Cold Start Injector Question
Thread Starter
Pro
Joined: Aug 2002
Posts: 715
Likes: 0
From: Warner Robins GA
Cold Start Injector Question
Hey guys, I've got an 88 Coupe that I'm about to do some more work on..
I've heard that you can unplug the cold start injector with no noticable difference other than an extra second of cranking time. I've got a bit of a cold start problem and have already eliminated all the other likely culprits (MAF, relays, TPS, IAC, vacuum leaks), so I'm going to concentrate on the cold start injector now.
Anyway, on mine when I unplug the cold start injector it has to crank for literally about 10 seconds. Then it starts for about a second and dies. Everything else about the car is great except my pesky cold start problem that I've been trying to fix since I bought the car.
Do you guys think I'd have any luck getting ahold of a new cold start injector and putting it in? I've already replaced my other 8 injectors with some 24 lb SVO injectors and a AFPR. My old injectors were leaky, but I didn't really notice any difference after changing the injectors.
I've heard that you can unplug the cold start injector with no noticable difference other than an extra second of cranking time. I've got a bit of a cold start problem and have already eliminated all the other likely culprits (MAF, relays, TPS, IAC, vacuum leaks), so I'm going to concentrate on the cold start injector now.
Anyway, on mine when I unplug the cold start injector it has to crank for literally about 10 seconds. Then it starts for about a second and dies. Everything else about the car is great except my pesky cold start problem that I've been trying to fix since I bought the car.
Do you guys think I'd have any luck getting ahold of a new cold start injector and putting it in? I've already replaced my other 8 injectors with some 24 lb SVO injectors and a AFPR. My old injectors were leaky, but I didn't really notice any difference after changing the injectors.
Racer
Joined: Nov 2002
Posts: 471
Likes: 0
From: Queens NY
Re: Cold Start Injector Question (Tourney3p0)
I also had a very hard time getting the carto run right for the first few minutes after unplugging the CSI. Get a custom chip burned that doesn't require it and just block it off.
Just out of curiosity, what were the symptoms of your leaky injectors?
Just out of curiosity, what were the symptoms of your leaky injectors?
Thread Starter
Pro
Joined: Aug 2002
Posts: 715
Likes: 0
From: Warner Robins GA
Re: Cold Start Injector Question (CarAteMyMoney)
I also had a very hard time getting the carto run right for the first few minutes after unplugging the CSI. Get a custom chip burned that doesn't require it and just block it off.
Just out of curiosity, what were the symptoms of your leaky injectors?
Race Director
Joined: Aug 2000
Posts: 14,130
Likes: 7
Cruise-In II Veteran
Re: Cold Start Injector Question (Tourney3p0)
5 minutes is too soon for the pressure to drop to zero.You may have a bad check valve in the pump or a leaky fuel pressure regulator.It should take maybe 20 minutes or so for the fuel pressure to bleed back slowly to the tank.
Team Owner
Joined: Dec 2000
Posts: 90,675
Likes: 304
From: SE NY
Cruise-In II Veteran
Re: Cold Start Injector Question (Spinman)
The CSI is a 9th injector used on '85-'88 L98s to provide cold start fuel enrichment.
The '89-'91 L98s use the main 8 injectgors to provide cold start enrichment, due to an ECM change in '89.
The '89-'91 L98s use the main 8 injectgors to provide cold start enrichment, due to an ECM change in '89.
Thread Starter
Pro
Joined: Aug 2002
Posts: 715
Likes: 0
From: Warner Robins GA
Re: Cold Start Injector Question (Bill's86Coupe)
5 minutes is too soon for the pressure to drop to zero.You may have a bad check valve in the pump or a leaky fuel pressure regulator.
My issue is now with why I can't unplug my CSI and so many others claim to do so with no problem at all. I'm still not sure whether or not my CSI is bad or if it's something else, but I'll probably just replace the injector anyway. Simply unplugging it turns the car into a deluxe paperweight.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Every 2027 Corvette Engine Explained
Joe Kucinski
Designer Imagines A Corvette That Looks More Like a Corvette Than the Corvette
Verdad Gallardo
10 Ugly Corvettes That We Still Kinda Love
Joe Kucinski
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Thread Starter
Pro
Joined: Aug 2002
Posts: 715
Likes: 0
From: Warner Robins GA
Re: Cold Start Injector Question (Spinman)
New term I'm not familar with - what is a "cold start injector"?
How and why would you unplug it?
How and why would you unplug it?
It's just like any of the other 8 injectors.. just push the clip and unplug it.
The reason I'm wondering about unplugging it is because it's yet another thing to troubleshoot in my cold start problem. As far as I know, they're not made anymore so they're hard to find (and probably expensive) in good shape.
Since I've heard of people unplugging them with little to no problem I was hoping to do the same.. it didn't work out that way unfortunately so I was hoping to find out why.
Race Director
Joined: Aug 2000
Posts: 14,130
Likes: 7
Cruise-In II Veteran
Re: Cold Start Injector Question (Tourney3p0)
5 minutes is too soon for the pressure to drop to zero.You may have a bad check valve in the pump or a leaky fuel pressure regulator.
Right. Like I said, I put in the SVO injectors and an AFPR and that problem cleared up.
My issue is now with why I can't unplug my CSI and so many others claim to do so with no problem at all. I'm still not sure whether or not my CSI is bad or if it's something else, but I'll probably just replace the injector anyway. Simply unplugging it turns the car into a deluxe paperweight.
Right. Like I said, I put in the SVO injectors and an AFPR and that problem cleared up.
My issue is now with why I can't unplug my CSI and so many others claim to do so with no problem at all. I'm still not sure whether or not my CSI is bad or if it's something else, but I'll probably just replace the injector anyway. Simply unplugging it turns the car into a deluxe paperweight.
Remember the CSI isnt dependent on the ECM but that switch.That may be something to check out if cold start problems have been getting ya.
:)
Thread Starter
Pro
Joined: Aug 2002
Posts: 715
Likes: 0
From: Warner Robins GA
Re: Cold Start Injector Question (Bill's86Coupe)
Thanks for the reply.
I hope to replace that sensor today. I'm showing a few different options for sensors though, and it's my understanding that our cars have 2 or 3 "temperature" sensors.
I'm showing "Air Charge Temperature", "Air Cleaner Temperature", and "Coolant Temperature" sensors. It's my understanding that the last one controls the readout on the dash. Since mine appears to be correct, I'd guess it's one of the first two. Any ideas? I have a sneaking suspicion the guys at the parts store won't be able to tell me which one is which.
I hope to replace that sensor today. I'm showing a few different options for sensors though, and it's my understanding that our cars have 2 or 3 "temperature" sensors.
I'm showing "Air Charge Temperature", "Air Cleaner Temperature", and "Coolant Temperature" sensors. It's my understanding that the last one controls the readout on the dash. Since mine appears to be correct, I'd guess it's one of the first two. Any ideas? I have a sneaking suspicion the guys at the parts store won't be able to tell me which one is which.
Burning Brakes
Joined: Apr 2001
Posts: 992
Likes: 0
From: Atlanta GA
Re: Cold Start Injector Question (Tourney3p0)
I got rid of my CSI and have no issues what so ever..I blocked it off when I had the runners and plenum off painting.....It starts just like it always did....perfect.....no extra time craking here....I am in a warm climate....but still....you don't need it....
Burning Brakes
Joined: Apr 2002
Posts: 1,083
Likes: 0
From: Spanish Fork Utah
Re: Cold Start Injector Question
** EDIT ** I also just read your post again and you said you already ruled out the relay, so this post might not help you much... ** EDIT **
I think it is also worth mentioning that the fuel pump starts functioning when the fuel injector relay gives a signal to starting firing them off. If you have a bad fuel injector relay, you can have very hard starts. After about 5-10 seconds of cranking, the computer will realize that it has a distributor pulse and will override a bad fuel injector relay. It will then start the fuel pump. Try the relay, it just might be that simple. They are less than $20 at AutoZone.
If the relay is bad, your fuel pump will not function for a few seconds until the backup systems kick in.
Shayne
** EDIT ** I might also mention that I switched out the intake manifold and throttle body for a TPIS Big Mouth and a SuperRam. I no longer have a 9th CS injector. My starts do take a second longer now but it's not too big of a deal. I just got an update from TunerCat for my ECM that allows me to change the cranking fuel pulse width, so I am going to tune that out and see if I can't make my car do what the '89's do as they have eliminated that injector. ** EDIT **
[Modified by sspackman, 8:20 PM 11/29/2003]
[Modified by sspackman, 8:22 PM 11/29/2003]
I think it is also worth mentioning that the fuel pump starts functioning when the fuel injector relay gives a signal to starting firing them off. If you have a bad fuel injector relay, you can have very hard starts. After about 5-10 seconds of cranking, the computer will realize that it has a distributor pulse and will override a bad fuel injector relay. It will then start the fuel pump. Try the relay, it just might be that simple. They are less than $20 at AutoZone.
If the relay is bad, your fuel pump will not function for a few seconds until the backup systems kick in.
Shayne
** EDIT ** I might also mention that I switched out the intake manifold and throttle body for a TPIS Big Mouth and a SuperRam. I no longer have a 9th CS injector. My starts do take a second longer now but it's not too big of a deal. I just got an update from TunerCat for my ECM that allows me to change the cranking fuel pulse width, so I am going to tune that out and see if I can't make my car do what the '89's do as they have eliminated that injector. ** EDIT **
[Modified by sspackman, 8:20 PM 11/29/2003]
[Modified by sspackman, 8:22 PM 11/29/2003]
Thread Starter
Pro
Joined: Aug 2002
Posts: 715
Likes: 0
From: Warner Robins GA
Re: Cold Start Injector Question (apollo30346)
I got rid of my CSI and have no issues what so ever..
Also for anyone else who reads this thread, my problem isn't that I have long cranking times.. I don't at all. It starts right up first time, every time. My problem is what happens after that. After the car starts like normal, my idle drops to about 300 rpm unless I feather the gas. After I give it a little gas it's fine and you would never know anything was ever wrong.
It's a minor inconvenience that I've spent probably 500 dollars in parts trying to fix. If I ever fix it, I'll write a book called "When the Helms Manual Can't Help You". It's going to be a horror novel.
Intermediate
Joined: Jan 2023
Posts: 32
Likes: 2
From: Phoenix
Hey guys, I've got an 88 Coupe that I'm about to do some more work on..
I've heard that you can unplug the cold start injector with no noticable difference other than an extra second of cranking time. I've got a bit of a cold start problem and have already eliminated all the other likely culprits (MAF, relays, TPS, IAC, vacuum leaks), so I'm going to concentrate on the cold start injector now.
Anyway, on mine when I unplug the cold start injector it has to crank for literally about 10 seconds. Then it starts for about a second and dies. Everything else about the car is great except my pesky cold start problem that I've been trying to fix since I bought the car.
Do you guys think I'd have any luck getting ahold of a new cold start injector and putting it in? I've already replaced my other 8 injectors with some 24 lb SVO injectors and a AFPR. My old injectors were leaky, but I didn't really notice any difference after changing the injectors.
I've heard that you can unplug the cold start injector with no noticable difference other than an extra second of cranking time. I've got a bit of a cold start problem and have already eliminated all the other likely culprits (MAF, relays, TPS, IAC, vacuum leaks), so I'm going to concentrate on the cold start injector now.
Anyway, on mine when I unplug the cold start injector it has to crank for literally about 10 seconds. Then it starts for about a second and dies. Everything else about the car is great except my pesky cold start problem that I've been trying to fix since I bought the car.
Do you guys think I'd have any luck getting ahold of a new cold start injector and putting it in? I've already replaced my other 8 injectors with some 24 lb SVO injectors and a AFPR. My old injectors were leaky, but I didn't really notice any difference after changing the injectors.
Team Owner
Joined: Dec 2000
Posts: 21,094
Likes: 282
From: Phila., PA burbs
