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Discussion Starter · #1 ·
just finished installing a TBI 350 out of a 95 burban in my YJ. seemed to run fine for a little while. I've only really ran it maybe 5-10miles max though.

its had a "wandering" idle since I installed it though, and just recently it has started backfiring through the exhaust.

if its idling and I give it some gas, it seems to stumble, and backfire through the exhaust. after you let off the gas, it'll backfire once or twice. it will backfire occasionally at idle.


I've swapped in new plugs, wires, cap, rotor already.

gonna check the base timing tonight, and try and get a fuel presssure gauge to check that too.

any ideas?


one thing I DON'T have connected right now is the knock sensor. I had to run blockhugger headers to clear the link suspension on the passenger side, and the knock sensor hits the headers. I've got to get a 45degree adapter to screw the knock sensor into. could that be the source of the whole problem?




base timing is set at 0 degrees BTDC. still backfiring.


base timing was set with the EST wire disconnected.


disconnected the EGR loop, and still backfiring.
 

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Discussion Starter · #2 ·
ok, pulled the codes tonight.

43,59,66,67,73,82

all of those except 43, are related to the auto transmission, which ain't there.

43 is the Electronic Spark Control. which is, I'm assuming from the missing knock sensor?
 

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Code 43 can be set two different ways. First is when you unhook the EST wire to set the timing, which is easily fixed by unhooking the battery for a few minutes to clear the code.

It sounds like your light is set from the forced knock test failing. The ECM will advance the timing untill it hears knock to make sure the knock sensor is working. The second time the engine fails this test it will set a code 43 and lock the timing at 20 degrees causing your drivability problems. This test is only ran when in PE mode, which is enabled under heavy throttle, if you notice that the code is set the second time you get in it then this is most deffinately the cause.

The cause is probably retarded timing, there could be two things causing this. First is if Darrell and Darrell simply set it wrong, most likely they set it at 6 degrees with the timing connector still hooked up. The second scenario is if the balancer has slipped and you set the timing to the timing mark that has now rotated several degrees retarded.

Check the timing and go from there.
http://www.thirdgen.org/techboard/posts/tbi/430152-code-43/3389766-post2.html
www.thirdgen.org
 

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Discussion Starter · #4 ·
got the knock sensor, just gotta get the adapters to make it fit in there.

hopefully I can pick the stuff up today.
 

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Discussion Starter · #5 ·
just finished installing the knock sensor.

started it up and the backfiring cleared within a few minutes.


runs MUCH better!!!


now I have a code 35 though, which indicates a bad IAC.
 

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just finished installing the knock sensor.

started it up and the backfiring cleared within a few minutes.


runs MUCH better!!!


now I have a code 35 though, which indicates a bad IAC.
This is good to hear....as I was putting my 350 in this weekend...noticed the knock sensor had been taken off. I'll have to replace it to avoid some of this!
 
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