car won't start

manjamojo

New Member
Jul 16, 2007
6
0
0
N.E. Wisconsin
Background: I was leaving work and tried to start my car. I turned the key and the starter starts turning the engine over. I hear the engine chugging and puffing, but it wouldn't start. Every now and then the engine would puff and the RPMs would slightly increase, meaning the engine seems to be getting fuel.

Diagnosis: I could smell fuel after a while and verified the fuel pump is working by jumping the B+ and Fp? (can't remember if those are correct without looking at them, but I assure you I did the right ones) connection in the diagnostic connector. I tested the spark between wires and plugs with a spark tester and everything is getting spark. I tested the Cam position sensor and got around 175 ohms for all connections, which is good per the TSRM. Even though those resistances checked out okay, can the air gap between the pickup coils and the mechanical lobe inside the CPS be bad? Then, I checked the engine codes as well and got the infamous 51. Therefore, I immediately thought TPS, but I initially thought Cam position sensor because I didn't think the TPS would cause my engine not to start, correct me if I am wrong please. I looked up the electrical schematics on the TSRM for the TPS and saw the water temperature sensor was in this circuit as well. I fixed the water temp sensor wire and code 51 was corrected, so I never checked my TPS. Can the water temp sensor cause my car to not start because now my car starts and idles just fine, but after about 30mins of running and varying RPMs, the car will die and shut off? That is my reason for this writeup. I need to know if the water temp sensor would cause my car to not start. If this is not the case, then what, if anything, am I possibly overlooking? I have faith in my CPS testing skills, but electronics get squirrely sometimes and maybe the CPS is working sometimes and not working other times, can this be the case? Thank you in advance for reading this long writeup and answering.
 

Nick M

Black Rifles Matter
Sep 9, 2005
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Even though those resistances checked out okay, can the air gap between the pickup coils and the mechanical lobe inside the CPS be bad?

Yes.

Do you understand what 51 is?

I need to know if the water temp sensor would cause my car to not start.

No . It could be difficult to start under certain conditions I suppose. Did you look at the tune up parts? Pull the number one plug and look at it.
 

manjamojo

New Member
Jul 16, 2007
6
0
0
N.E. Wisconsin

So, the CPS might still be bad and I should take the cover off and check the air gaps?

Do you understand what 51 is?

I understand that it means there is a bad TPS, something wrong with the TPS circuit, A/C amplifier, etc. I don't understand why you asked this question though. The code cleared after I fixed the water temp sensor wire. Can a bad TPS make my car not start? I thought it would just run poorly.



No . It could be difficult to start under certain conditions I suppose. Did you look at the tune up parts? Pull the number one plug and look at it.

The plugs are pretty corroded, but there is only around 20,000 miles on them and they are NGK platinum. I have MSD 8.5mm wires which have around 20,000 miles also.
 

jetjock

creepy-ass cracka
Jul 11, 2005
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Redacted per Title 18 USC Section 798
manjamojo said:
I don't understand why you asked this question though. The code cleared after I fixed the water temp sensor wire.

Do know what the term "post hoc" means? It's a logical fallacy, an error in reasoning common among people without training in diagnostic skills. You were a victim of it. That's why he's asking.
 

manjamojo

New Member
Jul 16, 2007
6
0
0
N.E. Wisconsin
jetjock said:
Do know what the term "post hoc" means? It's a logical fallacy, an error in reasoning common among people without training in diagnostic skills. You were a victim of it. That's why he's asking.

So I guess I will go test the TPS then because I shouldn't assume it is working correctly. Will a bad TPS cause my car to not start though?
 

Nick M

Black Rifles Matter
Sep 9, 2005
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I don't think so. The throttle position sensor is a potentiometer. That is a variable resistor like the dial on your wall in the dining room. It allows the lights to be bright, dim or in between. The TPS tells the computer what your intentions are. If you didn't have one, the car would still run, just not as well.

I suppose a back feed might screw up the computer, but in general, it won't cause a no start.

Take a look at the ignition parts closely. Toyota is pretty sensitive to those things.
 

ATL88Supra

The Asshole
Jun 22, 2007
497
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0
41
Atlanta, Georgia, United States
check the coils a bad tps would not alow the car to start

a failing tps would cause the car to start and run very badly or in some cases not at all

check it make sure it works

you have fuel so dont worry about that
 

Nick M

Black Rifles Matter
Sep 9, 2005
8,897
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I know if you lose the Ne signal, the car won't run. Normally, correction sensors just get a known good value to use.
 

jetjock

creepy-ass cracka
Jul 11, 2005
9,439
0
0
Redacted per Title 18 USC Section 798
Right, NE and Ks are critical signals but with trim sensors it doesn't matter much. That makes you right about the TPS. Since there are several failure modes of the TPS one has to define "bad" but in every case they won't prevent the engine from starting or being driven. Only one type of failure would greatly impact operation and even then the car could still be driven. I've said it many times: what good would an EFI system be if it stranded you every time a trim sensor failed? Anyone doubting this should go out and unplug their TPS then see if the engine can be started and the car driven.
 

BiLL'smk3

awholelotofboost
Jun 28, 2007
1
0
0
Palatine,IL
manjamojo said:
Background: I was leaving work and tried to start my car. I turned the key and the starter starts turning the engine over. I hear the engine chugging and puffing, but it wouldn't start. Every now and then the engine would puff and the RPMs would slightly increase, meaning the engine seems to be getting fuel.

Diagnosis: I could smell fuel after a while and verified the fuel pump is working by jumping the B+ and Fp? (can't remember if those are correct without looking at them, but I assure you I did the right ones) connection in the diagnostic connector. I tested the spark between wires and plugs with a spark tester and everything is getting spark. I tested the Cam position sensor and got around 175 ohms for all connections, which is good per the TSRM. Even though those resistances checked out okay, can the air gap between the pickup coils and the mechanical lobe inside the CPS be bad? Then, I checked the engine codes as well and got the infamous 51. Therefore, I immediately thought TPS, but I initially thought Cam position sensor because I didn't think the TPS would cause my engine not to start, correct me if I am wrong please. I looked up the electrical schematics on the TSRM for the TPS and saw the water temperature sensor was in this circuit as well. I fixed the water temp sensor wire and code 51 was corrected, so I never checked my TPS. Can the water temp sensor cause my car to not start because now my car starts and idles just fine, but after about 30mins of running and varying RPMs, the car will die and shut off? That is my reason for this writeup. I need to know if the water temp sensor would cause my car to not start. If this is not the case, then what, if anything, am I possibly overlooking? I have faith in my CPS testing skills, but electronics get squirrely sometimes and maybe the CPS is working sometimes and not working other times, can this be the case? Thank you in advance for reading this long writeup and answering.

check your injector fuse under the hood theres a bunch of fuses that should do it.

if its not that it a vacum leak
 

manjamojo

New Member
Jul 16, 2007
6
0
0
N.E. Wisconsin
Last night I got the car to start. The weird thing is that I didn't fix anything. It seems to bascially start when it wants to. I drove it around a bit and it boosted just fine and It didn't stall or anything. Being that it runs and starts just fine means I can eliminate the CPS right? I assume that if the CPS was bad, it stays bad and won't work when it wants to. I didn't get to check all the electrical connections last night, so I will do more tonight.

Can the fuel pump be working when it wants to? Something is funky with this car and leading me towards a loose connection in the wires, unless someone can verify the fuel pump will work when it wants (if it is going bad). I tried connecting B+ and Fp again and I didn't hear the fuel pump working, but my car would still start. I will look into this more.

I also disconnected the TPS and the car started and idled a little rough, which is expected. I even varied the RPMs and it never stalled, which is good.

So without the bad "car not starting" symptoms showing up, it will be harder to find the underlying reason for this happening. I will go through and look at all the ignition connections more closely though. So, being that the car is starting and running, are there any suggestions as to where to go next at finding the problem?

Thank you all for the replys.
 

manjamojo

New Member
Jul 16, 2007
6
0
0
N.E. Wisconsin
I tested the CPS a little more tonight. I inspected the air gaps and G1 and G2 were within spec. I could fit a .406mm feeler gauge into NE, but not .432mm. Is that close enough even though TSRM says 0.4mm max? I also decided to check the pickup coil resistance again, just for assurance. This time I got readings of around 196 ohms for all three, WTF? When I tested them the first time (4 days ago), I got around 175 ohms for all three. The car was not driven at all. When I tested them the first time the car was cold and now the car was warmed up because I was running it for a while. I don't believe the coils would read different if the coils were warm.

I also checked the timing and it was a little off. It was around 15 degrees when it should be 12 degrees max. So I adjusted the timing by connecting the terminals in the diagnostic and set the timing to 10 degrees BTDC. I am thinking all of these things might be contributing to my car problems. It also looks like I have a lot of work ahead of me...
 

JB91389

decisions...decisions...
Jun 22, 2006
698
0
0
35
Ottawa
i had a similar problem....but my problem was my igniter...replaced it and it was fine...
 

ATL88Supra

The Asshole
Jun 22, 2007
497
0
0
41
Atlanta, Georgia, United States
funny thing is i had a scare like this last night its funny how something will go wrong with this car and you can come back in the morning and it runs just fine, sorta like this car has mood swings

so i guess this is one of the things that comes with age.
 

manjamojo

New Member
Jul 16, 2007
6
0
0
N.E. Wisconsin
ATL88Supra said:
funny thing is i had a scare like this last night its funny how something will go wrong with this car and you can come back in the morning and it runs just fine, sorta like this car has mood swings

so i guess this is one of the things that comes with age.


Yet another reason why cars are like women...:biglaugh: