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I’ve tried to solve this problem för a long time now.
When cold the car starts fine but when hot it takes upp to 5 sec to start. I assumed that it was rich and tried to take out fuel by the crank fuel vs temp table with no effect. Coolant temp sensor reads fine.
Best way to start hot is to push the throttle to the floor for the first two sec and the let go. Worth mentioning is that two people with big knowledge about cars told me that it sounds rich during crank.
But adjusting the table above has no effect and part throttle during crank has no effect either.
Any ideas? Can I in the prom simulate the crank procedure mentioned above?
Be nice to know what we're working on. '85-'88 w CSI, '89-'92 no CSI, TBI etc...
If enabling fuel cut-off by depressing the throttle to the floor allows your hot start, I'm wondering if you're getting un-metered fuel introduced.
Sorry! 87 TPI with CSI removed. Regarding the unmetered fuel I agree. That has been the theory from the beginning. So I replaced all injectors and the CTS, removed the CSI and checked the hose from the FPR. It was dry. I've also tried different PROMs. Everything from stock to ARAP.. Always the same result. Thats why I was thinking It might be lean instead.
I’ve tried to solve this problem för a long time now.
For how long?
Do you have a datalog of your hot restart? It can give you a bit of information on what the ecm is seeing and doing.
When TPS is over 87% or so, on start-up, fuel gets cut off. So if it starts when you get the pedal to the metal, it is usually a sign of too much gas. Do you have a copy of your "Crank fuel vs temp" mods.
ECM needs to see 300rpm to activate injectors on cranking
does the fuel pressure bleed down when it happens?
Fuel pressure bleed down but pretty slow. And it doesnt matter how long the car sits. Today I stopped and restarted after three minutes. Long crank. So I actually dont think its injecting fuel from the injectors
I'm not nearly as good as some of the people here. But I don't see anything out of the ordinary with your tables. People have had long crank issues having the crank fuel PW multiplier zeroed at the top. I have 1's from my 1-8 values. My car starts with 1-2 cranks hot and cold.
Key on, ecm activates fuel pump for 2 seconds;
Crank, ecm monitors DRP, activates fuel pump if DRP and will activate injectors once over 300rpm will stay in cranking routine until over 300rpm + some DRP, then declare engine running.
Tables involved: Crank Fuel PW vs Coolant * Crank Fuel PW Multiplier vs DRP * Crank Fuel PW Multiplier vs TPS%. (There is also a scalar involved in the calculation)
ECM fires injectors with fixed amount of ms for each DRP
During cranking, EST is not activated, so SA is initial SA, OEM = 6*
Looking at your table, "Crank Fuel PW vs Coolant" does not look right. What conversion is being used by your XDF? If you could post the X values without conversion that would help.
You were saying pedal to the floor was fixing the problem, so it points to too much fuel. But now you are talking about "long crank" in post #8. A long crank which fires-up without pedal to floor indicates not enough fuel or not enough starter power to turn engine over 300rpm.
Usually, tuners will add value to DRP 1-8 to help with long crank. By doing so, it will add more fuel. See post #10 @RBob
The 2 tables "Start-up bla bla.." you posted are not involved during cranking
When cold it start instantly. I always found that a bit strange since the table avove indicates no fuel for the first 8 ref pulses. But if that is a very short time it migt be correct after all
From APYM. I think the original bin is ACXS. When I bought the car it had a ADS Superchip which I removed.
I'm not sure what you mean by X-values but this is from the &6E XDF file. I removed the authors name
%%TABLE%%
000002 UniqueID =0xD5
040005 Title ="Crank Fuel PW vs. Coolant Temp"
040011 DescSize =0x1
040010 Desc =""
040100 Address =0x373 040200 ZEq =0.781300 * X + 0.000000,TH|0|0|0|0|
I updated post #5 and 7 based on @RBob clarifications. He is always a great source of knowledge.
For table "Crank Fuel PW vs. Coolant Temp", I believe the right formula is 0.200004878 * X + 0.000000. Nonetheless, if you enter "X" in conversion instead of "0.781300 * X + 0.000000", you will get a non converted value. For APYM, I get:
So it looks like what ever modified version of APYM you have, it has reduced cranking fuel delivery.
My advise: If you have all original set-up, with OEM fuel pressure and injectors style, I would bring APYM back to original settings to start with.
I've had issues with weak battery which resulted in long cranking. I can't explain it other than it appeared while cranking the voltage was getting in low 9s high 8s volts. Engine rpm was flat at 200 rpm. Engine would not fire-up for 6 seconds of cranking. Once engine would reach mid 200 rpm with high 9s voltage, it would fire-up. Issue was present only when car had been sitting for a few days. Changed the battery and problem went away. Installed a on board battery charger. Car is now plugged whenever it sits. Never had the issue after. My only conclusion is, low voltage affected injectors or engine rpm was too low while cranking. But I can not verify that with certitude.
I updated post #5 and 7 based on @RBob clarifications. He is always a great source of knowledge.
For table "Crank Fuel PW vs. Coolant Temp", I believe the right formula is 0.200004878 * X + 0.000000. Nonetheless, if you enter "X" in conversion instead of "0.781300 * X + 0.000000", you will get a non converted value. For APYM, I get:
So it looks like what ever modified version of APYM you have, it has reduced cranking fuel delivery.
My advise: If you have all original set-up, with OEM fuel pressure and injectors style, I would bring APYM back to original settings to start with.
I've had issues with weak battery which resulted in long cranking. I can't explain it other than it appeared while cranking the voltage was getting in low 9s high 8s volts. Engine rpm was flat at 200 rpm. Engine would not fire-up for 6 seconds of cranking. Once engine would reach mid 200 rpm with high 9s voltage, it would fire-up. Issue was present only when car had been sitting for a few days. Changed the battery and problem went away. Installed a on board battery charger. Car is now plugged whenever it sits. Never had the issue after. My only conclusion is, low voltage affected injectors or engine rpm was too low while cranking. But I can not verify that with certitude.
I have attached an OEM version of APYM
Hope this helps
Ok. I will go back to the original APYM bin. But that this mean that there is an errror in my xdf file? How do I get an updated $6E XDF file? Or should I edit my XDF file? Sounds scary…
But the correct value seems quite a bit lower than in my file
Ok. I will go back to the original APYM bin. But that this mean that there is an errror in my xdf file? How do I get an updated $6E XDF file? Or should I edit my XDF file? Sounds scary…
But the correct value seems quite a bit lower than in my file
Errors all the time in XDF. It’s the nature of the beast. It’s an open source supported by volunteers.
In doubt, I always go back to non converted value or even HEX editor.
OEM APYM will work with OEM set-up. If anything was changed, sometimes you can get surprises.
Update
Since I replaced the injectors to Bosch II I changed the injector constant to 19. That keeps BLM at 128-131 in closed loop. Then I used the original Crank PW vs Ref pulses. 1.00 in all cells. It wouldn't start hot unless I give some throttle. I then tried the values from the Arap-code. A lot leaner. Now it only takes two seconds to start hot and with no throttle. Success! The first 8 ref pulse entrys are 0, as Rbob pointed out, so I figure I will try to move the values up in the table. All and all so much better. I really thank you all
05-15-2023, 12:44 AM
