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Need Help with a Crank, start , immediate die

Chaddfc

New member
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Regal custom
I have a 1996 Buick Regal that cranks and only starts if i hold the gas down. Backfires, and will immediately die. Ive checked fuel pressure by the fuel rail and it was perfect. New battery. Replaced the Cam sensor, crank sensor , harmonic balancer. Need suggestions on what to check next....at a loss. Car ran great a month ago.
 

Chaddfc

New member
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Buick Ownership
Regal custom
Disconnect MAF sensor cable. If car runs, then you know it is a problem related to MAF or related wiring. . .

Similar problem on our 2001 Regal in Oct.
Yup i tried that and still turns over but no start...unless im holding down gas pedal but then i get rough with some backfire and white smoke out exhaust
 

richardnewton

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Chaddfc

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Regal custom
Have you checked the TPS voltage @ idle & through the whole range, to WOT throttle?
Part 1 -How to Test the GM 3.8L Throttle Position Sensor (TPS)
I just checked EGR and it was ok with all multimeter tests...carbon. but i cleaned as much out as i could...then the TPS test... it failed so ill need to be replacing that. I also noticed the sensor right by the TPS sensor was ticking with car off but key in on position. I believe its the idle air control? Why is it ticking? Should i just replace this too?
 

HotZ28

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1996 Roadmaster Limited Collectors Edition 58k - 1996 PAU
The IAC will try to to set idle speed when the ignition is turned ON, so the engine can start with the correct RPM/PCM settings when cold/warm.
 

Chaddfc

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Regal custom
The IAC will try to to set idle speed when the ignition is turned ON, so the engine can start with the correct RPM/PCM settings when cold/warm.
Well the tps tested bad and iac is ticking ...if i replace both you think that may be the cause of the crank , start , immediate die?
______________________________
 

richardnewton

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It seems you are approaching the issue. . .

As TPS failed, I don't think they are really fixable at home. I recently replaced the TPS for $30 on our Buick Rendezvous (random surging idle so very difficult to diagnose that failed TPS as it tested fine). Replace TPS and see if that solves problem.

As HotZ28 notes, you may be able to very gently clean the IAC valve/ports; if there is an o-ring make sure it is in good nick and to carefully position it when reinstalling the IAC. I would do the cleaning whilst you are right there replacing the TPS so will only take a few minutes. I would clean and test before replacing to save money.

FYI - Low voltage can cause TPS and other systems to improperly calibrate at start-up. Do a quick check on your battery (big autoparts stores often test for free). You can also do voltage drop test to make sure grounds and power lines are not showing excessive resistance. There are some good youtube videos to get you started (I referenced a few on this forum).
 

Chaddfc

New member
14
6
3
Buick Ownership
Regal custom
It seems you are approaching the issue. . .

As TPS failed, I don't think they are really fixable at home. I recently replaced the TPS for $30 on our Buick Rendezvous (random surging idle so very difficult to diagnose that failed TPS as it tested fine). Replace TPS and see if that solves problem.

As HotZ28 notes, you may be able to very gently clean the IAC valve/ports; if there is an o-ring make sure it is in good nick and to carefully position it when reinstalling the IAC. I would do the cleaning whilst you are right there replacing the TPS so will only take a few minutes. I would clean and test before replacing to save money.

FYI - Low voltage can cause TPS and other systems to improperly calibrate at start-up. Do a quick check on your battery (big autoparts stores often test for free). You can also do voltage drop test to make sure grounds and power lines are not showing excessive resistance. There are some good youtube videos to get you started (I referenced a few on this forum).
I replaced rhe TPS and cleaned IAC valve and battery is new... still no start. I did notice however it looked like someone put the green coolant in at some point when its supposed to have dex cool . I pulled some spark plugs and cleaned them as they were very nasty and while they were removed i had someone turn it over and a puff of whiteish smoke came from the spark plug holes.... i dont really know what my next step should be. Any help appreciated.
______________________________
 

richardnewton

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Buick
3800 coils die somewhat frequently. Or ignition module underneath the coils. Here is simple diagnosis video to test. If bad, OEM only:


Since spark plugs are in terrible shape, you should clean, check gaps and check for damage. The plug wires need to be replaced on occasion as they are close to heat so can also cause very rough running. Getting back plugs is a struggle; search my post for some videos with "tricks". One clue to show you have original wires is that they will be labeled 1,2,3,4,5,6 (replacement wires rarely have numbers printed on them.)
 

Chaddfc

New member
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3
Buick Ownership
Regal custom
I wil
3800 coils die somewhat frequently. Or ignition module underneath the coils. Here is simple diagnosis video to test. If bad, OEM only:


Since spark plugs are in terrible shape, you should clean, check gaps and check for damage. The plug wires need to be replaced on occasion as they are close to heat so can also cause very rough running. Getting back plugs is a struggle; search my post for some videos with "tricks". One clue to show you have original wires is that they will be labeled 1,2,3,4,5,6 (replacement wires rarely have numbers printed on them.)
I will give it a shot thank you
 

HotZ28

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1996 Roadmaster Limited Collectors Edition 58k - 1996 PAU
Coolant color has nothing to do with coolant leaks into the combustion chambers! You should have a hot & cold level mark on the reservoir, how did you check that, hot or cold? Have you ever added any coolant? It sounds like you have coolant contamination on the plugs and in the combustion chambers. The plugs will not fire when coolant soaked.
 
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