blue_CA_yota

truck is an 89 with the 22re, stock motor.

I've had a high idle at start-up since I bought the truck a few months ago. On cold start up, it revs high (about 2000 rpm)..

as the truck is warming up, pressing the brakes will cause the idle to surge to about 1000 rpm, then shoot right back up..

For a while the truck was getting to operating temp (needle at halfway mark, sorry I dunno what op temp is off hand) within a couple mins of driving, and everything was normal, the truck idled at a normal rpm (didn't have a tach till a few days ago, not too sure what rpm it was specifically), and the brakes had no effect on the idle.

Over the past week or two, I've noticed the truck takes a little longer to warm up, and the needle never really reaches the halfway mark.. That is causing a permanent high idle (about 1500rpm), and surging when the brakes are pressed.. Even after driving half an hour, the needle never reaches halfway..

I've been referencing this thread https://www.yotatech.com/forums/f116...arched-183088/ summed up * TPS, IAC, and coolant level*

However my syptoms are sligtly different than the OP's were..
My coolant level is good, nice green colour too.. I think my Thermostat might be bad, will replace on the weekend..
My TPS hasn't moved/rotated out of place since I bought the truck..
My throttle body is clean, no build-up of carbon, oil, other junk..
My MAF moves freely, and the motor responds quickly when I manually adjust it..

Junkers88

I'm happy someone atually searched and used a previous thread for reference.

The idle surge with the brakes applied is due to a high idle. At operating temperature you should be idling at about 800 (I think it's 750 for 2 wheel drives and 900 for 4x4's). If the idle is higher then the ECU will cut the idle when the brakes are pressed, the high idle will come back in a second or so, then the ECU will cut it out again....... The end result is surging.

Get the rig to operating temp, check the timing and be sure it's at 5# BTDC, adjust the idle to 800ish and try that.

As far as the truck not getting to operating temp or taking a long time to get there it may well be your t-stat. I think the t-stats in our rigs are factory "fail open" so that if something goes wrong they don't slam shut like some of the other ones out there.

Hope this helps.

blue_CA_yota

Thank you for putting a reason behind the surging.. I never knew the reason behind it, but it seems all too simple now.

I will replace my t-stat and check the timing asap, and report back my results..

Thanks Junkers

Junkers88

I felt the same exact way when it was explained to me. It was one of those "smack in the head" moments.

blue_CA_yota

I changed the t-stat and my temp issue is still there..

However I lowered the idle (about 900) and the surging has stopped.. So far today I'd say this is a victory..

When the fan clutch is disengaged, does it stop spinning completely? My clutch is fuly engaged at startup, then quickly disengages (obviously quieter), however even after then it is still spinning and pulling air.. I've never paid close enough attention to it to notice if this is unusual..

Junkers88

I'm glad you got at least one thing fixed. I have no idea on the fan clutch, mine never stops spinning.

blue_CA_yota

I bought a new Engine Coolant Temp Sensor for the EFI, and the truck still doesn't register the correct temperature..

This problem with the truck not reaching operating temp has only started recently.. What is the path of the coolant through the motor? What I'm trying to determine, is if its possible there is a partial blockage through the part of the water jacket that the sensor sits in..

What is racking my brain, is that the truck is overcooling, and not overheating.. At least the sensor (new sensor) is reading that the truck is overcooling.. I'm going to try to trace the wires from the sensor tomorrow to see if there is something visibly wrong with them.. The t-stat is new as of friday, and I checked it before I put it in.. The ECT sensor is new as of this morning.. and the fan clutch engages and disengages easily..

blue_CA_yota

ok, scratch the idea of contaminants, I measured the resistance across the sensor and it is where it should be (.2 ohms when hot)..

somewhere between my sensor, and the ECU or EFI controller the signal is being corrupted..

I have googled many different key words, and think I came to the conclusion that there are 2 different sensors, one which measures the temp of the water and sends to the ECU for correct EFI operation, and there is a second sensor which sends to the gauge.. where is the second sensor..

EDIT: Unplugging the EFI sensor threw an error and the gauge still works. Conclusion 1: my wiring to the sensor is working Conclusion 2: I need to find my OTHER temp sensor.

I still have a high idle (about 1200 rpm), and can't seem to bring it down..

blue_CA_yota

I have found that my temp sending unit is faulty, but due to the long weekend, and being a dealer only part, I have to wait till tuesday to replace the sensor and see if that helps anything.

It is located jsut past the thermostat (firewall side), pointing downwards. One single wire with a blue connector, hiding underneath a mess of vaccuum lines..

guthriea

Did replacing the temp sending unit end up solving your problem? I have an identical problem and have tried just about everything on the web to cure my high idle and surging when brakes are pressed. Ill give this a shot if you had any change. Thanks.

blue_CA_yota

There are two separate coolant temperature sensors in the engine.. One of them is for the EFI, it is located on the front of the motor.. the second is the sending unit to the gauge cluster, and it is on top of the motor near the intake manifold (below the 3rd injector wire)..

Neither of these cured my problem, but my EFI sensor did need to be replaced..

I'm pretty sure my problem is rooted in an air leak to the intake manifold.. not too sure where its coming from, but I'm pretty sure thats my problem..

that explains the surging.. try to lower you idle, and that will stop the surging brakes..
idle problems:
1. idle screw.. located on the throttle body, try tightening it to lower the idle
2. vaccuum leak.. tricky to find, but check all your hoses are connected, and that the ends aren't broken
3. Air leak.. broken gaskets (which I believe my problem is)

hope this helps

DupermanDave

I have the same problem. Mine is a leak on the intake manifold. Tried multiple tests, did the propane torch test, squirt water on it from a bottle, and even carb cleaner on it. Found nothing. I got frustrated and just dumped the rest of the soapy water bottle I had over the intake manifold and it began to idle low and I heard a gurgling/hissing noise and found my leak.

Replaced the gasket, still leaks, so I'm going to try some RTV.

But the point it, keep testing over and over and you'll eventually find the leak.

Junkers88

Guys the intake gasket that goes between the lower "horns" on the intake (between the plenum and the head) have a tendency to get brittle and break around the back of the number 4 intake port. The best way to find that is to run some Seafoam into the system and after the initial insertion when the rig is sitting turned off get underneath it with a flashlight and check. You'll see a "wet" mark where the Seafoam is running out. I've had this happen on a couple of rigs and a 2.15$ gasket set cured it.


Besides that it's always good to repace gaskets that have seen 200,000+ miles like ours have. Toyota built some bad ass rigs and I can't understand why they didn't build gaskets to last a half million miles like they did everything else.

KcYotaChick21

I have a question I have the same problem high idle and surging when hitting the brakes... I just did a motor swap New 22re (Which is a dream come true)... The only issue is the idle surge when I touch the brakes. Im going to try to mess with the idle but I dont have a tac in the truck. Is it safe to do it just by sound? Im worried im going to hurt the new motor by messing with it but I also dont want the new motor to be hurt by the surging....

Junkers88

You can adjust it by ear but it's a pain to get it dead on. In that situation you could idle it down a little and then hit the brakes to see if it still surges. Repeat until the surge is gone.

The best thing you could do would be to swap in an SR5 gauge cluster that has the tach and go from there, or maybe buy an aftermarket tach (little one) and mount it under the hood for adjustment purposes.

blue_CA_yota

I noticed that when my engine idles at 750, its quiet and smooth, however at 700 it seems to vibrate and cause the cruise control wand to shake.. so I'd turn it way down, then bring it up to where it seems to be idling smooth..

I put a 2" tach from Princess Auto ($20) just above the vent on the driver side dash.. right in the corner of the windshield.. its small, came with a mounting bracket, has a 4 wire hook-up, and is illuminated when the headlights are switched on..

I've ordered an intake manifold gasket set from NAPA, to hopefully plug up my air leak.. Gonna clean the intake manifold while I'm at it..

yoterr

bought the same tach^^ good little guy it serves its purpose hope u cure your problem

KcYotaChick21

Im buying an aftermarket tac from my buddy he got a new one for his truck and is selling me his for like 40 bucks... I think im going to put it in my truck where I can see it so that I can feel more comfortable breaking in the new motor.... I adjusted it down by ear today but I know it needs to go down more but im going to wait for the tac I should have it around wed... When I idled it down it helped ALOT it only does the surging slightly sometimes... Also! I wanted to tell yall how excited I was.. I had a short in my taillights and had followed all my wiring and couldnt find it anywhere... After process of elmination I decided it was most likely the acutal switch for headlights.... Im not the best at working on my own stuff but I want to learn... So I went and bought a switch today and decided to put it in all by myself. Even after the guy at the parts store told me I wouldnt be able to do it by myself. ( He acutally said I should have one of my boyfirends do it as most women wouldnt be able to figure it out. ) Yeah... Well it did take me 3 hours but I INSTALLED IT & Fixed my short! I would say my day was very productive! Thank you guys for your help!

Junkers88

Feels good to do something on your own rig doesn't it.....

KcYotaChick21

Freakin Yes! I woke up at 6 am today and wired new speakers in it also so I have back speakers now to!
I never knew being laid off work would make me so productive on my truck...
Brakes are next they vibrate bad... I know how to do car brakes but never done em on my toyota