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 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?

 

I had the same problem after I took out the CSI .I asked about a custom chip to remedy this and was told it was not possible . Is this true?

 

I'm wondering what the circumstances are that others are running a blocked off CSI with no inconvenience other than an extra second of cranking time. I've heard of having a custom chip burned but I'm trying to avoid that. It sounds like I'll just need to get a CSI. Even if mine is fine right now, I'll feel a lot better eliminating it as a possibility.

My car smelled of gasoline and I had a half second extra of cranking time when the car was warm. So I bought a fuel pressure gauge and after about 5 minutes I'm down to next to zero. It holds much better now.

 

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.

 

New term I'm not familar with - what is a "cold start injector"?
How and why would you unplug it?

 

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.

 

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.

 

You have a 90, so you don't have one.

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.

 

AAhhhh...Ok I got it now...I would check two things...first be sure your timing isnt off or too far advanced.....and second,the CSI also gets its info from the CS Switch or thermo time switch.This sensor is in front of the intake manifold,below the Throttle body..If it is bad,you may get some problems on cold starts.The CS switch has a harness on it that looks just like an injector plug in.
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.
:)

 

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 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....

 

** 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]

 

So here's another vote for being able to perfectly function without the 9th injector. I'm not sure if that means my CSI is working and something else is up, or if it's in my cold start system. For what it's worth, it was in the 90 degree range outside when I was trying this.

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.

 

I put a MSD 6al box on mine there's a couple of other pieces that you need to make it work but that extra spark sure does help

 

I'm guessing he already sorted the issue since he posted the question 20 years ago.

 

Ya I noticed that a little to late🥱