hard start issue -> solution in the PROM?
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Junior Member
Joined: Mar 2005
Posts: 86
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From: Munich, Germany
Car: 91 TPI Caprice
Transmission: TH700R4
hard start issue -> solution in the PROM?
hi folks!
it still have my hard start issue (only after warming up the engine, let it sit for about 20 mins., then it needs to crank about 2-3 secs before it starts - every time else, when its completely cold, or even hot, it starts perfect), i spent the last weeks with replacing all TPI related parts, details are in this thread: https://www.thirdgen.org/forums/tpi/...art-issue.html so my last option is that it could be a tuning issue.
application: 5.7L L05 engine (stock crate engine), MAP TPI with 24 pph injectors, all sensors/parts new, including painless wiring harness, distributor... Base file for the PROM was the S_AUJP, but with VE tables for the mild L05 engine and of course much less spark advance (with die S_AUJP spark tables it knocks all the time)
Ok, now the question: any ideas which setting in the PROM could cause THIS? (see attached file). At the MAP-value you can see when the starter begins to crank the engine, it gets immediately it's reference pulses, but it waits with firing the injectors.
it still have my hard start issue (only after warming up the engine, let it sit for about 20 mins., then it needs to crank about 2-3 secs before it starts - every time else, when its completely cold, or even hot, it starts perfect), i spent the last weeks with replacing all TPI related parts, details are in this thread: https://www.thirdgen.org/forums/tpi/...art-issue.html so my last option is that it could be a tuning issue.
application: 5.7L L05 engine (stock crate engine), MAP TPI with 24 pph injectors, all sensors/parts new, including painless wiring harness, distributor... Base file for the PROM was the S_AUJP, but with VE tables for the mild L05 engine and of course much less spark advance (with die S_AUJP spark tables it knocks all the time)
Ok, now the question: any ideas which setting in the PROM could cause THIS? (see attached file). At the MAP-value you can see when the starter begins to crank the engine, it gets immediately it's reference pulses, but it waits with firing the injectors.
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From: Chasing Electrons
Car: check
Engine: check
Transmission: check
Check the values in this table:
RBob.
Code:
;=======================================
; CRANK FUEL DELIVERY DELAY vs MAT
;
; TBL = DELAY IN DRP'S
;=======================================
;--------------------------------------
; DRP ; DEG C
;--------------------------------------
L839C: FCB 2 ; 2 -40 C
FCB 2 ; 2 -26
FCB 1 ; 1 -16
FCB 0 ; 0 -4
FCB 0 ; 0 8
FCB 4 ; 4 20
FCB 4 ; 4 32
FCB 4 ; 4 44
FCB 4 ; 4 56
FCB 6 ; 6 68
FCB 8 ; 8 80
FCB 8 ; 8 92
FCB 8 ; 8 104
FCB 8 ; 8 116
FCB 8 ; 8 128
FCB 8 ; 8 140
FCB 8 ; 8 152 Thread Starter
Junior Member
Joined: Mar 2005
Posts: 86
Likes: 0
From: Munich, Germany
Car: 91 TPI Caprice
Transmission: TH700R4
thanks for your reply, the problem occurrs with the values in this table, and even with this table zeroed out
i did about 50 start-scans, so i can say the problem happens not at a specific coolant temp, but after about an half hour after the car was parked with hot engine; it depends on the outside temp how fast it cools down, so i have bad-start scans with 50°C coolant temp, and some with 70°C, but in the same temp-range i have scans with good starts too
i did about 50 start-scans, so i can say the problem happens not at a specific coolant temp, but after about an half hour after the car was parked with hot engine; it depends on the outside temp how fast it cools down, so i have bad-start scans with 50°C coolant temp, and some with 70°C, but in the same temp-range i have scans with good starts too
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From: Ventura, Ca
Car: 69 Camaro
Engine: LS1 converted to LS6
Transmission: 4L70
Axle/Gears: 12bolt 3:42
Every hard start issue I have had with TPI units have to do with no fuel. If you have not changed your relay and filter then do so now. Next in line is to make sure that you have the correct pressure just to make sure your pump is good and the filter is not clogging. From what I have seen the pump may stop for a while if it is overworked which usually means a clogged filter or a bad relay. Listen for the 2 second prime when you turn the key on. If you do not hear that it is the relay or the ECM. If you are using the older style relay make sure it is good even brand new ones may have problems. What happens is that the 2 second prime does not work and your cranking is bypassing the relay through the oil pressure switch. If you determine that it is pump related I believe there is a fuel relay bypass wire already -I am running an aftermarket harness. When it happens bypass the relay and run the pump. If it starts right away it is again either the relay or the ECM.
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