94 GTP LQ1 dies while slowing down to a roundabout, no start

[94GTP90SE]

After replacing the starter in my newly purchased GTP, I went for some good fashioned cruising at moderate speed. Coming back home the car is acting completely normal but when I slow down to a roundabout a mile from home she just binged a warning sound and died, dash flashed battery and oil, I think non related. I’ve verified gas is getting to the injectors, but not whether they are clogged. The starter cranks, and all accessories have power. There is some sludge in my radiator cap that I hadn’t noticed before but I feel like If the water pump seized up I would have noticed overheating first unless the thermostat is also bonkers. Could be but the previous owner has a whole list of supposed new parts on this motor (it’s a swap 60k miles) and I had done something similar (reliably) with my 90 se so I believed him. Not sure where to go or what to replace because I am a new to stuff. Sorry for my rambling I’m not good at writing thoughts 

[White93z34]

Start from the basics, Fuel, Spark, Air

Do you have fuel at the rail? not always a positive that you have fuel if you have good pressure at the rail, but a good place to start. circle back to this

spark? if not it could be an ignition control module or crank sensor

Air, there's no basketballs in the intake are there?

If fuel at rail and spark exist check the MAP sensor, is it plugged in, check the MAF sensor, same deal.

Then check for injector pulse, if a fuel injector gets shorted internally it can drag the other 5 down with it. pull a injector plug and put a noid light or just a small lightbulb across the connectors and see if it pulses while cranking.

[94GTP90SE]

46 minutes ago, White93z34 said:

Start from the basics, Fuel, Spark, Air

Do you have fuel at the rail? not always a positive that you have fuel if you have good pressure at the rail, but a good place to start. circle back to this

spark? if not it could be an ignition control module or crank sensor

Air, there's no basketballs in the intake are there?

If fuel at rail and spark exist check the MAP sensor, is it plugged in, check the MAF sensor, same deal.

Then check for injector pulse, if a fuel injector gets shorted internally it can drag the other 5 down with it. pull a injector plug and put a noid light or just a small lightbulb across the connectors and see if it pulses while cranking.

I don’t have a fuel pressure checker, but I did punch my thumb where it would go on the rail and clean fuel came up. I’m not sure if the injector itself is clogged, can I check that without starting the car? Fuel pump supposedly new sender works. I’ve ordered a high flow replacement air filter since the air box is dirty and due for replacement. I also ordered a coil pack. The sparkplugs and wires are new but I’m not sure how to check it for spark. Again I’m new but just because it cranks doesn’t mean you have spark right? The crank sensor concerns me because I cannot find information on where and how to replace it, but it did have issues starting while hot previously. Is the radiator sludge possibly rust? I will post pictures as soon as I can get out there. Thank you bros I’ve been stalking the forums a bit for years, just never had a car to wrench lol

[Cutlass350]

Are you a teenager?  It helps to know your semi-experience.
Still, you replaced the PITA GM starter.  Imho, 99% of all starters SUCK to replace.   
So, it's good that you were able to replace the starter.
 

A fewof things:
1)
The engine will turn over if the CPS is bad.
GM crank sensors are interesting.  Most have 2 independent sensors.  If one is bad the check engine light "should" light.
In Real Life, they often become flaky and often just die, or become flaky.
 

2)
It's unlikely that all 6 injectors clogged at once.  Even with 1-2 clogged injectors, the engine should "start/catch".


3)
You can go a search for:
testing ignition coil "LQ1"

https://www.google.com/search?q=testing+ignition+coil+"LQ1"

The quotes specify that the term must appear.


4)
For any sensor, buy Original GM ONLY!! 
Or, save yourself wasted time and money, and just send the otherwise wasted money directly to me - I take PayPal! 

The only reason anyone buys a non GM part is because of money!  So, those companies Very Often make Cheap Junk, so that their junk parts are cheaper than the junk parts from other companies.

Fwiw, back in the late 90's, for my '92 Achieva, I spent ~1 year, and replacing 4 crank sensors (CPS), before I went to my local GM dealer, and bought a sensor directly from them.  That was in the late 90's.  My '92 Achieva still starts and runs fine with that CPS I bought from the dealer.
 

5)
The BEST MONEY YOU WILL EVER EVER EVER SPEND:
Get the two red GM Service manuals in the picture below:

Search on ebay for:
94 grand prix service manual

https://www.ebay.com/sch/i.html?_from=R40&_nkw=94+Grand+Prix+service+manual&_sacat=0&LH_TitleDesc=0&_sop=15

Plus, they are dirt cheap for your car (~$25)!
The Dealer Service Manuals can often go for $100+/book.
 

6)
Neither you, nor anyone else, was born the the knowledge on how to fix a '94 GTP.
That's where the service manuals, for your specific car, will really help you.
There's also the forum, Google, and Youtube,
 

Good Luck!

Edited October 22, 2021 by Cutlass350

[Schurkey]

Connect a scan tool, find out what the computer is trying to tell you.  "Codes" can be helpful, but the real discovery is in the data stream.  Do you have an RPM signal when cranking?  In ten minutes you can verify EVERY sensor except O2 which will need a running engine.  In fifteen minutes. you can verify most of the computer outputs once the engine is running..

Agree on the service manual set being money well-spent.  I get mine on eBay, used, at advantageous prices.

Getting a fuel-pressure tester is easy.  Many parts stores have a loaner-tool program.  You "buy" the tool, and they refund your money when you return it.  O'Reillys is good for that, but there are other stores that do the same thing.

You may also want to invest in a spark tester calibrated for HEI ignitions.  My favorite style is this kind.  There are several brands, and it pretty much doesn't make any difference which brand you buy--IF (big IF) it's intended for HEI.  Insert it into the end of the spark plug wire just like a spark plug.  Ground it using the welded-on alligator clip.  Crank engine.  You should see the spark snap from the recessed center electrode to the edge of the shell.

https://www.amazon.com/dp/B003WZXAWK/?coliid=I3S98D7T1J0RLJ&colid=2VLYZKC3HBBDO&psc=1&ref_=lv_ov_lig_dp_it

Edited October 22, 2021 by Schurkey

[RPE1992GPSE]

I'd definitely start with a fuel pressure test.  The simple presence of fuel in the line doesn't tell you anything, and due to siphoning from the tank it's expected unless you are out of gas.  Pressure is what's necessary to supply the fuel to the injectors.  I wouldn't spend any time or money on swapping any other parts until you are able to test for fuel pressure.

[94GTP90SE]

1 hour ago, 1992GrandPrixSE said:

I'd definitely start with a fuel pressure test.  The simple presence of fuel in the line doesn't tell you anything, and due to siphoning from the tank it's expected unless you are out of gas.  Pressure is what's necessary to supply the fuel to the injectors.  I wouldn't spend any time or money on swapping any other parts until you are able to test for fuel pressure.

Definitely at least has fuel in the tank, I put some fresh from a jerry can to eliminate possibly of empty tank, I am going to get a fuel pressure tester today. Thank u bro for helping me 

[94GTP90SE]

12 hours ago, Schurkey said:

Connect a scan tool, find out what the computer is trying to tell you.  "Codes" can be helpful, but the real discovery is in the data stream.  Do you have an RPM signal when cranking?  In ten minutes you can verify EVERY sensor except O2 which will need a running engine.  In fifteen minutes. you can verify most of the computer outputs once the engine is running..

Agree on the service manual set being money well-spent.  I get mine on eBay, used, at advantageous prices.

Getting a fuel-pressure tester is easy.  Many parts stores have a loaner-tool program.  You "buy" the tool, and they refund your money when you return it.  O'Reillys is good for that, but there are other stores that do the same thing.

You may also want to invest in a spark tester calibrated for HEI ignitions.  My favorite style is this kind.  There are several brands, and it pretty much doesn't make any difference which brand you buy--IF (big IF) it's intended for HEI.  Insert it into the end of the spark plug wire just like a spark plug.  Ground it using the welded-on alligator clip.  Crank engine.  You should see the spark snap from the recessed center electrode to the edge of the shell.

https://www.amazon.com/dp/B003WZXAWK/?coliid=I3S98D7T1J0RLJ&colid=2VLYZKC3HBBDO&psc=1&ref_=lv_ov_lig_dp_it

Having a hard time finding a code reader to read the car, when I worked at the auto body (Parts guy/Detailer) our scanners are much newer and non compatible, do you know of any OBD 1.5 readers? I’ve got a decent multimeter (learning to use) I just and unfamiliar with location of sensors and such right now. Thank you for helping me bro y’all are awesome 

[94GTP90SE]

14 hours ago, Cutlass350 said:

Are you a teenager?  It helps to know your semi-experience.
Still, you replaced the PITA GM starter.  Imho, 99% of all starters SUCK to replace.   
So, it's good that you were able to replace the starter.
 

A fewof things:
1)
The engine will turn over if the CPS is bad.
GM crank sensors are interesting.  Most have 2 independent sensors.  If one is bad the check engine light "should" light.
In Real Life, they often become flaky and often just die, or become flaky.
 

2)
It's unlikely that all 6 injectors clogged at once.  Even with 1-2 clogged injectors, the engine should "start/catch".


3)
You can go a search for:
testing ignition coil "LQ1"

https://www.google.com/search?q=testing+ignition+coil+"LQ1"

The quotes specify that the term must appear.


4)
For any sensor, buy Original GM ONLY!! 
Or, save yourself wasted time and money, and just send the otherwise wasted money directly to me - I take PayPal! 

The only reason anyone buys a non GM part is because of money!  So, those companies Very Often make Cheap Junk, so that their junk parts are cheaper than the junk parts from other companies.

Fwiw, back in the late 90's, for my '92 Achieva, I spent ~1 year, and replacing 4 crank sensors (CPS), before I went to my local GM dealer, and bought a sensor directly from them.  That was in the late 90's.  My '92 Achieva still starts and runs fine with that CPS I bought from the dealer.
 

5)
The BEST MONEY YOU WILL EVER EVER EVER SPEND:
Get the two red GM Service manuals in the picture below:

Search on ebay for:
94 grand prix service manual

https://www.ebay.com/sch/i.html?_from=R40&_nkw=94+Grand+Prix+service+manual&_sacat=0&LH_TitleDesc=0&_sop=15

Plus, they are dirt cheap for your car (~$25)!
The Dealer Service Manuals can often go for $100+/book.
 

6)
Neither you, nor anyone else, was born the the knowledge on how to fix a '94 GTP.
That's where the service manuals, for your specific car, will really help you.
There's also the forum, Google, and Youtube,
 

Good Luck!

So much good stuff in this one! So to start I am 20 years old, basically a teenager but I have 2 kids so that makes me 69% dumber than you’re average one. I am definitely a beginner when it comes to mechanics and car diagnosis, but I am not completely unknowing. My previous project was a 1990 Pontiac Grand Prix SE, 3.1 MPFI, sunroof, grey leather 2+2. The motor was blown when I got it so I spent 9 months putting a new 3.1, and rebuilding damn near everything for it (with a lot of help from my bro Michael) that was when I was 16. Do you think the crank PS could have just gone out? I read it will not start if it’s completely bad that may be uneducated though. This whole ordeal is very odd to me because I did not experience any symptoms of anything, just the car dying and refusing to turn back on. It just goes wom wom wom wom wom wom when I start it but Nathan. Maybe a clogged TBS? THANK YOU ALL VERY MUCH FOR THE HELP, I hope my bastard car one day becomes part of the family 

[Schurkey]

1 hour ago, 94GTP90SE said:

Having a hard time finding a code reader to read the car, when I worked at the auto body (Parts guy/Detailer) our scanners are much newer and non compatible, do you know of any OBD 1.5 readers? I’ve got a decent multimeter (learning to use) I just and unfamiliar with location of sensors and such right now. Thank you for helping me bro y’all are awesome 

1.  A "code reader" is the mental retard of the diagnostic world.  They're trash.  A "code reader" is not a scan tool.  A scan tool does everything that a code reader does, and much more.  OBD 1.5 is NOT a factor.  "1.5" is used on this forum, but it's not in the service manuals.  Some scan tools will only work on OBD-II; clearly you need one that also works on pre-OBD-II systems.

2.  A multimeter is a GIGANTIC WASTE OF TIME, EFFORT, and ENTHUSIASM in this instance.  I'm not saying a multimeter doesn't have a use, just that it will take two days to check all the sensors and outputs for the engine computer system with a multimeter, and you can do it in fifteen minutes with a proper scan tool if the engine is running.  You won't be able to test the O2 sensor if the engine doesn't start, and you won't get thorough, complete readings from some of the other sensors--but you'd know which are not reporting at all.

3.  I spent 20+ years using a Snap-On MT or MTG 2500 scan tool I bought used on eBay. That will connect to Domestic vehicles from 1980 1/2 to 2008 or 2009, SOFTWARE DEPENDENT.  I had software from 80 1/2 to 2006 for Domestic, some Asian coverage 96--2005, and no European coverage at all.  These tools are very old, the MT2500 was first sold in the mid-to-late 1980s.  They're actually getting scarce on eBay, but they sell cheap.  You'll need the tool including software cartridges and connectors for whatever vehicle(s) you intend to use it on.  I don't really recommend the '2500 series any more unless you get it really cheap.  They quit making them while you were still in diapers.

When I spilled gasoline on my MTG2500, I damaged it.  Replaced it with a Snap-On Solus Pro (Solus family started with the original Solus, replaced by the Solus Pro, replaced by the Solus Ultra, replaced by the Solus Edge, replaced by the current version--Solus Legend.  The prices increase as you move to progressively newer platforms; the prices increase as the included software gets newer, and the prices increase with the number of accessories--adapters/connectors, power cords/chargers, "Personality Keys" for OBD-II vehicles, etc.  The original Solus has 2014 or 2015 as the newest software version, Solus Pro support ended in 2017, I think.  Solus Ultra support supposedly ends the end of this year.)  So if you don't need coverage for newer vehicles, you could buy a tool with software only new enough to cover 2007 or whatever, at reduced price.  I paid about $350 for a Solus Pro with Domestic and Asian software good to 2007, with many but not all the adapters and cables, a battery and battery charger, and a bigass suitcase to carry it all in.  No European software or connectors.  This tool sold new in 2008, so I bought it ~13 years old.

Depending on the scan tool software, and the vehicle it's connected to, a REAL scan tool will communicate with the engine computer, the body computer including transmission, ABS, air bags, instrument cluster, and more.  Older vehicles may only have engine, or engine + ABS.

There are competing products to the Snap-On Solus line. I have zero experience with those products.  OTC has the Genysis and Pegysis, and there's Communist Chinese clones of the "official" GM scan tool--Tech II.  There's "consumer grade" tools from a dozen brand names.  And there's connector cables and software you can load onto any laptop for use as a scan tool.

Point being, if you shop around on Craigslist, pawn shops, and eBay, you can get a (used) PROFESSIONAL-GRADE scan tool for a few hundred dollars.  Just be sure you get the connectors and software needed for the vehicles you're going to use it on.

 

1 hour ago, 94GTP90SE said:

Do you think the crank PS could have just gone out? I read it will not start if it’s completely bad that may be uneducated though. This whole ordeal is very odd to me because I did not experience any symptoms of anything, just the car dying and refusing to turn back on. It just goes wom wom wom wom wom wom when I start it but Nathan. Maybe a clogged TBS?

There's a dozen things it "could" be.  Maybe two dozen.  Verify your fuel pressure.  Make sure the fuel filter isn't plugged, and the fuel pump/pump wire harness isn't defective.  Connect a scan tool, and find out which sensors work, and which don't.

Have you checked all the fuses?  Maybe you popped the fuse for the computer; or the one that powers the injectors.

A compression test could verify that the cam chain hasn't slipped, and that the valves still seal.

 

Edited October 22, 2021 by Schurkey

[94GTP90SE]

On 10/22/2021 at 11:56 AM, Schurkey said:

1.  A "code reader" is the mental retard of the diagnostic world.  They're trash.  A "code reader" is not a scan tool.  A scan tool does everything that a code reader does, and much more.  OBD 1.5 is NOT a factor.  "1.5" is used on this forum, but it's not in the service manuals.  Some scan tools will only work on OBD-II; clearly you need one that also works on pre-OBD-II systems.

2.  A multimeter is a GIGANTIC WASTE OF TIME, EFFORT, and ENTHUSIASM in this instance.  I'm not saying a multimeter doesn't have a use, just that it will take two days to check all the sensors and outputs for the engine computer system with a multimeter, and you can do it in fifteen minutes with a proper scan tool if the engine is running.  You won't be able to test the O2 sensor if the engine doesn't start, and you won't get thorough, complete readings from some of the other sensors--but you'd know which are not reporting at all.

3.  I spent 20+ years using a Snap-On MT or MTG 2500 scan tool I bought used on eBay. That will connect to Domestic vehicles from 1980 1/2 to 2008 or 2009, SOFTWARE DEPENDENT.  I had software from 80 1/2 to 2006 for Domestic, some Asian coverage 96--2005, and no European coverage at all.  These tools are very old, the MT2500 was first sold in the mid-to-late 1980s.  They're actually getting scarce on eBay, but they sell cheap.  You'll need the tool including software cartridges and connectors for whatever vehicle(s) you intend to use it on.  I don't really recommend the '2500 series any more unless you get it really cheap.  They quit making them while you were still in diapers.

When I spilled gasoline on my MTG2500, I damaged it.  Replaced it with a Snap-On Solus Pro (Solus family started with the original Solus, replaced by the Solus Pro, replaced by the Solus Ultra, replaced by the Solus Edge, replaced by the current version--Solus Legend.  The prices increase as you move to progressively newer platforms; the prices increase as the included software gets newer, and the prices increase with the number of accessories--adapters/connectors, power cords/chargers, "Personality Keys" for OBD-II vehicles, etc.  The original Solus has 2014 or 2015 as the newest software version, Solus Pro support ended in 2017, I think.  Solus Ultra support supposedly ends the end of this year.)  So if you don't need coverage for newer vehicles, you could buy a tool with software only new enough to cover 2007 or whatever, at reduced price.  I paid about $350 for a Solus Pro with Domestic and Asian software good to 2007, with many but not all the adapters and cables, a battery and battery charger, and a bigass suitcase to carry it all in.  No European software or connectors.  This tool sold new in 2008, so I bought it ~13 years old.

Depending on the scan tool software, and the vehicle it's connected to, a REAL scan tool will communicate with the engine computer, the body computer including transmission, ABS, air bags, instrument cluster, and more.  Older vehicles may only have engine, or engine + ABS.

There are competing products to the Snap-On Solus line. I have zero experience with those products.  OTC has the Genysis and Pegysis, and there's Communist Chinese clones of the "official" GM scan tool--Tech II.  There's "consumer grade" tools from a dozen brand names.  And there's connector cables and software you can load onto any laptop for use as a scan tool.

Point being, if you shop around on Craigslist, pawn shops, and eBay, you can get a (used) PROFESSIONAL-GRADE scan tool for a few hundred dollars.  Just be sure you get the connectors and software needed for the vehicles you're going to use it on.

 

There's a dozen things it "could" be.  Maybe two dozen.  Verify your fuel pressure.  Make sure the fuel filter isn't plugged, and the fuel pump/pump wire harness isn't defective.  Connect a scan tool, and find out which sensors work, and which don't.

Have you checked all the fuses?  Maybe you popped the fuse for the computer; or the one that powers the injectors.

A compression test could verify that the cam chain hasn't slipped, and that the valves still seal.

 

Yes I have checked all the fuses. As much as I do appreciate what you’re saying here brotha and do not take this as sarcastic, I am familiar with scan tools, Mostly The Modi’s Edge, Atlas, and Opus Systems, I have also used a few other snap ons, currently I don’t have the money to purchase a scan tool, nor is the motor able to run at all for checking them (yes it will be completely helpful to have in the Future, but in the meantime I cannot swing it) the car was running very strong so I doubt there is multiple factors to it’s no start, I would assume just one (again just assume, and I’m sure there’s more problems just not related to this) sorry my message is a bit rushed my kid being a bastard 

[Schurkey]

On 10/22/2021 at 12:15 PM, 94GTP90SE said:

Having a hard time finding a code reader to read the car, when I worked at the auto body (Parts guy/Detailer) our scanners are much newer and non compatible, do you know of any OBD 1.5 readers?

11 minutes ago, 94GTP90SE said:

 I am familiar with scan tools,

Sounded to me like you were looking for advice on scan tools compatible with your vehicle.

[Schurkey]

13 minutes ago, 94GTP90SE said:

nor is the motor able to run at all for checking them

Engine doesn't have to run to basic-check most of the sensors.  It's better if the engine does run, but except for the O2, it's not required.

[Cutlass350]

On 10/22/2021 at 1:24 PM, 94GTP90SE said:

 My previous project was a 1990 Pontiac Grand Prix SE, 3.1 MPFI, sunroof, grey leather 2+2. The motor was blown when I got it so I spent 9 months putting a new 3.1, and rebuilding damn near everything for it (with a lot of help from my bro Michael) that was when I was 16. Do you think the crank PS could have just gone out?

Wow, you likely have more care wrenching experience than ~80% of the people that read the forum.

Yes, any sensor can go at any time.
Also, any sensor can work, not work, work, not work.
And so on.
 

As for Schurkey's comment about scanners, a lot of people that have done simple repairs (like alternators) will not go near a scanner with a 10-foot pole.  Even though there are a gazillion trillion  billion youtube videos on how to attach and use a scanner.  Maybe automotive scanners steal people's soul?

So, trying to convince people to buy and use a scanner is often frustrating, and can take a ton of posts and replies.
Fwiw, I often basically tell people to buy a scanner, or pour 5 gallons of gas on the car, and light it on fire.  Imho, in the end, it would often save the person time and money.   

One note, on my Fox Mustang, I have only codes.  There's no option to read live data.  Still, having error codes helps a lot.
Otherwise, imho, I agree that it's foolish to not have a scan tool that can read live data - especially with their low cost today.

 

Depending on where the CPS is, I suggest replacing it.  But, beware that the generic junk is much worse, and a cr*p shoot.
For GM, the fuel injection system "needs" to calibrate a new Crank Position Sensor.  If you had a Tech-II scan tool (like I do ), you could run that calibration directly.
Still, the tolerances on the generic CPS sensors are junk.
For 99.99% of GM CPS sensor replacements, the calibration difference is minor.  That's one reason why the dealer sensors cost more.
Also, just because a part is "made in the same factory, on the same line, by the same people", that does not mean that part is tested for the same tolerances.  Or, that 100% of the materials are the same.

Fwiw, for what ever reason, GM very rarely displays a CPS error code.
You would need at least a cheap Oscilloscope, to see if the CPS signal is bad.

 

Good Luck!

Edited October 24, 2021 by Cutlass350