Loss of Power

[GsX2gDsM]

Recently my 1990 gsx has been losing power every now and then. When I am at full throttle at any rpm there is this weird sound that my exhuast makes, kinda like a fluttering sound mixed in with the normal exhaust sound. It does this randomly but more and more recently. I took it around the block today and went up a slightly inclined hill, first through third all through the powerband, car seemed perfectly fine, plenty of power. When I started going up the slightly steeper hill to my house I started losing power, turbo was spooling fine but the weird exhaust sound started and the rpms just didn't up as fast as normal. I haven't done a boost leak test yet, don't have an air compressor, but could that possibly be a problem? I don't think its an exhaust leak because I don't see any exhuast coming out before the turbo in the engine bay when I rev. I do burn a good amount of oil but my symptoms are that of bad valve seals, blue exhaust only at a stop when I press on the gas. Could the seals be causing the power loss? Only mods are removed exhaust after cat and k&n filter.

 

[Abbadon]

sounds to me that your bov maybe leaking or maybe not closing all the way. I would trying checking that first.

Tyrel

 

[oldman]

Completing your profile so we know what mods you have would be helpful.

 

[leet]

sounds to me that your bov maybe leaking or maybe not closing all the way. I would trying checking that first.

Tyrel

Horus says your sig violates the rules.

Horus says to go read the rules.

 

[jmadison]

Your plugs could be fouled. Pull em and check what color they are white=too lean black=too rich. I had that same problem changed my plugs to some NGK's and no more fluttering at WOT. Good luck

 

[GsX2gDsM]

updated my profile, ill take a look at my plugs and see if my bov is leaking. thanks for the help so far guys.

 

[GsX2gDsM]

ok, i just took a look at my bov. at idle it is slightly open maybe half a centimeter, i can feel air coming out of it. then when i press on the throttle it closes until i let off when it opens all the way to release the pressure. is it normal for the bov to be partially open at idle? WTF

 

[Reese92tsi]

This sounds like a spark issue. Replace plugs and wires, if new plugs and wires fail to correct this problem you might have to do an ignition system rebuild (new coil pack & power transistor). Also check your ecu for any capacitor leakage. Its also normal for a stock bov to be slightly open at idle.

 

[GsX2gDsM]

Ok, I replaced the plugs with new standard ngk's. The old plugs did have some deposits on them and some weird discoloring on the white parts of two of em. Not sure if its due to fuel additives that the previous owner put in or what. With the new plugs the car ran MUCH better, no more fluttering at WOT. Felt like I had gained atleast 5-10 more horsepower. Here's a pic of the old plugs:

http://i8.photobucket.com/albums/a33/93egboi/100_1408.jpg

 

[GsX2gDsM]

Took my car on the freeway today and downshifted a couple times taking it to about 6500-7000 rpms. The exhaust still flutters above 5000-5500 rpms accompanyed by a significant loss in power all the way to redline. I should be getting some ngk wires sometime this week, so hopefully that fixes the problem. I'm still not sure what the two brownish rings on two of the spark plugs are from. arching possibly from the wires? anyone know?

 

[GsX2gDsM]

I installed the ngk wires and still have the same problem. About how much are we lookin at for a new coil pack and power transistor? And if those don't solve the problem what else could possibly be the cause?

 

[oldman]

1. Recirculate that BOV.

2. How much psi are you boosting? RPM @ full spool?

3. Have you done a boost leak test yet? hint hint....

 

[destruckeclipse]

1. Recirculate that BOV.

2. How much psi are you boosting? RPM @ full spool?

3. Have you done a boost leak test yet? hint hint....

These would be the first things to try. I had a similar problem and it was a boost leak, easy fix.

 

[tsidrift1]

I think I have a similar problem. My car gets that nasty sound from the exhaust too. It alost sounds like something is flapping back there. My power loss is at three thousand rpms. After three thousand is hit it runs like something is holding it back. I dont have to even get on it it just does that driving normally. I have got a fmic with 2.5" aluminum pipes with no leaks. I have replaced the coil, plugs and wires and still no change.

 

[oldman]

I have got a fmic with 2.5" aluminum pipes with no leaks.

And how did you know this? If you didn't find this out through a boost leak test, I would suggest doing so. I have yet to meet a person who had absolutely no leaks after a fmic/pipping install.

I had a similar problem and it was a boost leak, easy fix.

You have a N/T.

 

[95dsmracer95]

even though mine is a RS, It was my spark plugs first, and now its my distro. block melt down.

 

[Kapok6]

my friend had a similar sounding problem w/ his 95gsx, replaced the plug wires, problem is gone.

 

[tsidrift1]

And how did you know this? If you didn't find this out through a boost leak test, I would suggest doing so. I have yet to meet a person who had absolutely no leaks after a fmic/pipping install.


You have a N/T.

I tested all the pipes with a tester at 20lbs and had no leaks.

 

[GsX2gDsM]

Tommorrow I'm gonna do a boost leak test and install my turbotimer/boost gauge so I can let you know how much psi I'm running and how it varies throughout the rpms. I'll let you know how it goes.

 

[kgtalon95]

And how did you know this? If you didn't find this out through a boost leak test, I would suggest doing so. I have yet to meet a person who had absolutely no leaks after a fmic/pipping install.


Hi, I'm kgtalon95.....I did my fmic install w/ pipes with no boost leaks



Granted I used t-bolt clamps and 4ply silicone, but you didn't ask how

If plugs and wires don't work and the other tests Oldman suggested I'd do a compression test just to see whats up. It sounds like your lossing power when you're under alot of load, uphills downshifting and such. Besides that and knowing your compression is always a good thing.

Sorry my quote didn't work........i'm lame

 

[oldman]

Hi, I'm kgtalon95.....I did my fmic install w/ pipes with no boost leaks

Nice to meet you, you lucky bastard.

 

[GsX2gDsM]

Did a boost leak test today at 20psi and it went perfectly. No leaks what so ever except for a teeny tiny one on one of the egr vacuum hoses, barely noticeable. Since a boost leak could not be my problem I took the car to a local shop and had them diagnose it with a datalogger. Took it around the block and found out that my engine timing is being retarded due to knock. They took a look at the knock sensor and said it was fine for now, barely leaking, and would need to be replaced in about 10,000 miles. They said it was probably carbon deposits on my piston heads causing the knock. Could carbon deposits really be the cause of my knock issue because I always run 92 octane and even put in racing octane boost which didn't seem to help?

 

[GsX2gDsM]

oh btw also installed my turbo timer/boost gauge. full spool at about 3.5k-4k rpms at about .90kpa, when knock occurs it lowers to about .85-.82.

 

[GsX2gDsM]

well i guess my car is knocking becuase im spiking to 17.5 psi on a pretty much stock everything . my blitz turbotimer/boost gauge was off by like half a bar.. although im not quite sure why i have never hit fuel cut?

 

[sweet97]

Go to the dealer and get a can of Mopar Combustion Chamber Cleaner. Instructions are on the csan. It will clean the deposits that could be causing the preignition/knock. Mark
PS: Check the base timing as it soundslike you have not hadthis car very long, running on plugs that the previousn owner had. Change that stuff when you buy a car!