FJ62 Hesitates, no power, rough idles at times

[Sea Knight]

.....The problem I'm having is a horrible hesitation during acceleration and absolutely no power. Idles well sometimes but wants to die (runs rough) after hesitation. I have to blip the throttle a couple of times to get the idle smooth again after hesitation. Just doesn't feel like a fuel problem to me, I would think it would idle poor all of the time if it was the fuel pump....Or wouldn't run at all.

I'm stranded at my parent's house in Oklahoma with exactly the same symptoms. 90 FJ62, 129K miles, starts immediately and idles smoothly but hesitates, coughs and sputters when throttle is applied. FPR is new, coil is new, EGR valve is not stuck, all the usual culprits have been eliminated. I think my TPS is stuck in the idle position. I'll investigate further (after the outside temperature rises above 12 degrees) but I'm pretty sure a bum TPS is causing my issues. Maybe that's your problem as well?

 

[acoen]

I'm stranded at my parent's house in Oklahoma with exactly the same symptoms. 90 FJ62, 129K miles, starts immediately and idles smoothly but hesitates, coughs and sputters when throttle is applied. FPR is new, coil is new, EGR valve is not stuck, all the usual culprits have been eliminated. I think my TPS is stuck in the idle position. I'll investigate further (after the outside temperature rises above 12 degrees) but I'm pretty sure a bum TPS is causing my issues. Maybe that's your problem as well?

Same exact issue, I have new cats, exhaust, new FPR, Fuel Pressure, new fuel filter and air filter, clean PCV.....

Please let me know what you find, I'm going to pull mine and clean it, to see if I can make it run then replace the TPS. Cam from Iron Pig suggested the TPS, especially since I get no codes. The truck runs pretty good at idle, she will idle for ever it seems but as soon as I tip into the trottle she bogs and hesitates, surges...etc. I can tip in just a 1/4" and I think it will be ok any more than that it falls appart. Seems to do better dead cold, must be the cold start injector feeding the system. Keep me posted I will do the same....Thanks

 

[acoen]

Just another thought, Have you checked or adjusted the valves?

Good point, at 177k miles that could be an issue, seems to run pretty quite while idleing. I'm going to check my vacuum tomorrow afternoon, to check for leaks .....Thanks for the good response.

 

[acoen]

It is starting to sound like you have a blocked cat or both.

They will breath untill they get hot and then the truck wont run right.

Both cats are new, the PO punched the cats so I replaced them with magna flow high flow cats. New FPR, Fuel Pressure, new fuel filter, air filter and fuel, no codes, good compression, no smoke or steam or water in oil...fires up and idles and drives ok for the first minute or so then durning accelleration or tip in....she falls appart...I'm going to check the TPS tomorrow along with the vacuum.

Thanks again for the response...without your guys help it would take me three times as long to figure this out.....Thanks again.

Aaron

 

[cruiser88]

When you pull the TPS you will see a spring behind it.....they like to weaken .

 

[billmc]

When you pull the TPS you will see a spring behind it.....they like to weaken .

Of course, it's a return spring so under acceleration or constant throttle, a weak spring or sticking spindle wouldn't have any impact.

Aaron, if you get a chance, try running it with the TPS disconnected. That will force the ECU to run on its defaults. If the problem remains unchanged, then I doubt it's the TPS.

Bill

 

[acoen]

Of course, it's a return spring so under acceleration or constant throttle, a weak spring or sticking spindle wouldn't have any impact.

Aaron, if you get a chance, try running it with the TPS disconnected. That will force the ECU to run on its defaults. If the problem remains unchanged, then I doubt it's the TPS.

Bill

I'm doing things I promised myself I wouldn't do, I replaced the TPS today with a new Toyota unit. I also replaced the FPR yesterday as well (replace parts that I don't need to replace hoping I would get lucky) .

I have;
1. a good spark (coil will throw a 2" blue/yellow spark while running)
2. new FPR
3. new TPS,
4. recent plugs,
5. cleaned checked EGR
6. also isolated EGR and modulator
7. cleaned IAC/ISC
8. Cleaned throttle body
9. checked hoses
10. checked compression (138 across the board)
11. checked engine condition and leaks with vacuum gauge (20hg at idle normal, no sticky valves or anomalies)
12. has new fuel (but tomorrow I'm going to drain a gallon to see if there is any water in the tank)

I replaced the TPS adjusting it to where the old unit adjusted, not certain on how to adjust the TPS on these things.

The truck will idle great, hell perfect ,in closed loop or if it hasn't ran in 30 minutes or so, as soon as it starts to warm (closed loop) or I put her under any load she falls on her face no power, hiccup, fart and pop through the intake. I think I have a problem with my MAF, it seems to have trouble in closed loop, no power, hesitation...etc. I did have a code 31 and 24 today, but I did unhook the MAF and try to fire her off cold the other day, which may have set the codes.
Seems like I have fuel pressure, when I replaced my FPR, I pinched the O-ring fuel went everywhere.

Funny thing I can go out there now, truck will start and idle great, as soon as I drive it, she will sputter, choke, pop, fart, wheeze.

How and where can I find a MAF without breaking the bank....Anyone near Fresno with an FJ62 or FJ80 where I can try their MAF? Last one I purchased from Toyota was $400. I think they are double that now.

HELP!!!!!!!!!!!!!!!!!!!!!!!

 

[acoen]

I'm stranded at my parent's house in Oklahoma with exactly the same symptoms. 90 FJ62, 129K miles, starts immediately and idles smoothly but hesitates, coughs and sputters when throttle is applied. FPR is new, coil is new, EGR valve is not stuck, all the usual culprits have been eliminated. I think my TPS is stuck in the idle position. I'll investigate further (after the outside temperature rises above 12 degrees) but I'm pretty sure a bum TPS is causing my issues. Maybe that's your problem as well?

Mine is doing the same, replaced the TPS today with no real change....I think our problem is with the MAF.

 

[dwillmo]

No power

I have had experience with both clogged CAT and bad MAF in previous vehicles. The vehicle with the clogged CAT idled and ran fine, no missing, but you just couldn't get over an overpass over 30 mph. No power. But it never started missing.

A Volvo I had a few years ago had a bad MAF and it did sound a lot like this problem. It idled fine but missed, shook and had no power on the road.

I recently had to replace the TPS in my wife's Jeep. It would idle fine and run okay most of the time, but at certain speeds on the road it would start missing and try to slow or accelerate briefly--it would also kick off the cruise control. But it was very sporadic. Most of the time it was fine.

Another problem I had once which sounds like this, was a bad dist cap and plug wires. It would idle fine and you could go through the gears fine but when it got into high gear it would just start bucking and shaking and would hardly get over 30 mph.

Just thought I'd share my experience. I know how frustrating these things are.

 

[billmc]

I'm doing things I promised myself I wouldn't do, I replaced the TPS today with a new Toyota unit. I also replaced the FPR yesterday as well (replace parts that I don't need to replace hoping I would get lucky) .

Hey, I totally understand. The temptation to just buy replacement parts in the hope of getting lucky is very hard to resist. I just did the same thing trying to fix a high idle/bad mileage problem with my Volvo. I haven't installed the part yet, but I'm sure it's not going to fix the problem. Unfortunately, with systems as complex as these, there's no real substitute for making a positive diagnosis, which means putting a vacuum guage on it, check fuel pressure, testing sensors with a voltmeter, etc, etc. Could turn out that your dipstick isn't seated properly.


Bill

 

[acoen]

Hey, I totally understand. The temptation to just buy replacement parts in the hope of getting lucky is very hard to resist. I just did the same thing trying to fix a high idle/bad mileage problem with my Volvo. I haven't installed the part yet, but I'm sure it's not going to fix the problem. Unfortunately, with systems as complex as these, there's no real substitute for making a positive diagnosis, which means putting a vacuum guage on it, check fuel pressure, testing sensors with a voltmeter, etc, etc. Could turn out that your dipstick isn't seated properly.


Bill

I'm going to rig up a fuel pressure test to see if I have at least 30 psi then perform a flow test to see it air is getting into the lines. After that, I will check the cap and rotor for cracks....The problem doesn't seem mechanical, the vacuum test seemed that all systems are working. I will also pick up my dads 87-88 Toyota truck Toyota manual today....They have a process for testing the MAF. I found a good used one 150 miles from here for 40 bucks or so.....Any other suggestions appreciated.....Again thank you to everyone.

This site is just as good as TurboBuicks.com. Some great and helpful people on there as well.....Thanks guys! I have to admit one thing....All the bad stuff said about GM Buick had it down with the 86-87 Buick turbocharged 3.8.....Much easier to diagnose problems on my GN. This Landcruiser reminds me on now how hard it was to diagnose problems on my last 1990 Landcruiser. You just can't beat these things when they run right and how can you argue, 177k miles and looks so beautiful.

 

[COSkier1]

Acoen-
testing the MAF is pretty simple: pull the plug and measure resistance between a couple different pins. Sorry I don't have access to the manual right now, but can look it up for you tmw.
I think Bill is right, sometimes it's something as simple as the dipstick or the oilcap not being seated right. Most of us know by experience.
One note on the TPS: they need to be adjusted correctly. You need feeler gauges and voltmeter. Putting it on where the old one was did not work for me.
I certainly don't mind looking stuff up for you, but I think you're shortchanging yourself by not having a FSM.
If you're still convinced this has something to do with the fuel pump, try a search on fuel pump and ground. I remember a lengthy thread within the past few months about bad grounding.

 

[smtyblt]

The correct way to adjust the TPS has multiple steps. I just installed one on my 62 and it did not fix it, untill I adjusted it. Talking to one of the mechanics at the local TOYOTA dealer the spring has to be under a small bit of tension loosen is up and turn it a fraction to the left and snug it up and check again. that solved mine and the ohm readings read correctly after that, and it ran right.

 

[acoen]

understood, I will need to pick up a service manual. I will use my dads pickup manual for now. It should give me the correct proceedure for adjusting the tps....I will give that a try prior to doing anything else....thanks again

Aaron

 

[jpeg]

...she fired right up and idled, but if you drive it and give it any fuel she is just flat, no power. Runs pretty good when you first start it and go down the road a block or two, then it starts breaking up as it warms slightly and worse the warmer it gets... once I give it just a little more throttle she flattens out with no power. If I increase throttle during the hesitation, I get some popping out of the intake and sometimes exhaust. Almost like a lean condition. The exhaust smells lean to me, not like coolant or oil just lean.

i had this exact same problem last summer. i checked the fpr but it was fine. turned out to be the coolant temp. switch. you may also want to check the cold start timing switch.

 

[acoen]

i had this exact same problem last summer. i checked the fpr but it was fine. turned out to be the coolant temp. switch. you may also want to check the cold start timing switch.

I unplugged the coolant temp switch at the thermostat housing to see if it was the cuprete, but there was no change. I'm going to adjust the TPS tomorow with factory specs, check the MAF, fuel pressure and that Cold start timing switch.....Where is the switch located.....

Thanks....I will definitely let everyone know what I find out....

 

[acoen]

Just a suggestion, but are you sure that its got good fuel in it. You say you've had it only a week. Maybe the fuel is just bad and if it was sitting up any length of time it could have a lot of condensation in it. I'd dump some fuel additive in there and try to run all the fuel out of it and then put fresh back in it before I started try to replace everything.

Also, fuel lines break down on the inside and look good on the outside. It will allow air in the lines which causes all kinds of problems. Easy fix too.

I have to say last thing I checked, there was about 3/4 gallon of water in the tank.....I drained the tank and refilled the tank still can't get the truck over 30 mph. I adjusted the TPS, checked the AFM, coolant sensor, cold start sensor.....This cannot be that tough, I only have so much time to work on it.

 

[acoen]

I had a Toyota pickup once, it would run fine for about 15 minutes. Then it would start bucking and missing and eventually would die. After it cooled a while, it would start and run fine for a few minutes before it would do the same thing all over again. Eventually I could make it back home. I replaced the coil first. Then fuel filter and then plugs/wires. Nothing helped until somebody suggested that it sounded like it was vapor-locking. Had water in the fuel. Added some STP and the problem went away.

I had water in the tank.....about 3/4 gallon, I will ad some fuel stablizer and giver a try tomorrow....

 

[ozwick]

Did you change the fuel filter again since you had found th 3/4 gal of water? If not, maybe your fuel filter is full of water?

 

[acoen]

Did you change the fuel filter again since you had found th 3/4 gal of water? If not, maybe your fuel filter is full of water?

Good point, I should have drained that too. I just have a certain amount of time to work on this per week. I sat there stumped today then I checked fuel flow....The fuel didn't smell right, to I drained the tank....The good news is no big chunks of stuff fell out...tank seemed clean. I hate to do it but I'm going to install a pressure gauge just down stream of the fuel filter in the rubber hose connection...I need to check fuel pressure and I think that is the only way to do it .