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Post by bobbarker on Jun 17, 2009 17:19:36 GMT -5
It's kinda hard to explain but here goes.
The car is an 85 SVO, and as far as I know it's stock in the engine bay, except the turbo will boost to 20-21 lbs. Don't know why it does that either...
When I'm in say 3rd or 4th gear and I mash the gas pedal it pulls very well all the way up to around 4k maybe 4500 RPM, then it sorta stops pullin. and not like it's ran out of flow or is just planing out in power, but like it's not boosting as much. You can feel it in the seats, the car literally lurches forward as if I had let my foot off the gas but I didn't. It will surge and let off and eventually start backfiring and spitting like it has a plug gone out? Could the spark be getting blown out from too much boost? Or maybe could a valve get stuck open not allowing proper combustion? I really have no idea what is causing it, just throwing out random thoughts... Please help!
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Post by Stinger on Jun 18, 2009 1:27:55 GMT -5
It is probably a lean backfire/miss from too much boost for the stock fuel system. 21psi on the stock gauge is normally 24psi or so in reality...perfect combo for destruction of the engine.
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Post by bobbarker on Jun 18, 2009 4:17:45 GMT -5
ah... I guess I'll stop doing that then.... but it's an aftermarket gauge if that makes any difference. Thanks!
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jet1
Boosting 20 psi
Posts: 85
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Post by jet1 on Jun 18, 2009 8:33:51 GMT -5
I agree with what said, Althoug I am familiar with bacfiring LOL when i give to much fuel to where i see 9 on afr at 100 %deflection at any rpm over2800 , It will also backfire pretty good ecept it does not stop pulling like you stated it just immediatley will backfire and then want to stall due to over rich, Do you have a afr meter? What kind of boost controller do you use? Is the vaccum lines all hooked up according to stock. Cone filter, ect? I would assume you have a stock exaust.
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Post by Stinger on Jun 18, 2009 11:26:33 GMT -5
You should figure out why it is over boosting as well...that's not safe and is pretty easy to diagnose. Start by blowing with your mouth in the hose that goes to your wastegate actuator (below turbo) and see if you can blow air through it.
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Post by bobbarker on Jun 18, 2009 14:57:44 GMT -5
good idea... I knew that overboosting was a problem, but never really knew how to find out why or where! So just find the hose out of the bottom of the turbo and disconnnect the end from the turbo and blow? Seems simple enough. I may be a while trying this out, cause I literally have no idea what I'm doing when it comes to turbo's!!!
I have no AFR meter, boost controller is whatever came stock on it if there is one, I assume all vaccume lines are correct and hooked up, stock air filter and exhaust has a dynomax muffler and tailpipe, other than that it's stock...
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Post by Stinger on Jun 18, 2009 20:42:46 GMT -5
Wastegate actuator looks like a small can under the turbo near the block with a vacuum hose going to it. Remove the other end of that hose, put it in your mouth, and blow...then report back. No excuse to not do it right now...shouldn't take but a minute or two at most and could save you thousands of dollars.
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Post by bobbarker on Jun 21, 2009 13:23:56 GMT -5
I could not blow any air through that tube... I even took it off an checked it for cracks and there were none.
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Post by Stinger on Jun 21, 2009 15:04:35 GMT -5
Run the hose you blew through from the actuator to the port on the side of the compressor housing (should be two ports on a "T" on the housing) and see if it still overboosts.
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jet1
Boosting 20 psi
Posts: 85
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Post by jet1 on Jun 21, 2009 15:12:56 GMT -5
yeah
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Post by bobbarker on Jun 21, 2009 19:52:26 GMT -5
There's already two hoses ran to that "T"... which should I remove?
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Post by Stinger on Jun 21, 2009 23:53:41 GMT -5
It doesn't matter which you remove but I suppose the one going to the boost control solenoid on the passenger side strut tower.
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Post by bobbarker on Jun 22, 2009 8:47:59 GMT -5
The hose from the actuator was one of the ones ran to that "T"... the other goes to the little can you called the boost control solenoid on the strut tower... The boost control solenoid one always comes off the "T" you talked about though...
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Post by Stinger on Jun 22, 2009 13:41:24 GMT -5
Just cap the port going to the boost control solenoid temporarily and see what boost you get then.
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Post by bobbarker on Jun 22, 2009 20:52:22 GMT -5
Funny thing happened today... I put the hose back on the turbo side that runs to the boost control soleniod and it held boost at 15-16lbs... then about a few miles (and another full blast) it ran up to 20+lbs again... I think it's because the hose is falling off the boost control solenoid side? Maybe?
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