Hard to start and missing
Thread Starter
Pro
Joined: Jun 2004
Posts: 520
Likes: 2
From: Mandeville, LA / Clemson, SC
Hard to start and missing
The other day I got on it, it revved to 5700 and died. It took a while but started back up.
This morning I was just driving regular and it died. Started right back up though.
I washed the motor a little while ago and it would start. I thought for sure opti again (I just went though this a year ago when I did the same thing). I checked spark and had it so I put the plug back in and it fired up. I died after a while of rough running and threw a code 15. I just changed out my coolant temp senor a couple of weeks ago.
I'm a little unclear about this are there two coolant temp sensors. One for the ECM and one for the gauge??? Or is there only one on the water pump??
Well the car starts and runs but it takes a lot more time for it to start any ideas???
This morning I was just driving regular and it died. Started right back up though.
I washed the motor a little while ago and it would start. I thought for sure opti again (I just went though this a year ago when I did the same thing). I checked spark and had it so I put the plug back in and it fired up. I died after a while of rough running and threw a code 15. I just changed out my coolant temp senor a couple of weeks ago.
I'm a little unclear about this are there two coolant temp sensors. One for the ECM and one for the gauge??? Or is there only one on the water pump??
Well the car starts and runs but it takes a lot more time for it to start any ideas???
Melting Slicks
Joined: Oct 2004
Posts: 2,510
Likes: 4
From: Austin Texas
why would you wash your engine again, as it appears that you are aware of the Opti and it's adversion to getting wet????
Could be alot of things....are your codes clear now? Could be heat sensitive components: ICM, Coil, poor connection between coil wire and Opti...
More info. needed to diagnose your problem.
"I'm a little unclear about this are there two coolant temp sensors. One for the ECM and one for the gauge??? "
Yes, one for your instrument cluster, one for your ECM. The other sensor is on the driver side block....I think...someone else can clarify/substantiate this.
Could be alot of things....are your codes clear now? Could be heat sensitive components: ICM, Coil, poor connection between coil wire and Opti...
More info. needed to diagnose your problem.
"I'm a little unclear about this are there two coolant temp sensors. One for the ECM and one for the gauge??? "
Yes, one for your instrument cluster, one for your ECM. The other sensor is on the driver side block....I think...someone else can clarify/substantiate this.
Last edited by MikeC4; Jun 30, 2006 at 07:27 PM.
Thread Starter
Pro
Joined: Jun 2004
Posts: 520
Likes: 2
From: Mandeville, LA / Clemson, SC
Originally Posted by MikeC4
Yes, one for your instrument clusters, one for your ECM. The other sensor is on the driver side block
QUOTE=MikeC4]why would you wash your engine again???[/QUOTE]
I know...I know...well I was bringing my vette to a vette show and I work down a gravel road...sorry...I just wanted it to look good. I've probably washed the motor 15 times with the new opti. I just cover as much of the front of the motor as possible. It has always worked before.
Sorry for being vague in my post.
Bottom line now....it starts but it takes the starter more time for it to start. Before I could tap the key and it would fire right up...now it takes a few revolutions. Also, I took it on a ride and it would have a random miss. (pretty hard miss too). I am throwing code 15 the whole time. I am getting consistent spark on one cyl that I've kept checking so I don't know...I guess it could still be the opti. Would a coolant sensor do all of that???
The last 2 times I started it, it fired right up like normal but still had a miss every once in a while.
Thanks,
Jeff
Le Mans Master
Joined: May 2005
Posts: 5,214
Likes: 65
From: Queensland, AUSTRALIA
When this happens, have the digital info area set to "COOLANT TEMP" and if it flicks to "LO", there is your issue right there. Clean the plug, make sure its not damaged, make sure the sensor is in good looking shape. Its the one in the water pump.
Le Mans Master
Joined: Feb 2006
Posts: 8,753
Likes: 9
From: Louisiana
If you have a code 15 and it is the CTS, I would check into it. Could be a bad connection, circuit, sensor. You can ohm it to see if it matches the temp the engine/outside air is. If you do ohm it post what the ohm meter said so that we can match it up. Do you have a FSM?
Le Mans Master
Joined: May 2005
Posts: 7,310
Likes: 2,231
From: Central Maryland
The sensor that feeds ECT data to the ECM is the one in the water pump. This is the one that the ECM reads to learn what it nees to know about coolant temp for purposes of calculating spark timing, fuel trim, etc, and it's the sensor that'll cause the ECM to toss a Code 15 F (as a side note, the digital ECT reading in the Instrument Panel comes from the ECM, and is also derived from input from this sensor). Check the connection to this sensor carefully, and you may find your problem.
The sensor on the cylinder head only runs the analog gauge on the IP, and does not communicate with the ECM at all, so the ECM is blind to what it is doing.
Be well,
SJW
The sensor on the cylinder head only runs the analog gauge on the IP, and does not communicate with the ECM at all, so the ECM is blind to what it is doing.
Be well,
SJW
Thread Starter
Pro
Joined: Jun 2004
Posts: 520
Likes: 2
From: Mandeville, LA / Clemson, SC
I changed out the correct ECT (on the waterpump) and it is running fine. No more code and no more miss. Either the ECT was the problem or water got into the opti when I washed the motor and worked its way out after it cooled. Thanks for all the advice!!
Jeff
Jeff
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Water DID NOT get into the distributor.... everybody seems to love blaming this for every single little issue. I wash my engine almost every week and never had a problem!!!! 
Thread Starter
Pro
Joined: Jun 2004
Posts: 520
Likes: 2
From: Mandeville, LA / Clemson, SC
Originally Posted by RRT vette
My bet: the CTS was bad.Thanks again,
Jeff
