Hi all, been browsing the forum trying to search for a nagging problem on a truck I bought 3 weeks ago. It's an 89 4x4 4 cyl. 22R-E. When I bought the truck, it wasn't having this problem for the first two weeks. Then one day it stalled out on me on my way to and from work. Before it stalled, it was bogging down. I was hitting the gas pedal and nothing was happening. After it stalled, it took about 5 minutes of letting it sit for me to be able to restart it.

So I went to the Auto Parts store and bought everything for a tune-up.
Changed the plugs, wires, cap, rotor, and air filter. Also cleaned out the TB (throttle body).

When I turn the truck on, it is idling very high! I dont have a tach, but I would guess upward of 2,500 RPM's. The weird part is that it is fine for the first 20-30 seconds after starting up, but then it surges and stays high.

The truck is running pretty rough at idle too. It's shaking like it's missing. I triple checked the wires, they are in the proper firing order and all plugs are tight.

I jumped the E1 and TE1 terminals while the truck is running, but it did not help the idle drop. I believe I read this means the TPS is faulting??

When the IGN is on, but the truck is not running, I am getting 3 CEL codes.
22, 42, 51.

Can anyone help direct me from here?

 

I should also note, A mechanic friend came over Saturday. He used a meter on the wire harness that plugs into the TPS. He said the IDL wire was not getting the proper voltage. It was registering as 11.5V, even with throttle open.

We went to check the ECU and turns out, there is a hole in the wheel well, right in front of it! The corner of the ECU was corroded. We opened the box up and the board looks fine. He says I should replace the ECU, it might have shorted out.

Can somebody please help me here? I don't know what else to do. I am so frustrated, I am contemplating selling this truck and I just bought it 3 weeks ago. I don't have a ton of money to be replacing things that may not need replaced.

I've also read over this thread:
https://www.yotatech.com/forums/f116...ensive-199356/

I have checked vacuum lines and hoses.

Where is my EGR valve? I can try cleaning that. Same with my AFM. Where is that located? On top of the air box?

 

22 - engine coolant temp sensor signal. Open or short in coolant temp sensor for more then .5 sec

42 - vehicle speed sensor signal. speed signal is not input to the ECM for at least 8 sec of high load driving with engine at 2200 - 5000rpm

51 - switch condition signal. displayed when IDL contact off or shift position in R, D, 2 or 1 ranges with the TE1 and E1 terminals connected.

 

Do any of those codes make sense to explaining this problem? I have a manual, and the speedo works fine.

 

OK, if its an "on/off/on/off type idle surge, then base idle is too high. As soon as the engine hits around 1800 rpm with no throttle pressure, then the ECU turns off the injectors, as rpms drop under the threshold, they are turned back on. Other things that will let idle go too high, cooling system not filled completely. Air in there. The hot coolant must run through the throttle body, or this makes the IAC run higher (iac is idle air control)

If its just a slight up and down, bouncing around, check to see if timing is moving by using a timing light. The TPS (throttle pos sensor) adjustment may be just at the threshold. Easiest fix for that, clean the throttle blade so it can fully seat. Usually some gooey deposits hold it open. TPS only moves ignition timing, that is it. And just off idle, it bumps it like 10 degrees, if the TPS is right at tha threshold, timing can be erratic.

 

I am gonna lay down money on an intake leak or bad IACV. I see you had the throttle body off my money is on the intake leak. Check the IACV by blocking off the air ports...both sides.

 

Thanks for the reply. The idle is NOT an on/off/on/off type surge. I turn the truck on and it's fine for 20-30 seconds, then it is a steady high idle around 3,000 RPMS and continues that way.
It's definitely not a slight up and down surge bouncing around. It's very steady and high.

When I gave it a tune-up, I did not remove the throttle body, I only removed the intake hose connected to it and I just sprayed TB cleaner in there and used a toothbrush and rag to clean the inside of the housing and the butterfly blade. I got it pretty clean and there is no longer a lip where the blade closes.

I am going to try 3 things tonight:
1. Unplug the TPS to see if the system goes back to default.
2. Spray carb cleaner around the intake hoses to check for cracks.
3. Unplug the coolant temp. sensor (WHERE IS THIS LOCATED???)

 

Also, my idle adjustment screw is all the way in (set to low idle)

 

Its is on the intake manifold against the head inbetween number 2 & 3 cyclinders. I am still betting on the intake leak triple check every hose you have taken off for cracks if you are leaking air it will cause a high idle.

 

Ok thanks again. I will check that when I get home from work. I will update this thread after doing so.

 

Update:

I sprayed carb cleaner around the intake hoses to check for leaks - none found.
I unplugged the TPS sensor to see if it would restore back to default - nope; still had a high idle.

I then crawled under the truck and realized that I had a coolant leak from the bottom of the radiator, near the big lower hose. The overflow tank looked low, so I put water in there, and pulled the EFI relay to reset the computer. Sure enough, I fired her up and the idle was normal again!!!!
So my problem was low coolant! The ECU is fine.

Next issue:
I drove it around the block about 4 times and after 10 minutes or so of driving, it started bogging down on me. I would press the gas pedal and nothing would happen. Then all of a sudden it would catch and I'd accelerate again. Any suggestions as to why that is happening? Fuel filter need changed? Something to do with the exhaust (cat clogged or something)???

 

Check your throttle cable...

 

I lubricated it when I did the tune-up. It's not getting stuck or anything. TB is clean too. It's bogging down and stalls out. Then I have to wait 5 minutes or so before it will restart.

 

Turned out to be low coolant. My radiator had a leak. I replaced the rad and the idle came down.