Hi folks. 95 3vze 4Runner. I think I have some problem with the CSI or its circuitry.
Wx is warm, 85F. I'm in Puerto Rico. The CSI clicks with a 12v test and measures the correct resistance. Fuel is reaching it..Vehicle wants to run about 1 second upon cranking. With a voltmeter I see an initial blink hitting it but no voltage after that. Nothing at all comes out of the injector.

Question - is the injector normally closed and the voltage pulls it open or vice versa? I've read so many of these threads I'm getting dizzy - haha.
Should 12v remain at the injector after starting or just at that instant? Exactly how much 'time' is/should the time switch be allowing?
One poster mentioned cleaning a possibly clogged injector with an ultrasound cleaner, I have one but is that advisable? There's an electric relay in there.
The EFI temp sensor resistance measures correctly as does the CSI Time Switch. VAF checks out resistance wise.

Interestingly and possibly related...This first happened when I was poking around after doing something else. The problem cleared itself after 2 days. (yeah, uh-oh). Since I got the earlier non-related problem resolved I decided to treat the 4R to a new air filter and dist cap. After opening the VAF to take a look at the filter the problem re-occurred. Then it fixed itself again. Opened up the air filter one more time and the problem came back and has stayed and that's where I'm at now. Needless to say I can't find anything intermittent around the VAF but remain suspicious.
Thanks for any fresh ideas.
-

 

Remember, "cold" is a relative term. 85° F is "cold", to the engine, sensors, and ECU.

It sounds to me, for whatever it's worth, that you've got a broken wire somewhere in the CSI circuit. Whether from the temp sensor, or timer, to the ECU, or from the ECU to the CSI. I would break out the multimeter and start chasing the wires. 0 ohms is a good wire, anything over 1-2 is a bad one.
Don't forget to juggle and flex any harness they might run through while checking them, as sometimes a wire that has corroded through, or stressed and broken, inside the insulation, will make contact until it's moved, and then open up. Like during a start, for example. Dirty/corroded, or loose, pins in a connector will do the same thing. Look good, until it's moved. Check them all carefully.

Good luck to you!
Pat☺

 

Your cold start injector is not the problem, -7°F this morning and my csi isn't even plugged in yes it was sluggish but it's not a critical component.

You have a problem with the COR circuit, the is the relay that runs the fuel pump. It gets signal from the ignition switch or the AFM.

Given you manipulated the airbox for an air filter, you've got a broken wire or loose connection there somewhere.

 

Ok, its back to the VAF I guess. I've checked the COR relay and its ok.
Still wondering about my question, though. CSI remains normally closed and a brief 12v pulse opens it for a quick shot of fuel? Yes/no? I just want to fully understand the operation.
Thanks.

 

As I understand it, the CSI remains active, IE: squirting in fuel, until it's timing circuit shuts it off, or it's temp sensor shuts it off.
In the newer trucks than mine, I believe the ECU is involved in turning it on/off as well.

Does that help?
Pat☺

 

No. The CSI (should) only activate with the key to STArt. The "temp" part of the timer switch is not an off/on sensor, it just determines how quickly the timer opens. (Warm: opens quickly. Cold: not so quickly). So exray's "blip" is normal operation at that temperature.

The purpose of the "timer" is to avoid flooding on prolonged cranking.

I think CO_94_PU has it; this is almost certainly a VAF-COR circuit issue. Easiest thing on your truck to diagnose; if jumpering FP to B+ clears it up, you know where you need to look.

 

Ah!
Ok, well if I were right all the time I wouldn't be so broke

Thanks for the correction.
Pat☺

 

without the CSI plugged in, neither of my 4runners will start reliably in any condition, unless at nearly operating temp. with the CSI plugged in, both of my '87s start instantly. so, the CSI is important. can it be started without? sure. but not without prolonged cranking (which i HATE).

i agree that the COR circuit is the place to look.

 

Sorry, I've been gone awhile. Got sidetracked with another problem. No spark at all. That took some headscratching. One of the pins on the connector to the Igniter had broken inside the plug! I have this patched up now and am back where I started. *

I had not tried really hard to keep it running before but today I jumpered the B+ and FP and got it to crank and run a bit although very roughly. I removed my jumper and was able to repeat that. I could even get it to idle for a short while although it was doing a lot of missing.

Incidentally the tach isn't registering at all now. I wonder if this is telling me anything?

During all this messing around I have replaced the dist cap and rotor which I was intending to do along with the air filter just as routine maintenance.

Anyway, I think I'm making some progress but I'm not sure where to head next.

* if anyone has a junker being parted out I sure could use this plug with a pigtail. Most parter-outers are reluctant to chop the plug off of the harness unless I pay for the whole harness.

Thanks for all the help.

 

Update.
I played with it some more this afternoon and didn't really do anything but its running smoother now. Not perfect yet and I'm not bold enough to take it on a drive thru the neighborhood. Getting warmed up seems to make it happier.
I did uncover a bad connection with the cable at the top of the ignition coil. I can poke it with my stick and it will shut off. I have a spare coil due to "throwing parts at it" earlier but its one of those dirt cheap no-name ones. Yeah, yeah...I know. I left it idling with that one and it really seemed to be running quite well but after a minute or two it just went dead. Went back to my original coil and it ran again but not as smooth. Tried the new one again for a test and no cigar. Its a piece of junk so feel free to kick me in the butt for buying it.
I now have pulled the trigger for a new decent quality one from RA.
Both this and the broken contact in the Igniter plug certainly play into the car crapping out after I opened the air filter housing since they are right there. Maybe I'm not crazy after all - haha. In scouring things I found a broken port on the EGR modulator so that gets replaced too even though it doesn't seem to be related to the problem.
Oh, the tach came back but went again. Sigh.
Ah, 25-year old vehicles! What fun