No More High Idle on Cold Start

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Any update guys? Same problem here. No high idle during coldstart but the engine runs smoothly. I replaced the whole throttle body & the ECT but there's no improvement.
 
No news here. I'm convinced its an issue with the valvetrain when cold. I've gotten used to it as it runs like a champ once started. I've swapped every part possible externally.
 
...or intake manifold.
 
Ok...as I see it, you like to spend lots of money...is good...for whoever is selling you parts...what I have NOT seen you write is that you CHANGE the temp sensor...remember there are 2, one for the dial on the dash and one that tells the car is already hot and to turn the RPM's back down...replace the easy part, then go for the funny stuff
 
Well, you see it wrong, Panama Red. Easy parts were swapped from other Cruiser heads for the most part. It's my prerogative whether or not I want to purchase parts to rule things out. Temp sensor was swapped out early in the thread. Read the entire post before making comments. Obnoxious. Learn some manners. If you're not going to take the time to read the entire thread, don't post accusatory, condescending, defamatory comments. It's best for everyone. Have a great week.
 
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I have three sensors in my car...one for the dash needle...one for the diesel fuel pump to rev high when cold and the other one that I have no clue but think is for the front fan...the one for the pump is a two cable one and the other two are one cable each...if you have replaced and check the wiring, there is not much more to do, but to check the fuel system itself...if the car doesn´t stall when hot and doesn´t give you any other problem only that it does not start in high RPMs when cold, then it should be some sort of electrical part (kinda xtra) like the one that moves the accelerator when you turn on the AC and the compressor engages...in my car it is the same one...
 
When you tested the ECT sensor, was it perfectly within range per the FSM? I've tested two used sensors, and two new sensors from Napa and Oreilly and they all fell just slightly below the specified range at 68 degrees.
 
Well, here is an interesting update (I'm the OP). Changed my belts last week and I still do not get the high cold start idle I'm after BUT it doesn't not fall on its face now at initial start up before catching itself. Makes no sense really but has to be the belts. The old belts were not loose or that old but were getting noisy so I replaced them. I'll keep you posted as temps continue to drop this fall.
 
OP here. Still have this issue. I've bought a new TRD Tundra but have decided to keep the 80 as well so now I can devote a little more time to this. I'm convinced its the ECT sensor. It's been really cold here in the mornings and the thing starts and idles between 400-500 RPM which makes for interesting warm-ups. I've replaced the sensor with two new units so I'm ruling that out. I'm zeroing in on the actual wiring. I popped the connector off last night to take a look. Looks fine but who knows. Can anyone give me an idea how I should go about testing the actual sensor wiring at the plug? Additionally, is there a way to pull that wiring down below the truck to get better access to it. Thanks!

I've considered just buying an OEM hand throttle for it to get the revs up when it's warming up. Runs and idles great once it's warm.
:meh:

Tundra Porn

fto702.jpg
 
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Read thru this thread quickly and didn’t see if you verified that the wiring from the engine coolant sensor to the ECM is intact. Perhaps there is an open in the circuit. I saw where you tested the sensor and it was fine and also tried another erect sensor with no change in results.

Good luck...Don
 
Right. That's what I'm zeroing in now as it's the only thing left I can think of. I did test the ECU a few pages back with these results. Everything was in spec.

ECU looks good internally, no blown capacitors, etc.

E7 Pin 2: +12v
E7 Pin 13: +12v
E7 Pin 11: +9v (EWD says 9-12v is acceptable for pins 11 and 22 unless I'm reading the EWD incorrectly?)
E7 Pin 22: +9v

E10 Pin 13: .9 ohms
E10 Pin 26: .9 ohms
E10 Pin 24: .6 ohms
 
I suppose it could also be the IAC wiring. Throttle body and IAC valve are both squeaky clean.
 
Well, I hope there are a few people left watching this thread. Friend came over last night with his new OBD1 data tool and we grabbed a video of my cold startup. Anything jumping out to anybody? Note the idle is only at 775 RPMs at 87F when it should be around 1200-1500 at cold start. Let me know your thoughts. (FYI...when I started the truck bone cold the ECT was at 55 degrees with the same idle speed, I didn't start the video until a couple of minutes later at 87F ECT). I may need to start a new thread as this one has gotten really long and kind of fizzled out.

 
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Bump for the evening crowd. Feel like I’m getting close to solving this mystery.
 
Ha! You’ve been with me since the beginning!
 
I don't remember your year? But if it's a 94 or 93 you could check the pair system if it gets stuck open or close can cause issue. But like I said ect sensor I don't remember if you replaced with oem or aftermarket. I got mine back after ditching all the vacuum lines and pair system plus new o2s and timing check. I do not know what fixed it. I did try two different iac valves with no change. I think if you can eliminate the etc sensor that feeds the computer will go from there. God speed
 
'93. PAIR seems to be working fine. A little noisy as expected until the vehicle beings the O2 sensors online and then quiet. ECT was replaced with Toyota OEM. Have tried 3 different IAC loaners and no change.
 
I noticed a change in my high idle (for the better) when I changed several things at once...it wasn't my intended goal.

I removed the PAIR, put in a new AGM battery, new 2.0 kw starter, new fusible links and replaced all the battery cables with the larger ones made by some of the Mud members/vendors. I also cleaned the grounds before replacing the cables. It now sounds like a fan boat at startup.

Sometimes I get a CEL at highway speeds when it's below about 10 degrees. Don't know what that's about. Coolant temp lately has been about 155-165 at 70 mph.
 

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