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92 silverado 350 tbi power loss

92 silverado 350 tbi power loss

Postby doug48755 [OP] » Apr 30 2012, 9:43pm

i have a 1992 chevy silverado that i bought within the last couple months mainly for a engine swap. i also have a 95 gmc sierra that i am planning on putting the motor out of the 92 into this one. anyways the 92 when i first got it, it ran great. nice gas mileage great power, etc. i have given this engine a full tune-up. plugs, wires, dist.cap,rotor,oil change,coolant temp sensor, throttle position sensor, iac valve, egr valve, egr valve solenoid, o2 sensor and probably a few others that i am forgetting. so over the past month the vehicle started to run sorta rough. when idling it idles really high when first started and then after about 5 mins it lowers. unfortunately i don't have a tach to read my rpm's. when it idles down i notice the engine seems as if its missing juts a little, and will shake, not bad, but enough for me to notice my engine isn't running well. my gas mileage has also gone down alot. so over this period of time i have checked a few things. i notice my cel comes on. so i found the code and it comes back 43, knock sensor. i went and got a new one, but when i went to take the old one out it ended up snapping and leaving about a inch of the end in the engine. so now i am stuck without having a knock sensor. also i noticed that whenver i give the vehicle a bit of gas when on take off or turning a corner i will have a slight grind for just a second that sounds like its coming from my distributor or maybe even my clutch, not too sure, but the reason i mention this is that whenever i do that my cel will turn on with the same code. So since i was hearing the grinding noise from the distributor area, i began to believe maybe the distributor was going out and would maybe be the reason for teh grinding and the off idling and gas mileage and so on. but when i did this i ended up noticing the back of my throttle body was really wet right under the fuel pressure regulator. i also noticed taht the vacuum line right behind it was saturated with gas and was getting down into my valve covers and probably in my oil. so i changed the oil and rebuilt the throttle body the best i could without having the new gaskets and diaghram for the fpr. it seems like it is leaking a whole lot less.
So i guess the reason for this post is to ask others is my thoughts on the knock sensor and fpr could both be the reason for my trucks performance. whenever i take off or shift gears it always feels like something is trying to hold me back and then the truck will smooth out. I also forgot to mention that i do see black smoke out of the exhaust whenever i put the truck in neutral and rev it up. I also don't know if this helps any but it is also a 5 speed manual transmission.
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doug48755
Firing on 1 cylinder [L1]
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Re: 92 silverado 350 tbi power loss

Postby 01dually6.0 » May 01 2012, 2:42am

Cloged Cat Maby ? But i would really replace that knock sensor.
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Re: 92 silverado 350 tbi power loss

Postby johndeere9203 » May 01 2012, 2:51am

i had a similar problem with my 93 with the 350 if i parked it and reved it up it would blow black shit all over my garage lol and going down the road it would bog out really bad............ it was really dumping gas in the tb! so i changed the tb and it ran a lil better than i found out the motor was a 98 vortech and the older intakes would not work on there.......... so i sold the truck (did not feel like pulling a fresh rebuilt motor) lol and as for the cat i thought it was my problem also so i cut it out and found out someone hollowed it out lol
2014 Camaro SS 6.2L, 6 spd, npp dual mode exhaust, short throw shifter. (426hp stock)
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Re: 92 silverado 350 tbi power loss

Postby doug48755 [OP] » May 01 2012, 3:18am

can't be the catalytic converter, because the previous owner replace the exhaust from the manifolds back and didn't include a cat, however now that i think about it the exhaust manifold on the passenger side is cracked.
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doug48755
Firing on 1 cylinder [L1]
Firing on 1 cylinder [L1]
Posts: 10
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Joined: Apr 30 2012, 9:21pm
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Year: 1992
Make/Model: Chevrolet Silverado
Extra Info: 1500 350 v8
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Re: 92 silverado 350 tbi power loss

Postby doug48755 [OP] » May 01 2012, 2:03pm

i do have it planned to pull out the rest of the knock sensor when i pull out my motor. the only reason i haven't gotten it out is because i have very limited room to get channel locks or anything at that matter to remove the rest of the sensor. its really in there and not coming out. but seriously would my knock sensor be causing all this crap to happen with my truck?
Original Poster
doug48755
Firing on 1 cylinder [L1]
Firing on 1 cylinder [L1]
Posts: 10
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Joined: Apr 30 2012, 9:21pm
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Location: michigan
Year: 1992
Make/Model: Chevrolet Silverado
Extra Info: 1500 350 v8
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Re: 92 silverado 350 tbi power loss

Postby doug48755 [OP] » May 02 2012, 10:56am

small success. i rebuilt the throttle body yesterday. i am no longer gettin the fuel leak out of the fpr, but it still hesitates a little bit. gas mileage seems to be slightly better.
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doug48755
Firing on 1 cylinder [L1]
Firing on 1 cylinder [L1]
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Year: 1992
Make/Model: Chevrolet Silverado
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Re: 92 silverado 350 tbi power loss

Postby MaDDeNLXXX » May 02 2012, 3:30pm

some throttle position sensors need calibrated as every truck seems to be a little different. I changed one on my sisters 2000 Cherokee and it had a mid throttle hesitation, and was harder to start in colder weather, took it in got it calibrated and now its good as new. Not sure if yours is the same way just a thought.
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Re: 92 silverado 350 tbi power loss

Postby doug48755 [OP] » May 02 2012, 4:32pm

i had actually read that somewhere once before, but honestly i don't know how to calibrate it or if my vehicle requires it. any page that might be of use?
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Firing on 1 cylinder [L1]
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Re: 92 silverado 350 tbi power loss

Postby doug48755 [OP] » May 02 2012, 9:18pm

just curious on this a little bit but could advanced timing or retarted timing cause any of these issues? i was told that if your knock sensor is bad that it will retard your timing. also if the sensor is bad, its extremely hard to set the timing properly. is this true?
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doug48755
Firing on 1 cylinder [L1]
Firing on 1 cylinder [L1]
Posts: 10
Topics: 1
Joined: Apr 30 2012, 9:21pm
Years of membership: 2 years of membership2 years of membership
Location: michigan
Year: 1992
Make/Model: Chevrolet Silverado
Extra Info: 1500 350 v8
Group Membership:
Registered users

Re: 92 silverado 350 tbi power loss

Postby 01dually6.0 » May 02 2012, 10:37pm

I Would think it would be true . Did you disconect that little wire on the fire wall before you set the timing? I made that mistake once.
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