600 somewhat weak , but smoother than 3800-4200, but not as smooth as it should be

6600 on up nothing just no power

Is this a vaccum/ boost leak? and I have just not been able to find it?

My Air/fuel gauge reads perfect across idle to 6600 and my boost holds at 10 pounds perfectly.

Ps. My engine did this exact same thing when I had a bad turbo (no boost).

 

[MyBeatGSX]

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How's the regular stuff, plugs, wires, fuel filter etc? What do you mean the engine gets louder and noisey? What does louder sound like? Bad noises or just loud exhaust noise?

I don't think any car running a T25 has power after 6,600. So that's normal. When did it start doing it? Could it be related to anything or anything you did?

 

[blackrosenova40]

Sorry I have a 1990 Gsx which is a 14b turbo

Everything is bone stock

I have new wires, new plugs, new fuel filter, fuel pressure gauge, running 92 octane.

I have checked ignition timing and cam timing they are correct.

And after 6600 I mean it just seems dead dead , blah, it dont wanna go any further.

I hate describing noises on the internet but the noises are coming from the engine, engine also seems to make mad vibration. And yes it definitaly is a bad noise. I will have to record it and post it as a video somehow.

 

[Marc91GSX]

Sorry I have a 1990 Gsx which is a 14b turbo

Everything is bone stock

I have new wires, new plugs, new fuel filter, fuel pressure gauge, running 92 octane.

I have checked ignition timing and cam timing they are correct.

And after 6600 I mean it just seems dead dead , blah, it dont wanna go any further.

I hate describing noises on the internet but the noises are coming from the engine, engine also seems to make mad vibration. And yes it definitaly is a bad noise. I will have to record it and post it as a video somehow.

Does the engine only make the noise under a load or does it also make that noise with the clutch in? Also, Where is the noise coming from? Is it valvetrain or rotating assembly? With the bad vibration it sounds like it is something internal but it could also be surging from a bad tune. It could just be bucking when you come into boost because of bad fuel trims whcih could be the result of defective sensors or injectors.

 

[blackrosenova40]

I had mentioned it does this with boost or no boost. Load or no load. I cant tell where the noise is coming from but from the engine.

The engine seems to make a high vibration not a bucking vibration.

It also does this whether I have the clutch engaged or disengaged.

My car idles perfect, pulls 20 inches of vacuum when warm.

One goofy thing however , sometimes after I drive it and its fully warm and I stop it for a while, come back and start it the idle is very sparatic and sometimes kills during idle, until I drive off with it then it will idle fine.

 

[Ultimatedsm]

I recommend doing a compression test before you attempt anything. Give us the results. It could be your balance shafts could be broken which will cause alot of vibration, however, usually that takes out the timing belt but anything is possible right.

1. Boost Leak Test. If problem exists after this go to (2).
2. Compression Test. If passes go to (3).
3. Inspect balance shafts and check timing belt marks if they are aligned.

If your timing belt skipped a tooth, it will cause poor performance and vibration as well. So lets do the easy stuff first. Anyway, give us the results after these tests and inspections.

- Ultimatedsm

 

[Marc91GSX]

Well it sounds like you are having some sort internal engine problem. The only thing I can suggest right now is to pull your oil filter and cut it in half. Take a look at the media element and see what type of metal you have in there. If there is alot of non magnetic metal in there then your problem is probably in your bearings. What is your oil pressure? Also have you pulled your front cover and inspected your Balance shaft belt? If it is out of time with the rest of the engine it could also cause a bad internal vibration but it really would not affect performance.

 

[blackrosenova40]

I have checked compresion, its around this

Cyl #1 163
#2 160
#3 158
#4 155

I have also checked ignition and cam timing as well, they are both right on the money.

Oil pressure is normal.

 

[Marc91GSX]

What kind of A/F gauge are you using? Only trust a WB 02 for any A/F readings. Also do you have a logger? If so what are your logs saying while this is happening. We can check off your ignition timing, plugs, wires, compression, and transmission. Now we need to narrow it down some more. Like I said earlier check you BS belt if your balance shafts are still installed, cut your oil filter and inspect its filter element for metal shavings (if excessive amount then drop pan and inspect bearings), locate the location the sound is originating from ( the only way to get this accurately is with a stethoscope), and most improtantly get some logs. If this problem is electronic or fuel related it will show up in a log, if it does not show up in a log then it is more than likely a mechanical problem.

 

[blackrosenova40]

I always have thought the whole engine got noisy but today I decided maybe to pinpoint better what the noise is and the loud noise at around 4000 rpm is coming from under the timing belt cover.

It sorta sounds like a loud vaccum cleaner thats past its prime.

 

[MyBeatGSX]

You said timing was right on, but how was the belt? Could it be stretching at higher rpm and throwing the timing off? Could the belt be rubbing on something. Maybe the balance shaft belt came apart like everyone else suggested and its stuck down in there rubbing on a pulley or the timing belt. This is definately a strange one....

One goofy thing however , sometimes after I drive it and its fully warm and I stop it for a while, come back and start it the idle is very sparatic and sometimes kills during idle, until I drive off with it then it will idle fine.

You and half the DSM world (including me) have this problem. Its most likely unrelated so I wouldn't worry about it. If I remember correctly there's a VFAQ on it. If you ever figure it out though, let me know.