1970 Chevelle 5.3 swap ( stumbles in low rpm)
#1
1970 Chevelle 5.3 swap ( stumbles in low rpm)
Well officially took my car out on a test run tonight. Seems to be bog off the start but when it opens up ( around 3 to 3500) holy **** it runs like a raped ape. 5.3 with z06 cam 2500 stall. LS6 intake, 0411 PCM flashed to my specs. If you rev the car in park it never Boggs out. only does it under load. Have about 2 gallons in the tank ( tanks inc tank walbro pump). Hoping maybe that's the problem. But did have a code popping up after test starts. 0351 0353 0355 0357. When I got back from the test drive it read zero codes though. Have aftermarket coils on but all brand-new.
#4
No one video I got of it you can barely hear it breaking up but it seems like sometimes it's going into limp mode or the pedals not responding
https://www.facebook.com/groups/258057997644232/permalink/849559425160750/
https://www.facebook.com/groups/258057997644232/permalink/849559425160750/
#5
Check the throttle position sensor mounted on the side of the throttle body. Mine did the same thing twice don't buy a cheap one either. They are not cheap so maybe you could convince a buddy to swap his before you pull the trigger. Takes less then 10 mins to r&r.
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#9
Not really unless if you remove it & the rotation is stiff from dirt or gum. The electrical contacts get worn after awhile. You can diagnose with an ohm meter if you are electrically inclined. If you scanned it it should show faulty tps? It could be a bad fuel pressure regulator. Do you have a fuel pressure gauge? Should read around 58 to 60 psi at idle, partial & wfo.
#11
Did a pressure test today. When you hit the ignition and jumps up to 57then leaks down back to zero turn the ignition and start the car and it holds at 57. Reving it does not affect it... stays right at 57. Is it normal to leak down back to zero or should the Pump hold them rails at 57 with the key to on position
#12
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5.3 stumble
Your codes are all for coils and kind of indicates to me there is a small lack of ground somewhere. Recheck all grounds and add star washers. I think the Walbro pump does not have a check valve so pressure would bleed off quickly but while running you have good fuel pressure.
#14
It's a torco converter, but it seems fine though. But it hasn't been tuned yeah just set initial flash to get it running. Told all my specs converter stall all of it should have been specked to the motor. going to find a local shop to check it.