Slow cranking and won't turn over till you pump on the gas pedal
05-20-2014, 12:28 PM
#1
Slow cranking and won't turn over till you pump on the gas pedal Happens only when engine is hot. In the morning, it starts right up.
Already replaced the battery and starter. So you can take them off the list.
I replaced the battery even thou it passed all tests, but everyone kept on saying it was the battery so I said what the heck and replaced it knowing that it couldn't be it...and sure enough it wasn't. Not about to do the same with the starter.
Any ideas?
Already replaced the battery and starter. So you can take them off the list.
I replaced the battery even thou it passed all tests, but everyone kept on saying it was the battery so I said what the heck and replaced it knowing that it couldn't be it...and sure enough it wasn't. Not about to do the same with the starter.
Any ideas?
05-20-2014, 02:03 PM
#2
Could be many things. How long have you owned the car? What is the SCR? Has the car been modified &/or tuned?
Could be that the tune is pulling too much timing &/or fueling from the engine start, OL, ECT tables or IAT/ECT combined tables once the engine is warmed up. Once you push the gas pedal the TPS, MAP & MAF conditions add enough timing/fuel for the engine to start. It does sound like it's in the tune.
Could be that the tune is pulling too much timing &/or fueling from the engine start, OL, ECT tables or IAT/ECT combined tables once the engine is warmed up. Once you push the gas pedal the TPS, MAP & MAF conditions add enough timing/fuel for the engine to start. It does sound like it's in the tune.
05-20-2014, 03:01 PM
#3
Could be many things. How long have you owned the car? What is the SCR? Has the car been modified &/or tuned?
Could be that the tune is pulling too much timing &/or fueling from the engine start, OL, ECT tables or IAT/ECT combined tables once the engine is warmed up. Once you push the gas pedal the TPS, MAP & MAF conditions add enough timing/fuel for the engine to start. It does sound like it's in the tune.
Could be that the tune is pulling too much timing &/or fueling from the engine start, OL, ECT tables or IAT/ECT combined tables once the engine is warmed up. Once you push the gas pedal the TPS, MAP & MAF conditions add enough timing/fuel for the engine to start. It does sound like it's in the tune.
05-20-2014, 03:53 PM
#4
05-20-2014, 04:03 PM
#5
05-20-2014, 04:48 PM
#6
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You have an electrical heat soak issue. I know you said you replaced the starter but I would look into that especially if you replaced it with a rebuilt unit. Also, check your negative battery cable going to the block and the cable itself. A bad connection or high resistance in the cable will cause all sorts of problems.
05-20-2014, 06:02 PM
#7
You have an electrical heat soak issue. I know you said you replaced the starter but I would look into that especially if you replaced it with a rebuilt unit. Also, check your negative battery cable going to the block and the cable itself. A bad connection or high resistance in the cable will cause all sorts of problems.
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05-21-2014, 05:16 AM
#8
I still believe that the tune is pulling fuel/timing when warm for some reason. Can be from air flow or pressure @ certain temps. Some sensor may be telling the PCM to pull fuel/timing when warmed up. Find someone local who has tuning software that can log it when it happens. This is the best way to diagnose the problem.
Why was the MAF replaced? Maybe it's not matched to the scaling in the PCM.
05-21-2014, 07:28 AM
#9
I still believe that the tune is pulling fuel/timing when warm for some reason. Can be from air flow or pressure @ certain temps. Some sensor may be telling the PCM to pull fuel/timing when warmed up. Find someone local who has tuning software that can log it when it happens. This is the best way to diagnose the problem.
Why was the MAF replaced? Maybe it's not matched to the scaling in the PCM.
05-21-2014, 05:26 PM
#10
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A tune will not affect starter cranking speed. Slow cranking speed however will make the engine struggle to start.
You need to have a starter draw test done to see how many amps it's drawing while cranking. Test it both hot and cold. I would get the battery tested as well. Just throwing parts at it without knowing what the problem is will just make things more confusing. I've had plenty of new and remanufacterd parts bad right off the shelf.
You need to have a starter draw test done to see how many amps it's drawing while cranking. Test it both hot and cold. I would get the battery tested as well. Just throwing parts at it without knowing what the problem is will just make things more confusing. I've had plenty of new and remanufacterd parts bad right off the shelf.
05-21-2014, 08:03 PM
#11
You said that cold it cranks & starts normally. Hot, it won't start until you pump the gas pedal. If one or more of the programmed tables in the PCM are reducing timing &/or fueling when the engine reaches operating temperature, then a sensor is telling it to do so. ...if the problem is happening from a sensor related table.
When you push the gas pedal, there are tables that use the position of the throttle body & the added air/pressure created when the throttle body opens
that are adding back the reduced timing/fueling that's being pulled by the other tables when the car gets warm.
Because you had to change the MAF, it may be a culprit, IDK. You need someone to connect to your PCM & make a log of what is happening when the car has trouble starting when warm & what is happening in the PCM when you push the gas pedal to start the car when hot. ]
When someone says look @ the tune, they mean connect to the PCM & see what the PCM is doing while the problem is happening & again what is happening when you push the pedal to correct the problem. It requires a person with tuning software to do this. This will allow you to either find or eliminate a sensor/PCM as the problem. Good-luck
05-21-2014, 08:23 PM
#12
Ignore the term tune. The PCM contains tables that operate from sensor input.
You said that cold it cranks & starts normally. Hot, it won't start until you pump the gas pedal. If one or more of the programmed tables in the PCM are reducing timing &/or fueling when the engine reaches operating temperature, then a sensor is telling it to do so. ...if the problem is happening from a sensor related table.
When you push the gas pedal, there are tables that use the position of the throttle body & the added air/pressure created when the throttle body opens
that are adding back the reduced timing/fueling that's being pulled by the other tables when the car gets warm.
Because you had to change the MAF, it may be a culprit, IDK. You need someone to connect to your PCM & make a log of what is happening when the car has trouble starting when warm & what is happening in the PCM when you push the gas pedal to start the car when hot. ]
When someone says look @ the tune, they mean connect to the PCM & see what the PCM is doing while the problem is happening & again what is happening when you push the pedal to correct the problem. It requires a person with tuning software to do this. This will allow you to either find or eliminate a sensor/PCM as the problem. Good-luck
05-21-2014, 08:29 PM
#13
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Here's one easy thing to try. Under conditions where this
problem consistently happens, pop the hood, pull the IAT
and cool it off. Now try starting.
If it gets way better, then relocating the IAT is for you.
You could also benefit from allowing fan after-run, and
running them full time, both of which will drop engine bay
temps markedly and sensor-heat-soak issues along with.
problem consistently happens, pop the hood, pull the IAT
and cool it off. Now try starting.
If it gets way better, then relocating the IAT is for you.
You could also benefit from allowing fan after-run, and
running them full time, both of which will drop engine bay
temps markedly and sensor-heat-soak issues along with.
05-21-2014, 09:16 PM
#14
Here's one easy thing to try. Under conditions where this
problem consistently happens, pop the hood, pull the IAT
and cool it off. Now try starting.
If it gets way better, then relocating the IAT is for you.
You could also benefit from allowing fan after-run, and
running them full time, both of which will drop engine bay
temps markedly and sensor-heat-soak issues along with.
problem consistently happens, pop the hood, pull the IAT
and cool it off. Now try starting.
If it gets way better, then relocating the IAT is for you.
You could also benefit from allowing fan after-run, and
running them full time, both of which will drop engine bay
temps markedly and sensor-heat-soak issues along with.
Also I got 2 extra fans that come on with the ac clutch. And the ac is on all the time, which means all 4 fans are working all the time.
05-21-2014, 11:23 PM
#15
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Could check the catalytic converters might be restricted stick a vacuum gauge on it when it's hot and running see if it's below 14 in hg just a thought sometimes the do this when hot creates a lot of back pressure makes one slow to crank holding the throttle open relieves this back pressure
05-22-2014, 06:27 AM
#16
Could check the catalytic converters might be restricted stick a vacuum gauge on it when it's hot and running see if it's below 14 in hg just a thought sometimes the do this when hot creates a lot of back pressure makes one slow to crank holding the throttle open relieves this back pressure
05-22-2014, 11:33 AM
#17
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Ok well that's eliminated another thing you could try since it only does it when hot is take the PCM or computer out of its mounting bracket when it's cold get a hair dryer and heat the PCM up and see if it causes your condition a bad solder joint in the PCM could separate under heat and cause it to mess with your PCM values