racerseks

Is there a switch of it, or do you mean the whole cold start injector? Thanks!

slhawkins

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!

racerseks

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.

slhawkins

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.

aklim

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.

racerseks

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

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!

aklim

What model?

racerseks

It's a code scout 2500. Maybe it's strictly a code-reader? Thanks!

aklim

It is strictly a code-reader

racerseks

Okay, thank you.

slhawkins

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!

racerseks

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!

GREGGPENN

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.

slhawkins

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! :-)

racerseks

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

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.

slhawkins

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?

racerseks

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!

slhawkins

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.