CPI Unit gone bad? - S-10 Forum
S-10 Forum is the resource on GM S-series trucks, Suspension, engine information, Body Modifications, painting tutorials.  Modifications to suit every need, budget and whim

CPI Unit gone bad?

Go Back   S-10 Forum > Engine and Drivetrain Tech > 262ci Forum (4.3)
New User? Register Forgot Password


 
LinkBack Thread Tools
Old 07-23-2009, 10:20 PM   #1
Registered User
 
Join Date: Jul 2009
Posts: 205
Location:
User is: OffLine
CPI Unit gone bad?

I have been trying to diag. this idle problem i have been having for a while now. I will first start off with what i have done. 1. I have replaced the fuel pressure regulator as i found that the passenger side of the lower intake was washed out, but did not fix the idle issue. 2. Cleaned and installed screened gasket on egr valve, still same issue. 3. Replaced fue pump and filter, still no fix. 4. Replaced distributor cap and rotor, still same ruff idle. Ohh and the plugs and wires are new within the past couple of weeks. So I was out driving the truck around and then took it home for it to cool off so i could pull the plugs and inspect them. I pulled the pugs and found that everyone of them was wet and smelled somwhat like fuel. I cleaned them off and reinstalled them and it ran well for about 30 seconds and them it started running rough again. It only runs rough at idle but the problem i am having is I have no black smoke or any smell of fuel for that matter. Do you guys just think my injector is leaking? What else could it be? I have checked the spark with one of those testers and it seems good, very bright. I ordered a new cpi and supply and return lines do you guys think that will repair it? The truck still has tons of power while accelerating.

Last edited by 00bluegtp; 07-23-2009 at 10:22 PM.
Old 07-23-2009, 10:55 PM   #2
Wire Splicin Fool :-)
 
lesterl's Avatar
 
Age: 34
Join Date: May 2008
Posts: 8,691
Location: Harrisonville, MO
User is: OffLine
Re: CPI Unit gone bad?

Bad Nut kit? That is on drivers side tho.... How strong a spark does the coil have?
Old 07-23-2009, 11:45 PM   #3
Registered User
 
Join Date: Jul 2009
Posts: 205
Location:
User is: OffLine
Re: CPI Unit gone bad?

well i checked it with a hei tester and it looks good but i dont know what strong spark looks like. Wouldn't a week spark make it break up under higher load situations though? I come from a 3800 background and thats what happens on those..... these could be different. What color should spark be on one of those testers?

Last edited by 00bluegtp; 07-23-2009 at 11:48 PM.
Old 07-24-2009, 12:20 AM   #4
Registered User
 
Age: 34
Join Date: Mar 2008
Posts: 45
Location: Radcliff Kentucky
User is: OffLine
Re: CPI Unit gone bad?

Have you checked to see if your intake might be leaking? I've been having a similar problem, and found out the intake was leaking, sucking in air at idle causing it to run rough.
Old 07-24-2009, 01:25 AM   #5
Registered User
 
Join Date: Jul 2009
Posts: 205
Location:
User is: OffLine
Re: CPI Unit gone bad?

hmmmm.. that's a good question.... umm i have checked for leaks with a can of throttlebody cleaner and went over everything twice but i suppose it could be leaking.. ahhhh those gaskets are cheap, I might as well just change those gaskets while i am in there. Did yours just cause it to run rough at idle? Is there a different way to check for this? Wouldnt I be running low on vacuum then? My vacuum is around 18-19 in of vac. Thank you for the info guys.

Last edited by 00bluegtp; 07-24-2009 at 01:27 AM.
Old 07-24-2009, 11:45 AM   #6
Registered User
 
Join Date: Jul 2009
Posts: 205
Location:
User is: OffLine
Re: CPI Unit gone bad?

If it was the ignition coil, wouldn't it get worse when its hot too, I dont know thats my pevious expereience. Thats why I dont think its the coil to because I woud think it would start to run really rough when hot. Is there any way to check the coil? Ohm it?
Old 07-24-2009, 01:13 PM   #7
Registered User
 
Age: 34
Join Date: Mar 2008
Posts: 45
Location: Radcliff Kentucky
User is: OffLine
Re: CPI Unit gone bad?

The way I checked my intake was with a can of starting fluid, just spray it around the intake and see if you can hear the motor rev up. Mine just started to idle rough, but while I was driving it ran fine, ony acted up when it was at idle. Mine would start up and run fine sometimes too, but then start acting up. Never did check my vacum so can't really say if it would change any.
Old 07-24-2009, 09:15 PM   #8
Wire Splicin Fool :-)
 
lesterl's Avatar
 
Age: 34
Join Date: May 2008
Posts: 8,691
Location: Harrisonville, MO
User is: OffLine
Re: CPI Unit gone bad?

Bill Wheats is your man on the Vac Guage thing, he can make it sing.

If the primary winding has a winding shorted it could be over voltage if secondary has a winding shorted, it could be under voltage.

Blueish spark is what you are looking for. Orangeish is low voltage.
Old 07-25-2009, 01:19 PM   #9
Registered User
 
Join Date: Jul 2009
Posts: 205
Location:
User is: OffLine
Re: CPI Unit gone bad?

Yo may be on to something there. I am pretty sure the spark on that tester i have was orange. It may just be a shorted coil. I'll check it again and report back.
Old 07-25-2009, 02:18 PM   #10
Registered User
 
Join Date: Jul 2009
Posts: 205
Location:
User is: OffLine
Re: CPI Unit gone bad?

I have a somwhat blue spark but by the time it gets to the other side of the gap it turns orangish. Is that normal?
Old 07-25-2009, 05:06 PM   #11
Wire Splicin Fool :-)
 
lesterl's Avatar
 
Age: 34
Join Date: May 2008
Posts: 8,691
Location: Harrisonville, MO
User is: OffLine
Re: CPI Unit gone bad?

WWW.AUTOZONE.COM Set up your truck, look into the repair guide, they will have testing of coil and wiring/ etc.
Old 07-26-2009, 12:34 PM   #12
Registered User
 
Join Date: Jul 2009
Posts: 205
Location:
User is: OffLine
Re: CPI Unit gone bad?

I did the paper clip trick to check for codes and the ses light comes on long goes of and has 2 quick flashes. What does that mean?
Old 07-26-2009, 03:36 PM   #13
Registered User
 
Join Date: Jul 2009
Posts: 205
Location:
User is: OffLine
Re: CPI Unit gone bad?

Soo I replaced the ignition coil and it still has the ruff idle. I also replaced the IAC valve and still idles ruff. I also ran a half can of seafoam in through the brake booster line and the otherr half in the gas tank and its still ruff but seems that the seafoam helped more than anything else I have tried. I guess we will find out tomorrow when i replace the spider unit if that is whats causeing the prblem... I sure hope thats it. Somone on another forum suggested a coolant temp sensor but i cant figure out how to replace it without removing the steering shaft and i dont relly want to do tha. lol.
Old 07-26-2009, 03:49 PM   #14
Registered User
 
Join Date: Mar 2009
Posts: 13
Location:
User is: OffLine
Re: CPI Unit gone bad?

Quote: Originally Posted by 00bluegtp
Soo I replaced the ignition coil and it still has the ruff idle. I also replaced the IAC valve and still idles ruff. I also ran a half can of seafoam in through the brake booster line and the otherr half in the gas tank and its still ruff but seems that the seafoam helped more than anything else I have tried. I guess we will find out tomorrow when i replace the spider unit if that is whats causeing the prblem... I sure hope thats it. Somone on another forum suggested a coolant temp sensor but i cant figure out how to replace it without removing the steering shaft and i dont relly want to do tha. lol.

The coolant temp "sensor" is located on the front of the engine below the EGR valve. It is a pretty straightforward replacement. I believe the sensor next to the steering shaft is a knock sensor. You can test the ECT sensor with a digital meter to see if it is working.
Old 07-26-2009, 03:50 PM   #15
Registered User
 
Join Date: Jul 2009
Posts: 205
Location:
User is: OffLine
Re: CPI Unit gone bad?

should i try running more seafoam? Or can i hurt somthing by doing that?
Old 07-26-2009, 05:19 PM   #16
Wire Splicin Fool :-)
 
lesterl's Avatar
 
Age: 34
Join Date: May 2008
Posts: 8,691
Location: Harrisonville, MO
User is: OffLine
Re: CPI Unit gone bad?

The sensor in the side of the head is the Dash sensor, the Seafoam CAN foul spark plugs, wash the oil off the rings/ etc. Doesnt mean it will, but you can over do anything. Good luck man!
Old 07-26-2009, 08:56 PM   #17
Registered User
 
Join Date: Jul 2009
Posts: 205
Location:
User is: OffLine
Re: CPI Unit gone bad?

The truck never gets to even 200 so i am thinking that the coolant temp sensor in the front coud be bad... How do i test it. It could also be because it is running rich that it is running cool. I am going to replace the lower intake gaskets, cpi nit and nut kit, and the coolant temp sensor tomorrow morning and i will let you guys know what happens... But i appreciate the assistance.
Old 07-27-2009, 01:16 AM   #18
Registered User
 
xambitionx's Avatar
 
Join Date: Jun 2009
Posts: 162
Location:
User is: OffLine
Re: CPI Unit gone bad?

your temp shouldn't go over 200, thats the purpose of the thermostat. some auto parts stores used to sell a 165' thermostat for these motors before they stocked the 195'. i remember having to special order the 195'. if your temp gets up to either of these temps and stays there or lower, your cooling just fine. it never hurts to pull the cts, clean and replace it with a little dope on the threads. i hope you find the culprit. there are so many causes of the symptoms. my experience though, points at vacum.
once had a lower intake vacum leak that wouldn't rev higher when sprayed with starting fluid. but when i changed the gaskets from the lower intake up, problem solved
also check fuel pressure against spec.'s. gl. X
Sponsored Links
Advertisement
 

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the S-10 Forum forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.
User Name:
If you do not want to register, fill this field only and the name will be used as user name for your post.
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.
Email Address:

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.



Thread Tools

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



All times are GMT -4. The time now is 12:44 PM.

Powered by vBulletin® Copyright ©2000 - 2011, Jelsoft Enterprises Ltd. SEO by vBSEO 3.2.0
SEO by vBSEO
vBulletin Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.