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3800 SC SII W/4T65E-HD. NO PULSE AT INJECTORS by CC Rider
Started on: 06-20-2013 04:34 PM
Replies: 14 (366 views)
Last post by: CC Rider on 07-15-2013 09:12 AM
CC Rider
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Report this Post06-20-2013 04:34 PM Click Here to See the Profile for CC RiderClick Here to Email CC RiderSend a Private Message to CC RiderEdit/Delete MessageReply w/QuoteDirect Link to This Post
Need some help please.
No pulse signal at the injectors when cranking.
Car will start if carb cleaner applied.
All ECM grounds rung out.
Power at injectors with key on.
Injectors bench tested and working.
All engine sensors connected.

Any troubleshooting help appreciated.
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phonedawgz
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Report this Post06-20-2013 05:38 PM Click Here to See the Profile for phonedawgzClick Here to visit phonedawgz's HomePageClick Here to Email phonedawgzSend a Private Message to phonedawgzEdit/Delete MessageReply w/QuoteDirect Link to This Post
Q1 - Is the PCM running?

How to find out - Turn the key to on. Does the PCM run the fuel pump relay for two seconds and then drop off? It should. If not check for power to the PCM. Both switched and unswitched.

Q2 Is the PCM getting ignition pulses?

How to find out - AFTER passing the above, just bump the starter and see if the fuel pump relay comes on for two seconds again and then turns off again. It should. If not then look for why the PCM isn't getting ignition pulses. Note - If you crank the engine and oil pressure is built up, the oil pressure sender can also turn on the fuel pump. This is why you must only bump the starter for this test to be accurate.

Q3 Do you have an OBD2 scan tool/cable?

[This message has been edited by phonedawgz (edited 06-20-2013).]

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CC Rider
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Report this Post06-20-2013 05:59 PM Click Here to See the Profile for CC RiderClick Here to Email CC RiderSend a Private Message to CC RiderEdit/Delete MessageReply w/QuoteDirect Link to This Post
Hay Phonedawgz - was hoping you would respond - thanks
Will answer your questions I the next few days but thanks for the leads.
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darkhorizon
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Report this Post06-20-2013 11:23 PM Click Here to See the Profile for darkhorizonSend a Private Message to darkhorizonEdit/Delete MessageReply w/QuoteDirect Link to This Post
Spark?
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CC Rider
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Report this Post06-21-2013 09:09 AM Click Here to See the Profile for CC RiderClick Here to Email CC RiderSend a Private Message to CC RiderEdit/Delete MessageReply w/QuoteDirect Link to This Post
Yes
As I said above, it will run with carb cleaner.
Will be able to get back on it tomorrow and will report back.

Yes - I have a scan tool
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phonedawgz
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Report this Post06-21-2013 09:43 AM Click Here to See the Profile for phonedawgzClick Here to visit phonedawgz's HomePageClick Here to Email phonedawgzSend a Private Message to phonedawgzEdit/Delete MessageReply w/QuoteDirect Link to This Post
So watch with the scan tool. See if it hooks up (PCM working). See if it shows the engine rotating during cranking. Finally make sure it shows the throttle working properly and closed during cranking.
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CC Rider
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Report this Post06-21-2013 02:12 PM Click Here to See the Profile for CC RiderClick Here to Email CC RiderSend a Private Message to CC RiderEdit/Delete MessageReply w/QuoteDirect Link to This Post
OK - thanks
Fun weekend ahead
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CC Rider
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Report this Post06-23-2013 03:26 PM Click Here to See the Profile for CC RiderClick Here to Email CC RiderSend a Private Message to CC RiderEdit/Delete MessageReply w/QuoteDirect Link to This Post
Ended up being pin c1 20 Unswitched.
The fuse was blown. Changed and it fired right up.
Must had been blown prior to install and I did not notice it.
Getting a P0300 and P0134. That's a new 02 sensor so ill ring out the wires and if good change it out.
Thinking the miss fires are being caused because of the 02 problem.
Thanks for the help!!!
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phonedawgz
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Report this Post06-23-2013 05:43 PM Click Here to See the Profile for phonedawgzClick Here to visit phonedawgz's HomePageClick Here to Email phonedawgzSend a Private Message to phonedawgzEdit/Delete MessageReply w/QuoteDirect Link to This Post
O2 sensor problems won't cause your misfire problem.

Two separate problems. Just troubleshoot them both.
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Darth Fiero
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Report this Post06-24-2013 11:11 AM Click Here to See the Profile for Darth FieroClick Here to visit Darth Fiero's HomePageClick Here to Email Darth FieroSend a Private Message to Darth FieroEdit/Delete MessageReply w/QuoteDirect Link to This Post
A P0300 misfire code being present indicates misfires have been detected. Misfires can cause O2 sensor codes to set including the P0134 HO2S insufficient activity Sensor 1 code.

I would fix whatever is causing the P0300 code to set before worrying too much about the P0134 O2 sensor code. Whatever is causing the misfires could also be causing the O2 sensor code to set as well.

-ryan

------------------
OVERKILL IS UNDERRATED

Custom GM OBD1 & OBD2 Tuning | Engine Conversions & more | www.gmtuners.com

[This message has been edited by Darth Fiero (edited 06-24-2013).]

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CC Rider
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Report this Post07-11-2013 07:00 PM Click Here to See the Profile for CC RiderClick Here to Email CC RiderSend a Private Message to CC RiderEdit/Delete MessageReply w/QuoteDirect Link to This Post
Ok finally had time to work on the car again.
Got the miss-fire problem solved but still have the p0134
Looking at the wire colors on the harness connector and comparing to the 02 sensor
connector they do not match?
A & B do but C & D do not.
C on the harness is blk and on the 02 it's brn
D on the harness is pnk and on the 02 it's brn
When I got the code I also noticed there was no voltage to the 02.
Could C & D be switched or is it just the wrong 02 all together?
I going to check the harness to insure all wires ring out correctly right
now but any insight would be appreciated.
Thanks
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CC Rider
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Report this Post07-11-2013 08:33 PM Click Here to See the Profile for CC RiderClick Here to Email CC RiderSend a Private Message to CC RiderEdit/Delete MessageReply w/QuoteDirect Link to This Post
All the wires rung out correctly so I'm back to the 02 and the wire color difference.
I had a second 02 off another exact engine and it made the engine run poorly as well.
.
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phonedawgz
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Report this Post07-12-2013 10:52 AM Click Here to See the Profile for phonedawgzClick Here to visit phonedawgz's HomePageClick Here to Email phonedawgzSend a Private Message to phonedawgzEdit/Delete MessageReply w/QuoteDirect Link to This Post
C & D are the O2's heater circuit. Polarity doesn't matter for a simple resistive heating unit. That is why the O2 manufacturer put two brown wires that run to the heater circuit. It doesn't matter which of the browns connects to the pink, just as long as the other connects to the black.

It is fairy normal for O2 sensors to have the same color for the wires that run to the heating element.

So that is not your problem.
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CC Rider
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Report this Post07-12-2013 11:31 AM Click Here to See the Profile for CC RiderClick Here to Email CC RiderSend a Private Message to CC RiderEdit/Delete MessageReply w/QuoteDirect Link to This Post
Thanks for the brain check!
Cleared the codes and will run the car this weekend to see if it resets now that the missfire problem is solved.
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CC Rider
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Report this Post07-15-2013 09:12 AM Click Here to See the Profile for CC RiderClick Here to Email CC RiderSend a Private Message to CC RiderEdit/Delete MessageReply w/QuoteDirect Link to This Post
After having time to run the car it set the P0134.
Replaced the front O2 sensor and the car is running as it should.
Thanks all for the help!
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