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Discussion Starter #1 (Edited)
i just swaped in a TBI 350 into my cj, its out of a 94 chevy PU. before i put it in my jeep, i rebuilt it with aftermarket flattop pistons (i dont think thats whats causing the trouble) well anyways, at high RPMs it pops and misses. i have hooked it up to a scantool and it showes that the knock sensor is retarding the timing. but the motor runs perfect, just not at high RPMs. i am still using the fuel system that was in the cj (tank, pick-up, and lines), so maybe its not getting enuf fuel. i cant figure it out, maybe you guys can help.
 

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Discussion Starter #5
MrWillys said:
Did you disconnect the brown wire when you set the timing? If you think you need more fuel. Get an adjustable regulator. Sound like to much advance to me!
the brown wire to what??

i checked the fuel pressure and it was good, so i dont think fuel is the problem
 

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do a search on setting timing on tbi 350 use yahoo not pirate and then do it according to the write up and then get back to us
 

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tbi timing is 0*

there is a brown wire going into the distro where the ESC is. You have to unplug that wire to set the timing.
 

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PS: where did you get a fuel pressure guage? I need to check mine.
 

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Discussion Starter #9 (Edited)
well guys, thanks for trying to help (im not giving up) but this is to hard to fix over the phone. right now i am in Cali and my rig is in Minn so im trying to do this over the phone with some of my buddys. im sorry i wasted your guys time. when i go home for the thanksgiving and christmas ill take a look at it and get back to you. thanks again for your help.

edited: gipper,i got the fuel pressure guage from a friend.
 

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I might throw in what size throttle body you used, high RPM miss with a pop almost make me wonder if its fuel starvation related over bad timing.

Thought timing is definately the first thing i would check. The pop bothers me i would think..... i say again, think, that a pop is brought on by too little fuel at sustained high PRMs. Just a thought but until you rule out the timing issue your on trial and error mode. rule out the simplist things first
 

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cheap2.5 said:
You need a adjustable map sensor and adjustable fuel reulator.Or poke a couple holes in the vac line and see if that helps.
What in the hell for?

I'm running my TBI motor all stock. Unplug the brown wire timing clip, re-set your timing and try it. What are you using for a fuel pump? You need to be giving the motor 12-15psi of fuel. I'm running 3/8" feed, 5/16" return. If it's still being ghetto, heck, try replacing the knock sensor, they're pretty cheap.
 

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You're probably setting a code 43, which is the ESC circuit, that's why the timing is being retarded at higher RPM - i.e. full throttle.

Like the others have said, disconnect the EST wire (brown one that goes to the distributor from the ECM, should be close to the firewall and maybe 6" from the distributor), set your timing to 0*, disconnect the battery for about 30 seconds and try again. If the base timing is too far advanced, the motor will ping under full throttle, knock sensor will detect that and retard the timing to avoid damaging the motor.

If you do the above and it still runs the same, try a new knock sensor first. They are about $20 and easy to install. You may loose a little coolant when you change it, but it's not a big deal. Also make sure you torque it to the correct specs (about 13 lb/ft if I remember right) or you'll get bad readings again.

The only other component in that loop is the ESC module and it's an expensive mofo. About $100. They hardly ever go bad, so that would be the very LAST thing I would replace.

Did you put headers on the motor? Sometimes the knock sensor will detect the exhaust pulses from headers and send a signal as well.
 

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Discussion Starter #14
ok, i talked to my buddy at home (the one whos helping me with all this) he hooked it up to the scantool, and the knock retard was reading -16* with the motor NOT running, so we think it could be the ECM.
 

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Yea, I wouldn't bet on a bad ECM either. They are also another component that hardly ever goes bad.

If you had gotten the code 43 earlier, the ECM stores the code in there until you clear the memory, so that may be what you're seeing. Try disconnecting the battery and clearing the memory. Then BEFORE you start the motor again, hook your scan tool up and see if he's still reading that 16* retard. I'm betting you won't.
 

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One more thing, and this is ESSENTIAL!! (ask me how I know)

Make sure you have a SOLID 12V or more to the coil and ECM when the motor is running. I had an issue that I chased for about 6 weeks and it wound up being only having 10.5V to the ECM and coil from my Jeep "resistor" wire. I would get code 43 constantly because without proper voltage, your sensors read all kinds of funky.

If you used any of the original wiring in the Jeep, double check that it is getting proper voltage when RUNNING, mine would be fine with a key on scenario, but as soon as I started it, would drop to 10.5.
 

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Discussion Starter #18
Kendo said:
Yea, I wouldn't bet on a bad ECM either. They are also another component that hardly ever goes bad.

If you had gotten the code 43 earlier, the ECM stores the code in there until you clear the memory, so that may be what you're seeing. Try disconnecting the battery and clearing the memory. Then BEFORE you start the motor again, hook your scan tool up and see if he's still reading that 16* retard. I'm betting you won't.
we dont get a code, it just reads that the timing is retarding, and when we knock on the block the knock sensor picks it up. maybe something got messed up in the wiring?
 

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That's really odd. The fact that it's showing the timing as being retarded and not storing a code could be an ECM problem. That's about the only time an ECM goes bad, when it doesn't show a code but there is something legitimately wrong with the motor.

I know you're using a scan tool, but if you do the poor man's scan and just ground your ALDL connector, does it show a code then? If not, you just may have a bad ECM.
 

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Discussion Starter #20
the scantool was a snapon, so it was a good one.....and i dont have a check engine light hooked up.........im going to pull the ECM from my friends 95 chevy and hook mine up to his truck and see if we get the same reading in his truck.
 
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