brwise

Hello everyone,


First off, I want to apologize if I am posting this in the wrong section. I was not sure where it should go.





My name is Brian and I am a long time lurker, first time poster. I have searched this issue across many online forums and have a good idea of what it may be, but I wanted to run it by the pros here.


I have an 89 22re 4x4. Body has 180k, complete rebuild with less than 500 miles. The engine starts and runs great when it's cold. I know these engines aren't power houses, but it has some oomph at the bottom end when it's cold.


After the engine warms up, I start to lose any kind of bottom end power. Anything under say 3000 rpm is just gutless. I have to get the revs up in order to get any power out of the motor.


Now from what I have read, everything points to the TPS. I came across the guide on 4crawler on checking/adjusting the TPs which I plan on doing.


However, I would like to ascertain exactly what issues cause these symptoms when the engine is WARM. I have read that bad o2 sensor, misadjusted valve clearances, misadjusted timing, clogged throttle body, and many more issues can cause the lack of power on the bottom end.


My questions is: which of these issues cause symptoms to only become evident when the engine is WARM?


From what I could find, the only problem that specifically says that it is apparent only when the engine is WARM is the TPS issues. Can anyone else weigh in on any other possible problems that would cause the motor to lose bottom end power once it's warmed up?


I am just trying to be clear on what the most obvious problem is before I start throwing time and more importantly, money at this truck. It's in great shape and everything else about it works great. It just has this annoying power loss issue which I hope to resolve by fixing something simple (hey, I can dream right?)


Thank you so much and please let me know if I need to provide additional information.




Thanks,
Brian

thefishguy77

iTrader: (1)

Hi Brian. Welcome to the forum. You posted in an aright spot. It does sound like the tps could be the culprit. They are very easy to check. Kinda like a light bulb. Touch the multimeter prong to the appropriate terminals and read your meter. You will need some thickness gauges for the test but those are cheap enough. It's an easy one to test. Also have you run a compression test on it. I know it's a fresh rebuild but never hurts to eliminate the easy tests first. Check your o2 sensor as well make sure it's not a bosh one. They are notorious for causing problems on these trucks. What weight oil are you running? Did you break in the new motor or just run it. I shouldn't make that big of difference but just throwing out ideas. Good luck. Hope this helps

brwise

Thanks for the reply. I have feeler gauges and a multi-meter, just haven't had the time to bust into it yet. I have run a compression test and all cylinders are on the high side of spec. The motor has a LCE header on it, no cat, o2 sensor in the pipe after the header, before the muffler.


Also, this morning I stopped at the gas station which is only a mile or so down the road on the way to work. After I pumped my gas, I went to go get on the freeway and whatever the culprit is.. it's like a switch. I was in the bottom of second getting up speed to merge, and it's like a switch got flipped and it just loses a percentage of power.


Would a bad o2 sensor cause this? I am not familiar with what loops are open or closed depending on the temp/warm up status of the engine. What ever it is, it definitely feels sensor/computer related.


The truck has an LCE header, no cat. The o2 sensor is a good bit down from the header on the pipe before the muffler. I remember reading that if this isn't a heated sensor, it will have problems getting up to temp and providing a proper reading. Can anyone confirm whether or not they have had issues with the o2 after installing this header?


Thanks!

brwise

I also noticed the 3 bolt flange from the header to the pipe is missing a gasket. obviously this needs to be replaced and would have some effect on power, but would that missing gasket have anything to do with why it runs fine cold then hits a wall once it gets up to temp?

HighLux

You taken a look in the gas tank yet?

brwise

I have not. My fuel gauge was bobbing then stopped working, so I need to take a look at the sending unit and make sure it is working/hooked up properly.


I am not 100% positive if the fuel filter has been done, but the outside of it looks newer than the surfaces of the surrounding parts, so I would assume it has been done..

brwise

I have an update on this issue. After HighLux asked me if I have checked the tank, I started to look into what symptoms would be evident for fuel delivery problems. It turns out that the problem I am having is not so much related to the engine being warm as it is related to how long it has been running and how aggressive I am with the throttle.


For example, if I have the truck warm and shut it off and start it back up, it seems that the problem goes away until I get on the throttle. It's almost like the fuel filter is clogged and when I shut down the motor, the pressure is relieved. Then when I start it back up, I can intentionally reproduce the problem by getting on the throttle. I will have great bottom end power, then when it gets towards higher revs, it cant keep up with the demand for fuel and starts to struggle. Does that make sense to anyone? I am thinking in addition to adjusting the TPS, I should probably put in a new fuel filter.


DO you guys think it's also worth pulling the tank and taking a peek inside? I crawled under there last night and tried to fiddle with the fuel gauge sending unit connection, but no joy. Still not getting a reading. The gauge was working for a day or two when I first got the truck.




On an un-related note. Do you guys follow any kind of break in procedure following a rebuild on these trucks? It has a new/balanced crank, new main bearings, new rings, honed cylinders, resurfaced head, resurfaced flywheel and new clutch/throwout bearing. I ran the break in oil and changed that at 25 miles. Ran regular oil and changed that at 150 miles and again at 300 miles. Oil came out clean and it currently looks clean when checked from the dipstick. I have read everything from don't go over a certain RPM to run it like you stole it. Just wanted to get some insight on you guys here who have more extensive knowledge regarding these particular motors.


Thanks for the help!

FGZ

I don't see anything about a fuel pump, are you sure your fuel pump is OK?

brwise

I have not checked the pump. That is what I am trying to figure out.. What I should check and in what order..


I am trying to avoid just jumping from possible cause to possible cause without any real method to what order they should go in.


Can anyone offer any insight on if I should do filter then pump, or pump then filter? I guess depending on how complicated it is the check the pump.. It's a P/U so I have no access panel..


Can't I check for fuel pressure at the cold start injector?


Can anyone point me in the right direction for checking the pump based on the symptoms I have described for an '89 P/U?

HighLux

You picked up on my clue Dr. Watson. I suggest we investgate the fuel tank. It may contain the clue we need to solve this riddle.


The fuel tanks have a reservoir inside it is there to keep from fuel starving when sloshing around. Like a ring the fuel basket sits in. It gets clogged up....there is a tube that runs between the reservoir and the rest of the tank. Also your sock may be blocked.

1st gen runners have a panel to access tank under rear seat....trucks...you will have to drop tank.

I wanna see in the tank.

Gamefreakgc

Fuel delivery issues could be the culprit, it's not unheard of.

If that is unsuccessful, grab yourself a multimeter and check your ECT sensor, TPS and VAFM. See the FSM for the correct readings, easiest done on a cold engine. Some of the sensors have air/fuel controls that only kick in when the engine is in closed loop when it warms up. Or you can check them first, it's free and literally all you have to do is unplug them and test.

Gevo

Seems like dropping the fuel tank is a lot of work on these cars. I would start from a pressure test.

I borrowed the kit form autozone and was successful in testing the fuel pressure. You can read the pressure as you throttle up and reference to the FSM what the proper range is. If you go this route, I reccommend to connect the pressure gauge to the cold start injector. It is easier than the other methods.. imo.

brwise

Thanks for the replies!

If it was a sensor issue, would it still make sense for the problem to go away for a short period after stopping the engine and cranking it back up even after it is warm? I can literally be rolling down the street and stop the motor, crank it back up, and it runs great until I get to a certain point in the revs. That can be in less than 15 seconds or over 1 minute... I will check the fuel pressure and go from there. Is the kit from AutoZone pretty straight forward?

Thanks again for the replies guys.

Gamefreakgc

I've had some sensors do some really odd things as they fail... so it's possible. I'd just hate to see you go through all the trouble dropping the tank and it not being the issue, when it only takes 5 min to test the sensors.

HighLux

Dropping the tank is easy. Hell toyota even put in a drain plug. Talk to me when you have one teetered on a jack with 15 gallons in it.

Remember...its not about finding the exact issue. Its about going through systems and diagnosing them and ruling things out.

I'd look in the tank on any older Toyota that was new to me. The sock is like 2 bucks...and I have personally seen a truck clog one up in less than an hour and have running issues. Most of the trucks have been abused by this point. You would almost have to assume someones had it in water at some point. Lord knows what you will find in a gas tank. I had one I pulled in a mustang once...reeked my entire house up like varnish for a few days...just from having it in the garage. The fuel basket from that one looked like some sort of crystal castle like structure that had no resemblance to an auto part.

Bad stuff happens in gas tanks. Go peek in it.

brwise

hey guys, I have the procedure printed for testing the TPS. can anyone point me in the right directions for checking the ECT and VAFM?


I also just found out that the o2 sensor was unplugged. the truck has an LCE header to magnaflow and the o2 is way downstream of the collector. I connected the sensor and the truck seems to have better power on the bottom end now. I still need to check my fuel pressure which I plan on doing this weekend.

AdmiralYoda

If your O2 sensor was unplugged I'm surprised the check engine light wasn't on. Is it on? Does the light even work? Any codes stored?

Also, having the O2 sensor that far from the head may cause longevity issues. If your sensor is a one wire it may not get hot enough and may foul prematurely. It really should be in the header.

brwise

its a 4 wire. I doubt there is a bulb for the CEL in the dash, as I have never seen it come on. I have it on my list to pull the dash off to check. the truck came with the header which I am not a big fan of, but the bung for the 02 sensor is welded in the location that LCE suggests for that header.




I am sure there are codes stored since the o2 was unplugged. going to pull codes this evening.

Gevo

From what I have understood reading through many a articles about the ignition system and the O2 sensor system... your car would be running rich without the O2 sensor.

Running to rich I think would cause low end stutter. I currently have a low end stutter as well. It was really bad with popping and all a few days ago before I put in the new distributor. One of the pickup coils was way out of spec.

Just some thoughts.

brwise

well I just got back from testing it out and it runs worse with the 02 plugged in. starts to sputter, miss, and backfire when I get on the throttle. runs a lot better with it off. I am anxious to see what the results are of the fuel pressure test. it just feels like it is struggling to get fuel through a clogged filter or something.