New Big T28, trouble after install?

[Trigger Jack]

Went in this weekend, had an AGP Big T28 installed (though it may have been a t25, who knows...it looks exactly like my t25, including double fins etc....though the inner diameter was larger for the new one). Anyway.....after a few hours, the car is running absolutely great now. Good, considering the old turbo had the compressor wheel clipping the housing, apparently. Never knew. However, I've now noticed a few things. I have an A/F gauge, and while I know it's not much more than a pretty light show, it's now acting completely different. I start the car, I get one led, and then it basically turns off. Every once in a while (maybe once an hour), it'll flicker around stoich, then go back to sleep. Doesn't matter if I'm idle, full throttle, etc. Also, I'm only running about 9psi right now, because the shop didn't have my MBC in yet. I figured 9psi is fine to just give it a test run for a few days. Also, car seems to be idling a little oddly now. Lower rpm than normal, I think. Might be my imagination, but I'm just wondering if anyone else has experienced symptoms like this, and could point me towards what it is. I'm thinking it could be the O2 sensor, which would explain the wacky readings on the A/F. Performance is fine, pulls great....still spools up at 2,500 rpms (thought the big t28 spooled faster?), but holds it all the way, where my last turbo would start to die off at about 4,800, losing boost until i shifted. I really don't want to believe that i could be running so lean that it wouldn't register....and the car doesn't act like that anyway. Any suggestions/ideas would be great.

 

[noz]

Went in this weekend, had an AGP Big T28 installed (though it may have been a t25, who knows...it looks exactly like my t25, including double fins etc....though the inner diameter was larger for the new one). Anyway.....after a few hours, the car is running absolutely great now. Good, considering the old turbo had the compressor wheel clipping the housing, apparently. Never knew. However, I've now noticed a few things. I have an A/F gauge, and while I know it's not much more than a pretty light show, it's now acting completely different. I start the car, I get one led, and then it basically turns off. Every once in a while (maybe once an hour), it'll flicker around stoich, then go back to sleep. Doesn't matter if I'm idle, full throttle, etc. Also, I'm only running about 9psi right now, because the shop didn't have my MBC in yet. I figured 9psi is fine to just give it a test run for a few days. Also, car seems to be idling a little oddly now. Lower rpm than normal, I think. Might be my imagination, but I'm just wondering if anyone else has experienced symptoms like this, and could point me towards what it is. I'm thinking it could be the O2 sensor, which would explain the wacky readings on the A/F. Performance is fine, pulls great....still spools up at 2,500 rpms (thought the big t28 spooled faster?), but holds it all the way, where my last turbo would start to die off at about 4,800, losing boost until i shifted. I really don't want to believe that i could be running so lean that it wouldn't register....and the car doesn't act like that anyway. Any suggestions/ideas would be great.

hey my t25 can hold boost 9lbs all the way to redline too

 

[Trigger Jack]

Well, mine sure didn't, . Not really worried with how the turbo is working, just the rest of it....

 

[TSiBER RYDER]

check to make sure you have no exhaust leaks off the manifold.

 

[98FWDSM]

when i installed my bigt28 i was a dummy and reused that little metal circular gasket type thing that goes half way into the exhaust manifold and halfway into the exhaust side of the turbo....it took about 3 or 4 months but the turbo eventually sucked it way down in there and i couldnt boost above 9 either...i wasnt having any problem with the idle though...hope this helps

 

[Trigger Jack]

Hmm. The manager told me all new gaskets were used for the install, but it might still have something to do with that, or a bad fitting, to create a leak. Going to give them a call tomorrow and have them take a look at it. Just trying to get a better idea of what I might be trying to hunt down. Won't be able to take it in, they close the same time I get released from work, but I'll also do a boost leak test, see if that helps narrow it down.... Appreciate the ideas, fellas, let me know if there's any others i can look into while i'm at it.

 

[Trigger Jack]

Talked to the manager of the shop (Drift Tech of Oceanside Cali, if anyone was curious at all), and ran the whole scenario by him. Basically advised me to get a tune up done, since I was due anyway, and to take a look at the sparkplugs. Also told me that nothing they did should have any effect on my a/f ratio, or the gauge acting screwy, said it might be that dsms have a tendency to arc between coils or something like that. Bad cell reception, didn't hear all of it. He had also taken apart the t28 to inspect it before it went on, and confirmed it was a Big T28, so I didn't install something thinking it was something else. Very cool guys at this place. Since there's no engine lights, no drop in performance, no smoke or anything else...going to still give it a pressure test, tune up, see if that helps any. I'll post my findings after the test/tune up, just in case anyone else ever runs into something like this.

 

[Trigger Jack]

Would still like some input if anyone might know why the gauge has gone wacky, though. Going to yank it out this weekend, get a logger and see what's really going on, but in the meantime......

 

[boostvr4]

The shop must have messed the o2 sensor up. I've done it. Maybe unplug the o2 sensor and see if it does the same thing?

 

[Trigger Jack]

Well, messed with the o2 sensor today, got new sparkplugs, oil change, etc and so forth. Here's what we found. I am currently achieving about 5-6 miles to the gallon. Yep. FIVE or SIX mpg. I can go from home to work and watch my gas gauge drop, it's quite impressive. The sparkplugs are confusing. They're not white, they're not black. Instead, they are striped. Black, white, black, on each one. As far as we can ascertain, my car is convinced that i'm so incredibly lean, that i need to dump as much fuel as possible into the engine. Oh, and we did figure out one thing, which i should have thought of, and i'm somewhat disappointed no one else did.....with a new turbo install, it changes the settings for things...so the ecu needs to be reset, generally. We hadn't done this, so the ecu still thought it was a t25 it was using. The extra airflow, therefore, would goof things up. Unfortunately, even resetting the ecu gave us nothing. The only change was marginal, and that was my idle going back to normal. Also, nothing seemed wrong with the o2 sensor. Tomorrow, the manager is going to be taking a look, since I exhausted the knowledge of the mechanic that was there today. Wife gets to handle that though, since I'll be working.

 

[boostvr4]

Oh, and we did figure out one thing, which i should have thought of, and i'm somewhat disappointed no one else did.....with a new turbo install, it changes the settings for things...so the ecu needs to be reset, generally. We hadn't done this, so the ecu still thought it was a t25 it was using. The extra airflow, therefore, would goof things up. Unfortunately, even resetting the ecu gave us nothing..

Maybe that’s why nobody told you to do it? The ECU doesn’t work one set way unless you reset it. It is constantly making changes because of air flow, temp, coolant temp, barometric pressure, timing, knock, ect... the o2 sensor can me bad without looking like it is. You should be able to know this because your gauge isn’t doing anything. This will also cause your bad gas mileage.

 

[jtmcinder]

All of this points to the O2 sensor. Maybe it was unplugged for the install? Maybe it was bashed during the install? Maybe something was dislodged and trashed it? In any event, 5 mpg and no cycling (once warmed up) implies the O2 sensor.

Stop thinking about the turbo, itself. The ECU has no idea and couldn't give a rat's tush what turbo you have. All it "sees" is air. And at 9 psi, it sure as heck isn't seeing any more air than before.

- Jtoby

 

[Trigger Jack]

Wife took in the car today.....and after 30 minutes of computer logging....my a/f is correct...both at the sensor and at the ecu. The o2 sensor is working perfectly fine. The error is occuring from my boost gauge being tapped into the hose that connects to my fuel regulator solenoid. That I installed. I don't mind if someone laughs, because all I did was follow the directions exactly as detailed on the RRE page. Both mechanics I talked to at Drift Tech (after they got done telling me i was a retard...in not so many words) said it was basically a horrible place to have it tapped into. I have since returned home, and removed the gauge from the line, and the car is back to running normally as far as i can tell. Basically there was a flaw in the t-adaptor, and it was causing a considerable sized leak. So...this leads me to the a/f gauge. According to the diagnosis computer, the a/f is fine...so why does it read crazy? Because the gauge is most likely malfunctioned. You get what you pay for, and it was a 15$ job of ebay. Pretty likely it just got fried somehow. I wouldn't really doubt it. After I run it around a bit tonight, i'll be able to verify that this fixed the problem.

 

[luv4turbos]

OK, I understand that the pretty lights are working fine now. If your only getting 5-6 mpg. then something is deffinately not right.
Where you tap your boost has nothing to do with your car running crapy. It just means your boost guage reads incorrect.
Have you come to the conclusion to change your o2 like everyone has previously stated.

 

[boostvr4]

there was a flaw in the t-adaptor, and it was causing a considerable sized leak.

That would cause problems, it was bleeding off manifold pressure.

 

[Trigger Jack]

luv4turbos.....as I already stated, the o2 sensor is completely fine. And the a/f gauge is NOT working...it still says i'm so lean that it can't register it........and after I removed the boost gauge tap from the fuel regulator line, i am now getting perfectly normal gas mileage .....so....I'm not sure that I understand your post.....sorry to disappoint everyone who believes it was the o2, but that was never the problem.

 

[blk95tsi]

Hello Trigger Jack

And all other DSM'ers out their.
Trigger Jack, after all of that working out problems after the install of thec T28 you never mentioned how your new T28 preformes. Are you getting some nice results? How does it feel compared to your stock T25? Is there a big difference? Tell us what you think. Are you happy with your T28 buying decission?

 

[Trigger Jack]

Hey blk95tsi,

Unfortunately, since my T25 was mostly bad anyway, I can't give the best comparison to it, since I never knew what it was supposed to run like. Saying something is better than crap, doesn't say much. There's a post with my recent dyno on it, whicn resulted in about stock hp (plus a bit for my exhaust/intake), since the turbo is running only 9psi right now. I do have to say that so far I'm very pleased with it. Once I get an mbc and turn up the boost, and get a new dyno, I'll be able to have a better critique of it. Also....i traded out about 500$ worth of parts, and got a 900$ turbo....I'd have to say that it was an excellent deal.

 

[saw wave analog]

t28 spools a bit slower, and feels almost exactly like the t25 under 4k, past there it keeps pulling where the t25 drops off. its an ok turbo but looking back im never running anything smaller than a 50 trim again. congrats on getting your problem figured out, the most likely cause was a bad o2 connection as was mentioned.. a leak at the vac line to the fpr is not something that is common or anyone would have suggested