new motor bugs
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Junior Member
Joined: Jul 2001
Posts: 70
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From: ct
new motor bugs
i just finished putting my new motor in my 91 Z (gm caprice 350 long block).the motor is running real rough. I did change the cam comp cams roller 218-224 485" 503". im sure this is part of the reason but what else should i check.Iac? tps? how do i adjust these. anything else i should check. Also i added a 160 therm. and a hypertech fan switch should i keep them or put the stock parts back on?
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91 Z28 slp headers adj reg accell cap rotor coil comp cam roller
random tech cats flowmaster catback
new motor in
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91 Z28 slp headers adj reg accell cap rotor coil comp cam roller
random tech cats flowmaster catback
new motor in
Supreme Member
Joined: Nov 2000
Posts: 1,078
Likes: 0
From: San Antonio, TX
Car: Damn
Engine: This
Transmission: New Stuff
Does it run rough at just idle or all over? I'd say a deffinate thing to do is check very carefully for vacuum leaks. I have a very small leak and mine idles rough cause of it, but runs like the wind.
Check the tps voltage, it should be .54 with no throttle (at idle). To set this get a voltmeater and stick the positive in the very top contact on the tps, and the negative in the middle, the bottom is power to the tps and will read 5 volts.
Once you've done that loosen the to small torx bolts holding the tps on the throttle-body so that you can move the tps. Adjust till you get .54 volts. I like to do this with the car running, that way you know that is what the computer is getting, with the car off the volatge is lower when you set it, and when the car is running it will read a little high.
While your in there go ahead and make sure the tps is working right, slowly open the throttle while watching the voltmeter, it should smoothly go up to over 4.5 volts. If the needle spikes or is jumpy, you need to replace the tps.
Next check fuel pressure, plugs and wires- alot of times a miss can be found and will fix your problem.
I would also re-check your timing, this has screwed me up plenty. Sometimes that distributor moves on you!
Hope some of this helps.
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'88 RS (originally 2.8)
-350, .040 over, vette alum. L98s, stock tpi.
-305 injectors & chip
-TES headers & edelbrock cat back
-3.73 gears, 700r4.
Best with 2.8-17.4@77mph
Best with 305-15.0@93mph
Best with 356-13.7@101mph
on a 2.050 60 ft.
(Damn the 2.8!)
Check the tps voltage, it should be .54 with no throttle (at idle). To set this get a voltmeater and stick the positive in the very top contact on the tps, and the negative in the middle, the bottom is power to the tps and will read 5 volts.
Once you've done that loosen the to small torx bolts holding the tps on the throttle-body so that you can move the tps. Adjust till you get .54 volts. I like to do this with the car running, that way you know that is what the computer is getting, with the car off the volatge is lower when you set it, and when the car is running it will read a little high.
While your in there go ahead and make sure the tps is working right, slowly open the throttle while watching the voltmeter, it should smoothly go up to over 4.5 volts. If the needle spikes or is jumpy, you need to replace the tps.
Next check fuel pressure, plugs and wires- alot of times a miss can be found and will fix your problem.
I would also re-check your timing, this has screwed me up plenty. Sometimes that distributor moves on you!
Hope some of this helps.
------------------
'88 RS (originally 2.8)
-350, .040 over, vette alum. L98s, stock tpi.
-305 injectors & chip
-TES headers & edelbrock cat back
-3.73 gears, 700r4.
Best with 2.8-17.4@77mph
Best with 305-15.0@93mph
Best with 356-13.7@101mph
on a 2.050 60 ft.
(Damn the 2.8!)
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