Help. I have an 88 4X4 pickup 22RE/5spd. I started having trouble with cold starts last year. I went through the cold start system-temp switch, timer, injector, TPS adjust- all worked good for about a month. It started having trouble under load like a fuel pump or filter, coughing and sputtering. I decided to go through the fuel system as it had 325k feeding three engines over it's life. New fuel pump, filter, regulator, injectors(2.5 ohm correct plug no adapters), O2 sensor. Took it for a test drive and it ran good. Stopped at the local 7-11 to get a congratulatory cold beverage and it wouldn't start. Walked home and got stuff to tow it the two blocks home. When I returned the truck had cooled and it fired right up. I had a local shop look into the issue and after a long time-several months- I got it back with no cause found. They did find that after it's warmed up if you shut it off it looses the injector pulse until it cools off all the way. I can not deny or confirm this. Is there an easy way to check injector pulse? I do have a high impedance DVOM with peak hold. Anybody else ever have this happen.

 

Had a buddy with injector issues. Turned out to be an issue in wiring harness. You'll need a noid light, not sure if a generic LED will work. The harness for injectors splits so 2 feeds split to feed 4 injectors. Figure out if its all injectors or 2.

Did you check injector ground at upper/lower air intake plenum? Intermittent electrical issues are a pain.

 

Resistance increases with temperature. Sounds like marginal connection. Check the crimps that connect ECU pins 10 and 20 to make all 4 injectors fire all at the same time could get corroded and/or brittle and/or break.
While you're at it, I suggest you reroute all wires that do not absolutely have to run there to keep wiring cleaner and easily-accessible.

 

If the ECU doesn't pick up the IGF signal from the igniter (signifying that the spark fired), it shuts off the injectors (this is to prevent pumping raw gas into the exhaust if the ignition fails). That should throw code 14. Other than the fact that all electronics are somewhat heat-sensitive, that has nothing to do with temperature.

Since we don't know exactly how your shop determined that the injector pulse was gone, you may have to check again. As muddpigg points out, it's a short ground pulse, so it may be hard to see even with an LED. You could try using a mechanic's stethoscope right to an injector; they're loud enough to hear.

There are plenty of other things that can cause a problem with heat (notably vapor lock). If you want to look at the ignition, here's everything I know about that: https://www.yotatech.com/forums/f116...gniter-287857/

 

So I did some checks yesterday. 1) pulled codes - 22 which makes sense since I had a bad ECT sensor. No other codes. It runs decent until warmed up. Once warm if you let it idle for any time it doesn't want to accelerate at all and you have to nurse the throttle until the RPMs are over 2000, then it's sluggish but drivable. Real rich and loading up be the feel of it. I put a timing light on it and running no load, jumper wire in, if you stab the throttle there is no advance until 2000ish then it jumps to full advance around 40* I'm guessing. If you add throttle slowly it advances smoothly through the RPM range.. Engine RPM drops when I poke the flapper in the AFM. TPS is new and adjusted per LCE procedure. CSITS tested good.
Restarting when hot I have spark, fuel pressure( don't know psi ) 12v going to injectors after the resistor on the passenger fender, pulsing voltage at the 10,20 pins on the ECU when cranking, no fuel squirting or dribbling at the cold start injector. Won't start until cooled down.

 

Sounds like a wiring or grpund issue. Oh are they fun to track down, not at all i'm being sarcastic.

Fortunately they are usually cheap to fix. Sadly finding is super hard.

i had a wire in fuel pump harness thats sheathing had broken and exposed copper to elements. Was in area nice an tucked between frame rail and cab. Corrosion had developed on copper and fouled wire for about 6" of the small nick in sheathing. Took forever to find. Loads of colorful word and the throwing of tools.

So pick an end of the electrical circuits for injectors and measure resistance both cold and hot. Get a copy of FSM for actual values. Once you find circuit then search for where issue is. Don't use cheap part store vinyl sheathed wire to fix or you'll be doing this again in a short time. Check out low temp solder connectors they are the ˟˟˟˟. You can scavenge good donor wire from junked toyota.

 

Did you find a solution?
sounds similar to what I am struggling with. Very similar

 

What I have found "when hot" issues occur for the injectors.....there are 3 wires in the harness that runs above the exhaust manifold, from the main harness in the middle of the intake area to the ignition module. these 3 wires are what control injector pulse because it is signal from distributor to computer (distributor is the cam sensor too). These wires, the insulation starts cracking the wires start falling apart. What I normally do, is make the wires longer like the 89 and up trucks. I run them along the firewall and up to the igniter, instead of right over the exhaust. Turbo trucks get this the worst because of the higher temps. I am working on a POS 1987 right now that someone completely hacked, and the only thing done right, was the redirection of the 3 wires from the intake harness to the igniter.