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White92Cutlass

Car Hesitating/Dying

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White92Cutlass

Shop says computer so I replaced it and it's not fixed. Where do I go from here?

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55trucker

Forget the shop recommendations, personally I feel they are not taking the time to properly diagnose the issue.

Going on just what Info you've supplied & nothing more I'm leaning to an error where the signal back to the ECM from either/both the CTS/ECT sensor & the IAT sensor is concerned.

When the engine is cold the fuel system is running off the default tables programmed into the ECM,  sensors made use of when cold are the CPS (crank position sensor), CTS/ECT (engine coolant temp sensor), IAT (intake air temp) & the MAP sensor.

If the IAT & the CTS signals are out of range with respect to what the ECM is expecting to see the engine will stall. If the MAP is questionable the ECM will not be receiving the accurate info where barometric pressure is concerned to adjust the fuel injector pulse width & engine timing.

 

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White92Cutlass

Car has been at 3 shops- none have been able to fix it. Car has recently had the following replaced by shops:

Fuel pump, fuel filter, 2 coils, coil pigtail, throttle position sensor, PCV and hose, crankshaft position sensor, idle air control.

I replaced all 6 plugs, the computer, the upper intake gasket, all 6 fuel injectors, coolant temp sensor, map sensor, canister purge valve, 02 sensor, and intake air temp sensor. I also did a compression test and fuel pressure regulator test- both test results were fine.

Code 33 and 35 are gone, but it pulls code 45 after short drives (kicks on after car is stopped and idling). No longer smokes like a freight train (with white smoke), but it does have a little white smoke when giving it gas. Never had black smoke. Exhaust no longer smells like gas.

Power is fine, but engine still stumbles upon giving it gas from a dead stop while in drive and still frequently dies when pulling forward from stop signs or putting it in reverse.

Any ideas? Thanks.

Edited by White92Cutlass

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Schurkey

This problem needs a scan tool to look at the data stream.  I bet this would have been solved last November, and without firing the parts cannon.  Find a service manual: (paper book, DVD, or online.)  The manual will tell you WHY the code sets.  There's a specific procedure used to diagnose it.  Follow the procedure, get the results.  Or spend another three months and three more shop charges.  Who knows?  You could get lucky.

Edited by Schurkey

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White93z34

It sounds like the car is dumping fuel, WHY its dumping fuel is what i'd be looking into.

In order I'd check, and before anyone gives me shit i'm using the service manual as a guide.

- Coolant temp sensor, probably a bit tricky to check if you don't have a scantool of some kind but if its showing -40* it will basically be dumping fuel at an alarming rate.

- Fuel pressure regulator, check the vacuum line for gasoline, I'll usually take it a step further and make sure the bladder in it is good with a small hand vacuum pump, they're cheap and you'd be amazed how useful they are. if it can hold -15in its good if it leaks down immediately its bad.

-Check fuel pressure at the rail and see how long after the engine is shut off that pressure drops off. it will drop off, but if it falls like a rock you have issues. 

- The manual says to check TPS performance, again kind of difficult if you don't have a scantool. you can kind of ghetto check with a multimeter on the signal line, that should give you a rudimentary idea if its operating linearly or not. I rather doubt this is the issue.

- The manual calls out checking EGR... I think by 92' it was a digital EGR. might be a bit harder to verify if its staying open or not. you could trace the EGR valve out on a coke can or sheet gasket and make a block off plate of sorts to sandwich in between for testing if you don't have a spare on hand.

 

 

 

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55trucker

All valid points Chris, but why the hell didn't the shop(s) pick up on the 45?

The OP stated he's not a seasoned diagnostician, he's having to rely on paid third parties to solve this vehicles issues & that' doesn't appear to be happening.

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White93z34

Because shops are by and large parts changers and not technicians. Its also not OBD 2 so it may as well be hieroglyphics to many at this point

For something like this its IMO largely unnecessary to even poses a scantool, its a really simple EFI system. I did diagnosis on this sort of thing for many years before I bought a scantool.

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55trucker

That position is fine for the individual who troubleshoots his own vehicles,  for the shop manager who is faced with a comeback  it's unacceptable for the customers vehicle to leave without having been properly checked over before handing the keys back to the owner. I'm left with the opinion that the car wasn't properly real time tested on the road to look for reocurring codes which is precisely what happened.

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White93z34

Obviously, that is the case. Just because you can work at a shop, change parts and dress the part doesn't mean you can troubleshoot anything.

[anecdotal evidence] I just had my new to me Outback in the dealership for the Takata recall, it also had a flashing Brake lamp that seems to indicate something with the electronic park brake, asked them to check that out when it was in. They fixed something or other related to that but also said it had a bad brake lamp switch that was causing it, $250 to change that please. I said no thanks I'll check it out. 2 burned out lamps later the car is fine, cost me $7 in light bulbs. Draw your own conclusion... [/anecdotal evidence]

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mfewtrail

Was the code 45 present before the injector installation? What injectors did you use?

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White92Cutlass
On 5/18/2020 at 8:06 AM, White93z34 said:

It sounds like the car is dumping fuel, WHY its dumping fuel is what i'd be looking into.

In order I'd check, and before anyone gives me shit i'm using the service manual as a guide.

- Coolant temp sensor, probably a bit tricky to check if you don't have a scantool of some kind but if its showing -40* it will basically be dumping fuel at an alarming rate.

- Fuel pressure regulator, check the vacuum line for gasoline, I'll usually take it a step further and make sure the bladder in it is good with a small hand vacuum pump, they're cheap and you'd be amazed how useful they are. if it can hold -15in its good if it leaks down immediately its bad.

-Check fuel pressure at the rail and see how long after the engine is shut off that pressure drops off. it will drop off, but if it falls like a rock you have issues. 

- The manual says to check TPS performance, again kind of difficult if you don't have a scantool. you can kind of ghetto check with a multimeter on the signal line, that should give you a rudimentary idea if its operating linearly or not. I rather doubt this is the issue.

- The manual calls out checking EGR... I think by 92' it was a digital EGR. might be a bit harder to verify if its staying open or not. you could trace the EGR valve out on a coke can or sheet gasket and make a block off plate of sorts to sandwich in between for testing if you don't have a spare on hand.

 

Coolant temp sensor was replaced with a known good one from parts car earlier this month. Fuel pressure/fuel pressure regulator have been checked and are fine. TPS is brand new (shop installed). Pulled known good EGR valve from parts car, haven't installed it yet.

 

 

 

Edited by White92Cutlass

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White92Cutlass
On 5/19/2020 at 5:07 AM, mfewtrail said:

Was the code 45 present before the injector installation? What injectors did you use?

Yes, code 45 was present before the injectors were replaced (Rock Auto injectors) along with codes 33 and 35. After the previously mentioned parts were installed, it got full power back, stopped smoking like a freight train (white smoke), stopped smelling strongly of gas from the exhaust and code 33 and 35 disappeared. Now it just pulls code 45 and dies frequently when taking off from a stop when in drive or reverse.

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