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Won't start and temp guage pegging all of a sudden by Tweeder
Started on: 10-08-2013 12:18 AM
Replies: 21 (339 views)
Last post by: phonedawgz on 10-10-2013 03:07 PM
Tweeder
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Report this Post10-08-2013 12:18 AM Click Here to See the Profile for TweederSend a Private Message to TweederEdit/Delete MessageReply w/QuoteDirect Link to This Post
All I did was disconnect the battery and took off plug wires to remove the tunkside exhaust to weld up a leaking header and weld a wideband bung in the down pipe. I also replaced the map sensor. With a new one. It cranks and I have fuel pressure. I also checked and verified spark on two random wires. I also noticed that while cranking the temp guage peggs which it never has before. Any suggestions?

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Report this Post10-08-2013 12:31 AM Click Here to See the Profile for trotterlgClick Here to Email trotterlgSend a Private Message to trotterlgEdit/Delete MessageReply w/QuoteDirect Link to This Post
Fuel pressure does not say there it fuel to the cylinders, but spark does say there is spark to the cylinders, so if you have spark then you have no fuel. Larry
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Report this Post10-08-2013 12:48 AM Click Here to See the Profile for TweederSend a Private Message to TweederEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by trotterlg:

Fuel pressure does not say there it fuel to the cylinders, but spark does say there is spark to the cylinders, so if you have spark then you have no fuel. Larry


I wonder what happened then to cut the fuel, yeah I just went out and cranked it for several seconds and pulled the number 4 plug and it was dry.

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Tweeder
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Report this Post10-09-2013 12:41 AM Click Here to See the Profile for TweederSend a Private Message to TweederEdit/Delete MessageReply w/QuoteDirect Link to This Post
I went out and verified there's power to both injector wires.

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[This message has been edited by Tweeder (edited 10-09-2013).]

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trotterlg
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Report this Post10-09-2013 12:51 AM Click Here to See the Profile for trotterlgClick Here to Email trotterlgSend a Private Message to trotterlgEdit/Delete MessageReply w/QuoteDirect Link to This Post
But that does not show that the injectors are delivering fuel. Spray some starting fluid in the intake and see if it starts. Larry
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Tweeder
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Report this Post10-09-2013 12:56 AM Click Here to See the Profile for TweederSend a Private Message to TweederEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by trotterlg:

But that does not show that the injectors are delivering fuel. Spray some starting fluid in the intake and see if it starts. Larry


I will have to try that tomorrow. Say for giggles the injectors aren't firing, what wires? should I check.

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Report this Post10-09-2013 01:09 AM Click Here to See the Profile for TweederSend a Private Message to TweederEdit/Delete MessageReply w/QuoteDirect Link to This Post

Tweeder

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I hooked up hptuners and scanned as I cranked it over and nothing readin on the injector duty or either injb1 or injb2. Looks like up the injectors ain't firing.

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trotterlg
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Report this Post10-09-2013 01:21 AM Click Here to See the Profile for trotterlgClick Here to Email trotterlgSend a Private Message to trotterlgEdit/Delete MessageReply w/QuoteDirect Link to This Post
If you have spark and the engine does not run that is a good guess. Larry
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Report this Post10-09-2013 01:24 AM Click Here to See the Profile for TweederSend a Private Message to TweederEdit/Delete MessageReply w/QuoteDirect Link to This Post
Yeah but what did I do to stop them from firing is there some wires specifically to check? Also I'd the temp guage pegging have something to do with this?

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Report this Post10-09-2013 01:02 PM Click Here to See the Profile for trotterlgClick Here to Email trotterlgSend a Private Message to trotterlgEdit/Delete MessageReply w/QuoteDirect Link to This Post
If you are sure you did not do anyting else then the MAP sensor is the only difference in running and not running. Put the old one back. Larry
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Report this Post10-09-2013 01:18 PM Click Here to See the Profile for TweederSend a Private Message to TweederEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by trotterlg:

If you are sure you did not do anyting else then the MAP sensor is the only difference in running and not running. Put the old one back. Larry


There's a bulkhead connector that goes through my firewall into the cab where the comp is. That enables me to leave the computer there and disconnect the motor for easy drop out. All I did was unbolt it but not disconnect it to move it to the sides bit to be able to pass the wideband wires through. That's why I'm wondering what wires control the injectors. I will have to recheck but when I was checking for power as the injector wires I think there was power to both wires even while cranking.

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Report this Post10-09-2013 01:37 PM Click Here to See the Profile for Kevin87FieroGTSend a Private Message to Kevin87FieroGTEdit/Delete MessageReply w/QuoteDirect Link to This Post
Check fuses.
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Report this Post10-09-2013 01:42 PM Click Here to See the Profile for Kevin87FieroGTSend a Private Message to Kevin87FieroGTEdit/Delete MessageReply w/QuoteDirect Link to This Post

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Oops

[This message has been edited by Kevin87FieroGT (edited 10-10-2013).]

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phonedawgz
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Report this Post10-09-2013 06:10 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
Key on, engine off, scanner connected - Does the TPS read correctly? If the TPS is showing 100% throttle, the PCM won't fire the injectors.

When scanning during cranking do you see the engine RPM rise and then drop back to zero when you stop cranking?

[This message has been edited by phonedawgz (edited 10-09-2013).]

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Tweeder
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Report this Post10-09-2013 06:11 PM Click Here to See the Profile for TweederSend a Private Message to TweederEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by phonedawgz:

Key on, engine off, scanner connected - Does the TPS read correctly? If the TPS is showing 100% throttle, the PCM won't fire the injectors.


Now that you mention that, I noticed in hptuners the TPS was 4%. Yeah the rpm fluctuates while cranking.


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[This message has been edited by Tweeder (edited 10-09-2013).]

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Report this Post10-09-2013 08:01 PM Click Here to See the Profile for FIEROFLYERSend a Private Message to FIEROFLYEREdit/Delete MessageReply w/QuoteDirect Link to This Post
Check to make sure you have battery power to the ECM and was any welding done on the exhaust with it bolted to the engine with the battery and ECM connected as some computers will get damaged while welding especially with a mig. Dan
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Report this Post10-09-2013 08:03 PM Click Here to See the Profile for TweederSend a Private Message to TweederEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
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Originally posted by FIEROFLYER:

Check to make sure you have battery power to the ECM and was any welding done on the exhaust with it bolted to the engine with the battery and ECM connected as some computers will get damaged while welding especially with a mig. Dan


No it was done with the exhaust off the car. I'm pretty sure I have ECM power as it cranks over and I get some readings in hptuners.


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[This message has been edited by Tweeder (edited 10-09-2013).]

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Report this Post10-09-2013 10:00 PM Click Here to See the Profile for TweederSend a Private Message to TweederEdit/Delete MessageReply w/QuoteDirect Link to This Post
Welli found the problem, it's the new map sensor, I unplugged the new one and plugged it into the old one but left the vacuum line connected to the new one. It took a few cranks but it fired up. I left it running and plugged it back into the new sensor and it stayed the same. If I shut it off and restart it in the new, it won't start. I figured out the 4% TPS, the throttl cable was snagged. This is the sensor I bought.
http://www.ebay.com/itm/231...id=p3984.m1439.l2649

Andy suggestions as to why the new one don't work?
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phonedawgz
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Report this Post10-10-2013 10:25 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
Is your MAP sensor connected to the correct vacuum? It needs to be connected to lower intake manifold vacuum not the vacuum sources between the throttle body and the SC. The LIM vacuum port is located under the snout of the supercharger. That one should run to the fuel pressure regulator, the MAP and the BBV if you have retained it.

The vacuum sources between the SC and TB should connect to the power brake booster and to the evap solenoid, if equipped.

If connected to the correct vacuum source, what does the MAP sensor read with the key on engine off? It should read about 1 bar or 30 inHG or 14.7 PSI. That is normal air pressure at sea level.
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phonedawgz
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Report this Post10-10-2013 10:42 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
Oh - and your temp gauge always pegged when you turned the key to start. GM fked up on the design of the wiring for the temp gauge/temp light. Leaving the temp gauge pegging will over time cause your temp gauge needle to slip on it's post and will cause it to be inaccurate.

To fix - at C500, swap the pins D3 (Dk Green) and C2 (Dk Green/Yellow). Then follow the dash swap on this page. http://www.fierosails.com/tempgage.html You have to do both swaps or the result is you will leave your temp gauge disconnected.

You have to do the engine bay fix at C500 rather than at the temp sender because your 3800 does not have a dual temp light/temp gauge sender. If you followed Ryan's sheet, you now have the PCM controlling the temp light and the gauge running to the green wire of the 3 pin dual (CTS & temp gauge) CTS sensor.

One you have preformed both swaps your temp gauge will no longer peg when the key is turned to start, and the TEMP light will come on during cranking (check bulbs) like it is supposed to.

Remember you have to pull the fork out of C500 before you attempt to remove the pins. Even after removing the fork you still need to depress the tang of the terminal to get the pin to back out of C500.








It makes me feel the world is just a bit more 'correct' when I see the TEMP light come on during cranking.

[This message has been edited by phonedawgz (edited 10-10-2013).]

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Tweeder
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Report this Post10-10-2013 11:26 AM Click Here to See the Profile for TweederSend a Private Message to TweederEdit/Delete MessageReply w/QuoteDirect Link to This Post
G
 
quote
Originally posted by phonedawgz:

Is your MAP sensor connected to the correct vacuum? It needs to be connected to lower intake manifold vacuum not the vacuum sources between the throttle body and the SC. The LIM vacuum port is located under the snout of the supercharger. That one should run to the fuel pressure regulator, the MAP and the BBV if you have retained it.

The vacuum sources between the SC and TB should connect to the power brake booster and to the evap solenoid.


I belielieve I have them correct, i've been running it for a couple months this way ( fuel pressure regulator to a T. One goes to the port under the snout in the LIM and the other to the map on the firewall). I have no bbv or evap. The purge solenoid is by itself from the fuel tank to the port on the side of the throttlebody. I have the octopus thingy blocked off except the large that goes to the break booster.

Thanks for that info on the sender, to tell you the truth, i've never noticed it during cranking, I only seen that it was operational durring running. I will do this correction this winter.
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[This message has been edited by Tweeder (edited 10-10-2013).]

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phonedawgz
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Report this Post10-10-2013 03:07 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
Well if it's hooked up correctly then the thing to do is to look to see if the PCM is reading the MAP correctly. Key on engine off you should be able to see the MAP reading. Like I said at rest it should be the equivalent of 1 bar/30 inHg/14.7 psi. Then check to make sure the pressure goes down when you apply vacuum to the MAP and pressure goes up when you apply some air pressure to it. Don;t blow it up with compressed air, it can only handle 14 psi above atmosphere. If the indicated pressure moves in the opposite direction of the actual pressure that would indicate you have the Black and Gray wires swapped.

A - Black - or Orange/Black - Ground
B - Green - Signal from MAP -> PCM
C - Gray - +5v reference from PCM.

My guess is the MAP is not reading correctly for whatever reason. If however it seems to be reading correctly, and electrically connecting the MAP makes the engine die, that would seem to indicate a problem with the programming of the PCM.

If wired correctly, but the MAP reading still seems messed up, what did the old MAP sensor scan as in the same situations?
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