Weak Start When Warm
Thread Starter
Staging Lane
Joined: Oct 2011
Posts: 84
Likes: 0
From: 'Merica
Weak Start When Warm Car is a 2002 Trans Am with 97xxx, auto trans.
I've been trying to figure this problem out for awhile now but still no idea.
Basically, cold start is perfect, car fires up and sounds like it should (VROOM).
Warm start (say I go into the gym for an hour and come back out) the starter cranks fine, but the engine barely sounds like it starts. Like the weakest little vroom and then it builds in a few seconds to normal warm idle. It's never failed to start but it is not even a tenth of the loudness as cold start. Sometimes it will flat out miss the first explosion- the cranking stops and you expect the exhaust sound but you get nothing for a split second and then the weak sound.
My thinking is that something gets heat soaked when the car is left for 1-3 hours but less than 8.
If I stop the car, and start it back up immediately it sounds fine. Quieter like you expect but not sounding like it's going to barely start.
Could it be the injectors going bad/being dirty? Found a guy online with a Toyota that was having what sounded like the same problem but I never heard what his resolution was.
Replaced the battery with a new Optima RedTop about a week ago. Was hoping that would help- it has done nothing.
I've been trying to figure this problem out for awhile now but still no idea.
Basically, cold start is perfect, car fires up and sounds like it should (VROOM).
Warm start (say I go into the gym for an hour and come back out) the starter cranks fine, but the engine barely sounds like it starts. Like the weakest little vroom and then it builds in a few seconds to normal warm idle. It's never failed to start but it is not even a tenth of the loudness as cold start. Sometimes it will flat out miss the first explosion- the cranking stops and you expect the exhaust sound but you get nothing for a split second and then the weak sound.
My thinking is that something gets heat soaked when the car is left for 1-3 hours but less than 8.
If I stop the car, and start it back up immediately it sounds fine. Quieter like you expect but not sounding like it's going to barely start.
Could it be the injectors going bad/being dirty? Found a guy online with a Toyota that was having what sounded like the same problem but I never heard what his resolution was.
Replaced the battery with a new Optima RedTop about a week ago. Was hoping that would help- it has done nothing.
TECH Addict
Joined: Mar 2013
Posts: 2,628
Likes: 30
Could be a few things, 1st thing comes to mind is dirty leaky injectors. 2nd thing is a small coolant leak into one of the cylinders can cause a funny hot start like this too BUT I'd bet on the injectors. Another thing is how old are the spark plugs and wires? They can cause funky starts too. I've experienced the same thing in all my LS1 cars when they needed a injector cleaning. I use Regane every 1000 miles or so.
In a situation like this, I'd first check the temperature inputs to the PCM, namely the coolant temperature sensor and the IAT. If they are lying to the PCM and it thinks that the engine is cold when it is really warm, things won't go well.
Thread Starter
Staging Lane
Joined: Oct 2011
Posts: 84
Likes: 0
From: 'Merica
Thanks for the replies though guys! I will try the injectors first and if that doesn't work, I will see what the PCM is reading. Is there a specific procedure that you remove and clean the injectors?
