Engine will not hot start, need to wait

Tiny
WILLIINTALKEETNA
  • MEMBER
  • 2000 CHEVROLET TRACKER
  • 1.6L
  • 4 CYL
  • 4WD
  • MANUAL
  • 101,000 MILES
My vehicle has developed a problem, and there are no associated error codes from the computer. It runs perfectly, but if taken on a long highway run, especially when the weather in warm (Alaska), as in never in winter, if the engine is shut off it will not hot start until you wait about twenty minutes. Then it starts and runs fine. In warm weather it will occasionally stall when idling in traffic for too long, or going at slower speed up a steep hill after a highway run. I replaced spark plugs and wires (needed after 101,000 miles) and did other tune up chores. No difference. A GMC dealer was convinced that it was due to both catalytic converters being plugged, I was skeptical but had them replace them. No difference. I was able to catch the engine when it wouldn't start and pulled a plug and attached a spark tester and there was no spark. I replaced both coils (no distributor in this model) thinking it may be a coil pack failure. No change. The only other think I can think of is a malfunctioning control unit (computer). Anyone have any thoughts?
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Friday, June 7th, 2019 AT 1:14 PM

18 Replies

Tiny
JACOBANDNICKOLAS
  • EXPERT
Welcome to 2CarPros.

What you described sounds nothing like catalytic converters, but rather a bad crankshaft position sensor. When they start going bad, they are adversely affected by heat and cause the engine to lose spark. Once they cool down, they work again. Also, it is common for them to not set a trouble code. Take a look through these links:

https://www.2carpros.com/articles/how-a-crank-shaft-angle-sensor-works

https://www.2carpros.com/articles/symptoms-of-a-bad-crankshaft-sensor

I feel somewhat sure this is the problem. Here is a link that explains in general how one is replaced. It's not hard to do.

https://www.2carpros.com/articles/crankshaft-angle-sensor-replacement

Here are the directions for replacement specific to your vehicle. I attached a picture so you can see where it is located. Honestly, get the sensor and replace it yourself. I realize you don't have a hoist, but you should be able to craw under the vehicle to access it.

++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

REMOVAL PROCEDURE

CAUTION: Refer to Vehicle Lifting Caution in Cautions and Notices.

1. Raise the vehicle on a hoist.
2. Disconnect the CKP sensor electrical connector (2).
3. Remove the CKP sensor retaining bolt (3).
4. Remove the CKP sensor (1).

INSTALLATION PROCEDURE
1. Install the CKP sensor (1) into the oil pan.

NOTE: Refer to Fastener Notice in Cautions and Notices.

2. Install the retaining bolt (3).

Tighten
Tighten the retaining bolt to 6 N.m (54 lb in).

3. Reconnect the CKP sensor electrical connector (2).
4. Lower the vehicle.

++++++++++++++++++++++++++++++++++++++++

Let me know if this helps. Also, if you have other questions, let me know.

Take care,

Joe
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Friday, June 7th, 2019 AT 7:47 PM
Tiny
WILLIINTALKEETNA
  • MEMBER
Thanks for the great details! On my to do list, and I'll keep my fingers crossed.
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Sunday, June 9th, 2019 AT 9:49 AM
Tiny
JACOBANDNICKOLAS
  • EXPERT
Welcome back:

Let me know if that takes care of the problem or if you have other questions.

Take care,
Joe
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Sunday, June 9th, 2019 AT 7:00 PM
Tiny
WILLIINTALKEETNA
  • MEMBER
I tested the sensor with Ohm meter (I do not have an oscilloscope) and it was fine cold, but slightly out of spec when hot, so I replaced it. It did not solve the problem. My understanding is that if a camshaft sensor is bad it will be slow to start, but not stall out or totally not start. When the car is hot and not starting, there is no spark (tested with tester and one plug removed). Any thoughts? I also replaced both coils as they were suggested to be a potential problem (I had earlier replaced spark plugs and plug wires tuning up the engine). It has been suggested to me that the computer may be bad...
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Sunday, June 16th, 2019 AT 7:10 PM
Tiny
JACOBANDNICKOLAS
  • EXPERT
Welcome back:

My first suspect was the crankshaft position sensor. If that is working, then my next suspect is the camshaft sensor. The powertrain control module (PCM) uses reference pulses from the camshaft position sensor (CMP) sensor in order to determine engine speed. The PCM cannot operate the ignition system - or the fuel injectors - without the engine speed signal from the CMP.

The CMP is located top rear of the engine. See pic 1.

Here are the directions for replacement. Pic 2 correlates with the directions.

____________________

CAMSHAFT POSITION (CMP) SENSOR REPLACEMENT

See Pic 2

REMOVAL PROCEDURE
1. Remove the CMP sensor electrical connector (2).
2. Disconnect the ground strap.
3. Remove the CMP sensor retaining bolt (1).
4. Remove the CMP sensor (3).

INSTALLATION PROCEDURE
1. Apply a thin coat of engine oil to the sensor O-ring.
2. Install a CMP sensor (3).

NOTE: Refer to Fastener Notice in Cautions and Notices.

3. Install the retaining bolt (1).

Tighten
Tighten the retaining bolt to 9 N.M (78 lb in).

4. Reconnect the CMP sensor electrical connector (2).
5. Reconnect the ground strap.

Let me know if this helps.

Joe
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+1
Sunday, June 16th, 2019 AT 8:35 PM
Tiny
WILLIINTALKEETNA
  • MEMBER
My manual gives input voltage specs for the camshaft position sensor, but no actual testing for the sensor itself. The input voltages are within spec when cold, but I need to check when hot. If this checks out okay, I guess I will try replacing the camshaft position sensor and see if that fixes the problem. Okay, checked hot also while engine would not start, and the input voltages for the camshaft sensor are within spec.
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Thursday, July 4th, 2019 AT 9:41 AM
Tiny
JACOBANDNICKOLAS
  • EXPERT
Welcome back:

Did you check the crankshaft position sensor?

Let me know.

Joe
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Thursday, July 4th, 2019 AT 6:40 PM
Tiny
WILLIINTALKEETNA
  • MEMBER
As noted above, yes. Engine has a new crankshaft position sensor in it.
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Friday, July 5th, 2019 AT 2:48 PM
Tiny
JACOBANDNICKOLAS
  • EXPERT
Okay, next check to make sure the ignition meter fuses is good. See pic 1. I highlighted the fuse. Also, check the two fuses indicated in picture 2. Picture 1 is in the vehicle and 2 us under the hood.

If the cam and crank sensors are good, the coils (which have a built in ignition control module) are new, you have power to the sensors, and the fuses are good, the next thing is the power control module. However, you checked the cam sensor connections and they checked good. That was coming from the PCM, so lets hope it's just a blown fuse.

Let me know what you find.

Joe
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Friday, July 5th, 2019 AT 5:39 PM
Tiny
WILLIINTALKEETNA
  • MEMBER
I don't quite get why a fuse problem would allow the engine to run fine cold and not run hot. But in the interests of being thorough, I checked everything. I have good fuses, good clean connections with no corrosion at all in any connection, and electrical continuity everywhere...
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Wednesday, July 10th, 2019 AT 4:51 PM
Tiny
WILLIINTALKEETNA
  • MEMBER
I guess it is time to start shopping in earnest for a Power-train Control Module...
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Wednesday, July 10th, 2019 AT 4:53 PM
Tiny
JACOBANDNICKOLAS
  • EXPERT
Welcome back:

You know, that's a last resort and I feel you have covered everything else. However, we never checked anything with fuel related issues. It honestly doesn't seem related, but I want you to try something. When the engine is hot and it won't restart. See if it will for a couple seconds using starting fluid. If it starts for a couple seconds, then we have a fuel related issue.

Try that and let me know. I don't want to replace the PCM without being sure it is an ignition related issue.

Joe
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Wednesday, July 10th, 2019 AT 8:07 PM
Tiny
WILLIINTALKEETNA
  • MEMBER
I pretty much already ruled that out. At the beginning of this very long train of correspondence, when the engine will not hot start, there is no spark checked with a spark tester on a plug lead with the spark plug removed from the cylinder, When the engine cools sufficiently, the spark comes back.
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Thursday, July 11th, 2019 AT 6:23 AM
Tiny
JACOBANDNICKOLAS
  • EXPERT
Welcome back:

I hate to ask this and I reread everything we talked about. You mentioned checking the cam sensor. You indicated you replaced the crank sensor. Did you replace the camshaft position sensor? My guess is if you were here, you would slap me for asking. But honestly, there is a mention of it, but I don't know if it was replaced. You mentioned you were going to but I never confirmed it. Sorry.

Also, if everything checks good and you have no spark when hot, I guess the PCM is the issue. It is the only thing left. You did check everything when there was no spark, correct?

Also, if you look at the attached picture, it is an OEM schematic of the camshaft circuit. When the vehicle fails, I need you to confirm power and ground to the ground circuit at the PCM. If there is no ground, then the PCM has failed. That is what completes this circuit. Maybe heat is affecting it.

Let me know.

Joe
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Thursday, July 11th, 2019 AT 7:32 PM
Tiny
WILLIINTALKEETNA
  • MEMBER
Slight hiccup! When I next got time to work on the car, I did replace the camshaft sensor. Unfortunately it must have been an aftermarket one made in China that the physical specs were not quite right. I installed the sensor and snapped the wire in and remember thinking, wow, that is a tight fit. Then I tried the car and it would not cold start (for the first time). Bad sensor? Tried to take out the sensor and put the old one back in to test it, but cannot unplug the wire from the new sensor whatever I try, including using small screwdrivers to try and release the locking tab on the wire plug in too tight! It will be a few days before I have time to do battle with it again.
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Thursday, July 18th, 2019 AT 10:35 AM
Tiny
JACOBANDNICKOLAS
  • EXPERT
Could you have forced it on the wrong direction?
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Thursday, July 18th, 2019 AT 6:55 PM
Tiny
WILLIINTALKEETNA
  • MEMBER
Nope, definitely not. I haven't had time to get back to it yet...
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Friday, July 19th, 2019 AT 4:57 PM
Tiny
JACOBANDNICKOLAS
  • EXPERT
Welcome back:
You mentioned it was tighter going together. That's why I asked. Thinking something may have been put together differently.

When you get back to it, let me know.

Take care,
Joe
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Friday, July 19th, 2019 AT 7:17 PM

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