Aloha guys! So I've been working on this one issue on my truck for a while. It's a 94 T4R with 22re motor. It's idling too low on warm starts. I think it may relate to another issue with pining I'm dealing with which I'll get into later.

So if I cold start the truck it idles high and then at operating temperature drops idle down. So if I set the idle then to 750 rpm and set the timing it seems great. That is until I shut the truck off again and restart it. Then it idles too low. We're talking 400-500 rpm it's to the point where I just have to raise the idle back up to 750 at warm start. This isn't that big a deal except that then on cold starts after warming up the truck idles around 1000rpm. I could live with this, BUT I'm having issues with pinging and I'm trying to get the timing set right to resolve that or at least help. I've adjusted it from 5 back to 2 and even 0 and that has helped with the pinging (so has running premium gas) However. I'm wondering if the pinging is related to this idle issue. Because I've adjusted the idle up then setting the timing is going to be different correct? Do I reset the timing with the E1 TE1 jumped at this new warm start 750 rpm? I'm sure it would be different than the first setting at a cold start 750 rpm?

Ideally I'd like to fix the issue that's causing the engine to do this. I've done quite a bit of research and work on the truck and haven't found any solution.

Just did new belts, battery, spark plugs, wires, distributor cap, and rotor, flushed the radiator and put Toyota red back in her.

New exhaust (including cat and everything back) and new o2 sensor. Turns out the PO couldn't get the nuts off to change the o2 sensor so they just hollowed out the cat which cleared the code. When I started the truck after new exhaust the computer threw CEL and bad o2 code. I got a new Denso sensor in there and it's all clear now. (That is after dremeling off the bolts that were nearly welded on hahaha, a sensor swap is a 15 minute job that took 2 hours, I'm getting used to this type of stuff now on this 27 year old truck that's lived most of it's life in Hawaii)

After the exhaust I reset the timing to 5 after a cold start warm up with rpm at 750 and E1 and TE1 jumped, but the Pinging was WAY worse. (I also had to fill it up with regular which again increased the pinging) I read about a few guys getting good results with the pining going away by throwing in a 180 thermostat from the turbo 22RE engine so I've got one of those on order to try. I think I'm going to try and set timing to 5 with the idle set at 750 on warm start and see if it improves. I don't mind running premium because I get it from Costco so it's still cheaper than regular everywhere else, but ideally I'd be running regular in this thing like It's meant to and save even more on gas and sometimes I can't get to Costco when I need gas and don't like spending 4.50 plus a gallon.

My TPS is set perfectly (I dealt with that early on and after pulling the TPS code I set it to spec and it helped with some early on issues.)

I've also checked my MAF and looked over the IAC pretty well.

It's had a coolant flush and I put a two stage thermo from LCE in there but none of the above has helped with the idle issue or the pinging for that matter hahaha. The truck other wise runs good, no misses or rough, I just want to be able to drive these big hills around here in third gear and not feel like my engine is going to explode

Currently it has no CEL codes


So primary issue. Truck idles really low on warm starts. I.E. Truck has warmed up, did a drive, shut down for gas or something, then jumped back in started and it idles 250-300 rpm below 750.

Secondary issue. Pinging! Hopefully solved by the new T-stat coming next week If not maybe I'll try run no thermostat? It's always warm in Hawaii if it's not HOT and this thing probably will never leave the islands.

 

Here's one other thing I'm just wanting to check when I have a chance. When I swapped the distributor cap I had a thought that maybe the distributor was replaced or removed and reinstalled wrong. If it was reinstalled with the engine not at TDC and the rotor pointing to the number 1 position then surely it could throw the engine off. I just figure it's running two smooth (other than the pinging) for that to be the case. That being said How would I know it's in TDC without taking off the valve cover?

That's another thing I've done. The valves are set to spec!

And just to clarify! It's not the timing chain guide It has a new chain and guide and both are intact and in good shape. I got to scoop out the old one when I did the clutch and pulled the oil pan hahahah.

 

Best, and only way I know of, to verify #1 is at TDC is to pull the valve cover, and check the valves of #1 are both loose. If not, you need to rotate the crank 1 revolution to get to #1 to TDC.
When it's at 5° BTDC timing, with the jumpers in, the distributor should be about the center of it's adjustment throw. If it's at one end or the other, it may be off a tooth. Just has to be stabbed again.
Did you check the air gap of the sensor in the distributor? That's pretty important.

Is the Idle Adjust screw near one end of it's adjustment or the other when it's set to 750? Did you check the o-ring on it? If the o-ring is shot, it can cause all kinds of problems. Just make sure to count how many turns the idle adjust screw is out from the bottom before you remove it to check the o-ring. Let's face it, it's 30+ years old! Rubber doesn't last forever. While the idle adjust screw is out, make sure the air passages that it controls are good and clean. Throttle body gets a lot of crud in it over the years.
The o-ring is very easy to locate, most auto parts store have o-ring sets that will include the right size, for less than $5.00-$10.00. A thin layer of Vaseline rubbed on it will make it last longer, and seal up better, too.

Did you check the EGR valve for proper operation? If it's not working right, like it's stuck open, that can cause problems. Where it feeds into the TB frequently gets clogged with crud and needs to be cleaned out.
Same for the PCV valve, to a lesser extent. It needs to be checked for proper operation. The grommet for the PCV valve gets stiff and will break apart very easily, so checking it while the valve cover is off is the best idea. That way, any bits and chunks don't fall down into the engine. If you replace the valve and grommet, use OEM, not some auto parts store cheapie. It's well worth the money to ensure it functions as designed.

Are ALL the vacuum lines in good shape and routed correctly? Ue the sticker on the underside of the hood as reference.
Does the big tube from the MAF to the TB have ANY air leaks in it? Especially in the pleated, corner pieces? May need to flex them to detect any cracks there may be.

Hope something in all my rambling may be some help...
Pat☺

 

I do think I found a little insight into it. I've read a few more threads after digging deeper and it appears to have to do with the FPU switch. Some guys were saying that they grounded that switch and the issue went away. One guy put a switch inline into his dash that he could flip on warm starts. Apparently there's a TSB about this issue and they recommended swapping some parts but those are now longer available. I'm having trouble seeing the TSB because it's from about 6-7 years ago and most of the links are dead. It was also primarily for the older 22re motors with an engine temp sensor on the thermostat housing. Mine doesn't have that so I'm still trying to figure out where my sensors are and if I can check them and try the ground trick. I would happily just do that if I can figure it out. One extra switch flip on warm starts is a small price to pay for the truck to operate properly!

 

Not hard to adjust the air gap on the sensor in the distributor. Just takes a feeler gauge. Turn the engine, with the distributor in, until the sensor "projection" points directly at the pickup, measure the air gap, and adjust if required. It's supposed to be 0.2-0.4mm. You can loosen the screws holding the pickup, and adjust it a little. The FSM says if it's no good, to replace the distributor. Just so you know.

Sounds like you've got a lock on all the rest, so I'll shut up, and wish you good fortune!
Pat☺

 

great info Pat! I’ll play with this when I get the o rings!

It definitely seems like a fuel pressure thing. The simplest solution is to blip the throttle and then the engine gets it’s idle backup. I think the fuel gets loaded in the fuel rails and needs to get flushed/burned off and a bit off throttle clears it.

 

Ok guys I think I’m on to something. I’ve had another issue which is smelling gas. I notice it around the fuel cap. I think my charcoal/evap can needs cleaning or replacing.

I was reading in fsm about pinging and read that charcoal canister can cause this.

I also learned that filling your tank past the pump first shut off can cause fuel to end up in the can saturating the charcoal. This can lead to you guessed it poor idling especially when warm!

So there’s three issues in one. The poor warm idle caused by too much fuel in the injectors/intake. Smelling gas. And pinging 🕵️‍♂️

now my question is can I clean and refill the canister? I can’t even find a new one anywhere online and don’t want to chance another used and abused one. Should I just delete it all together?

 

Well I've got a little more info but still haven't fixed it. As far as the idle issue, it appears to be related to the coolant temperature sensor. I'm going to test the one that's in there when I can borrow an ohm meter, but from the threads I've dug up it sounds like it was an issue with the original design not having the correct temperature range. Unfortunately most of those threads are for the older 22re which has the sensor on the thermostat. The next gen has it in a different spot. I'm not exactly sure, but I'm going to dig into it the next few days and test it. They're cheap enough for aftermarket 15-20 and 75 for a toyota one. My thing is are these new one's actually going to have the correct range set on them? Also on Toyota parts site there's a couple different parts numbers listed that all say engine coolant temperature sensor and all say they fit the 2.4L engine in my 94 4runner...... Talk about confusing hahaha

There was a whole TSB in the 80s covering this and the suggested replacement sensors but none of those are available any more and not to mention they're for the older engine thermo design.

A couple guys did a little trick grounding the sensor with a throw switch wired in the dash. If it looks like the same sensor then I'm considering trying that, but for the price of a switch and trouble of wiring I could also try a temp sensor from the autoparts store. I have to swap thermostats anyway so I can burp the system at the same time.

Here's a good link on the 80s series fix with the switch

https://www.yotatech.com/forums/f116...-issue-288051/



I'm still working on the charcoal canister and the fuel smell. I pulled the can and tested it and it appears the valve is working properly. Next step will be to try low pressure air to clean it out. I considered that the 27 year old gas cap might be faulty and that could cause the gas odor by the filler, but a brand new one didn't change anything. I pulled the little panel in the wheel well and the filler itself doesn't appear to be leaking even after a drive getting it up to warm. I'm going to get under there and check more closely the lines on top of the tank to make sure there's no leak.

At this point the smell could be a broken or leaky line, or fumes backing up because the canister isn't doing it's job.... it's 27 years old! I am a little concerned with the odor especially when someone pulls up smoking a cig next to me. I don't like it, but it's my daily, and I gotta just be careful till I can diagnose it.

I'm thinking a leaking fuel line could cause some issues with idle too? If it's sucking air instead along with the fuel.... I feel like my mpgs are down 16.5 last check, but that was after new exhaust system and I couldn't help but romp on it for that tank. The new Magnaflow cat and Flowmaster 50 Delta muffler sound pretty good for a 4banga!!!

This tank I'm primarily trying to see how good of mileage I can get driving like a grandpa, with a few more spirited pulls here and there.

 

Thing is, the fuel lines are under pressure. About 45 PSI. No suction. Even in the return line, there's some pressure, but even if it was under a suction somehow, all it would do is feed some air into the tank, which could/would vent it overboard.

All you can do, really, is sniff around to get close, and then scan very carefully, visually. The last leak I hag was an injector's gasket got damaged during installation, after installing a new knock sensor. My mechanic replaced the gaskets, free, since it was his men that did the work, and I've been fine since.
A possibility, also, is one of the metal lines that come out of the tank through the hanger lid. They're known to rust, and develop pinhole leaks that just get bigger.

Or one of the banjo fittings, especially the ones on the filter, the pulsation damper, and the cold start injector. If the banjo bolts aren't torqued to spec, the crush washers aren't the right metal, things like that.

No matter what, I wish you luck.
​​​​​​​Pat☺

 

So I haven't figured out the fuel smell/possible leak yet. I worked on the truck ALL DAY and half of yesterday and still am having the same issues with the low warm idle, pinging, and I haven't had a chance to check for the smell but I will tomorrow.

I replaced the thermostat from a two stage 190 to a 180 from the rte which some guys had suggested could cure the pinging as it had in their cases. It did nothing honestly The gauge is in the same place at warm and with the timing at 5deg it pings like mad. Set to 0 and it's 97% ping free on regular grade ethanol free from costco. I might be able to get it to stop pinging at 5 with premium, but I'm just wanting this thing to run on regular and save some money.

I also tried a new coolant temp sensor the ECU one and it did nothing. I'm glad I picked it up and swapped it though because when I went to take the old one out the plug snapped clean in half! It was definitely on it's way out even if it wasn't causing the warm idle issue.



Crapped out Temp Sensor