Hard to start after replacing injectors... - Page 2 - CorvetteForum - Chevrolet Corvette Forum Discussion


C4 Tech/Performance
L98 Corvette and LT1 Corvette Technical Info, Internal Engine, External Engine

Hard to start after replacing injectors...

Reply
 
 
 
Thread Tools Search this Thread
Old 05-22-2017, 08:12 PM   #21
racerseks
CF Senior Member
Thread Starter
 
racerseks's Avatar
 
Member Since: Apr 2007
Posts: 535
Thanked 1 Time in 1 Post
Default

Quote:
Originally Posted by Triple Black 88 View Post
Cold start injector switch. Fixed my hard start on my 88.
Is there a switch of it, or do you mean the whole cold start injector? Thanks!
racerseks is offline   Reply With Quote
Old 05-22-2017, 08:36 PM   #22
slhawkins
CF Senior Member
 
Member Since: Sep 2016
Location: Milwaukee WI
Posts: 128
Thanked 16 Times in 16 Posts
Default

Quote:
Originally Posted by racerseks View Post
Is there a switch of it, or do you mean the whole cold start injector? Thanks!
There's a coolant temp switch on the intake manifold that controls the cold start injector. If you look at the front of the manifold from the passenger side, there will be two sensors. I believe the coolant temp switch will be the one closest to you. Keep in mind there is coolant behind the switch, so if you're replacing it you'll want to either drain the coolant or be quick about switching it out. If it has been a while since you've drained the coolant, now might be a good time.

Here's the testing info for an 87, I believe it's the same for yours.






I had the hard start issue when I completely removed my cold start injector. Since I was already putting in a custom chip I went ahead and just used an 89 bin which (as mentioned before) uses the other 8 injectors for extra fuel.

Edit: Since it worked previously, it might be as simple as double checking the seating of the connectors to the switch and injector. I have disconnected the temp switch every time I pulled the injectors, you might have done the same. Make sure it's plugged back in!

Last edited by slhawkins; 05-22-2017 at 08:41 PM.
slhawkins is offline   Reply With Quote
The Following User Says Thank You to slhawkins For This Useful Post:
racerseks (05-22-2017)
Old 05-22-2017, 08:41 PM   #23
racerseks
CF Senior Member
Thread Starter
 
racerseks's Avatar
 
Member Since: Apr 2007
Posts: 535
Thanked 1 Time in 1 Post
Default

Quote:
Originally Posted by slhawkins View Post
There's a coolant temp switch on the intake manifold that controls the cold start injector. If you look at the front of the manifold from the passenger side, there will be two sensors. I believe the coolant temp switch will be the one closest to you. Keep in mind there is coolant behind the switch, so if you're replacing it you'll want to either drain the coolant or be quick about switching it out. If it has been a while since you've drained the coolant, now might be a good time.

Here's the testing info for an 87, I believe it's the same for yours.






I had the hard start issue when I completely removed my cold start injector. Since I was already putting in a custom chip I went ahead and just used an 89 bin which (as mentioned before) uses the other 8 injectors for extra fuel.
Oh, okay...that one. I put a new connector in for that one, but maybe I'll go ahead and replace the sensor as well. The word "switch" just threw me off...

What's "bin"?

Thank you.
racerseks is offline   Reply With Quote
Old 05-22-2017, 08:50 PM   #24
slhawkins
CF Senior Member
 
Member Since: Sep 2016
Location: Milwaukee WI
Posts: 128
Thanked 16 Times in 16 Posts
Default

Quote:
Originally Posted by racerseks View Post
Oh, okay...that one. I put a new connector in for that one, but maybe I'll go ahead and replace the sensor as well. The word "switch" just threw me off...

What's "bin"?

Thank you.
Sorry - a "bin" is essentially the program the car runs on. There's a chip in the ECU that I replaced with a custom one which contained the program used in a 1989 C4. The advantage to using a custom chip is that you can modify things like when the coolant fan comes on or the fuel map. I just wanted it for a few small things and since my cold start injector wasn't looking good I figured it was as good a time as any to get one. It requires a bit of learning and may not be worth it in your case unless you like to spend money and tinker. :-)

Double check the connections on the new wiring. I'm sure it's fine, but I've kicked myself in the butt a couple of times by assuming I didn't need to double check my previous work. I believe you could do that by just checking continuity between that sensor connector and the cold start injector connector.
slhawkins is offline   Reply With Quote
The Following User Says Thank You to slhawkins For This Useful Post:
racerseks (05-23-2017)
Old 05-22-2017, 10:04 PM   #25
aklim
CF Senior Member
 
aklim's Avatar
 
Member Since: Jul 2004
Location: Hartford WI
Posts: 11,954
Thanked 506 Times in 497 Posts
Default

Quote:
Originally Posted by racerseks View Post
What kind of scanner will I need for that?

I could probably get it serviced if need be, but I didn't have any problems in that way before replacing the injectors.

Thanks...
Same kind you need to have for future work. Maybe an MT2500 from Snap On? Some have recommended the ALDL droid. I have the MT2500 and an older AutoX-ray. You are past the bad year of 85 so if you can, get an OBD1 and OBD2 scanner so you can read all cars.
aklim is offline   Reply With Quote
The Following User Says Thank You to aklim For This Useful Post:
racerseks (05-23-2017)
Old 05-23-2017, 04:17 PM   #26
racerseks
CF Senior Member
Thread Starter
 
racerseks's Avatar
 
Member Since: Apr 2007
Posts: 535
Thanked 1 Time in 1 Post
Default

Quote:
Originally Posted by slhawkins View Post
Sorry - a "bin" is essentially the program the car runs on. There's a chip in the ECU that I replaced with a custom one which contained the program used in a 1989 C4. The advantage to using a custom chip is that you can modify things like when the coolant fan comes on or the fuel map. I just wanted it for a few small things and since my cold start injector wasn't looking good I figured it was as good a time as any to get one. It requires a bit of learning and may not be worth it in your case unless you like to spend money and tinker. :-)

Double check the connections on the new wiring. I'm sure it's fine, but I've kicked myself in the butt a couple of times by assuming I didn't need to double check my previous work. I believe you could do that by just checking continuity between that sensor connector and the cold start injector connector.
Thanks for explaining. Does that bypass the cold start injector, or are there other reasons? I've chosen to keep it mostly stock, to hopefully make troubleshooting easier. Some guys love that part of things, but I guess I don't so much.

Double-checking is definitely not a bad idea. I hardwired the connector in, as I'm not that crazy about using butt connectors. I used shrinkwrap, so maybe the leads are touching. Connector was hard to get in too, so I'll make sure it's in all the way.

Thank you!
racerseks is offline   Reply With Quote
Old 05-23-2017, 04:19 PM   #27
racerseks
CF Senior Member
Thread Starter
 
racerseks's Avatar
 
Member Since: Apr 2007
Posts: 535
Thanked 1 Time in 1 Post
Default

Quote:
Originally Posted by aklim View Post
Same kind you need to have for future work. Maybe an MT2500 from Snap On? Some have recommended the ALDL droid. I have the MT2500 and an older AutoX-ray. You are past the bad year of 85 so if you can, get an OBD1 and OBD2 scanner so you can read all cars.
Oh, okay...yea, I have an auto-xray. I've used it for code-reading, but wasn't aware I could use it to check that. Know anywhere that might explain how to use it that way? Not sure I still have the manual...

Thanks!
racerseks is offline   Reply With Quote
Old 05-23-2017, 04:23 PM   #28
aklim
CF Senior Member
 
aklim's Avatar
 
Member Since: Jul 2004
Location: Hartford WI
Posts: 11,954
Thanked 506 Times in 497 Posts
Default

Quote:
Originally Posted by racerseks View Post
Oh, okay...yea, I have an auto-xray. I've used it for code-reading, but wasn't aware I could use it to check that. Know anywhere that might explain how to use it that way? Not sure I still have the manual...

Thanks!
What model?
aklim is offline   Reply With Quote
Old 05-23-2017, 04:37 PM   #29
racerseks
CF Senior Member
Thread Starter
 
racerseks's Avatar
 
Member Since: Apr 2007
Posts: 535
Thanked 1 Time in 1 Post
Default

Quote:
Originally Posted by aklim View Post
What model?
It's a code scout 2500. Maybe it's strictly a code-reader? Thanks!

Last edited by racerseks; 05-23-2017 at 04:38 PM.
racerseks is offline   Reply With Quote
Old 05-23-2017, 04:39 PM   #30
aklim
CF Senior Member
 
aklim's Avatar
 
Member Since: Jul 2004
Location: Hartford WI
Posts: 11,954
Thanked 506 Times in 497 Posts
Default

Quote:
Originally Posted by racerseks View Post
It's a code scout 2500. Maybe it's strictly a code-reader? Thanks!
It is strictly a code-reader
aklim is offline   Reply With Quote
The Following User Says Thank You to aklim For This Useful Post:
racerseks (05-23-2017)
Old 05-23-2017, 04:49 PM   #31
racerseks
CF Senior Member
Thread Starter
 
racerseks's Avatar
 
Member Since: Apr 2007
Posts: 535
Thanked 1 Time in 1 Post
Default

Quote:
Originally Posted by aklim View Post
It is strictly a code-reader
Okay, thank you.
racerseks is offline   Reply With Quote
Old 05-23-2017, 05:30 PM   #32
slhawkins
CF Senior Member
 
Member Since: Sep 2016
Location: Milwaukee WI
Posts: 128
Thanked 16 Times in 16 Posts
Default

Quote:
Originally Posted by racerseks View Post
Thanks for explaining. Does that bypass the cold start injector, or are there other reasons? I've chosen to keep it mostly stock, to hopefully make troubleshooting easier. Some guys love that part of things, but I guess I don't so much.

Double-checking is definitely not a bad idea. I hardwired the connector in, as I'm not that crazy about using butt connectors. I used shrinkwrap, so maybe the leads are touching. Connector was hard to get in too, so I'll make sure it's in all the way.

Thank you!
No problem!

I have the custom chip for:
  • Removing the cold start injector by using the other 8 injectors instead
  • Disabling the AIR system
  • Disabling EGR
  • Changing coolant fan on/off temperatures
  • Disabling VATS since I've got a custom alarm system

For me, all of those things made it well worth it. However, I totally understand wanting to keep it stock - it makes following the service manual much easier, especially for the next guy who owns it and doesn't know what you did. If someone looked for the VATS module or TDM in my car they'd be in for a surprise and find something else instead. ;-)

I really wouldn't recommend putting in a chip unless you have the urge to figure something out that will likely only be applicable to that car, it really does take a couple bucks and some time learning to make sure you do it right. Probably best to just fix the issue according to the manual and keep things "right". Good luck!
slhawkins is offline   Reply With Quote
Old 05-23-2017, 09:07 PM   #33
racerseks
CF Senior Member
Thread Starter
 
racerseks's Avatar
 
Member Since: Apr 2007
Posts: 535
Thanked 1 Time in 1 Post
Default

Quote:
Originally Posted by slhawkins View Post
No problem!

I have the custom chip for:
  • Removing the cold start injector by using the other 8 injectors instead
  • Disabling the AIR system
  • Disabling EGR
  • Changing coolant fan on/off temperatures
  • Disabling VATS since I've got a custom alarm system

For me, all of those things made it well worth it. However, I totally understand wanting to keep it stock - it makes following the service manual much easier, especially for the next guy who owns it and doesn't know what you did. If someone looked for the VATS module or TDM in my car they'd be in for a surprise and find something else instead. ;-)

I really wouldn't recommend putting in a chip unless you have the urge to figure something out that will likely only be applicable to that car, it really does take a couple bucks and some time learning to make sure you do it right. Probably best to just fix the issue according to the manual and keep things "right". Good luck!
Makes total sense. Those were all things I was considering deleting as well while I had the plenum, rail, runners, etc. off,, but decided to stay stock and keep things simple. I took 'em on and off so many times, I could probably do it pretty fast if I ever want to go that way. Maybe down the line...it'll eliminate guesswork while I am getting the car to just be reliable right now. Thanks!
racerseks is offline   Reply With Quote
Old 05-24-2017, 10:11 PM   #34
GREGGPENN
CF Senior Member
 
GREGGPENN's Avatar
 
Member Since: Nov 2003
Location: Overland Park Kansas
Posts: 10,918
Thanked 88 Times in 85 Posts
Default

Quote:
Originally Posted by Tod Stiles View Post
Let me just jump in here with a theory. I have an 86 with the same problem.

My theory:
The injectors used to leak down in a matter of minutes-less than 15 usually. New injectors don't seem to leak, it takes hours for the pressure to go down and I think that's mostly past the regulator seat. I think what was happening was the old injectors leaked enough to create a rich condition-always started right up. I'd bet my cold start injector has been clogged for years but was covered up by this rich condition. Now that is not the case anymore so hard start.
I talked to KellyAnn Conway and will provide an "alternate fact"! LOL

I think it's just as possible old injectors lose resistance/flow over time.
Some will be worse than others....and will have different effect depending on whether they are the same/opposite side as the 02 sensor. Failing (coil) injectors on the same side as the O2 sensor will be adjusted for -- by increasing pulsewidth (fuel). Over time, this could make your engine run richer and richer. As you know, the richer it is, the better it'll run when COLD. That includes start-up.

When replacing the injectors...even if the ECM is disconnected, you might not regain ideal start-up if you didn't replace the CSI too. If it degraded over time...and was compensated for/by wider PW from the ECM, that may account for worse cold-starts after servicing.

Plus, I don't discount the possibility of fuel leakage as theorized above!



Quote:
Originally Posted by slhawkins View Post
No problem!

I have the custom chip for:
  • Removing the cold start injector by using the other 8 injectors instead
  • Disabling the AIR system
  • Disabling EGR
  • Changing coolant fan on/off temperatures
  • Disabling VATS since I've got a custom alarm system
Be aware that disabling VATS -- in the chip -- doesn't disable the function of the key pellet. To complete the disabling process, it is suggested that you place a resistor (equivalent to the range of your key pellet) in the ignition wiring. IIRC, this procedure is described on VATSUCKS.com.
GREGGPENN is offline   Reply With Quote
The Following User Says Thank You to GREGGPENN For This Useful Post:
racerseks (06-01-2017)
Old 05-24-2017, 10:30 PM   #35
slhawkins
CF Senior Member
 
Member Since: Sep 2016
Location: Milwaukee WI
Posts: 128
Thanked 16 Times in 16 Posts
Default

Quote:
Originally Posted by GREGGPENN View Post
Be aware that disabling VATS -- in the chip -- doesn't disable the function of the key pellet. To complete the disabling process, it is suggested that you place a resistor (equivalent to the range of your key pellet) in the ignition wiring. IIRC, this procedure is described on VATSUCKS.com.
Indeed, this is normally the case. I know a lot of people dislike messing with or disabling the VATS (for good reason), but I took it a step further than most. I removed all functionality of the VATS as far as wiring goes and transferred it all over to the custom alarm. This includes the starter relay that the VATS enables, something that is no longer in the car since the alarm system I used has the same thing built in. This isn't without it's own security risks though - it means I'm susceptible to theft when the car isn't armed, such as when it's in the garage or if I forget to do so when I'm parked elsewhere. The next step is to transfer it over to a fob style setup like what newer cars have where the starter enable relay is bound to a fob being in the vicinity.

Regardless, still a good heads up for anyone reading this and attempting the same thing. Disabling VATS in the chip definitely isn't a fix-all solution.

As a side note, the one headache I did/do have is that I didn't hook up the manual key unlock/lock to the alarm. When I was unlocking the car manually the alarm went off, so I need to get back in there and add that functionality to it. Thankfully the TDM harness has all that! :-)

Last edited by slhawkins; 05-24-2017 at 10:31 PM.
slhawkins is offline   Reply With Quote
Old 05-25-2017, 05:04 PM   #36
racerseks
CF Senior Member
Thread Starter
 
racerseks's Avatar
 
Member Since: Apr 2007
Posts: 535
Thanked 1 Time in 1 Post
Default

Quote:
Originally Posted by GREGGPENN View Post
I talked to KellyAnn Conway and will provide an "alternate fact"! LOL

I think it's just as possible old injectors lose resistance/flow over time.
Some will be worse than others....and will have different effect depending on whether they are the same/opposite side as the 02 sensor. Failing (coil) injectors on the same side as the O2 sensor will be adjusted for -- by increasing pulsewidth (fuel). Over time, this could make your engine run richer and richer. As you know, the richer it is, the better it'll run when COLD. That includes start-up.

When replacing the injectors...even if the ECM is disconnected, you might not regain ideal start-up if you didn't replace the CSI too. If it degraded over time...and was compensated for/by wider PW from the ECM, that may account for worse cold-starts after servicing.

Plus, I don't discount the possibility of fuel leakage as theorized above!





Be aware that disabling VATS -- in the chip -- doesn't disable the function of the key pellet. To complete the disabling process, it is suggested that you place a resistor (equivalent to the range of your key pellet) in the ignition wiring. IIRC, this procedure is described on VATSUCKS.com.
Thanks for the info. I ordered a new sensor. Hoping that's it. Guess I'll start simple, and check the things people mentioned. Might be a week before it gets here...
racerseks is offline   Reply With Quote
Old 05-25-2017, 05:07 PM   #37
racerseks
CF Senior Member
Thread Starter
 
racerseks's Avatar
 
Member Since: Apr 2007
Posts: 535
Thanked 1 Time in 1 Post
Default

Quote:
Originally Posted by slhawkins View Post
Indeed, this is normally the case. I know a lot of people dislike messing with or disabling the VATS (for good reason), but I took it a step further than most. I removed all functionality of the VATS as far as wiring goes and transferred it all over to the custom alarm. This includes the starter relay that the VATS enables, something that is no longer in the car since the alarm system I used has the same thing built in. This isn't without it's own security risks though - it means I'm susceptible to theft when the car isn't armed, such as when it's in the garage or if I forget to do so when I'm parked elsewhere. The next step is to transfer it over to a fob style setup like what newer cars have where the starter enable relay is bound to a fob being in the vicinity.

Regardless, still a good heads up for anyone reading this and attempting the same thing. Disabling VATS in the chip definitely isn't a fix-all solution.

As a side note, the one headache I did/do have is that I didn't hook up the manual key unlock/lock to the alarm. When I was unlocking the car manually the alarm went off, so I need to get back in there and add that functionality to it. Thankfully the TDM harness has all that! :-)
Thanks for the info. Hope it's something more simple, as I don't have the time to invest right now. Glad to have it running again. Hopefully I'll get this solved.
racerseks is offline   Reply With Quote
Old 05-25-2017, 05:10 PM   #38
slhawkins
CF Senior Member
 
Member Since: Sep 2016
Location: Milwaukee WI
Posts: 128
Thanked 16 Times in 16 Posts
Default

Quote:
Originally Posted by racerseks View Post
Thanks for the info. Hope it's something more simple, as I don't have the time to invest right now. Glad to have it running again. Hopefully I'll get this solved.
You'll definitely be able to get it solved without touching the chip, just need to figure it out.

If the switch doesn't do it, grab a fuel pressure gauge and see if the pressure drops when attempting to start the car cold. I believe that step is in the FSM images I posted - but it is basically checking to see whether the cold start valve is injecting fuel or not. Hopefully you don't have to mess with it though.

Did you already check your wiring to ensure it's all good?
slhawkins is offline   Reply With Quote
The Following User Says Thank You to slhawkins For This Useful Post:
racerseks (06-01-2017)
Old 05-25-2017, 05:14 PM   #39
racerseks
CF Senior Member
Thread Starter
 
racerseks's Avatar
 
Member Since: Apr 2007
Posts: 535
Thanked 1 Time in 1 Post
Default

Quote:
Originally Posted by slhawkins View Post
You'll definitely be able to get it solved without touching the chip, just need to figure it out.

If the switch doesn't do it, grab a fuel pressure gauge and see if the pressure drops when attempting to start the car cold. I believe that step is in the FSM images I posted - but it is basically checking to see whether the cold start valve is injecting fuel or not. Hopefully you don't have to mess with it though.

Did you already check your wiring to ensure it's all good?
Thanks...good tip. Is it supposed to drop? No, I had not checked yet. Will try to today, if I get a chance. Thank you!
racerseks is offline   Reply With Quote
Old 05-25-2017, 05:23 PM   #40
slhawkins
CF Senior Member
 
Member Since: Sep 2016
Location: Milwaukee WI
Posts: 128
Thanked 16 Times in 16 Posts
Default

The FSM claims it'll drop at least 3psi for 2+ seconds on a cold start, I've never tried it for myself though.

Check out the second page of the FSM that I posted, it's got all the steps to see what the problem is. I'd only go through it after checking the wiring though since that might be your problem.
slhawkins is offline   Reply With Quote
The Following User Says Thank You to slhawkins For This Useful Post:
racerseks (05-25-2017)
Go Back   CorvetteForum - Chevrolet Corvette Forum Discussion >
Reload this Page
  • Hard to start after replacing injectors...
  •  
     
    Reply

    Related Topics
    Thread Thread Starter Forum Replies Last Post
    Engine idles rough after sitting and gas smell for about a minute skullandbones C4 General Discussion 14 06-27-2017 06:25 PM
    Original 19 lb Bosch injectors work with super ram and 1.7 RRs? Opa C4 Tech/Performance 7 06-12-2017 07:22 PM
    anyone have a similar problem with vats not firing injectors 88383convertable C4 Tech/Performance 6 04-07-2017 11:06 AM
    Question regarding gasoline... racerseks C4 Tech/Performance 15 03-14-2017 09:50 AM
    1990 Rough Idle but clears out driving clovergamecock C4 Tech/Performance 11 09-16-2016 01:52 PM


    Thread Tools Search this Thread
    Search this Thread:

    Click for Advanced Search

    Posting Rules
    You may not post new threads
    You may not 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 Off
    Pingbacks are Off
    Refbacks are Off

    Forum Jump

    Sponsored Ads
    Vendor Directory

    All times are GMT -4. The time now is 06:13 AM.


    We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.
     
    • Ask a Question
      Get answers from community experts
    Question Title:
    Description:
    Your question will be posted in: