rough cold start and idle. - LS1LT1 Forum : LT1, LS1, Camaro, Firebird, Trans Am, Engine Tech Forums
 
LinkBack Thread Tools
post #1 of 4 (permalink) Old 07-06-2019, 08:04 PM Thread Starter
Regular Member
 
Join Date: Jul 2019
Location: Tonawanda Ny
Posts: 1
 
rough cold start and idle.

Hello everyone, new to the forum! I own a 1994 z28 Camaro. I was hoping y'all could help provide some answers for the problem I'm having with the old girl. When I start my car cold it struggles to fire sometimes cranking for almost thirty seconds before firing or even the occasional backfire that terrorizes my neighborhood. Once the car is running it idles poorly smelling of fuel, misses, and bogs under heavy throttle. But once the engine warms up and the car gets up to operating temp it runs perfectly fine, and when I shut it off after the engines warmed up, it will start right up with no hesitation. Can anyone tell me what is wrong? Bad opti? I was told maybe the coolant temp sensor on the water pump? Some insights would be greatly apprecitated!
ryanstollz28 is offline  
Sponsored Links
Advertisement
 
post #2 of 4 (permalink) Old 07-06-2019, 08:44 PM
Regular Member
 
Join Date: Sep 2017
Posts: 19
 
Sounds like fuel pump might be going. I had very similar symptoms when fuel pump was getting ready to fail. I had to prime engine to start car by turning key from off to on several times before I would start the engine. Almost as if to pressurize the fuel line.

See if that helps.


Sent from my iPhone using Tapatalk Pro
Mark611 is offline  
post #3 of 4 (permalink) Old 07-07-2019, 07:18 AM
Regular Member
 
Join Date: Sep 2017
Posts: 19
 
Also, I did have the coolant temp sensor go bad. It was very corroded when I yanked pig tail off. Replaced pigtail and sensor and car fired right up. I remember a lot of black smoke and backfiring when it was bad.


Sent from my iPhone using Tapatalk Pro
Mark611 is offline  
Sponsored Links
Advertisement
 
post #4 of 4 (permalink) Old 07-07-2019, 07:25 AM
Global Moderator
 
cocobolo95's Avatar
 
Join Date: Sep 2008
Location: Fruitland Park,Florida
Posts: 12,881
 
If you suspect fuel pump problems, get a fuel pressure tester and attach it to valve on fuel rail. Do key on prime, pressure should be about 43 psi.

Since car starts & runs well when warm, I suspect fuel pump is not the problem. You need to put your car on an obd 1 scanner. One that not only does codes, but also will show running sensor data. First check for codes as the 4 ignition biggies don't light the check engine light. And on a 94, you can't connect the aldl terminals to read codes like on the 93 & older cars.

After reading codes, I suggest doing a running sensor data scan. See what the sensor data is telling you. CTS will cause problems when it's bad. But they usually don't magically fix themselves when engine warms up. If you haven't a clue to what sensor data means, PM me with your email address. I'll send you the PDF file " scanner readings and what they mean".

Get the 94 service manual at the following link. It has a driveability & emissions section. It will have troubleshooting, code explanations, wiring diagrams, etc. My Files

If you have codes 16 & 36, you have opti problems.
cocobolo95 is offline  
Sponsored Links
Advertisement
 
Reply

Bookmarks

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the LS1LT1 Forum : LT1, LS1, Camaro, Firebird, Trans Am, Engine Tech Forums forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in










Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page



Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome