22RE Cold Start - Delayed Start - Exhaustive Troubleshooting
 

Hi everyone,

I've been through the countless 22RE cold start issue threads across various forums, and while some have been helpful, I haven't been able to address a nagging issue I have. So I figured I would give an exhaustive list of what was tested, what was replaced and the tests performed in hopes someone could find this information valuable or give some advice.

Symptoms

Cold start (coolant-wise), starter cranks, can hear initial combustion like it's going to start, then I let go of key, it's silent and catches fire/starts after 0.25/0.5 seconds of silence. It's not a full on hard cranking cold start issue, but no where near what I would expect a normal functioning cold starting engine to behave. I liken it to "pulling the parachute" at the last second, in terms of when the engine finally catches at the last possible second before stalling. Warm starts = hot fire. Instant, no issues, due to the many many new OEM parts installed I will list out below.

Note: This is after a full engine replacement from Yota1 performance. This issue has nothing to do with the new engine as it existed beforehand as well on the old engine to my recollection. If it didn't exist before, I don't see how the new engine would contribute given the warm starts are definitely better than with my old engine/parts.

Related New Parts Installed

Engine - long block :)

Ignition Based Parts
- Spark Plugs - OEM
- Ignitor - OEM ($$$$)
- Coil - OEM
- Spark Plug Wires - OEM
- Cap and Rotor - OEM
- Starter - OEM

EFI System
- Cold Start Timing Switch - OEM ($$$$)
- Coolant Temperature Switch
- Rebuilt Fuel Injectors - LCE
- Fuel Rail - OEM
- CSI Fuel Rail - OEM
- Fuel Filter - OEM

Misc
- Intake manifold and plenum -> completely restored/tanked/deposits removed. These look brand new internally prior to first startup on the engine.
- Throttle body cleaned
- Timing set to 5/12 degrees BTC (jumped/not-jumped respectively)
- Silicone vacuum hoses
- PCV valve/hoses - OEM

Electrical Tests Per FSM
- Cold Start Time Switch: PASSED
- Coolant Temperature Switch: PASSED
- Cold Start Injector Resistance: PASSED
- AFM: All tests PASSED
- Circuit Opening Relay: PASSED
- EFI Relay: PASSED
- TPS: PASSED/In spec

Other Tests Performed

- Cold Start Injector Firing Fuel on START - w/Fuel Pump Check Connector - PASSED
- Cold Start Injector Firing Fuel on START - normal/no fuel pump check connector - PASSED

What I Haven't Replaced
- Fuel Pump (apparently it's a newer NAPA one)
- Fuel damper
- Fuel regulator

Conclusion

What I don't understand, is the results of the physical CSI tests (with or without fuel check connector), I see it instantly spraying fuel upon someone starting the car while I watch. Couple that with testing the COR, AFM, it's obvious the CSI circuit checks out per the FSM and physically. So where could the issue be?

1. Is my fuel pump on the edge and after a night of sitting, it takes time to build pressure in the actual fuel rail (not the CSI fuel tube)? But this doesn't make sense, since the CSI fuel tube is at the end of the fuel rail, so if there was a leak/pressure lost and the FP was weak, I certainly wouldn't see fuel spray instantly from the CSI as it would take even longer to build up enough pressure at the end of the fuel rail where that tube sits.

2. It's interesting that it "catches" at the last second while starting before stalling after I let go of the key. What is happening during that period of silence before something catches fire, especially knowing there is fuel from the CSI sprayed and the circuit is functioning properly? That delay is what is killing me because I would expect it to start or not start after that initial combustion happens.

Given the tests, new OEM parts, does anyone have suggestions? It's not a huge deal, but given I have replaced every part under the hood over the past year and more importantly the last 2 months with the engine and accessory part replacements, I really want this thing to start like it should every time, even when cold.

I am going to take a short video and perhaps I'll link it here to give you an idea of that "parachute pulling" metaphor in describing the cold start issue.

Also, look for an update in my thread regarding the engine install and other activities. I've been breaking in the engine and having too much fun driving around to get back to documentation of the build process.

Given your list of new and tested parts, my gut tells me it’s nothing under your hood. Im not familiar with all the vacuum and egr stuff since I pulled all of that out of my runner years ago when I had it. You may want to do some research regarding that in case there’s some correlation between the egr system and cold starting. Aside from that, maybe hang test (plug in another ecu and try without installing it) another ecu, yours may have an issue causing this. It definitely doesn’t sound like a sensor or mechanical issue under the hood since it catches itself and starts every time.

Thanks for the tips. I'm not certain that EGR plays a role, but I have a new OEM EGR valve as well. The cooler plate was cleaned before I reassembled the engine.

You bring up a good point with the ECU. It's probably not a terrible idea to source a known working spare. But you bring up another idea, though it may just end up confirming my diagnostic tests. I never did any testing at the ECU end per the FSM on the related circuits. I'll put that on the list as well.

My last item is the TPS. While mine checks out, my idle is still not as smooth as I would hope given all the new components, OEM motor/transmission mounts included (gear shifter has random larger vibrations). It's the original TPS from 1985 and I have a new OEM one sitting in my parts bin. I figured since the original one passed the tests, it was ok. But I'd like to swap in the new one this weekend and see what happens there.

I just finished my first 500 miles of engine break-in, so I'll be swapping out the break-in oil and checking the valve adjustment. So that's first on the list to get done.

I'm no expert, but have you actually tried another cold start injector, even a used one? I see where you've tested it electrically for resistance and also checked visually for fuel. But maybe there's a problem that those tests don't reveal. Just a thought.

I can definitely try, though it sprays a fierce fan of fuel during my tests. LCE still carries rebuilt ones so probably not a bad idea to get a spare before the stock dries up.

I saw a video on YouTube where a guy found a pin in the connector for that injector that wasn't fully seated. In his case it caused a hard failure, but I've worked on machines for a long time, and that type of thing can also cause intermittent or positional problems. Perhaps push in or flex those wires while someone turns the key?

Interesting developments this weekend. So the temperature in the morning has been between 65F and 70F over the past 4 days. In looking through some documentation, and specifically a TSB put out for a different issue (long crank after 3-4 hours hot soak), I see the original Cold Start Time Switch referenced to activate the CSI at a threshold of 95F and below (89462-30011). The TSB mentions a new part number for a cold start switch which increases that threshold to 113F to combat this hot soak issue (89462-20050). Why is this relevant to my issue? Well, I can't get a hard answer on when the Cold Start Time Switch will stop activating the CSI and this seems to indicate the lowest any part number would have activated would be 95F. This seems high as I've seen people reference temperatures like 65F - 75F being the cutoff, but no documentation or testing to back it up.

I decided to completely unplug the CSI connector to try a cold start in the morning. Seems counterintuitive but I was curious. Started right up. Two days in a row, same temperature (~70F), same 12 hour cool down period, quickest starts I've ever had on this vehicle since I've owned it. I connected it back up and tried on the 3rd morning, same temperature ... back to the delayed hang start. What does this tell me as it seems to make no sense?

1. The CSI was definitely firing when it was connected, and having the delayed hang start at temperatures <= 70F. This goes along with my testing where I pulled the CSI out and watched it spray a mist upon a cold start. Could it be flooding too much fuel? I saw a spray when I tested it, not a stream or drip so this doesn't add up.
2. The CSI cannot be firing any fuel into the intake on a cold start when it's disconnected, and this somehow helps it to start better. Unless it was leaking overnight and dripping fuel into the intake? But that wouldn't make sense as I think I would have starting issues similar to when it's plugged in (and possibly getting too much fuel). Plus, that means I would have pressure issues across the main injectors too (see next point below) and the startup wouldn't be nearly as quick as fuel pressure would need to build.
3. My fuel pump/regulator operation must be ok, as it's able to hold pressure enough overnight to not need any help to get fuel to the main injectors to fire right up when the CSI is unplugged. So this can't be a main injector problem (never thought so, as they are freshly rebuilt).
4. The IACV must be ok for cold starting purposes and be letting enough air in. It Ohm'd out per the FSM fine when I had it off the engine, but I never bothered to open it up to actually check the vane/window activity across temperatures. But it seems to be open to allow the quick cold start. I still need to take this off and check it, as I've got a random warm idle stumble as well, maybe it's not closing properly ... the EFI gremlins are killing me (all 3).

I'm guessing I should probably get my CSI cleaned/replaced? Unfortunately, the only source for rebuilt ones (LCE) is out of stock and that means, they will be out of stock for a while as they are probably lacking cores.

The only other thing I will do is order that updated Cold Start Timing Switch, as I also have that TSB long crank problem. My Cold Start Time Switch is new but it's the original part number (95F), not the updated one per the TSB.

At this point, it has to be the actual CSI not delivering the fuel properly (spray pattern, amount of fuel, etc). Unless anyone else has ideas?

sounds as if your CSI is working fine; don’t buy a replacement yet, or you will probably be disappointed (when the problem persists). my ‘87s are both difficult to start with the CSI unplugged and cold temps. something else is possibly causing a rich condition, and when the CSI operates, it compounds the richness. figure out why it’s rich, and you’ll be able to plug your CSI back in.

I'm at a loss to understand what could be dumping that much fuel in for the 1/8th of a second I'm cranking before it starts with the CSI unplugged to make it run rich enough where a quick spray from the CSI floods the engine. There's just not enough time. If it were leaky main injectors, I would notice the smell and probably a really bad idle/performance during normal driving. It's sitting for 8 to 10 hours so I don't see how it could be related to off hours fuel pressure issues. AFM tested fine. I doubt there's enough time for the o2 sensor to make a contribution to fuel mixture, plus no o2 sensor code. IAC issue? Again, it tested fine too.

This is such an odd problem, it's the opposite of 99% of the cold start issues on the forums (i.e. csi not firing due to electrical or mechanical issues). So searching for "my truck starts better with the CSI unplugged" brings up zero results :)

Did you check the air valve connections and adjustment? This component controls the fast idle RPM and if working properly will reduce rpm after the coolant warms.

I planned on pulling off the IACV this weekend and taking it apart to actually see if the vane is functioning properly, as it tests fine per the multimeter.

I'm not sure this would have an affect though, since the truck is sitting for 8 hours, then starts instantly. So there would have to be some air getting in via the IACV, indicating it's open enough at this temperature to provide air to mix with the fuel to start. If it were faulty and closed off during the cold start, I would expect a longer crank whereby the only source of air would be coming in through the idle air screw. But I'm not 100% on the operation of air flow during starts (i.e. IACV vs idle air screw as source) so I may be understanding this wrong.

The previous theory posted: excess fuel would have accumulated in the intake (leaky CSI) or leftover in the combustion chamber (leaky main injectors), causing there to be enough there to start without aid of fuel from the CSI (which hampers the starting if plugged in). I'm still leaning towards the CSI leaking, since the main injectors are brand new rebuilt OEM's, and I don't have any indicative problems while it's running that the injectors are dumping too much fuel.

you stated that with the CSI unplugged (connector), the engine starts right up. you haven't physically disconnected the CSI from the fuel line i'm sure; so, your injector isn't leaking enough to cause problems (it will leak whether the connector is plugged or not, and it would leak ALL the time you had sufficient fuel pressure present in the rail). something is clearly not correct, but what? from your described test of the CSI, it is working correctly.

I'm not claiming victory yet, as I've only had 2 overnight cold start attempts, and it's been about 80F in the mornings (about 4 to 6 degrees F hotter than when I was testing). But I replaced my original TPS with a new OEM TPS this weekend, and reset my throttle stop screw correctly. Not only did it improve my idle shake, but the 2 cold starts I've tried have been instant. I'll update if I see things getting worse or going back to the original problem, but I'm a bit dumbfounded that the TPS would have caused this issue for cold starts.

It's interesting to note though, that my original TPS did adjust properly, and was in spec per the FSM. My only indicator was a code 7, and I was able to see bad voltage at the ECU side for VTA (it would never change and wasn't in the range). With the old TPS still on there, jiggling the connector and wires caused the voltage to go back in spec. So I was wary that the new TPS was the problem, and I'd still have to replace the wiring. I'm still thinking I may have gotten lucky when putting the new TPS on and the connector is just in the right place. But I do know that when I was getting good voltage at the ECU after jiggling the connector on the old TPS, I was *still* having my delayed cold start issue. This seems to still point the actual old TPS itself, and not the connector or wiring.

tldr; Replacing the TPS (which was functionally sound per Ohmmeter) seems to have fixed the issue for my delayed cold start, and improved my warm idle shakes (separate thread).

Victory claimed too early. Back again this morning with the delayed hang cold start .. and back to the drawing board. Going to be focusing on my shaky idle for a bit since I don't know where to go from here on this CS issue.

Appreciate the thoroughness of your posts, sorry it was a red herring.