armycook1981

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I have a question for those that might have the same problem or know what the fix could be

Stage:

( AEM electric fuel psi gauge/ AEM wideband)

Im using also an AEM elec BOOST controller/gauge to adjust it you increase or decrease the manifold psi so daily is usally set at 55%
i think its 55% manifold psi gets me like 13-15 psi
and I blieve 65% manifold psi is like 17-19 psi.
PSI motorsports has it tuned
tranny is stock with expection 2800 stall, and a ftvb

Now I can WOT at the current boost setting which is 55% average is 15.6 psi untill i will let out and i get 50+ fuel and a/f is like 10.0 and then will increase to 11.7ish towards the top end..

Now heres my issue.
If i increase the Boost to try and see 17-19 psi under WOT i set it to 65% on the gauge.
When i do a pass as soon as I go WOT it shoots to 10-11psi and it feels like its hitting a speed limiter as i move up in RPMs and MPH.. I can continue to WOT and it just stays in the 10-11 psi range and the whole gear(s) feels like its hitting a speed limiter you can actually see and hear it doing it the truck will chug like when it happens prime example for the thrid time is like its hitting a Speed limiter.. A/F and FUEL PSI stay normal as if im running @ 15 psi WOT.

Any idea.

thanks,

Joey

turbodgumby

Joey does your boost controller have an overboost safety built into it? I know the E-Boost 2 does but not sure on yours?

Agent 00 L

Are you using an AEM TruBoost? I had one but I can't remember if it had an overboost deal on it. You can get a manaul online from AEM.

Be careful with the Truboost, since it doesn't have feed back so the boost can vary with the same setting. If you change things the boost will change too, ie opening the DP on my truck would up the boost about 4lbs

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2001 Silver Lightning, Stock Engine Turbo in the works
2000 Black Turbo Lightning RIP.
SCT Pro Racer Tuned, Stock Engine
540 hp/580 tq - 16psi, Pump Gas, Open DP
11.68 @ 120

Emmanuel

95 850 turbo engine/boost problem
Ok here goes, I bought this car a year ago, it’s a stock 1995 850 T5, I bought it with 82k miles on it. When I received it, it ran ok, but there was barely any boost. The boost gauge needle would barely get into the white range.

So I did some research on various forums, and I learned that the first thing to look for was the vacuum lines. I did that, and they were all busted, so I replaced each one with new ones and those leaks were gone. After that the boost was a little better, but it was behaving erratically. Whenever I would floor the pedal, the car would boost to like 8psi and even though the rpms were climbing slowly, the engine sounded like it was decelerating (sort of like a limiter kicked in and made it back down a bit) and it would fade to like ~4psi, and then the engine(felt like a limiter was bypassed) and accelerating kicked in and the psi would rise to about 7, power would vary during this.

So I thought there were more boost leaks, so after reading about some DIY turbo boost leak testers, I made one out of a PVC cap air compressor connector and tested for more leaks. I found a leak on the Intercooler so I plugged it up. I also found a couple of other hoses that were busted, so I replaced all hoses that I could. There were no more boost leaks of any kind. That didn’t fix the problem.

Then I figured the problem could be electrical, so I bought a new cap and rotor, plugs, and wires. I bought bosch wires, bosch platinum plugs, and the cap and rotor were some autozone brands. I installed those and then the car started misfiring. So after some research I replaced the plugs with bosch coppers and the misfire was gone. But the main problem still wasn’t fixed, same power surge. After messing with the wires a bit try to re-gap the plugs, one of the wires broke, so I re-installed the old bugicourds since new wires didn’t seem to help.

Then after some more research I read that it might possible be the CBV diaphragm, or the wastegate lever needed to be hammered down if there was a gap, so I checked and there was no gap, but I did get a new CBV and installed it and it didn’t change a thing. Now I was getting very frustrated.

Then I kept asking questions on forums and got varying opinions on what the problem could be. Some said that the ECU could be the problem, could be the MAF, could be the TCV, the CAT could be the problem(the car passed smog, so I didn’t think there was a problem), an O2 sensor could be bad, the fuel pump could be bad, low fuel pressure, wastegate could be fubered, charge pipes could be bad. So taking those into consideration, I got a MBC and installed it, the boost characteristics were different, but the same problem remained. I replaced the MAF, nothing changed. I got a custom 3” turboback exhaust with a new cat. I tested the car after that, the car built boost faster(but there was no power behind that boost, 12psi on the gauge felt like 5 before), so the same problem was there still. After that I thought it could be the ecu, so I decided I should get a ST Chip. I got the 17psi chip and I installed. I also got a FMIC kit and installed that, so all hoses are aluminum and are not leaking or collapsing under boost. The car felt the same, but now the car would boost higher, but the power still wasn’t there. I then got a fuel pressure gauge and checked the fuel pressure, the pressure was about 35psi idle, and like 55psi when I blipped the throttle, so it seemed normal. I then decided I should try a different wastegate, so I bought a t3 10lb wastegate and installed that, didn’t help. The car would boost to like 15 really fast and felt like the car hit a limiter again and then would sound like it wouldn’t let the rpm climb and the boost was falling again(but I was at WOT).

Now I was very frustrated. So I put back the old wastegate cuz there was no point in having it on, it was boost fast and high, but the car wouldn’t move. Then one of my friends said reset the ECU, so I let it reset over night and then i started to drive the car and the car felt different, it was more powerful, but not as powerful as it should be. It would hit 13psi and it would feel fast, but it would still bog like before.

After all this I gave up on the car and just drove it for like 4-5 months (I did change the PCV system for maintenance). Then after not boosting for like 4-5 months, I started punching the the car felt a lot better, it would boost to like 14-15psi(never hit 17psi that it was tuned for), and it would feel fast. Then after a day or 2, it went back to the same old problem. I had a local volvospeeder test out the car for me and he couldn’t figure it out either, so I gave up again. Now this last week the car got a check engine light and said the O2 was slow, and in my head I was thinking maybe the O2 was failing all this time and it just finally went and that was the problem. So I got a new universal O2 bosch unit and spliced it in, and it did not work. After this I give up again, I do not know what the problem is. Someone said it could be the tranny, but It feels fine and shifts fine and doesn’t throw any codes, and sometimes when the car pulls hard the tranny doesn’t feel fubered.. I even put some redline treatment in there just in case, and the fluid was pink before adding it.

And another thing, sometimes under part throttle when the boost would rise fast, I could feel some vibration coming from the engine bay, I don’t know if its pinging, knocking, detonation. And there are no codes or check engine lights.

So far , I’ve replaced:
Plugs, wires, cap, rotor, frontO2, MAF, CBV, PCV, vacuum hoses, tried MBC, tried different wastegate, exhaust(cat), added custom CAI, I added new grounding wires, custom FMIC, ST 17sp chip.

I really don't know what to do anymore, I feel like I have to get rid of it, but I don't want too, Ive put so much money into this car, lots of things have been replaced, the car has been acting like this since day one. Any advice is greatly appreciated.

I chopped up some videos of the problems in real time .
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