I recently changed the engine on my '85 pickup, auto trans, 4X4. Along with the engine I changed plugs, wires, cap, rotor, injectors, airflow sensor, throttle position sensor, and O2 sensor. It idles great. The problem appears at higher RPM. While sitting stationary at higher RPM I can hear the engine misfire and see it shake. On the road I have to be accelerating or decelerating all the time. Light throttle and it surges rapidly and badly. I'm out of ideas.

 

Did you test/adjust the TPS after installing it?
- http://www.4crawler.com/4x4/CheapTricks/TPS/index.shtml

And test the AFM?
- http://www.4crawler.com/4x4/CheapTricks/AFM/index.shtml

Also, is that vacuum getting to the fuel pressure regulator (that cuts the fuel pressure at light load):
- http://www.4crawler.com/4x4/CheapTri...ine_Pix/8.html

Also, any vacuum leaks or stored trouble codes?
- http://www.4crawler.com/4x4/CheapTri...CheckConnector

 

what about fuel filter Change?

 

The problem I'm experiencing was happening before I did all of the below. Yes it does run better after changing and adjusting the items below, but the running rough under no load or light load persists.

TPS tested bad at first, I replaced, tests ok now and adjusted per the instructions at cheap tricks. Also replaced the wiring connector.

AFM was bad, replaced with new and test OK per cheap tricks specs

vacuum is getting to the pressure regulator. When I pull the hose off at idle the engine speeds up a few RPM is that normal? How do I tell if the regulator is bad? Would too much pressure cause the engine to limp under light load?

No stored trouble codes. If there is a vacuum leak it is hiding really well. I have sprayed carb cleaner on everything trying to detect a change in idle speed.

Fuel filter is new.

My next step, I was planning to watch the voltage on each of the wires coming out of the TPS, AFM, and O2 sensor. Any advice on what those voltages should be?


Thanks for the assistance!!

 

And here's something even more interesting. Looking at the repair manual it appears that the 1&2 injectors are supposed to be wired together as well as 3&4. So I tried that. In this configuration the engine idles a little rough but the limping under light load problem has gone away. I'm looking on another web site and it looks like injectors 1&3 want to be wired together as well as 2&4, which is the way the harness fits and is the way it was wired at first. Can anyone confirm which way the injectors are supposed to be wired?

 

Back to 1&3 injectors connected and 2&4 injectors connected. Back to limping at fast idle or light load. I plugged off the EGR. No change. I pulled the vacuum line to the pressure regulator while the engine was limping at fast idle. No change. Normal slow idle is smooth.

 

buy a new truck with out this problem

 

Great idea on the new truck.

 

take it to toyota and see how much they want to charge you to fix it. then get more motovation to fix it yourself

 

Did you figure out the problem? my truck is acting the same way as yours and im trying to figure out why.

 

The "take it to toyota and see how much they want to charge you to fix it. then get more motivation to fix it yourself" idea was the best one. Toyota wanted $150.00 to just look at it. Then they prescribed changing out all of those aftermarket parts I had just installed and replacing them all with genuine Toyota parts for somewhere around $1,000.00. Because, after all, you know, if the part doesn't have Toyota stamped on it and didn't cost four times as much it just can't possibly work right. Right? Then after putting all new Toyota parts on it, if that didn't fix the problem, they would start the troubleshooting. Yes. I'm serious.

That was Just the Motivation I needed.

So, I readjusted the valves. It turned out that I had somehow set all of the exhaust valves on the new engine with no clearance. Who knows how I did it but they were all the same. Go figure... I reset all of the valves to proper specs and it has run great ever since.

 

My most recent upgrade has been a LC Engineering header, with a high flow cat and 2 1/4 exhaust all the way back. I should have done this years ago. Significantly more power and it sounds good too. Fuel economy seems to be up by about 10% but I'm still checking. I have only burned two tanks of gas with the new setup. Passed Colorado smog test with flying colors.

DO NOT purchase a Pace Setter header. Yes, they are far less expensive. And that would be great if it fit. Which it doesn't. Crazy.

I highly recommend LC Engineering. Great products. And they are great to work with. Just call them and they talk to you like you are a real person. No I don't have any relationship with LCE other than being a very happy customer. My next upgrade will be their Pro Cam. Then I'll likely replace the fuel injection system with their SDS version so I can get away from the highly restrictive air flow flapper.

God Bless the 22RE!