[BeyondBiscuits2]

See what this sounds like to all you force induction savvy members out there.

Setup:
GA16DE
259cc injectors
S-AFC 2
SR20DET T25 turbo

Yesterday, when I drove to work, my car felt rather sluggish. So, on the way home, I tried to bring it back to life by getting on boost. Normally, around 26% throttle or so, my T25 spools up to 5 lbs in 2nd gear, and then creeps up to 8 lbs fairly quickly. Yesterday, it took until nearly 3800-4000 rpm to reach 5 lbs of boost, when it is pretty much normally instantaneous. It was almost impossible to get 8 lbs (it took a 2nd to 4th gear pull to hit it).

So, when I did get home, I decided to check out everything I thought it could be. I let the engine cool down, and checked the spark plugs first of all for signs of leaning out or detonation. The plugs themselves were a slight bit white, but that was from when we first tuned the car and didn't have the air/fuel mixture correct. No signs of detonation or impact. Next, I allowed the car to heat up, and then used the soapy water technique to test for boost leaks (my next thought). No leaks were discovered!

This only started happening yesterday! The turbo sounds fine, spools up with no problems (you can hear it and no unusual noises from it), doesn't leak any oil, and no oil out the exhaust or white smoke. I am going to do a compression check this afternoon, but I seriously doubt my head gasket is gone (the car runs acceptable without boost just sluggish). I am going to change out the spark plugs anyway, as well as remove the inlet to the turbo and check for shaft play. My friend (who has quite a lot of turbo experience) thinks that it is just bad gas (I run 93 octane), since I filled up on Saturday and this started Monday (I didn't drive the car on Sunday). I put in some octane booster last night, and it did seem to help initial response. Any ideas????

 

[BeyondBiscuits2]

Update:

I removed the intake to the compressor housing, and checked the T25 for shaft play or damage. There is a very slight bit, but it was there when I installed the turbo to begin with, and I don't think it has increased.

My mother has also been complaining about her car (2003 Mercedes-Benz C230 Kompressor w/h supercharger) being sluggish over the last week. I think perhaps my town got a bad batch of 93 octane fuel or something. I know when I filled up, I was more than likely scrounging the bottom of the tank (the pump was incredibly slow in pumping). Could this explain all my problems... bad gas causing bad combustion? Can I correct this by increasing my fuel ratio, or just dumping a whole lot of gas treatment in my tank?

 

[turbo200sx007]

Update:

I removed the intake to the compressor housing, and checked the T25 for shaft play or damage. There is a very slight bit, but it was there when I installed the turbo to begin with, and I don't think it has increased.

My mother has also been complaining about her car (2003 Mercedes-Benz C230 Kompressor w/h supercharger) being sluggish over the last week. I think perhaps my town got a bad batch of 93 octane fuel or something. I know when I filled up, I was more than likely scrounging the bottom of the tank (the pump was incredibly slow in pumping). Could this explain all my problems... bad gas causing bad combustion? Can I correct this by increasing my fuel ratio, or just dumping a whole lot of gas treatment in my tank?

never put gas treatment shit into ur car, just dump the tank or drive it til it runs out not going to hurt anything, then change out the fuel filter. are u just runnin a safc?

 

[dburone]

Any exhaust leak?
I think your injectors are to small, my 370cc are close to the limit on 10-12 psi

 

[BeyondBiscuits2]

I have a slight exhaust leak between the turbo elbow and downflow pipe, but nothing major. Also, the 259cc injectors are fine for my current setup. We tuned everything using a wideband and S-AFC 2, and the car runs perfect under boost (normally) without leaning out at all. I do not plan on pushing over 10 lbs of boost, so I think the 259cc injectors should hold up fine.

I changed out my spark plugs this evening, and response once again seemed to increase again with the turbo hitting 6 lbs now. We also thought perhaps it could be the wastegate sticking open or malfunctioning, so I ran a boost controller I borrowed for the evening. The result was the same, even with the wastegate essentially completely bypassed it only hit 6 lbs of boost under a full load. On Thursday, we are going to pressure test the system to check for any boost leaks again. I am currently almost to a 1/4 tank of fuel, so I am hoping I'll burn all this junk out soon!

Before we pressure test the system on Thursday, we are also going to check ignition timing and run the wideband again to make sure everything is still running correctly. We theorised that my ECU has backed off timing due to the poor quality of fuel and this is causing my turbo to not reach the 8 lbs. Also, we did a compression check on all 4 cylinders and it is perfect across the board, no blown head gasket.

 

[BeyondBiscuits2]

Update:

My car started smoking oil on the way home from work this morning. I think the turbo is on its way out . I'll confirm it when I pull the spark plugs and check for oil residue (there shouldn't be any). Most likely it is just the seals... the turbo still boosts alright though it does feel a bit sluggish. My engine oil level hasn't dropped significantly, so I figure my engine is still fine... just the turbo. Anybody have a T25g turbo laying around they want to sell?

 

[dburone]

The sparks dont shouldnt have any oil because of the turbo, The turbo is after the engine and the oil goes to the exhaust and burns.
If you have a leak in the compresor housing you should se oil easily in all the pipes.
Also if youre turbo loses Oil youre engine oil WILL go under the level, its the same oil for both things!

 

[BeyondBiscuits2]

I was talking about oil on the spark plugs from an engine problem (i.e. bad rings, etc.) not in regards to the turbo. The piping from the compressor housing to throttle body is clean, and surprisingly, the exhaust elbow from the turbo is clean too. While I was disassembling things, I did notice a kink in the oil drain line, and I have since replaced the line. Perhaps oil backing up into the turbo coming off boost caused my problem. The blue smoke from my exhaust was barely noticeable, I only saw it because I left my car idling in my driveway and ran into the garage (I had just come down off boost about 2 minutes prior). When driving, you cannot even see it. This afternoon, my friend and I are going to put a restrictor into the oil feed line, and see if this helps any.

 

[BeyondBiscuits2]

An oil restrictor did the trick! My car only pops a puff of blue smoke when shifting under full boost. Unfortunately, I am still unable to achieve 8 lbs again... this boost leak lingers on and on.

 

[dburone]

Do you have an IC?